Wire Rope Selection Chart: Diameter, Breaking Force & Safety Factor
Core Value
Choosing the wrong wire rope is a safety hazard. This quick-reference chart covers 3 mainstream rope constructions (6×19W, 6×36WS, 35W×7) across 30+ specifications, with each entry listing nominal diameter, minimum breaking force, allowable tension at safety factors of 5 and 6, and reference lifting capacity. It also includes 10 rejection criteria and rope clip fastening specifications—everything you need from selection to maintenance.
Core Wire Rope Selection Formula
The selection principle is simple: Minimum breaking force of the wire rope ÷ Safety factor ≥ Maximum static working tension. Safety factors per ISO 4301:
- Hoisting mechanism (Work Duty M5 and above): Safety factor ≥6
- Hoisting mechanism (Work Duty M4 and below): Safety factor ≥5
- Luffing mechanism: Safety factor ≥4.5
- Tensioning / equalizing ropes: Safety factor ≥3
Quick Reference: Three Main Rope Constructions
| Rope construction | Rope core | Diameter range | Application Scenarios | Reference price |
|---|---|---|---|---|
| 6×19W | FCFiber core | φ6~30mm | Standard Hoisting·≤12tHoisting / Lifting·Electric Hoist | Lower |
| 6×36WS | IWRCIndependent wire rope core (IWRC) | φ12~36mm | Heavy duty·≥20tHoisting / Lifting·Frequent operation | Medium |
| 35W×7 | IWRCIndependent wire rope core (IWRC) | φ14~28mm | High Lift Height·Many Pulley Ratio Pulley Block·Not Rotation Requirement | Higher |
| Diameter (in) | Approx. Weight per 100 ft (lb) | Minimum Breaking Strength (tons) |
|---|---|---|
| 1/4 | 12.3 | 5.35 |
| 5/16 | 19.2 | 8.35 |
| 3/8 | 27.6 | 12.0 |
| 7/16 | 37.5 | 16.3 |
| 1/2 | 49.0 | 21.3 |
| 9/16 | 62.0 | 27.0 |
| 5/8 | 76.5 | 33.3 |
| 3/4 | 110.0 | 47.8 |
| 7/8 | 150.0 | 65.2 |
| 1 | 196.0 | 85.2 |
6×19W Wire Rope Quick Reference (Excerpt)
| Diameter (in) | Approx. Weight per 100 ft (lb) | Minimum Breaking Strength (short tons) |
|---|---|---|
| 1/4 | 12.3 | 5.35 |
| 5/16 | 19.2 | 8.35 |
| 3/8 | 27.6 | 12.0 |
| 7/16 | 37.5 | 16.3 |
| 1/2 | 49.0 | 21.3 |
| 9/16 | 62.0 | 27.0 |
| 5/8 | 76.5 | 33.3 |
| 3/4 | 110.0 | 47.8 |
| 7/8 | 150.0 | 65.2 |
| 1 | 196.0 | 85.2 |
| Diametermm | Breaking forcek N | Safety5Allowablek N | Safety6Allowablek N | Applicable Lifting Capacity |
|---|---|---|---|---|
| φ10 | 65.0 | 13.0 | 10.8 | ≤1.3t |
| φ16 | 167 | 33.4 | 27.8 | ≤3.3t |
| φ20 | 261 | 52.2 | 43.5 | ≤5.2t |
| φ24 | 376 | 75.2 | 62.7 | ≤7.5t |
| φ28 | 511 | 102 | 85.2 | ≤10.2t |
| Discard criteria (red line)(Basis ISO 4309) | acceptance criteria |
|---|---|
| Number of broken wires | Within one rope lay length, Number of broken wires reaches ... of total wires 10% |
| Concentrated wire breaks | Locally concentrated wire breaks, Even if the number does not reach 10%, But wire breaks are concentrated in the same strand or area |
| Rope diameter reduction | Wire rope diameter reduction exceeds ... of nominal diameter 7%(Due to outer wire wear or corrosion) |
| Corrosion | Visible corrosion on surface, Pitting, Or internal corrosion causing diameter reduction |
| Wear | Outer wire wear reaches ... of original diameter 40% |
| Deformation | Kinking, Flattening, Bending, Cage distortion, Permanent deformation such as core protrusion |
| Heat damage | Due to electric arc, Welding sparks or overheating causing discoloration or performance degradation |
| End termination | Slippage at end termination, Crack or wear |
| Core protrusion | Fiber core or steel core protrusion, Or core fracture causing structural loosening |
| Broken strand | Complete strand fracture, Regardless of number of broken wires, Immediate discard |
The full PDF includes all 13 specification tiers plus data for both 1770 and 1960 strength grades.
10 Scrap Criteria That Require Immediate Replacement (ISO 4309)
| Inspection criterion | Threshold | Consequence |
|---|---|---|
| 6×19Wwire break | Any rope lay≥10wires | Immediate discard |
| 6×36WSwire break | Any rope lay≥20wires | Immediate discard |
| Diameter reduction | ≥Nominal diameter7% | Immediate discard |
| Strand breakage | 1Complete strand | Immediate discard |
| Kink/Flattening/Bending | Any visible Deformation | Immediate discard |
| Electric arc burn | Any burn marks | Immediate discard |
Rope Clip Fastening Quick Guide (GB/T 5976)
"U-bolt on the dead end, spacing at six times the rope diameter, retighten 24 hours after initial tightening" — Use 3 rope clips for ropes up to φ16mm, 4 clips for φ16–25mm, and 5 clips for φ25–32mm. Position the first clip approximately 150mm from the rope end. After tightening, the rope should be compressed to about one-third of its original diameter.
FAQ
Q: FC fiber core or IWRC steel core — which should I choose?
A: FC cores are more economical and flexible, but they offer poor crush resistance and tend to fail in high-temperature environments. IWRC steel cores deliver approximately 7% higher breaking force, resist crushing, and are ideal for multi-layer spooling and high-temperature applications. Choose FC for standard duty up to 10t; choose IWRC for heavy loads of 20t and above or frequent operation.
Q: What's the difference between 1770MPa and 1960MPa strength grades?
A: At the same diameter, 1960MPa wire rope offers roughly 11% higher breaking force than 1770MPa — allowing a thinner rope for the same lifting capacity. However, 1960MPa requires a larger pulley D/d ratio and is slightly less flexible. For standard applications, 1770MPa is sufficient; choose 1960MPa for heavy lifting capacities or small drum diameters.
Q: Why is 35W×7 more expensive than standard wire rope? When is it required?
A: 35W×7 uses multiple layers of strands laid in opposite directions to virtually eliminate rotation torque. When lifting height exceeds 30m or with multi-pulley blocks (4/2 and above), standard rope rotation can cause the hook to spin or even the rope to kink. It costs roughly 1.8–2.5 times more than a 6-strand rope of the same diameter, but it's essential for high-lift applications.
Q: How long does wire rope last? How can I extend its service life?
A: Under normal operating conditions, expect 8 to 18 months (based on 2,000 hours per year). Three key factors for longer life: pulley D/d ratio of 25 or greater (the larger, the longer the life), regular lubrication (apply wire rope lubricant every 1–3 months), and avoiding impact loads. Contact the Kelude Heavy Industry technical team for a full life-cycle wire rope management program — phone 13903802779, email 3915269@qq.com.
Wire Rope Selection Quick Reference.pdf
83KB · 3 rope types, 30+ specifications · 10 discard criteria · 5-step clip specification · A4 printable
This quick reference is compiled and provided free of charge by Henan Kelude Heavy Industry Co., Ltd. in accordance with GB/T 20118-2017, GB/T 5972, and GB/T 5976. Data is for selection reference only; actual engineering must follow the design documents and the wire rope manufacturer's quality certificate.
Related News
-
Crane Inspection Checklist: 41-Point Brake & Wire Rope Audit
Download a 41-point crane annual inspection checklist covering brakes, limit switches, wire rope, and metal structure. Use this practical self-audit guide to verify accep
【常见问题】该内容包含「常见问题」等FAQs。克鲁德重工提供专业解决方案。 -
Crane Export Certifications: CE, EAC, GSO & ASME Guide
Compare crane export certification requirements, costs, and timelines across CE, EAC, GSO, and ASME for five key regions, including the Middle East and Southeast Asia.
【常见问题】该内容包含「国内企业拿CE认证最大的坑是什么？」「CE证书有有效期吗？拿到后就可以一直用？」「出口中东是否必须做GSO认证？能不能用CE证书替代？」等FAQs。克鲁德重工提供专业解决方案。 -
Overhead Crane Retrofit: Height, Rail & Foundation Fixes
Download this free technical guide covering overhead crane retrofit challenges in old plants, including low ceiling height, rail deviation, and foundation problems with g
【常见问题】该内容包含「这本手册和网上的通用指南有什么不同？」「手册里的费用数据准确吗？参考价值有多大？」「我们工厂情况比较特殊，手册里的方案能直接用吗？」等FAQs。克鲁德重工提供专业解决方案。 -
Ten No-Lift Rules for Riggers: Safety Procedures Poster
Download the Ten No-Lift Rules safety operating procedures for riggers, including hand signal diagrams, accident case studies, and emergency response steps. Ideal for wor
【常见问题】该内容包含「常见问题」等FAQs。克鲁德重工提供专业解决方案。 -
Crane Selection Chart: Match Lifting Capacity, Span & Duty Class
Use this crane selection quick-reference chart to match rated lifting capacity, span, and work duty classification to the right overhead crane model for your application.
【常见问题】该内容包含「选型时工作级别算出来是A4，能不能按A3省钱？」「非标跨度的起重机比标准跨度贵多少？」「欧标双梁QDhs和国标QD的主要区别在哪里？」等FAQs。克鲁德重工提供专业解决方案。 -
Crane Installation & Acceptance Checklist: Rail, Load Test
Download a free crane installation acceptance checklist covering rail alignment, static and dynamic load tests, and electrical system checks per GB 50278 standards.
【常见问题】该内容包含「常见问题」等FAQs。克鲁德重工提供专业解决方案。
