Doc #52 — Wire Rope Production and Maintenance

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RECOMMENDED ACTIONS

First month (Phase 1)

1. Include wire rope as a specific category in the national asset census (Doc #8). Count: all wire rope by diameter, length, construction type, age, and condition, across forestry, maritime, construction, mining, industrial, and distributor holdings. This is the single most important action — everything else depends on knowing the actual stock.
2. Issue wire rope preservation guidance to all sectors: maximise lubrication, enforce retirement criteria (do not use rope to failure), store unused rope properly (under cover, coiled on reels, lubricated).
3. Identify NZ’s wire rope splicing and rigging specialists — experienced forestry and maritime riggers — and classify them as critical-skills personnel.
4. Inventory swaging equipment, wire rope clips, thimbles, and termination hardware nationally. These are finite consumables.

First 3 months (Phase 1)

5. Assess NZ Steel’s capability to produce medium-carbon wire rod suitable for wire rope. This is the critical go/no-go question for the entire production chain.
6. Survey Pacific Steel’s wire drawing equipment and assess what modifications are needed for rope-grade wire production.
7. Survey NZ cable manufacturers and rope-making operations for adaptable stranding machinery.
8. Begin knowledge capture from experienced riggers: film splicing, termination, and inspection procedures. Pair experienced riggers with 2–4 learners each.

First year (Phase 1–2)

9. Begin wire drawing trials for rope-grade wire using existing Pacific Steel equipment and medium-carbon wire rod (if available from NZ Steel).
10. Begin design of a simple 6x7 stranding machine. Assign a design team of 2–3 engineers with access to historical patent literature and wire rope machinery references.
11. Establish harakeke rope core production in partnership with Maori fiber practitioners (Doc #100). Test harakeke rope cores for suitability.
12. Begin die-making programme at designated machine shops (Doc #91). Develop tool steel die production capability.
13. Establish training programmes for riggers and wire rope splicers at Te Pukenga polytechnics and through on-the-job apprenticeship in forestry and maritime operations.

Years 2–4 (Phase 2–3)

14. Build and test prototype stranding machine. Produce trial 6x7 strands and test for mechanical properties and consistency.
15. Build and test closing machine. Produce first NZ-made wire ropes (6x7 construction, fiber core, ungalvanized).
16. Test first production ropes under controlled conditions before deploying to critical applications. Destructive testing (break testing), fatigue testing (cyclic bending over sheaves), and comparison against imported rope performance.
17. Scale up production based on test results. Address quality issues identified in testing.

Years 4–7 (Phase 3)

18. Establish routine production of 6x7 wire rope in useful quantities for standing rigging, guy wires, and static applications.
19. Develop 6x19 class production for general-purpose rope (cranes, hoists, general industrial use).
20. Begin galvanized wire rope production if zinc supplies permit, prioritising marine applications.
21. Develop IWRC (independent wire rope core) production for crane and drum-winding applications.

Ongoing

22. Maintain and expand the rigger/splicer workforce through continuous training.
23. Monitor and refine production quality — wire rope production is an iterative learning process and quality will improve with experience.
24. Investigate trade-sourced wire rope from Australia as maritime trade develops.
25. Research and develop larger-diameter rope production for forestry hauler applications (the most demanding application and the last to be served by domestic production).

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ECONOMIC JUSTIFICATION

Labour investment: person-years required

Establishing domestic wire rope production requires a permanent skilled workforce across four roles:

Wire drawers (wire drawing line operators): Responsible for die selection, drawing process control, annealing, lubrication, and quality checks on drawn wire. Estimated staffing for a production line adequate to supply NZ’s wire rope programme: 4–6 wire drawers per shift, two shifts per day, at a facility co-located with Pacific Steel’s existing drawing equipment. Total: 8–12 wire drawer FTEs, plus 2–3 lead operators with patenting heat-treatment expertise.

Rope-laying operators (stranding and closing machine operators): Operating the stranding machines (one per strand type) and the closing machine. A minimal production line running two stranding machines and one closing machine requires 2–3 operators per machine per shift. Total: 12–18 FTEs for production staffing, plus supervisors. In the build-up phase (Years 1–3), these people are trained on the job as machinery is developed — this doubles as the commissioning workforce.

Quality inspectors and break-test technicians: Wire rope intended for load-bearing service must be tested before deployment. Quality inspection requires: (a) dimensional checking of drawn wire and finished rope, (b) visual strand inspection during production, and (c) destructive break-testing of rope samples on a tensile testing machine. Estimated: 2–4 quality inspection FTEs, with at least one person capable of operating or maintaining a tensile testing rig (improvised or repurposed from existing NZ materials testing equipment).

Die makers (precision machinists): The highest-skill role in the chain. Wire drawing dies made from tool steel require precision machining and lapping to tolerances of ±0.01 mm or better. Estimated 2–4 die-making machinists, producing perhaps 5–20 dies per week to keep pace with tool steel die wear rates (see Section 5.2).

Summary table — steady-state workforce estimate:

Role	FTEs (steady-state)	Training pathway
Wire drawers	10–15	From Pacific Steel personnel + metalworking tradespeople; 3–6 months to competence
Rope-laying operators (stranding and closing)	12–18	Trained on job during machinery commissioning; 3–6 months
Quality inspectors / break-test technicians	2–4	From engineering technician background; 3–6 months specific training
Die makers (precision machinists)	2–4	From qualified machinists; 6–18 months additional specialisation
Total production workforce	~26–41	—

This does not include the engineering team (2–3 engineers) responsible for machinery design and improvement, or the field rigger and inspector workforce that manages wire rope in use (estimated 200–400 experienced riggers across NZ’s forestry, maritime, and construction sectors — already present but declining through attrition).

The capital investment in building stranding and closing machinery (Section 8) is primarily the labour of the fabrication team: approximately 5–10 machinists and fabricators working for 12–24 months (60–240 person-months, or 5–20 person-years), plus engineering design time (6–15 person-months). Total one-time capital-phase labour: approximately 6–22 person-years. This is a bounded and achievable commitment for a recovery economy with a functioning machine shop network (Doc #91).

Comparison: domestic production versus managing stock depletion

The alternative to establishing domestic production is managed depletion — using existing wire rope stocks as carefully as possible until they are exhausted, then losing capability.

Managed depletion scenario:

• Existing stock estimated at 5,000–15,000 tonnes (Section 2.1).
• Forestry sector annual consumption at even 50% of pre-recovery activity: approximately 500–1,500 tonnes per year.
• Other sectors (maritime, construction, mining, industrial) combined: approximately 200–600 tonnes per year.
• Total consumption rate under reduced activity: approximately 700–2,100 tonnes per year.
• Estimated stock duration: 2–20 years, with the lower end applying if stocks are at the low estimate and forestry continues near normal volume, and the upper end only if stocks are at the high estimate and wire rope use is severely rationed across all sectors. The most likely range, assuming moderate rationing and mid-range stock estimates, is roughly 5–10 years.
• After depletion: steep-terrain forestry stops. Port cargo handling degrades. Crane operations cease or revert to chain hoists and manual methods. The productivity losses compound across every sector that depends on lifting and hauling.

The managed depletion path requires no up-front investment but produces a capability gap that becomes progressively harder to close. Once the engineering knowledge and trained workforce are lost through attrition — and once the machine shops redirect their capacity to other priorities — re-establishing wire rope production requires rebuilding both the knowledge base and the equipment from a lower starting point. The practical window for establishing production overlaps with the existing stock lifespan: roughly Years 1–7.

Domestic production scenario:

• Capital phase (Years 1–3): engineering design and machinery construction (~6–22 person-years), plus workforce training.
• Production begins (Years 2–4): initially small quantities (6x7 rope for standing rigging and static applications), growing over time.
• Meaningful production scale (Years 4–7): 6x19 class rope for general use, supplementing rather than replacing the imported stock.
• Long-term (Years 7+): domestic production provides a sustained supply, though large-diameter forestry rope remains a gap until production capability advances.

The domestic production path requires front-loaded investment but preserves the capability indefinitely. It also generates transferable industrial capability: the wire drawing, precision machining, and machinery fabrication skills developed for wire rope production directly support other manufacturing sectors.

Breakeven timeline

Wire rope is not a commodity with a simple price crossover. The economic case rests on capability preservation, not cost minimisation.

The critical sectors dependent on wire rope — forestry, maritime, construction, mining — collectively account for a substantial fraction of NZ’s productive capacity:

Forestry: NZ’s plantation forestry sector was worth approximately NZ$6–7 billion in export value annually (pre-recovery, primarily log and processed timber exports).¹ Even under recovery conditions, timber is essential for construction, boatbuilding (Doc #138), and wood-gasification fuel (Doc #56). Steep-terrain forestry (cable logging) accounts for an estimated 30–50% of harvest volume.² Loss of cable logging capability reduces timber output by roughly that proportion from affected regions — a sustained, compounding loss in the absence of alternative harvesting methods for steep terrain.

Maritime operations: Wire rope is the enabling technology for cargo handling gear on vessels and at port. The transition to sail trade (Doc #138) makes maritime wire rope more critical, not less — sail-powered vessels depend on wire standing rigging for rig integrity, and smaller crews increase the importance of mechanical lifting advantage at ports.

Construction and infrastructure: Building and maintaining the infrastructure needed for recovery — bridges, dams (Doc #65), buildings — requires crane and hoist capability. Without wire rope, construction equipment reverts to chain blocks, gin poles, and manual labour, reducing the pace of infrastructure repair substantially for large lifts — heavy crane operations become impractical and multi-storey construction is severely constrained.

The breakeven point is not measured in years-to-cost-recovery but in the question: At what point does the loss of wire rope capability become a binding constraint on recovery? Given that the stock depletes progressively and the capability gap becomes harder to close the longer production is deferred, the economic case for beginning production investment in Year 1 is strong. The opportunity cost of not acting — measured in foregone forestry output, impaired port operations, and constrained construction capacity — almost certainly exceeds the cost of the production programme (26–41 FTEs in steady-state, plus 6–22 person-years of capital-phase engineering) within the first 3–5 years of depletion.

Opportunity cost of deferral

The opportunity cost of delaying the wire rope production programme is not the cost of the programme itself, but the cost of the capabilities that become unavailable as stock depletes:

• Each year of deferral adds approximately 700–2,100 tonnes of consumption against a finite stock, narrowing the window available for production ramp-up before the stock is critically low.
• Skills depreciate: NZ’s experienced cable riggers and wire rope specialists are predominantly 40–60 years old (Section 12.2). A 5-year deferral means a smaller, older knowledge base to train from. The cost of reconstructing tacit knowledge lost through retirement or death is not recoverable.
• Engineering capacity is fungible: The machine shop capacity (Doc #91) needed to build stranding and closing machinery is also needed for other recovery priorities. Beginning the wire rope machinery programme early, before other priorities fully consume that capacity, is preferable to competing for the same resources later.
• No sunk cost from early action: Investments in wire drawing capability improvement (patenting furnace, die tooling) and stranding machine design are not wasted if the programme is later scaled back — they produce capability useful across metalworking sectors regardless of whether the full rope programme is completed.

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1. WHY WIRE ROPE MATTERS

1.1 Applications in NZ’s recovery economy

Wire rope serves applications where no locally producible substitute matches its combination of strength, flexibility, abrasion resistance, and durability:

Forestry (largest use by volume): NZ’s plantation forestry industry uses wire rope extensively in cable logging (hauler) operations. Hauler skylines, mainlines, and haulback lines are typically 20–35 mm diameter wire rope, with individual ropes 300–1,000 m long. The South Island’s West Coast, Bay of Plenty, Gisborne/East Coast, and Northland regions depend on cable logging for steep-terrain harvesting that cannot be done with ground-based equipment.³ Under recovery conditions, forestry becomes more important, not less — timber is needed for construction, boatbuilding (Doc #138), fuel (Doc #56), and export trade. Without wire rope, steep-terrain logging stops.

Maritime: Standing rigging (shrouds, stays) for sailing vessels (Doc #138) uses wire rope — typically 6–12 mm galvanized. Mooring lines for larger vessels and port operations use 20–40 mm wire rope. Cargo handling gear (cranes, derricks, winches) on vessels and at ports depends on wire rope. As NZ’s maritime economy develops, wire rope demand grows.

Construction: Tower cranes, mobile cranes, hoists, and lifting equipment all depend on wire rope. Building construction, bridge maintenance, and infrastructure repair require lifting capability.

Mining: Coal mining in the West Coast and Waikato regions, and aggregate quarrying throughout NZ, use wire rope for draglines, hoists, and conveyors.

Agriculture: Fencing tensioners and strainers, hay bale handling, irrigation equipment, and general farm rigging. Wire rope is less central to farming than to forestry, but numerous specific applications depend on it.

General industrial: Elevators, dam gates (Doc #65), tramways, aerial ropeways for transport in steep terrain, and miscellaneous lifting and pulling applications throughout the economy.

1.2 Why fiber rope is not a substitute for all applications

Harakeke (NZ flax) rope (Doc #100) is a valuable locally producible cordage material, and for many applications it is adequate or even preferred. But fiber rope — whether harakeke, hemp, cotton, or synthetic — has fundamental limitations compared to wire rope:

• Strength-to-diameter ratio: A 20 mm wire rope has a breaking strength of approximately 150–250 kN depending on construction. A 20 mm harakeke rope has a breaking strength of perhaps 15–30 kN — roughly one-tenth.⁴ For high-load applications (forestry hauling, crane operations, mooring), wire rope is the only option short of enormously oversized fiber cordage that would be impractical to handle.
• Abrasion resistance: Wire rope running over sheaves and drums, or dragging through bush and over rock, outlasts fiber rope by an order of magnitude.
• UV and weather resistance: Steel wire rope is unaffected by UV. Harakeke and other natural fibers degrade in sunlight and when repeatedly wetted and dried.
• Creep and stretch: Wire rope has minimal stretch under load — essential for crane operations and standing rigging where dimensional stability matters. Fiber rope stretches significantly, particularly natural fiber.
• Fire resistance: Wire rope does not burn. In forestry and industrial environments where fire risk exists, this matters.

The practical division: Fiber rope (harakeke, Doc #100) for running rigging, lashing, general-purpose cordage, and applications under approximately 30 kN. Wire rope for standing rigging, heavy lifting, forestry hauling, and any application requiring high strength, minimal stretch, or abrasion resistance.

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2. NZ’S EXISTING WIRE ROPE STOCK

2.1 Estimating the inventory

NZ does not publish aggregate wire rope stock data. The following estimates are based on industry scale and typical usage patterns, and should be treated as rough order-of-magnitude figures pending verification through the national asset census (Doc #8).

Forestry: NZ’s plantation forestry sector harvests approximately 30–35 million cubic metres of logs per year, of which a significant proportion (estimated 30–50%) comes from steep terrain using cable hauler systems.⁵ A typical hauler operation uses 3–6 wire ropes (skyline, mainline, haulback, strop lines) totalling 2,000–5,000 m of rope per operation. With an estimated 200–400 hauler operations active at any time across NZ, the in-service forestry wire rope stock is approximately 2,000–5,000 tonnes. Additionally, forestry companies hold spare ropes in inventory — estimated at 500–2,000 tonnes nationally.

Maritime: NZ’s commercial fleet (fishing vessels, coastal freighters, tugs, port equipment) uses wire rope for rigging, mooring, and cargo handling. The recreational fleet adds wire standing rigging on an estimated several thousand sailing yachts.⁶ Estimated maritime stock: 500–1,500 tonnes.

Construction: Crane companies, construction firms, and equipment hire operators hold wire rope stock for cranes, hoists, and general lifting. Estimated: 500–1,500 tonnes.

Mining: Coal and aggregate mining operations. Estimated: 200–500 tonnes.

General industrial and agricultural: Distributed across thousands of businesses and farms. Estimated: 500–2,000 tonnes.

Distributor and importer stocks: Companies such as Bridon-Bekaert (formerly Bridon NZ), Bullivants, Nobles, Certex, and other rigging suppliers hold imported wire rope inventory. Estimated: 500–2,000 tonnes at any given time.⁷

Sector	Estimated stock (tonnes)
Forestry (in-service + spare)	2,500–7,000
Maritime	500–1,500
Construction	500–1,500
Mining	200–500
General industrial/agricultural	500–2,000
Distributor inventory	500–2,000
Total	~5,000–15,000

Honest assessment: These are estimates with wide ranges. The actual figure could be outside this range. The national asset census (Doc #8) must include wire rope as a specific inventory category — this is a strategic material.

2.2 Depletion rates

Wire rope is consumed by wear, fatigue, and corrosion:

Forestry (highest depletion rate): A hauler skyline in heavy use may last 6–18 months before reaching retirement criteria. Mainlines and haulback lines typically 3–12 months. Forestry is extremely hard on wire rope — abrasion from logs and terrain, shock loading, and repetitive bending over sheaves all accelerate wear. If NZ’s forestry sector continues at even half its pre-recovery volume, annual forestry wire rope consumption could be 1,000–3,000 tonnes.⁸

Maritime: Standing rigging on a well-maintained vessel lasts 10–20 years. Running rigging and cargo handling ropes last 2–10 years depending on use. Maritime depletion is slower but steady.

Construction: Crane ropes last 1–5 years in heavy use. Construction activity will likely be lower than pre-recovery, reducing depletion.

Overall: Without new supply, the existing forestry stock (2,500–7,000 tonnes) could sustain forestry operations for approximately 2–14 years depending on activity level and stock size, with a most-likely range of 3–7 years at reduced activity levels. Other sectors have somewhat longer timelines. The forestry sector is the primary consumer and will drive the depletion timeline.

2.3 Cost of delay

If wire rope production is not established, the consequence is not immediate crisis but progressive loss of capability:

• Years 1–3: Existing stocks adequate if managed carefully. Forestry operations begin prioritising ground-based logging where possible, reserving wire rope for steep terrain where there is no alternative.
• Years 3–5: Forestry wire rope stocks become tight. Some hauler operations shut down for lack of replacement rope. Steep-terrain forestry output declines.
• Years 5–10: Wire rope scarcity constrains forestry, port operations, and construction. Workarounds (reduced capacity, more dangerous operations with worn rope, shift to ground-based methods) become necessary.
• Years 10+: Without domestic production or trade-sourced imports, wire rope becomes a critical bottleneck affecting multiple sectors.

The urgency is real but not immediate. Wire rope production development is a Phase 2–3 priority — beginning in Year 1 with planning and equipment assessment, progressing to pilot production in Years 2–4, and aiming for useful-scale production by Years 4–7.

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3. THE PRODUCTION CHAIN: WIRE ROD TO WIRE ROPE

3.1 Overview

The production chain from raw steel to finished wire rope has four main stages:

1. Wire rod production — NZ Steel, Glenbrook (Doc #89)
2. Wire drawing — Reducing wire rod diameter through dies
3. Stranding — Twisting drawn wires into strands
4. Closing — Twisting strands around a core to form rope

Each stage has specific equipment, material, and skill requirements. The chain is sequential — each stage depends on the output of the previous one. NZ has existing capability for stages 1 and 2, partial capability that could be adapted for stage 3, and no existing capability for stage 4.

3.2 Stage 1: Wire rod production (NZ Steel, Glenbrook)

NZ Steel’s Glenbrook works, located south of Auckland near Waiuku, is NZ’s only steel mill. It produces steel from ironsand (titanomagnetite) mined at Waikato North Head, using a unique rotary kiln direct reduction process followed by electric arc furnace steelmaking and continuous casting.⁹

The Glenbrook works includes a rod and bar mill that produces wire rod — long coils of round steel typically 5.5–16 mm in diameter. Wire rod is the starting material for wire drawing and is also used directly for reinforcing steel, fencing wire, nails, and other products.

Key facts:

• NZ Steel’s total crude steel capacity is approximately 600,000–650,000 tonnes per year, though production has varied and may be lower under recovery conditions.¹⁰
• Wire rod is a fraction of total output — estimated at tens of thousands of tonnes per year under normal production.
• Wire rod grades include low-carbon (for general wire, fencing, nails) and medium-carbon (for higher-strength applications). Wire rope requires medium to high-carbon wire rod (approximately 0.4–0.8% carbon) for adequate tensile strength after drawing.¹¹
• Whether NZ Steel currently produces wire rod grades suitable for wire rope, or could adjust its process to do so, is a critical question. Standard low-carbon fencing wire rod (approximately 0.08–0.15% carbon) will not produce wire strong enough for wire rope. Medium-carbon rod (0.4–0.6% carbon) is needed. NZ Steel’s capability to produce this grade requires verification (Doc #89).

Assumption: This document assumes that NZ Steel can produce medium-carbon wire rod suitable for wire rope production. If this assumption is wrong — if Glenbrook’s steelmaking and rolling process cannot produce the required carbon range — then wire rope production requires either modifying the Glenbrook process or sourcing high-carbon wire rod from existing stocks or trade. This is a critical uncertainty.

3.3 Stage 2: Wire drawing

Wire drawing is the process of pulling wire rod through a series of progressively smaller dies to reduce its diameter. A 5.5 mm wire rod might be drawn down to 1.5–3.0 mm wire through 5–10 successive drawing passes, with annealing (heat treatment to restore ductility) between some passes.¹²

The process:

1. Wire rod is cleaned (descaled) by acid pickling or mechanical cleaning to remove surface oxide.
2. The rod end is pointed (swaged or ground) to fit through the first die.
3. The rod is pulled through a die — a hardened block with a precisely shaped conical hole — by a draw bench (batch process) or continuous drawing machine (the rod wraps around a capstan drum that provides pulling force, then feeds into the next die).
4. Each pass reduces diameter by approximately 15–30% (area reduction). Greater reductions per pass require more force and cause more work-hardening.
5. Between passes (or after several passes), the wire may be annealed — heated to approximately 600–700°C and cooled — to restore ductility that was lost through cold working. Without annealing, the wire becomes too brittle and breaks during subsequent drawing.
6. Lubrication is applied at each die — the wire passes through a lubricant (traditionally soap or tallow-based; modern practice uses calcium or sodium stearate-based dry lubricants) before entering the die. Lubrication reduces friction, extends die life, and improves wire surface quality.¹³

Equipment required:

• Dies: The critical consumable. Traditionally made from tungsten carbide (cemented carbide) for long life and consistent hole quality. Without tungsten carbide imports, dies can be made from tool steel (D2, W1, or similar grades) but will wear significantly faster — perhaps 10–50 times faster than carbide dies, requiring frequent replacement and reworking.¹⁴ Die-making requires precision machining and lapping to achieve the correct internal profile (Doc #91). Polycrystalline diamond dies, used for fine wire, are not producible in NZ.
• Draw benches or continuous drawing machines: Continuous drawing machines are more productive but more complex. A draw bench (a linear machine that grips the wire end and pulls it through a die in a single stroke) is simpler and can be improvised or built from available components — essentially a strong frame, a gripping mechanism, and a power source (hydraulic cylinder, chain drive, or screw drive). Continuous machines use rotating capstan drums.
• Annealing furnace: A controlled-atmosphere furnace capable of reaching 600–700°C. Atmosphere control (nitrogen or reducing gas) prevents surface oxidation during annealing. A simple furnace without atmosphere control works but produces oxidized wire that requires re-cleaning.
• Cleaning equipment: Acid pickling tanks (hydrochloric or sulfuric acid) or mechanical descaling (bending, brushing, shot blasting).
• Lubricant: Tallow-based soap, calcium stearate, or sodium stearate. Tallow is domestically available (Doc #34). Stearates can be made from tallow by reaction with lime (calcium stearate) or caustic soda (sodium stearate) — both achievable from NZ materials.¹⁵

NZ’s existing wire drawing capability:

Pacific Steel, based at Otahuhu, draws wire for fencing, nails, and reinforcing applications.¹⁶ This represents existing wire drawing equipment and expertise in NZ. However, fencing wire drawing and wire rope wire drawing differ in important ways:

• Wire rope wire must be drawn to tighter diameter tolerances (typically ±0.02 mm) than fencing wire.
• Wire rope wire requires higher tensile strength (1,500–1,900 MPa for rope-grade wire, vs. 400–700 MPa for fencing wire), achieved through a combination of higher-carbon starting material and controlled drawing and heat treatment (patenting — a specific heat treatment that produces a fine pearlite microstructure optimised for drawing).¹⁷
• Wire for rope should have consistent mechanical properties along its length — variation causes weak points.

Assessment: NZ has wire drawing equipment and basic capability. Adapting this to produce wire rope-grade wire is feasible but requires: (a) medium-carbon wire rod from NZ Steel, (b) appropriate die tooling, (c) patenting heat treatment capability, and (d) tighter process control than current fencing wire production demands. This is a [B]-level challenge — feasible with existing infrastructure and knowledge, requiring process development.

3.4 Stage 3: Stranding

Stranding is the process of twisting multiple drawn wires together to form a strand. A typical wire rope strand contains 7, 19, or 37 wires arranged in concentric layers, with each layer twisted (laid) in alternating directions for stability.¹⁸

The process:

1. The required number of wires (e.g., 7 for a simple strand: 1 centre wire + 6 outer wires) are fed from individual spools through a closing die or forming plate that holds them in the correct geometric arrangement.
2. The forming plate rotates around the axis of the strand, twisting the wires together at a controlled pitch (lay length).
3. Tension on each wire must be controlled to ensure even load distribution in the finished strand. Uneven tension produces a strand that is internally stressed and has reduced fatigue life.
4. The finished strand is wound onto a reel.

Equipment required:

• Stranding machine (tubular strander or planetary strander): This is specialized rotating machinery. A tubular strander consists of a central tube through which the centre wire passes, surrounded by rotating cradles or bobbins carrying the outer wires. The entire assembly rotates to twist the wires together. A planetary strander uses a different geometry where the bobbins orbit the centre wire. Both types are precision machines — the rotational speed, wire tension, and lay length must be coordinated.¹⁹
• Wire bobbins and tension devices: Each wire feeds from its own bobbin with a tensioning brake.
• Forming die/plate: Guides wires into the correct geometric arrangement before twisting.
• Capstan and take-up reel: Pulls the strand through the machine and winds the finished product.

NZ’s existing capability: NZ does not have wire rope stranding machinery. However, the basic mechanical principles — controlled rotation of wire bobbins around a central axis — are achievable with general engineering capability (Doc #91). A stranding machine is essentially a rotating frame with bobbin cradles, a forming die, a drive system, and tension controls. It is not trivially simple — the precision requirements for tension control and lay length consistency are real — but it is within the capability of a well-equipped NZ machine shop to build, given adequate design information.

Historical precedent: Wire rope stranding machinery was developed in the 1830s–1840s, most notably by Andrew Smith in the UK and Wilhelm Albert in Germany, using technology available at the time — cast iron frames, gear trains, manual or water-powered drive.²⁰ The fundamental machinery is well within 19th-century engineering capability, which is roughly the technology level NZ can sustain domestically.

3.5 Stage 4: Closing

Closing is the final stage — twisting multiple strands (typically 6) around a core to form the finished rope. The process is mechanically similar to stranding but at larger scale: the strands are heavier and stiffer, the forces involved are greater, and the machinery must be proportionally larger and more robust.

The process:

1. Six strands (or another number, depending on rope construction) are fed from large reels through a closing die that arranges them symmetrically around a core.
2. The core — either a fiber rope (hemp, sisal, or harakeke) or an independent wire rope core (IWRC) — feeds through the centre.
3. The closing die and strand reels rotate, twisting the strands around the core at a controlled lay length.
4. The finished rope passes through a closing die that compresses it into its final cross-section and is wound onto a shipping reel.

Equipment required:

• Closing machine: Similar in principle to a stranding machine but larger and heavier. Strand reels for typical 20–32 mm rope weigh 200–800 kg each and must rotate smoothly under controlled tension.
• Core supply: For fiber core rope, the core rope must be produced first (harakeke or other fiber — see Section 5.4). For IWRC, a seventh strand must be produced in the stranding stage.
• Pre-forming equipment (optional but desirable): Pre-forming shapes each strand into a helix before closing, so that the strands hold their position in the rope without internal stress. Pre-formed rope is easier to handle and has better fatigue life. Pre-forming is done by passing each strand through a set of rollers that bend it into the desired helix. This can be integrated into the closing machine or done as a separate step.²¹

NZ’s existing capability: No closing machinery exists in NZ. As with stranding, this must be built. The closing machine is the largest and most demanding piece of equipment in the production chain, and represents the primary bottleneck for domestic wire rope production.

3.6 Full dependency chain summary

Stage	Input	Equipment	NZ Status	Key Constraint
Wire rod	Ironsand	NZ Steel Glenbrook	[A] Exists	Medium-carbon grade needed
Wire drawing	Wire rod	Draw bench/continuous machine, dies	[B] Partially exists	Dies (tool steel without carbide imports), patenting heat treatment
Stranding	Drawn wire	Stranding machine	[C] Must build	Machine must be designed and built
Closing	Strands + core	Closing machine	[C] Must build	Largest and most demanding machine

Total production chain feasibility: [C] Difficult. The chain is achievable in principle — every step uses known technology within NZ’s engineering capability — but the stranding and closing machinery represents a genuine multi-year development project.

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4. WIRE ROPE CONSTRUCTION AND TYPES

4.1 Nomenclature

Wire rope is described by its construction — the number of strands and the number of wires per strand. Common designations:²²

• 6x7: Six strands of 7 wires each, around a core. Stiff, abrasion-resistant. Used for standing rigging, guy wires, static applications.
• 6x19 class: Six strands of 15–26 wires each (the “19” is a class designation, not exact count). General-purpose rope. Good balance of strength, flexibility, and abrasion resistance. The most widely used construction for cranes, hoists, and general industrial applications.
• 6x36 class: Six strands of 27–49 wires each. Flexible, bends easily around small sheaves. Used for running rigging, elevator ropes, and applications requiring flexibility. Less abrasion-resistant than coarser constructions.
• 6x7 is simplest to produce (fewest wires per strand, largest individual wire diameter). This should be the first construction attempted in NZ production.

4.2 Production priority

For initial NZ production, the recommended priority is:

First priority: 6x7 construction. Simplest stranding (only 7 wires per strand). Suitable for standing rigging (Doc #138), guy wires, fencing, and static applications. A 6x7 stranding machine is the simplest to build — each strand requires only 7 bobbins (1 centre + 6 outer).

Second priority: 6x19 class construction. The workhorse general-purpose construction. More complex stranding but serves the widest range of applications including cranes, hoists, and forestry (for lighter-duty uses). A 6x19 stranding machine requires more bobbins and more sophisticated tension control.

Third priority (if achievable): 6x36 class. For applications requiring high flexibility. This is significantly more complex to produce.

Forestry skylines: Forestry hauler operations typically use locked-coil or compacted strand rope in large diameters (28–35 mm), which is more specialized than standard 6-strand rope. Producing forestry-grade skyline rope domestically is a long-term goal, not a near-term possibility. In the interim, forestry should extend the life of existing skyline ropes through careful maintenance and prioritise their allocation.

4.3 Lay direction and type

Wire rope is laid in one of two patterns:

• Regular lay: Wires in the strand are twisted one direction; strands in the rope are twisted the opposite direction. The surface wires run roughly parallel to the rope axis. Most common for general use — good resistance to kinking and easier to handle.
• Lang lay: Wires and strands twisted in the same direction. Surface wires run at an angle to the rope axis. Better fatigue life and abrasion resistance but more prone to kinking and must be used with both ends fixed.

For initial NZ production, regular lay is recommended. It is more forgiving of handling errors and suitable for a wider range of applications.

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5. MATERIALS AND CONSUMABLES

5.1 Wire

Wire for rope production should be medium to high-carbon steel (0.4–0.8% carbon), cold-drawn to achieve tensile strengths of 1,500–1,900 MPa for standard rope grades.²³ Higher-strength wire (1,960–2,160 MPa) is used in some applications but is harder to produce consistently and is not needed for initial production.

For comparison, standard fencing wire has a tensile strength of approximately 400–700 MPa. Wire rope wire must be substantially stronger, which is achieved through:

• Higher carbon content in the starting rod
• Patenting heat treatment (austenitizing at approximately 900–950°C, then cooling in a lead bath or fluidised bed at approximately 500–550°C to produce a fine pearlite microstructure)²⁴
• Controlled cold drawing with appropriate area reduction per pass

NZ production pathway: NZ Steel produces medium-carbon wire rod (assumption requiring verification). Pacific Steel draws wire. The additional step required is patenting — a heat treatment that NZ’s wire drawing facility would need to add. A patenting furnace is a tube furnace followed by a controlled-cooling bath (traditionally molten lead at 500–550°C, but a fluidised sand bed or forced-air cooling system can substitute). This is achievable with existing NZ engineering capability.

5.2 Dies

Wire drawing dies are the primary consumable. Each die has a precisely shaped conical hole that reduces the wire diameter as it passes through. The die material must be harder than the wire being drawn.

Tungsten carbide dies (preferred): Extremely hard and wear-resistant. A carbide die can draw tens to hundreds of tonnes of wire before requiring rework. NZ does not produce tungsten carbide and existing stocks of carbide tooling are finite. Carbide dies for wire drawing may exist in NZ at Pacific Steel and other wire-drawing operations — these should be inventoried and preserved.

Tool steel dies (NZ-producible): D2 (high-carbon, high-chromium tool steel) or W1 (water-hardening carbon tool steel) can be used for wire drawing dies. They wear much faster than carbide — perhaps 10–50x faster — requiring frequent replacement or rework. Die-making from tool steel requires precision machining (Doc #91) and heat treatment (hardening to 58–64 HRC). The internal die profile (a specific bell-entrance, reduction zone, bearing zone, and back relief geometry) must be finished by lapping or polishing to a high surface quality to produce good wire.²⁵

Die production rate: A well-equipped machine shop (Doc #91) with a lathe, a precision grinder, and lapping capability could produce perhaps 2–5 tool steel dies per day. A wire drawing operation consuming dies at the rate dictated by tool steel wear would need a steady supply — perhaps 5–20 dies per week for a single drawing line, depending on wire grade and drawing speed. This creates significant ongoing demand on the machine shop network.

5.3 Lubricant

Wire drawing requires lubricant at every die to reduce friction, prevent wire and die overheating, and produce acceptable surface quality.

Dry drawing lubricant (for steel wire): The wire passes through a box of powdered lubricant (traditionally calcium stearate or sodium stearate — “drawing soap”) before entering the die.²⁶ The lubricant coats the wire surface and is carried into the die.

NZ production pathway: Calcium stearate can be produced by reacting tallow (rendered animal fat — abundant in NZ from the livestock industry) with lime (calcium hydroxide — producible from NZ limestone). The reaction: tallow + lime = calcium stearate + glycerol. This is well-understood chemistry (closely related to soap-making) achievable at small scale, requiring a heated mixing vessel, temperature control to approximately 80–100°C, and several hours of reaction time per batch.²⁷ Sodium stearate (produced by reacting tallow with caustic soda) is an alternative. The lubricant quality may not match commercial grades, but it will function.

Wet drawing lubricant: For some drawing operations, a liquid lubricant (oil-based emulsion) is used. Tallow-based emulsions are feasible (Doc #34).

5.4 Rope core

The core of a wire rope provides support for the strands and affects the rope’s flexibility, crush resistance, and shape retention.

Fiber core (FC): A rope of natural fiber (traditionally hemp, sisal, or manila) running through the centre. Fiber cores make the rope more flexible and act as a lubricant reservoir (the core is saturated with oil or grease). Fiber core rope is suitable for most general applications but has lower crushing resistance and is not suitable for multi-layer winding on drums.

Harakeke fiber core: Harakeke (NZ flax, Phormium tenax) rope (Doc #100) is a suitable material for wire rope cores. Harakeke muka (fiber) is strong and was traditionally used for heavy-duty cordage by Maori.²⁸ A three-strand harakeke rope of appropriate diameter, saturated with tallow or lanolin, would serve as a wire rope core. This is one of the few components of the production chain that NZ can produce entirely from local materials using existing knowledge.

Independent wire rope core (IWRC): A small wire rope used as the core of a larger wire rope. IWRC provides higher crushing resistance and is used for crane and hoisting applications where the rope winds onto a drum under load. IWRC rope is stronger and more crush-resistant than fiber core rope, but stiffer. Producing IWRC requires making a separate small wire rope first, adding a step to the production process.

For initial NZ production: Fiber core (harakeke) is strongly recommended. It is locally producible, simpler, and adequate for most applications. IWRC can be developed later for crane and drum-winding applications.

5.5 Galvanizing

Galvanizing — coating the drawn wire with zinc — is the standard corrosion protection for wire rope, particularly for marine and outdoor applications. Zinc provides sacrificial cathodic protection: the zinc corrodes preferentially, protecting the underlying steel.

NZ’s zinc situation: NZ does not mine or refine zinc. All zinc is imported. Existing NZ stocks of zinc (at galvanizing plants, distributors, and in galvanized products) are finite and will deplete over years. Galvanizing wire for rope production competes with other zinc demands (structural steel galvanizing, roofing, guttering).²⁹

Implications:

• Galvanized wire rope for marine applications should be prioritised while zinc stocks last.
• Ungalvanized (bright) wire rope is adequate for many non-marine applications and should be the default for forestry, construction, and industrial use. Its life is shorter in wet conditions but can be extended significantly through lubrication (Section 6).
• As zinc stocks deplete, all wire rope production will shift to ungalvanized, with increased emphasis on lubrication and maintenance.
• Trade with Australia (which has zinc mining and smelting) could provide zinc supply if maritime trade develops (Doc #138). This is a reasonable expectation for Phase 3+ but should not be depended upon for planning.

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6. WIRE ROPE MAINTENANCE — EXTENDING THE LIFE OF EXISTING STOCK

Given that domestic wire rope production will take years to establish, extending the life of existing wire rope is the highest-impact near-term action. Well-maintained wire rope lasts significantly longer than neglected rope — the difference can be 2–5x in working life.³⁰

6.1 Inspection

Regular inspection identifies deterioration before it causes failure. The NZ standard for wire rope inspection is based on international standards (ISO 4309 for cranes, AS/NZS standards for general applications).³¹

Visual inspection (every use for critical applications, weekly for general):

• Broken wires: Count visible broken wires per rope lay length. Retirement criteria depend on rope construction and application — typically 5–10% of total wires in a rope lay length for running ropes.³²
• Corrosion: Surface discolouration, pitting, rust. Internal corrosion is harder to detect (see below).
• Wear: Flattening of outer wires from contact with sheaves and drums. Measured by diameter reduction — a rope worn beyond 90% of its nominal diameter is losing strength significantly.
• Deformation: Kinks, birdcaging (strand separation), core protrusion, waviness, crushing. Any significant deformation is cause for retirement or at minimum careful assessment.
• Rope diameter: Measured with calipers at multiple points. Decrease in diameter indicates wear and/or internal wire breaks. Increase may indicate core distortion or internal corrosion (corrosion products expand).
• End terminations: Check for wire slippage in sockets or clips, damage to thimbles, loosening of swaged fittings.

Internal inspection (periodically for critical ropes):

• Rope can be opened slightly by twisting against the lay to expose the inner wires and core for visual inspection of internal corrosion and wire breaks. This should be done by experienced personnel to avoid damaging the rope.
• Electromagnetic testing (MRT — Magnetic Rope Testing) is a non-destructive method that detects broken wires and cross-section loss electromagnetically. NZ has some MRT capability in the mining and forestry sectors. MRT equipment should be identified, maintained, and made available as a shared national resource.³³

6.2 Lubrication

Lubrication is the single most effective maintenance action for wire rope. It reduces internal friction (which causes wire fatigue), inhibits corrosion, and extends rope life.

What works:

• Tallow-based grease: Rendered animal fat mixed with lime (to form a calcium grease) or used neat. Tallow has been used as a wire rope lubricant historically and is available in NZ. It is not as durable as petroleum-based rope dressings but provides genuine protection.³⁴
• Lanolin-based grease: Wool grease (lanolin) is a byproduct of NZ’s wool industry and is an excellent rust inhibitor. Lanolin-based products were commercially available for wire rope lubrication before the event. Raw lanolin can be applied to wire rope as a corrosion preventive — it adheres well, penetrates between wires, and provides long-lasting protection.³⁵
• Pine tar: Pine tar (producible from radiata pine by destructive distillation) mixed with tallow or lanolin creates a tenacious, water-resistant coating suitable for wire rope in marine environments. This is historically documented practice — tarred rigging was standard on sailing vessels for centuries.³⁶
• Petroleum-based rope dressings: While stocks last, commercial wire rope lubricants are superior in durability and penetration. These should be reserved for the highest-priority applications (forestry skylines, critical marine rigging).

Application method:

• For standing rigging and ropes accessible along their length: Apply lubricant manually by brush, cloth, or pouring, working it into the rope by flexing.
• For running ropes (passing over sheaves): A drip or trough applicator at a sheave applies lubricant as the rope passes through. This can be improvised from a container with a V-notch that the rope passes through.
• Frequency: Depends on environment. Marine ropes: monthly or more often. Forestry ropes: at each rope change or monthly. Industrial ropes: quarterly to annually.

6.3 Proper use practices

Many wire rope failures are caused by misuse rather than age:

• Correct sheave and drum diameters: A wire rope bent around too small a sheave or drum suffers accelerated fatigue. The minimum recommended sheave diameter depends on rope construction: typically 20–30x the rope diameter for general applications, larger for high-cycle applications.³⁷ Undersized sheaves are one of the most common causes of premature wire rope failure.
• Avoid shock loading: Sudden jerks (snatching loads, uncontrolled drops) cause stress spikes that break individual wires and accumulate fatigue damage. Smooth, controlled lifting and pulling extends rope life significantly.³⁸
• Proper fleet angle: The angle at which a rope approaches a sheave or drum should be within design limits (typically less than 1.5–2 degrees for smooth drums, less than 4 degrees for grooved drums). Excessive fleet angle causes rope to climb on itself on drums and wear against sheave flanges.
• Avoid reverse bending: If a rope bends one direction over one sheave and the opposite direction over the next, fatigue life is greatly reduced. Reeving systems should be designed to avoid reverse bends where possible.
• Correct termination: Improperly made terminations (too few clips, wrong clip orientation, inadequate thimble size) are a leading cause of wire rope failure under load. See Section 7.

6.4 Retirement criteria

Wire rope must be retired before failure. The cost of a rope failure — in equipment damage, project disruption, and potentially human life — far exceeds the cost of timely replacement. Under recovery conditions, the temptation to extend rope life beyond safe limits will be strong. This must be resisted.

Standard retirement criteria include:³⁹

• Broken wire count exceeding the applicable standard for the rope construction and application
• Diameter reduction exceeding 5–7% of nominal diameter (indicating internal wear or core degradation)
• Core failure visible through strand separation
• Kinks or other permanent deformation
• Severe corrosion (loss of wire cross-section visible to the eye)
• Heat damage (discolouration from exposure to fire or electric arc)
• Crushing or flattening of the rope cross-section

Retired rope is not waste. It can be re-used for lower-load applications (fencing, tying down loads, as reinforcement in concrete — see Section 9).

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7. TERMINATIONS AND SPLICING

7.1 Why terminations matter

The connection between wire rope and the thing it is attached to — the termination — is often the weakest point in the system. A wire rope is only as strong as its worst termination.

7.2 Termination types

Wire rope clips (bulldog clips): U-bolts with a saddle that clamp two parts of the rope together around a thimble to form an eye. Simple, adjustable, and require no specialized equipment. Efficiency: approximately 80% of rope breaking strength if correctly installed (correct number of clips, correct spacing, correct orientation — “never saddle a dead horse”).⁴⁰ This is the most important termination method for NZ under recovery conditions because it requires only clips, thimbles, and a wrench.

Swaged (pressed) fittings: Metal sleeves hydraulically compressed onto the rope end to form a permanent termination. Efficiency: 90–100% of rope breaking strength. Requires hydraulic swaging equipment (swaging presses or portable swaging tools). NZ has swaging equipment in rigging shops and forestry operations — this equipment should be identified and maintained. Swage fittings themselves are imported and finite.⁴¹

Spelter (poured) sockets: The rope end is inserted into a conical socket and individual wires are spliced apart and held in place by molten zinc or resin poured into the socket. Efficiency: 100% of rope breaking strength. The highest-strength termination. Requires zinc or suitable resin and the skill to prepare the socket. Used for critical applications (crane main ropes, forestry skylines).⁴²

Hand splicing: The strands of the rope are unlaid and tucked back into the rope body to form an eye or a join. This is the traditional method and requires no equipment beyond a marlinspike and seizing wire. Efficiency: 70–80% of rope breaking strength for a standard hand splice.⁴³ Hand splicing is a critical skill for NZ’s wire rope economy — it works without any imported consumables and can be performed anywhere with basic tools. However, it is a skill that requires training and practice to execute correctly, and incorrect splices can fail catastrophically.

7.3 Skill development priority

Hand splicing and clip termination are the two methods that NZ can sustain indefinitely without imports. Training in these methods should be included in all maritime (Doc #138), forestry, and industrial rigging training programs. The knowledge exists among NZ’s riggers, particularly in the forestry and maritime sectors — it needs to be captured and disseminated before the practitioners retire or become unavailable.

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8. BUILDING THE STRANDING AND CLOSING MACHINERY

8.1 The core challenge

The gap in NZ’s capability is stranding and closing machinery. This section describes what is needed and how it might be built.

8.2 Design principles for a simple stranding machine

A stranding machine for 6x7 construction (the simplest useful rope) needs:

Frame: A rigid structure, typically tubular, that supports the rotating components. Can be fabricated from NZ Steel sections.

Bobbin cradles: Six cradles arranged symmetrically around a central axis, each holding a spool of drawn wire. The cradles must rotate around the central axis (this is what twists the wires into a strand). Each cradle must allow the bobbin to pay out wire under controlled tension.

Centre wire path: The centre wire of the strand feeds from a stationary spool through the axis of rotation, through the forming die. The six outer wires twist around it.

Forming die: A hardened plate with a shaped hole that arranges the seven wires in the correct 1+6 pattern and compresses them slightly as they pass through. Can be machined from tool steel (Doc #91).

Drive system: An electric motor (or other power source) driving the rotating frame through a gearbox. Speed must be controllable. A typical stranding speed is 30–100 m/min of finished strand output, depending on machine size and rope specification.

Tension control: Each bobbin needs a braking system to maintain consistent wire tension. This is critical for strand quality — uneven tension produces uneven strands that do not perform well in the finished rope. Simple friction brakes (a spring-loaded pad pressing against the bobbin flange) can work but require careful adjustment.

Take-up: A capstan or powered reel pulls the finished strand through the forming die and winds it for storage.

8.3 Scale of the engineering effort

Building a functional stranding machine is a significant but bounded project for a well-equipped NZ engineering workshop:

• Design: 1–3 months of engineering design time, drawing on published wire rope machinery descriptions and general rotating machinery principles. Historical patent literature (from the 1840s onward) contains detailed stranding machine designs.⁴⁴
• Fabrication: 3–6 months for a team of 3–5 machinists and fabricators (Doc #91), assuming steel stock and standard workshop equipment are available.
• Testing and refinement: 3–6 months of trial production, identifying and correcting problems with tension control, lay length consistency, and wire breakage.
• Total: Approximately 6–18 months from design start to usable production, for a simple 6x7 stranding machine.

The closing machine (twisting strands into rope) follows a similar design logic but at larger scale. A separate 6–18 month development cycle should be expected.

Realistic total timeline from project start to first usable wire rope: 1–3 years.

8.4 Where to build

The stranding and closing machinery should be developed at a site with access to:

• NZ Steel wire rod supply (Glenbrook/Auckland region)
• Existing wire drawing equipment (Pacific Steel, Otahuhu/Glenbrook)
• Machine shop capability for die-making and machinery fabrication (Doc #91 — Auckland’s Onehunga-Penrose industrial area has the highest concentration)
• Engineering design expertise

The Auckland/Waikato region is the logical location for NZ’s wire rope production facility, co-located with or near the existing steel and wire production infrastructure.

8.5 Adaptation from existing equipment

Before building stranding machinery from scratch, NZ should survey existing rotating machinery that might be adapted:

• Rope-making machinery: If any NZ operation has fiber rope-making equipment (rope walks, stranding machines for synthetic rope), the principles and potentially the machinery itself can be adapted for wire stranding. Wire rope machinery evolved from fiber rope machinery historically.
• Cable-making equipment: Electrical cable manufacturers twist multiple conductors together — the machinery is conceptually similar to wire stranding. NZ has some cable manufacturing capacity (e.g., General Cable NZ / Nexans NZ at various locations).⁴⁵ Their stranding equipment may be adaptable.
• Textile machinery: Spinning and twisting machinery from textile operations shares the basic mechanical principle of twisting multiple strands around a central axis. Adaptation would require significant modification but the starting point is closer than building from scratch.

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9. RECYCLING AND SECONDARY USE OF RETIRED WIRE ROPE

9.1 Down-rating for less critical applications

Wire rope retired from a high-criticality application (forestry skyline, crane hoist) may still have useful life in a less demanding role:

• Fencing and tie-downs: Retired rope cut into short lengths is strong fencing material and useful for securing loads.
• Towing and pulling: For ground-based pulling at loads well below the rope’s degraded capacity.
• Guard rails and barriers: Physical barriers at edges, loading docks, and similar locations.
• Guy wires: For supporting poles, masts, and temporary structures.

9.2 Concrete reinforcement

Cut wire rope makes effective concrete reinforcement, substituting for conventional reinforcing bar in some applications. The high tensile strength of wire rope wires (far exceeding standard rebar) means that smaller quantities provide equivalent reinforcement. Wire rope can be cut into lengths and placed in concrete formwork in the same way as rebar. The lack of deformed surface (unlike ribbed rebar) reduces bond strength with the concrete, but this can be partially compensated by bending the rope ends into hooks.⁴⁶

9.3 Wire recovery

Individual wires can be recovered from decommissioned wire rope by unlaying the strands and straightening the wires. Recovered wire can be used for:

• Fencing wire
• Binding wire
• Spring-making (if adequate carbon content)
• Re-drawing into finer wire (if the wire is not too work-hardened or corroded)

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10. ALTERNATIVE APPROACHES AND STOPGAPS

10.1 Chain

For some applications (mooring, anchor rode, short lifting slings), chain can substitute for wire rope. NZ can produce chain by forging from NZ Steel bar stock — chain-making is a blacksmithing operation (Doc #92, Doc #91) requiring a forge capable of reaching welding temperature (~1,100–1,300°C for steel), an anvil, tongs, a bending jig, and either forge-welding skill or electric/oxy-acetylene welding capability to close each link. Production rate is slow — an experienced blacksmith can produce perhaps 5–15 chain links per hour depending on size, making chain labour-intensive compared to wire rope for equivalent length. Chain is substantially heavier than wire rope for equivalent strength (approximately 3–5x heavier per unit of safe working load), stiffer, and cannot be flexed around sheaves, but it works for static and low-cycling applications. Chain is not a substitute for wire rope in running-rope applications (continuous movement over sheaves and drums) because chain causes shock loading and rapid wear on sheaves.

10.2 Rod rigging

For yacht standing rigging (Doc #138), solid stainless steel or mild steel rod can substitute for wire rope. Rod rigging is stiffer, has lower windage, and requires fewer production steps than wire rope — it is drawn rod with threaded or swaged end fittings, requiring wire drawing capability (Section 3.3) and termination hardware but not stranding or closing machinery. Its disadvantages are significant: it cannot be coiled or easily stored in long lengths, it has no fatigue-indicating failure mode (it breaks suddenly rather than showing progressive wire breaks as wire rope does), and it lacks the energy absorption capacity of wire rope under dynamic loading. Rod rigging is suitable only for static standing rigging on vessels, not for any application involving running loads, shock loading, or bending over sheaves. For small vessels with simple rigs, rod rigging from NZ-drawn steel rod is a viable option.

10.3 Harakeke rope for marginal applications

As noted in Section 1.2, harakeke rope (Doc #100) can substitute for wire rope in applications where loads are moderate, stretch is acceptable, and the rope can be replaced frequently. Expanding harakeke rope production can reduce demand on the wire rope stock for lower-duty applications: mooring springs, light lifting slings, lashing, running rigging on smaller vessels, and agricultural tie-downs.

10.4 Trade-sourced wire rope

If maritime trade with Australia develops (Doc #138), wire rope is a high-value, low-volume import that would be a strong candidate for trade. Australia has wire rope manufacturing capability (e.g., Bridon-Bekaert Ropes, formerly Wire Rope Industries, in Newcastle).⁴⁷ A single cargo vessel load could supply several years of NZ’s wire rope needs. This possibility should be factored into trade negotiations but not relied upon for planning — NZ must develop domestic production capability regardless of trade prospects.

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11. GALVANIZING AND CORROSION PROTECTION

11.1 The zinc constraint

As discussed in Section 5.5, galvanizing requires zinc that NZ does not produce. While zinc stocks last, galvanized wire rope should be produced for marine applications. When zinc stocks are exhausted, the options are:

Ungalvanized wire rope with heavy lubrication: This is the realistic medium-term approach for most applications. A properly lubricated ungalvanized wire rope can have a service life approaching that of galvanized rope in non-marine environments. In marine environments, the service life of ungalvanized rope is significantly shorter — perhaps 30–60% of galvanized rope life even with good lubrication — but it remains functional.⁴⁸

Tin coating: Tin provides some corrosion protection and NZ may have limited tin stocks (tin is imported but present in tinplate, solder, and bronze). Tin-coated wire rope was used historically for some marine applications. However, tin stocks are likely too limited to allocate to wire coating.

Aluminium coating (Aluminium-clad wire): NZ produces aluminium at the Tiwai Point smelter (Doc #89). Aluminium coating of wire is theoretically possible but requires specialized equipment (hot-dip aluminium coating or aluminium cladding) that does not currently exist in NZ for wire applications.

11.2 Practical approach

• Prioritise galvanized wire rope production for marine applications while zinc stocks last.
• Default to ungalvanized (bright) wire rope for non-marine applications and for all production after zinc depletion.
• Invest in lubrication discipline: Train all wire rope users in proper lubrication practice. Establish supply chains for tallow-based and lanolin-based rope lubricants. The difference between a lubricated and an unlubricated ungalvanized wire rope in terms of service life is dramatic — lubrication is essential when galvanizing is unavailable.

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12. TRAINING AND SKILLS

12.1 Skills needed

The wire rope production and maintenance programme requires people with the following skills:

Wire drawing operators: Understanding of drawing process, die selection, annealing, tension control. Can be trained from existing Pacific Steel personnel or from general metalworking tradespeople. Training time: 3–6 months to basic competence.

Stranding and closing machine operators: Operating the machines that NZ will build. These people will largely be trained on the job as the machines are developed. Training time: 3–6 months after machines are operational.

Die makers: Precision machinists who can machine, heat treat, and lap wire drawing dies from tool steel. These are the most highly skilled people in the chain. Requires machining skills (Doc #91) plus specific die-making knowledge. Training time: 6–18 months for a competent machinist to add die-making specialisation.

Riggers: People who select, install, inspect, maintain, and terminate wire rope in the field. NZ has existing riggers in forestry, maritime, and construction — their knowledge must be preserved and expanded. Rigging is a regulated trade in NZ (administered by WorkSafe NZ) and training programmes exist at Te Pukenga polytechnics.⁴⁹

Wire rope splicers: The specialised subset of rigging skill focused on hand-splicing wire rope. This is a declining skill even in NZ’s forestry and maritime sectors, and practitioners should be identified and paired with learners immediately.

12.2 Knowledge capture priority

Wire rope splicing, inspection, and field rigging skills are held by an aging workforce, particularly in the forestry sector where experienced cable-logging riggers are often 50+ years old. The same knowledge-capture urgency described for machinists in Doc #91 applies to experienced riggers. Filming experienced riggers performing splicing, termination, and inspection procedures should be included in the heritage skills programme (Doc #159).

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CRITICAL UNCERTAINTIES

Uncertainty	Impact if Wrong	Resolution Method
NZ Steel’s ability to produce medium-carbon wire rod (0.4–0.8% C)	If only low-carbon rod available, wire rope wire will be too weak. Entire production chain fails at the first step.	Direct assessment of NZ Steel capability (Doc #89). Highest priority question.
Size of existing NZ wire rope inventory	If less than estimated, depletion occurs sooner and production urgency increases	National asset census (Doc #8) — wire rope as a specific category
Forestry wire rope consumption rate under recovery conditions	Determines how fast stocks deplete and how soon production must replace them	Assessment of forestry operations under reduced harvest volumes
Feasibility of building stranding and closing machinery in NZ	If machinery proves harder to build than assessed, production timeline extends	Prototype development (the only way to know is to try)
Tool steel die durability for wire drawing	If dies wear out faster than estimated, die production becomes a bottleneck	Empirical testing with NZ-produced tool steel dies
Zinc stock levels for galvanizing	Determines how long galvanized wire rope can be produced	National zinc inventory (Doc #8)
Existence of adaptable stranding machinery in NZ	If cable or rope making equipment exists, timeline accelerates significantly	Targeted survey of NZ cable and rope manufacturers
Wire rope splicing and rigging skill base	If fewer skilled riggers exist than assumed, more users will make improper terminations	Census (Doc #8) — include rigging skills
Harakeke fiber suitability for rope cores	If harakeke rope cores perform poorly (too much stretch, water absorption issues), alternative core material needed	Testing programme with harakeke rope under compression in wire rope

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CROSS-REFERENCES

• Doc #8 — National Skills and Asset Census (wire rope inventory and rigger skills)
• Doc #34 — Lubricants (tallow and lanolin for wire rope lubrication and wire drawing)
• Doc #89 — NZ Steel (wire rod production — the starting material)
• Doc #91 — Machine Shop Operations (die-making, machinery fabrication)
• Doc #92 — Blacksmithing (chain production as partial wire rope substitute)
• Doc #100 — Harakeke Fiber (rope cores, fiber rope for lighter applications)
• Doc #105 — Wire Drawing (detailed wire drawing procedures — complementary document)
• Doc #138 — Sailing Vessel Design (standing rigging, marine wire rope demand)
• Doc #160 — Heritage Skills Preservation and Transmission (wire rope splicing as a heritage skill)

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APPENDIX A: WIRE ROPE SIZE AND STRENGTH REFERENCE

Approximate breaking strengths for common wire rope constructions and diameters (regular lay, fiber core, rope grade 1770 MPa wire).⁵⁰ These values are for new, undamaged rope. Working load limits are typically 1/5 to 1/6 of breaking strength (safety factor of 5:1 to 6:1).

Nominal diameter (mm)	6x7 FC (kN)	6x19 FC (kN)	6x36 FC (kN)
8	30	35	33
10	47	55	52
12	68	79	75
16	120	140	133
20	188	219	208
24	270	315	299
28	368	429	407
32	480	560	531

Note: Values are approximate and vary with exact construction, wire grade, and manufacturing quality. NZ-produced rope may initially have somewhat lower strength than these figures due to the learning curve in production quality. All rope should be break-tested before being assigned a working load limit.

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APPENDIX B: WIRE ROPE CLIP INSTALLATION

Correct installation of wire rope clips (bulldog grips) is critical and commonly done incorrectly.⁵¹

Key rules:

1. “Never saddle a dead horse” — The saddle (curved part) of the clip sits on the live (load-bearing) side of the rope. The U-bolt sits on the dead (tail) end. Reversed clips can damage the live rope and reduce termination efficiency by an estimated 30–50%.⁵²
2. Minimum number of clips: Depends on rope diameter. General guide: 3 clips for rope up to 16 mm, 4 clips for 16–28 mm, 5 clips for 28–38 mm, 6 clips for larger.
3. Spacing: Clips are spaced approximately 6x the rope diameter apart.
4. Torque: Clips must be tightened to the manufacturer’s specified torque. After initial loading, re-torque all clips — wire rope compresses slightly under first load, loosening the clips.
5. Thimble: Always use a thimble (a formed metal insert) in the eye of the rope. Without a thimble, the rope crushes and kinks at the eye, reducing strength.

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1. NZ forestry export value from Ministry for Primary Industries (MPI), “Situation and Outlook for Primary Industries,” annual report, pre-recovery figures. https://www.mpi.govt.nz/news-and-resources/open-data-and-...↩︎

2. NZ forestry harvest statistics from Ministry for Primary Industries (MPI). https://www.mpi.govt.nz/forestry/ — The proportion of cable-logged vs. ground-based harvest varies by region and year. The 30–50% cable-logged estimate is based on the proportion of steep terrain in NZ’s planted forest estate.↩︎

3. NZ forestry cable logging is documented in: Visser, R. and Stampfer, K., “Cable Logging Studies in New Zealand,” University of Canterbury School of Forestry publications. Also: Forest Owners Association, “Facts and Figures,” annual reports. https://www.nzfoa.org.nz/ — NZ’s steep terrain (much of the North Island east coast and South Island West Coast) makes cable logging essential for a significant portion of the harvest.↩︎

4. Wire rope breaking strengths from manufacturer data (e.g., Bridon-Bekaert wire rope catalogue). Harakeke fiber strength from Wehi, P.M. and Clarkson, B.D., “Biological flora of New Zealand: Phormium tenax,” NZ Journal of Botany, 2007. The 10:1 strength ratio is approximate and varies with rope construction, fiber preparation, and wire grade, but the order-of-magnitude difference is consistent across comparisons.↩︎

5. NZ forestry harvest statistics from Ministry for Primary Industries (MPI). https://www.mpi.govt.nz/forestry/ — The proportion of cable-logged vs. ground-based harvest varies by region and year. The 30–50% cable-logged estimate is based on the proportion of steep terrain in NZ’s planted forest estate.↩︎

6. NZ yacht fleet size estimate: Maritime NZ vessel registration data and recreational boating surveys. NZ has one of the highest per-capita boat ownership rates in the world. The number of registered sailing yachts with wire standing rigging requires verification through Maritime NZ records or the national asset census (Doc #8).↩︎

7. NZ wire rope distributors include Bridon-Bekaert (the largest global wire rope manufacturer, with NZ distribution), Bullivants (rigging and lifting equipment), Nobles (rigging hardware), and Certex (wire rope and lifting). These companies import wire rope from manufacturers in Asia, Europe, and Australia.↩︎

8. Forestry wire rope consumption estimate based on typical rope replacement cycles in hauler operations and the scale of NZ’s cable logging sector. Exact figures are commercially sensitive and not publicly available. The estimate should be verified through industry consultation as part of Doc #8.↩︎

9. NZ Steel’s Glenbrook process is described in NZ Steel corporate publications and in: Wright, M., “NZ Steel: The First 40 Years,” NZ Steel, 2008. The ironsand-to-steel process using rotary kilns and electric arc furnaces is unique to Glenbrook. https://www.nzsteel.co.nz/↩︎

10. NZ Steel production capacity figures from company reports and MBIE manufacturing data. The 600,000–650,000 tonne figure refers to crude steel capacity; actual production varies with market conditions and may be lower under recovery conditions (reduced demand, potential raw material constraints). See Doc #89 for detailed NZ Steel assessment.↩︎

11. Wire rope wire carbon content requirements from: Wire Rope Technical Board, “Wire Rope Users Manual,” 4th edition, AISI, 2005. Also standard specifications: ASTM A1007 (carbon steel wire for wire rope), AS 3569 (steel wire rope). The 0.4–0.8% carbon range covers most standard wire rope grades (plow steel, improved plow steel, extra improved plow steel).↩︎

12. Wire drawing process description based on standard metallurgical texts: Hosford, W.F. and Caddell, R.M., “Metal Forming: Mechanics and Metallurgy,” Cambridge University Press, various editions. Also: Wright, R.N., “Wire Technology: Process Engineering and Metallurgy,” Butterworth-Heinemann, 2011 — the definitive modern reference on wire drawing.↩︎

13. Wire drawing lubrication: Wright, R.N., “Wire Technology,” Chapter 10 (Lubrication). Calcium stearate and sodium stearate have been the standard dry drawing lubricants for steel wire since the early 20th century, replacing earlier tallow and soap-based lubricants. The older lubricants still work — they were used for decades of wire production.↩︎

14. Tool steel wire drawing dies: Wright, R.N., “Wire Technology,” Chapter 9 (Die Materials and Die Making). Tool steel dies are feasible but wear 10–50x faster than tungsten carbide, depending on wire grade, drawing speed, and lubrication. The internal die geometry (entry angle typically 8–12 degrees half-angle, bearing length 25–50% of wire diameter) must be precisely formed and polished. See also Doc #91 for die-making capability.↩︎

15. Calcium stearate production: The saponification of tallow (animal fat) with calcium hydroxide (slaked lime) produces calcium stearate and glycerol. This is standard industrial chemistry, closely related to soap-making (which uses sodium hydroxide instead of calcium hydroxide). NZ has both tallow (from livestock) and limestone (for lime production) in abundance.↩︎

16. Pacific Steel Ltd operates wire drawing and nail-making facilities at Otahuhu, Auckland. Pacific Steel products include reinforcing steel, wire, nails, and fencing products. The wire drawing equipment at Pacific Steel represents NZ’s primary existing capability in this area. Note: Pacific Steel’s corporate ownership has changed over the years and it no longer operates as a BlueScope/NZ Steel subsidiary. https://www.pacificsteel.co.nz/↩︎

17. Patenting is a specialised heat treatment for wire that produces a fine pearlite (or sorbite) microstructure optimised for cold drawing to high strength. The wire is austenitized (heated to ~900–950°C) and then cooled at a controlled rate, traditionally in a bath of molten lead at ~500–550°C. The name derives from the original patents granted for the process in the 19th century. See: Wright, R.N., “Wire Technology,” Chapter 7; Pops, H., “Processing of Wire from Antiquity to the Future,” Wire Journal International, 2006.↩︎

18. Wire rope construction standards: ISO 17893 (wire rope — vocabulary, designation, and classification), AS 3569 (steel wire rope — product specification), and the Wire Rope Technical Board’s “Wire Rope Users Manual.”↩︎

19. Stranding machine types and principles: Costello, G.A., “Theory of Wire Rope,” Springer, 1997. Also: Feyrer, K., “Wire Ropes: Tension, Endurance, Reliability,” Springer, 2007 — the most comprehensive modern engineering reference on wire rope, including production machinery.↩︎

20. Historical development of wire rope: Sayenga, D., “Modern History of Wire Rope,” Wire Rope Technical Board, 2000. Andrew Smith (Edinburgh) and Wilhelm Albert (Clausthal mining academy, Germany) independently developed wire rope in the 1830s. Albert’s 1834 rope used three strands of four wires each, twisted by a simple rotating frame. Smith developed more sophisticated stranding machinery. Both used technology available to any competent 1830s engineering workshop.↩︎

21. Pre-forming of wire rope strands: described in Feyrer, K., “Wire Ropes,” Chapter 3. Pre-forming was introduced commercially in the 1930s by the American company Preformed Line Products. It reduces internal stresses and makes the rope easier to handle (strands do not spring apart when the rope is cut).↩︎

22. Wire rope nomenclature and construction types: Wire Rope Technical Board, “Wire Rope Users Manual,” 4th edition. Also: AS 3569, Tables of standard wire rope constructions.↩︎

23. Patenting is a specialised heat treatment for wire that produces a fine pearlite (or sorbite) microstructure optimised for cold drawing to high strength. The wire is austenitized (heated to ~900–950°C) and then cooled at a controlled rate, traditionally in a bath of molten lead at ~500–550°C. The name derives from the original patents granted for the process in the 19th century. See: Wright, R.N., “Wire Technology,” Chapter 7; Pops, H., “Processing of Wire from Antiquity to the Future,” Wire Journal International, 2006.↩︎

24. Patenting is a specialised heat treatment for wire that produces a fine pearlite (or sorbite) microstructure optimised for cold drawing to high strength. The wire is austenitized (heated to ~900–950°C) and then cooled at a controlled rate, traditionally in a bath of molten lead at ~500–550°C. The name derives from the original patents granted for the process in the 19th century. See: Wright, R.N., “Wire Technology,” Chapter 7; Pops, H., “Processing of Wire from Antiquity to the Future,” Wire Journal International, 2006.↩︎

25. Tool steel wire drawing dies: Wright, R.N., “Wire Technology,” Chapter 9 (Die Materials and Die Making). Tool steel dies are feasible but wear 10–50x faster than tungsten carbide, depending on wire grade, drawing speed, and lubrication. The internal die geometry (entry angle typically 8–12 degrees half-angle, bearing length 25–50% of wire diameter) must be precisely formed and polished. See also Doc #91 for die-making capability.↩︎

26. Wire drawing lubrication: Wright, R.N., “Wire Technology,” Chapter 10 (Lubrication). Calcium stearate and sodium stearate have been the standard dry drawing lubricants for steel wire since the early 20th century, replacing earlier tallow and soap-based lubricants. The older lubricants still work — they were used for decades of wire production.↩︎

27. Calcium stearate production: The saponification of tallow (animal fat) with calcium hydroxide (slaked lime) produces calcium stearate and glycerol. This is standard industrial chemistry, closely related to soap-making (which uses sodium hydroxide instead of calcium hydroxide). NZ has both tallow (from livestock) and limestone (for lime production) in abundance.↩︎

28. Harakeke muka (fiber) properties and traditional Maori use: Te Papa Tongarewa (Museum of New Zealand) ethnographic collections and publications. Also: Wehi, P.M. and Clarkson, B.D., “Biological flora of New Zealand: Phormium tenax,” NZ Journal of Botany, 2007. Harakeke was used for heavy-duty applications including anchor lines for large waka, fishing nets, and carrying ropes — demonstrating its suitability for load-bearing cordage.↩︎

29. NZ zinc imports and consumption: Stats NZ trade data. NZ imports all zinc, primarily from Australia (which has significant zinc mining and smelting at Mount Isa, Broken Hill, and Century). NZ’s galvanizing industry (for steel products, roofing, fencing) is the primary zinc consumer.↩︎

30. The effect of lubrication on wire rope life: Feyrer, K., “Wire Ropes,” Chapter 7 (Corrosion and Lubrication). Properly lubricated wire rope can have 2–5x the service life of unlubricated rope, depending on environment and application. The benefit is greatest in corrosive environments (marine, wet conditions) where corrosion is the primary degradation mechanism.↩︎

31. Wire rope inspection and retirement criteria: ISO 4309 (Cranes — Wire ropes — Care and maintenance, inspection and discard), AS 2759 (Steel wire rope — Use, operation and maintenance). NZ’s WorkSafe requirements reference these standards. Broken wire counts, diameter reduction, and deformation criteria are specified by application.↩︎

32. Wire rope inspection and retirement criteria: ISO 4309 (Cranes — Wire ropes — Care and maintenance, inspection and discard), AS 2759 (Steel wire rope — Use, operation and maintenance). NZ’s WorkSafe requirements reference these standards. Broken wire counts, diameter reduction, and deformation criteria are specified by application.↩︎

33. Magnetic Rope Testing (MRT): Weischedel, H.R., “The Inspection of Wire Ropes in Service: A Critical Review,” Materials Evaluation, 1985. Also: ASTM E1571 (Standard Practice for Electromagnetic Examination of Ferromagnetic Steel Wire Rope). MRT equipment is used in NZ primarily by mining and forestry operations for critical rope inspection.↩︎

34. Historical use of tallow for wire rope lubrication: tallow (animal fat rendered to remove protein) was the standard wire rope lubricant before petroleum-based products became available in the late 19th century. Lime-tallow mixtures (tallow cooked with slaked lime) produce a calcium soap grease that adheres well to wire and provides corrosion protection. See: Sayenga, D., “Modern History of Wire Rope,” for historical lubrication practices.↩︎

35. Lanolin as a corrosion inhibitor: lanolin (wool wax, recovered during wool scouring — an established NZ industry) is an excellent rust preventive. Commercially, lanolin-based corrosion inhibitors are sold for marine and industrial applications. NZ’s wool industry produces lanolin as a byproduct — estimated NZ lanolin production is several thousand tonnes per year. See: Moldoveanu, S.C., “Analysis of Lipids and Lipoproteins,” Chapter on lanolin chemistry.↩︎

36. Pine tar for cordage preservation: pine tar (from destructive distillation of pine wood) has been used to preserve ropes and rigging for centuries, particularly in Scandinavian and Northern European maritime traditions. “Stockholm tar” was a major export commodity of Sweden and Finland. NZ radiata pine can produce pine tar by the same pyrolysis process. Combined with tallow or lanolin, pine tar provides a tenacious, water-resistant rope coating.↩︎

37. Sheave and drum diameter recommendations: Wire Rope Technical Board, “Wire Rope Users Manual,” Chapter on sheaves and drums. Also: Feyrer, K., “Wire Ropes,” Chapter 5 (Wire Ropes Over Sheaves). The D/d ratio (sheave diameter to rope diameter) directly affects bending fatigue life — smaller ratios cause dramatically faster fatigue.↩︎

38. Sheave and drum diameter recommendations: Wire Rope Technical Board, “Wire Rope Users Manual,” Chapter on sheaves and drums. Also: Feyrer, K., “Wire Ropes,” Chapter 5 (Wire Ropes Over Sheaves). The D/d ratio (sheave diameter to rope diameter) directly affects bending fatigue life — smaller ratios cause dramatically faster fatigue.↩︎

39. Wire rope inspection and retirement criteria: ISO 4309 (Cranes — Wire ropes — Care and maintenance, inspection and discard), AS 2759 (Steel wire rope — Use, operation and maintenance). NZ’s WorkSafe requirements reference these standards. Broken wire counts, diameter reduction, and deformation criteria are specified by application.↩︎

40. Wire rope clip installation: Crosby Group, “Wire Rope Clip Application Guide” (widely distributed in NZ rigging industry). The “never saddle a dead horse” mnemonic means the U-bolt goes on the dead end — the saddle (which has a smooth, rope-friendly surface) goes on the live end.↩︎

41. Swaged fittings for wire rope: produced by companies including Crosby, Flemish, and others. Swaging equipment (hydraulic presses fitted with matching dies) is held by NZ rigging companies and forestry operations. The fittings themselves (aluminium or steel sleeves) are imported products.↩︎

42. Spelter sockets: ISO 7595 (Zinc-poured resin socketing procedures for wire rope). This is the highest-efficiency termination and is standard for critical applications (crane main ropes, forestry skylines, structural stays). Zinc-poured sockets use molten zinc; resin-poured sockets use a polyester or epoxy compound. Zinc-poured is preferred for NZ because the resin is an imported consumable while zinc can be recycled.↩︎

43. Wire rope hand splicing efficiency: approximately 70–80% for a properly made 6-tuck splice. Splicing technique is described in standard rigging manuals and in: The Crosby Group, “User Information — Rigging Applications.” Hand splicing skill is declining in NZ as swaged and pressed fittings have become dominant.↩︎

44. Historical development of wire rope: Sayenga, D., “Modern History of Wire Rope,” Wire Rope Technical Board, 2000. Andrew Smith (Edinburgh) and Wilhelm Albert (Clausthal mining academy, Germany) independently developed wire rope in the 1830s. Albert’s 1834 rope used three strands of four wires each, twisted by a simple rotating frame. Smith developed more sophisticated stranding machinery. Both used technology available to any competent 1830s engineering workshop.↩︎

45. NZ electrical cable manufacturing: Nexans (formerly Olex NZ, formerly BICC) has cable manufacturing operations in NZ. The stranding equipment used for electrical cable conductors operates on similar principles to wire rope stranding, though at different scale and with different materials (copper and aluminium vs. steel).↩︎

46. Use of wire rope as concrete reinforcement is documented in various construction engineering references and was practised during WWII and in developing countries where conventional rebar was unavailable. Bond strength with concrete is lower than deformed rebar due to the smooth surface, but mechanical anchorage (bent ends, hooks) compensates.↩︎

47. Bridon-Bekaert Ropes (formerly Wire Rope Industries) has wire rope manufacturing facilities in Newcastle, Australia. Australia also has other wire and wire rope manufacturers. Australia’s proximity and existing maritime connection to NZ makes it the most likely trade source for wire rope if sail trade develops per Doc #138.↩︎

48. The effect of lubrication on wire rope life: Feyrer, K., “Wire Ropes,” Chapter 7 (Corrosion and Lubrication). Properly lubricated wire rope can have 2–5x the service life of unlubricated rope, depending on environment and application. The benefit is greatest in corrosive environments (marine, wet conditions) where corrosion is the primary degradation mechanism.↩︎

49. Rigging qualifications in NZ: WorkSafe NZ administers competency requirements for riggers under the Health and Safety at Work Act 2015. NZ Certificate in Crane Operation and NZ Certificate in Rigging are administered through Te Pukenga polytechnics. The Crane Association of New Zealand (CANZ) also provides industry guidance.↩︎

50. Breaking strength values based on AS 3569 (Steel Wire Rope — Product Specification) and wire rope manufacturer catalogues (Bridon-Bekaert, Usha Martin, Kiswire). Values are for 1770 MPa wire grade, fiber core, right regular lay. Actual values vary ±5–10% depending on exact construction and manufacturer. Independent Wire Rope Core (IWRC) ropes are approximately 7–10% stronger than equivalent fiber core ropes.↩︎

51. Wire rope clip installation: Crosby Group, “Wire Rope Clip Application Guide” (widely distributed in NZ rigging industry). The “never saddle a dead horse” mnemonic means the U-bolt goes on the dead end — the saddle (which has a smooth, rope-friendly surface) goes on the live end.↩︎

52. Wire rope clip installation: Crosby Group, “Wire Rope Clip Application Guide” (widely distributed in NZ rigging industry). The “never saddle a dead horse” mnemonic means the U-bolt goes on the dead end — the saddle (which has a smooth, rope-friendly surface) goes on the live end.↩︎