Torque, Tension & Torque Coefficient Testing Machine

What is a High-Strength Bolt Tester?

A High-Strength Bolt Tester is a precision testing system designed to measure the axial force, tightening torque, and torque coefficient of high-strength fasteners such as bolts, screws, and studs.

It is widely used in fastener manufacturing, quality inspection laboratories, and structural engineering industries to ensure that bolted connections meet safety and performance standards.

By simulating real tightening conditions, the machine evaluates the relationship between torque and preload, helping manufacturers guarantee reliable fastening performance.

Technical parameters:

Item	Specification
Testing Range	10 – 1000 kN (customizable)
Torque Range	50 – 5000 N·m
Bolt Size Range	M12 – M64
Measurement Accuracy	±1%
Data Output	Torque, axial force, K-value
Control System	PLC + Industrial computer
Display	Real-time curve analysis software
Power Supply	220V / 380V, 50Hz

Testing Purpose of Bolt Testing Machine

The High-Strength Bolt Tester is used to evaluate the mechanical behavior of fasteners during tightening and loading conditions.

Main testing purposes include:

• Measuring bolt axial clamping force (preload)
• Testing torque–tension relationship
• Calculating torque coefficient (K-value)
• Evaluating friction performance of threads and bearing surfaces
• Ensuring consistency in mass production
• Quality control of high-strength fasteners

This ensures that bolts used in critical structures such as bridges, steel buildings, and machinery assemblies meet safety requirements.

Working Principle

The system applies controlled torque and axial force to a fastener while simultaneously measuring mechanical response in real time.

Testing process:

1. The bolt is installed into a dedicated fixture
2. The system applies tightening torque via a servo or hydraulic drive
3. Axial force is measured using a high-precision load cell
4. Torque and preload data are collected synchronously
5. The torque coefficient is automatically calculated and displayed

The system generates real-time torque–tension curves for accurate analysis of fastening performance.

Standards Compliance

The High-Strength Bolt Tester is designed in accordance with international fastener testing standards:

• ISO 16047 – Determination of torque/preload relationship
• EN 14399 – High-strength structural bolting assemblies
• ASTM A325 / ASTM A490 – Structural bolt specifications
• GB/T 1231 – High-strength bolt testing standard
• GB/T 50205 – Acceptance standard for steel structures

Compliance with these standards ensures reliable and globally recognized test results.

Applications

This bolt testing machine is widely used in:

• Steel structure engineering inspection
• Bridge construction quality control
• Railway fastening systems
• Automotive fastener manufacturing
• Wind power tower bolt testing
• Fastener R&D laboratories
• Third-party inspection institutions

It is an essential instrument for industries requiring high fastening safety and reliability.

FAQ

Q1: What does a High-Strength Bolt Tester measure?

It measures torque, axial force (preload), and torque coefficient during bolt tightening.

Q2: What is torque coefficient in bolt testing?

Torque coefficient (K-value) is the ratio between tightening torque and resulting preload force, indicating fastening efficiency.

Q3: Which standards are used for bolt testing?

Common standards include ISO 16047, EN 14399, ASTM A325/A490, and GB/T 1231.

Q4: What industries use bolt testing machines?

Steel construction, automotive manufacturing, wind power, railways, and fastener production industries.

Q5: Why is preload important in bolts?

Preload ensures joint stability and prevents loosening under vibration and load conditions.

Q6: Can this machine test different bolt sizes?

Yes, it supports multiple bolt sizes such as M12 to M64 (customizable).

Q7: Does the machine generate test reports?

Yes, it automatically generates torque curves and test reports in digital formats.