Technical White Paper Overview
This Steel Wire Rope FAQ provides a comprehensive technical guide to steel wire rope used in lifting, offshore, marine, mining and industrial applications. The performance, safety and service life of steel wire rope depend on rope construction, mechanical properties, manufacturing processes, quality control and proper maintenance.
As a professional steel wire rope manufacturer, KNKT provides this technical guide to answer common questions related to steel wire rope selection, construction, manufacturing and application.
This guide provides practical knowledge of steel wire rope selection, including mechanical properties, construction types, strength grades, manufacturing processes and quality requirements.
Steel Wire Rope FAQ
- What Are the Common Calculation Formulas for Steel Wire Rope Mechanical Properties and Weight?
- What Is the Purpose of Steel Wire Rope Pre-Stretching?
- What Does the Internal Quality Inspection of Steel Wire Rope Include?
- Does Rope Lay Length Affect Steel Wire Rope Flexibility?
- What Is the Production Range and Diameter Capability of KNKT Steel Wire Rope?
- How Are Different Steel Wire Rope Strength Grades Represented According to API 9A?
- Can Different Core Types Be Used for the Same Wire Rope Construction?
- Does Galvanization Affect the Strength of Steel Wire Rope?
- What Is the Maximum Diameter Capability of Different Wire Rope Series and Strength Grades?
- What Do W, WS, S, F, FNS and WSNS Mean in Line Contact Wire Rope Structures?
- Can All Standard Steel Wire Rope Specifications Be Manufactured?
- What Is the Manufacturing Principle of Steel Wire Rope Stranding and Closing?
- What Are the Main Characteristics of Steel Wire Rope?
- What Are Point Contact, Line Contact and Surface Contact Wire Ropes?
- Why Is Proper Use and Maintenance of Steel Wire Rope Important?
- What Are the Main Manufacturing Equipment Used for Steel Wire Rope Production?
- What Does Steel Wire Rope Elongation Mean?
- What Is a Rotation Resistant Steel Wire Rope?
- What Is a Sealed Steel Wire Rope?
- What Is a Semi-Sealed Steel Wire Rope?
1. What Are the Common Calculation Formulas for Steel Wire Rope Mechanical Properties and Weight?
Answer:
The commonly used calculation formulas for steel wire rope mechanical properties and weight include minimum breaking force, total breaking force and theoretical weight.
Minimum Breaking Force
Formula:
F₀ = K × D² × R₀
Where:
- F₀: Minimum breaking force of steel wire rope (kN)
- K: Breaking force coefficient
- D: Nominal diameter of steel wire rope
- R₀: Nominal tensile strength
Total Breaking Force of Steel Wires
Formula:
F = (F₁ + F₂)N
Where:
- F₁: Measured breaking force of tested wires in one strand
- F₂: Calculated breaking force of untested wires according to wire diameter and nominal strength before rope manufacturing
- N: Total number of strands
Theoretical Weight of Steel Wire Rope
Formula:
M = KD²
Where:
- M: Theoretical weight of steel wire rope
- K: Weight coefficient
- D: Nominal diameter of steel wire rope
2. What Is the Purpose of Steel Wire Rope Pre-Stretching?
Answer:
The main purpose of steel wire rope pre-stretching is to eliminate structural elongation.
Structural elongation is mainly related to:
- Steel wire rope construction
- Lay length
A smaller lay length results in greater structural elongation, while a larger lay length reduces structural elongation.
Pre-stretching is important for applications where structural elongation is not allowed, including:
- Bridge main cables
- Suspension cables
- Stadium steel wire ropes
- Large electric shovel tie rod ropes
3. What Does the Internal Quality Inspection of Steel Wire Rope Include?
Answer:
The internal quality inspection of steel wire rope includes:
- Complete rope breaking force test
- Strand dismantling test
- Fatigue test
- Adhesion strength test for conveyor belt wire ropes
- Zinc coating test of galvanized steel wire rope
- Rotation test of rotation-resistant steel wire rope
- Zinc coating weight test
- Salt spray test for corrosion resistance
4. Does Rope Lay Length Affect Steel Wire Rope Flexibility?
Answer:
Yes. Rope lay length has a direct relationship with steel wire rope flexibility.
Generally:
- Smaller lay length provides better flexibility.
- Larger lay length reduces flexibility.
Besides lay length, steel wire rope flexibility is also affected by:
- Rope construction
- Tensile strength
- Core material
- Stranding method
5. What Is the Production Range and Diameter Capability of KNKT Steel Wire Rope?
Answer:
KNKT produces steel wire ropes with diameter ranges from:
Ø12.5 mm to Ø140 mm
| Type | Diameter Range |
|---|---|
| Small diameter steel wire rope | Ø12.5 mm–Ø30 mm |
| Medium diameter steel wire rope | Ø26 mm–Ø80 mm |
| Large diameter steel wire rope | Ø36 mm–Ø140 mm |
6. How Are Different Steel Wire Rope Strength Grades Represented According to API 9A?
Answer:
According to API 9A-2020 Specification for Wire Rope for the Petroleum and Natural Gas Industries (27th Edition), different steel wire rope strength grades are represented as:
- Grade 2
- Grade 3
- Grade 4
- Grade 5
- IPS
- EIPS
- EEIPS
The relationship between steel wire rope strength grades and tensile strength is shown below:
| Steel Wire Rope Strength | Equivalent Grade |
|---|---|
| 1570 MPa | Grade 2 |
| 1770 MPa | Grade 3 |
| 1960 MPa | Grade 4 |
| 2160 MPa | Grade 5 |
| IPS | Grade 2 or 1570 MPa to Grade 4 or 1960 MPa |
| EIPS | Grade 3 or 1770 MPa to Grade 5 or 2160 MPa |
| EEIPS | Grade 4 or 1960 MPa to Grade 5 or 2160 MPa |
According to API 9A, the minimum steel wire rope strength grade is 1370 MPa, and the maximum strength grade is 2160 MPa.
7. Can Different Core Types Be Used for the Same Wire Rope Construction?
Answer:
There is no steel wire rope construction that can only use a fixed core type.
Generally, the same wire rope construction cannot freely replace different core types.
Under special conditions, different core types can be used, such as:
- Same construction
- Same strength grade
- Same production machine
- Same rope specification
For example, a fiber core can be replaced by a metallic core.
The selection of core type depends on the application requirements and performance requirements of the steel wire rope.
8. Does Galvanization Affect the Strength of Steel Wire Rope?
Answer:
Steel wire galvanization mainly includes:
- Hot-dip galvanization (including zinc-aluminum alloy coating)
- Electro-galvanization
The influence on steel wire strength is different:
- Hot-dip galvanization has a certain influence on steel wire strength and may reduce strength.
- Electro-galvanization does not affect steel wire strength.
9. What Is the Maximum Diameter Capability of Different Wire Rope Series and Strength Grades?
Answer:
The maximum diameter capability depends on:
- Wire rope construction
- Strength grade
- Manufacturing capability
For example, the maximum diameter range of galvanized 6×36 series steel wire rope with 2160 MPa strength grade is shown below:
| Steel Wire Rope Series | Construction | Diameter Range |
|---|---|---|
| 6×36 Series | 6×31WS | 18–60 mm |
| 6×36 Series | 6×29F | 18–60 mm |
| 6×36 Series | 6×36WS | 16–80 mm |
| 6×36 Series | 6×37FS | 16–60 mm |
| 6×36 Series | 6×41F | 60–88 mm |
| 6×36 Series | 6×41WS | 38–88 mm |
| 6×36 Series | 6×46WS | 40–98 mm |
| 6×36 Series | 6×49SWS | 42–88 mm |
| 6×36 Series | 6×55SWS | 44–98 mm |
10. What Do W, WS, S, F, FNS and WSNS Mean in Line Contact Wire Rope Structures?
Answer:
For line contact steel wire ropes, the main wire arrangement types include:
- W: Warrington type
- S: Seale type
- F (Fi): Filler type
- WS: Warrington-Seale type
Additional designations include:
- FNS: Compound filler type
- WSNS: Compound Warrington-Seale type
The letter N does not represent a specific wire arrangement.
N is an additional designation placed after the basic construction type.
11. Can All Standard Steel Wire Rope Specifications Be Manufactured?
Answer:
Not all standard steel wire rope specifications can be manufactured by every factory.
The production capability depends on:
- Manufacturing equipment
- Production technology
- Quality control capability
Common steel wire rope standards include:
Domestic Standards
| Standard | Description |
|---|---|
| GB/T8918-2006 | Steel Wire Ropes for Important Uses |
| GB/T20118-2017 | Steel Wire Ropes for General Technical Conditions |
| GB/T20067-2017 | Large Diameter Steel Wire Ropes |
| GB/T34197-2017 | Steel Wire Ropes for Electric Shovels |
| GB/T33955-2017 | Steel Wire Ropes for Mine Hoisting |
| GB/T33026-2017 | High Strength Steel Strand for Building Structures |
| YB/T5359-2020 | Compacted Strand Wire Ropes |
| YB/T5295-2010 | Sealed Wire Ropes |
| GB/T34198-2017 | Steel Wire Ropes for Cranes |
| MT716-2019 | Technical Conditions for Acceptance of Steel Wire Ropes for Important Uses in Coal Mines |
| YB/T4506-2016 | Steel Wire Ropes for Rotary Drilling Machines |
International Standards
| Standard | Description |
|---|---|
| ISO2408 | Steel Wire Ropes for General Purposes — Characteristics |
| ISO10425 | Steel Wire Ropes for Petroleum and Natural Gas Industries — Minimum Requirements and Acceptance Conditions |
| API 9A 27th Edition | Specification for Wire Rope for Petroleum and Natural Gas Industries |
| ASME A586 | Zinc-Coated Parallel and Helical-Lay Structural Strand |
| EN12385-4 | Steel Wire Ropes — Safety Part 4: Stranded Ropes for General Lifting Applications |
| EN12385-10 | Steel Wire Ropes — Safety Part 10: Spiral Ropes for General Structural Applications |
| AS2841 | Galvanized Steel Wire Strand |
| JIS G3525 | Steel Wire Ropes |
12. What Is the Manufacturing Principle of Steel Wire Rope Stranding and Closing?
Answer:
The manufacturing process of steel wire rope mainly includes strand formation and rope closing.
Strand Formation
Through the rotational movement of the stranding machine and the linear movement of the traction system, wires arranged according to a specific pattern are twisted into strands with the required structure.
Rope Closing
Through the rotational movement of the closing machine and the linear movement of the traction system, strands arranged according to a specific pattern are twisted together to form the final steel wire rope.
The relative movement between rotation and traction determines the lay length of the strand or steel wire rope.
By accurately adjusting the speed ratio between these two movements, steel wire ropes with different lay lengths can be produced.
13. What Are the Main Characteristics of Steel Wire Rope?
Answer:
The main characteristics of steel wire rope include:
- Structural characteristics
- Breaking force
- Corrosion resistance
- Fatigue resistance
- Rotation performance
- Steel wire rope elongation
These characteristics determine the performance and application range of different steel wire rope constructions.
14. What Are Point Contact, Line Contact and Surface Contact Wire Ropes?
Answer:
Steel wire ropes can be classified according to the contact condition between wires in the strand.
Point Contact Wire Rope
Point contact wire rope is also called non-parallel lay wire rope.
It refers to a steel wire rope in which, except for the center wire, all other wires have the same diameter and adjacent wires are in point contact.
Characteristics:
- Same wire diameter in each layer
- Same lay angle
- Different lay lengths between layers
The production process generally includes:
- Lower stranding
- Middle stranding
- Upper stranding
Line Contact Wire Rope
Line contact wire rope is also called parallel lay wire rope.
It refers to a steel wire rope in which adjacent wire layers are in line contact.
Characteristics:
- Different wire diameters with a certain proportional relationship
- Different lay angles
- Same lay length
- Strand produced through one-time stranding
Surface Contact Wire Rope
Surface contact wire rope is also called compacted wire rope.
It refers to a steel wire rope in which wires in the strand contact each other through spiral surfaces.
It is produced through deformation processes including:
- Drawing
- Rolling
- Roller pressing
- Forging
15. Why Is Proper Use and Maintenance of Steel Wire Rope Important?
Answer:
Proper use and maintenance of steel wire rope, understanding common damage causes and solutions, and knowing different steel wire rope end connections are important skills for:
- Steel wire rope operators
- Sales personnel
- After-sales service personnel
Correct use and maintenance are important for:
- Guiding steel wire rope production
- Improving steel wire rope service life
- Ensuring safe and reliable application
16. What Are the Main Manufacturing Equipment Used for Steel Wire Rope Production?
Answer:
The main manufacturing equipment used for steel wire rope production includes:
- Wire payoff stand
- Pre-former
- Closing die
- Post-former
- Sizing device
- Grinding and drawing device
- Forging device
These equipment and tools are important parts of the steel wire rope manufacturing process and directly affect product quality.
17. What Does Steel Wire Rope Elongation Mean?
Answer:
Steel wire rope elongation includes:
- Structural elongation
- Elastic elongation
Structural Elongation
Structural elongation is mainly related to:
- Steel wire rope construction
- Lay length
The smaller the lay length, the greater the structural elongation.
The larger the lay length, the smaller the structural elongation.
After a period of use, structural elongation becomes permanent elongation.
Structural elongation is not allowed in some applications, including:
- Bridge main cables
- Suspension cables
- Stadium steel wire ropes
- Large electric shovel tie rod ropes
Therefore, structural elongation must be eliminated before use. The commonly used method is steel wire rope pre-stretching.
Elastic Elongation
Elastic elongation refers to the temporary elongation caused by elastic deformation when the steel wire rope is subjected to load.
18. What Is a Rotation Resistant Steel Wire Rope?
Answer:
A rotation resistant steel wire rope is a steel wire rope in which adjacent layers have opposite lay directions.
The rotational moments of different layers tend to balance each other, giving the rope certain rotation-resistant performance.
Rotation resistant steel wire ropes are generally:
- Multi-layer stranded steel wire ropes
They are mainly used in applications where rope rotation needs to be controlled.
19. What Is a Sealed Steel Wire Rope?
Answer:
A sealed steel wire rope is a special type of steel wire rope.
Its structure consists of:
- One or more layers of round wires helically wound around the center wire.
- The outer layer consists of one or more layers of shaped wires.
The shaped outer wires form a compact structure and provide specific performance advantages for special applications.
20. What Is a Semi-Sealed Steel Wire Rope?
Answer:
A semi-sealed steel wire rope is a steel wire rope in which:
- One or more layers of round wires are helically wound around the center wire.
- The outer layer consists of shaped wires and round wires arranged alternately.
Compared with sealed steel wire rope, the outer layer of semi-sealed steel wire rope contains both shaped wires and round wires.
Conclusion
This Steel Wire Rope Technical Guide provides a professional reference covering steel wire rope construction, mechanical properties, manufacturing processes, quality inspection, standards and application knowledge.
Understanding steel wire rope design, production technology and application requirements helps engineers and purchasers select the most suitable wire rope solutions for different working conditions.
As a professional steel wire rope manufacturer, KNKT provides reliable steel wire rope products and technical support for lifting, offshore, marine, mining and industrial applications.
