ISO 7500-1

Introducing ISO 7500-1 – Industrial Physics

ISO 7500-1 is an international standard that sets out how to calibrate and verify the force-measuring system of tension and compression testing machines – the universal testing machines used for the static uniaxial testing of metallic materials. It gives quality, R&D, and operations experts a recognized, traceable way to confirm that the force a machine reports is the force it is really applying.

By grading a machine’s force accuracy into defined classes, ISO 7500-1 turns “we think the load is right” into a documented, audit-ready statement. That matters because every tensile, compression, or flex result a machine produces is only as trustworthy as the force behind it.

What ISO 7500-1 Covers

ISO 7500-1 specifies the calibration and verification of tension/compression testing machines used for the static uniaxial testing of metallic materials. The method has three parts:

• A general inspection of the testing machine and its force-application accessories
• A calibration of the force-measuring system, using calibrated force-proving instruments
• A confirmation that the machine meets the limits set for a specified accuracy class

Machines are graded into accuracy Classes 0.5, 1, 2 and 3, where the class reflects how closely the indicated force must match the true applied force. Importantly, a class is assigned per force range, not per machine – a frame may hold a tighter class across its upper range and a looser one at very low loads.

The current version is ISO 7500-1:2018 (the fifth edition), prepared by ISO Technical Committee ISO/TC 164, Mechanical testing of metals, Subcommittee SC 1, Uniaxial testing. It covers static calibration – the values are not automatically valid for high-speed or dynamic testing. A companion part, ISO 7500-2, covers tension creep testing machines rather than extensometers.

Why Force Verification Matters

Force accuracy is the foundation of valid mechanical testing. A verified force-measuring system helps quality, R&D, and operations experts to:

• Produce results that are accurate, repeatable, and comparable across machines, sites, and borders
• Maintain traceability of force measurement back to national standards
• Support compliance with tensile testing methods such as ISO 6892-1, which call for a Class 1 force-measuring system
• Stand up to external audit and customer scrutiny, and support ISO/IEC 17025 accreditation
• Reduce the risk of accepting bad material or rejecting good material on the basis of a mis-reading machine

Because force is easy to assume and hard to argue with once it is verified, a standardized method like ISO 7500-1 protects the integrity of both the test data and the products that data signs off. That is exactly what our purpose – to protect the integrity of our customers’ brands and products – is about.

How ISO 7500-1 Testing Works

Verification is carried out by comparing the machine’s indicated force against reference forces from calibrated force-proving instruments – typically load cells, and themselves calibrated to ISO 376. Sets of known dead-weight masses may also be used. After a general inspection and a check of the machine’s resolution, known forces are applied incrementally across the calibration range, usually over several runs.

From these readings, the relative accuracy, repeatability, and reversibility errors are calculated, and a measurement uncertainty is estimated. The machine is then assigned the class it meets across each force range. The reference instrument must be substantially more accurate than the class of machine it is verifying, which is why the calibration chain always runs from a more accurate standard down to the machine under test.

ISO 7500-1 Testing Equipment

Industrial Physics offers universal testing machines whose force verification conforms to ISO 7500-1, giving you a defensible calibration path for standards-based testing.

United Testing DFM Series Floor Model Universal Test Machine (UTM), 100-600 kN

Manufactured by United Testing Systems, our advanced materials testing brand, the DFM Series is a family of high-capacity floor-model universal testing machines available in four force capacities – DFM-100 (100 kN), DFM-150 (150 kN), DFM-300 (300 kN), and DFM-600 (600 kN). Force verification conforms to ASTM E4 and ISO 7500-1, so quality control data stands up under external audit.

Typical features include:

• Dual-column load frame with twin ball-screw drive and closed-loop servo control
• Speed accuracy of ±0.1% of set speed, and position accuracy the greater of 0.025 mm or 0.025% of movement
• DragonFly UTS software with a pre-configured test method library spanning ASTM, ISO, BS, EN, GB, and DIN standards
• Support for tensile, compression, flex, adhesion, and creep-to-fail testing across metals, composites, plastics, rubber, textiles, and fasteners

View the full specification on the DFM Series product page. If you are not sure which force capacity fits your typical test loads, our United Testing Systems specialists can help you choose.

Related Standards

ISO 7500-1 works as part of a wider family of force and materials-testing standards. Those most commonly referenced alongside it include:

• ISO 376 – calibration of the force-proving instruments used to verify uniaxial testing machines (the reference standard for the load cells used in an ISO 7500-1 verification)
• ISO 9513 – calibration of extensometer systems, the strain-measurement companion to ISO 7500-1
• ISO 6892-1 – metallic materials tensile testing at room temperature, which calls for a Class 1 force-measuring system verified to ISO 7500-1
• ISO 7500-2 – the sibling part covering tension creep testing machines
• ASTM E4 – the US practice for force verification of testing machines, the counterpart to ISO 7500-1 (see our ASTM E4 page)
• ASTM E74 – the US counterpart to ISO 376, covering the force-measuring instruments used as references

Your Global Test and Measurement Partner for ISO 7500-1

Industrial Physics supports quality, R&D, and operations experts around the world with the materials test and measurement equipment and expertise needed to work confidently with standards like ISO 7500-1. Whether you are specifying a new universal testing machine, planning a force verification, or building a documented QC workflow, we can help you achieve accurate, repeatable, and reliable results.

Get in touch to talk through your force verification and materials testing requirements.