Knowledge Base
UTM Glossary & Fact Sheet
UTM Key Terms: Glossary & Fact Sheet
A quick-reference guide to the most important terms in Universal Testing Machine (UTM) operation and materials testing. For a full explanation of how these terms are applied in practice, see our Test Method Explainer.
Load frame The structural component of a UTM that houses the crosshead, columns, platens, and drive system. Designed to minimise deflection under load to ensure accurate force measurement.
Crosshead The moving part of the load frame that travels up or down to apply tensile or compressive force to the specimen. Speed and position are controlled by the computer system and measured by an optical encoder.
Load cell A strain-gauge transducer that converts mechanical force into an electrical signal. The load cell determines both the measurement range and the accuracy of a UTM. Cells are interchangeable to match specimen type and force range.
Frame stiffness (kN/mm) A measure of how much the load frame deflects under load. Higher stiffness means less deflection and more accurate results — particularly important in high-force applications. The UTM 5–25kN delivers 35kN/mm; the UTM 100–600kN achieves 140kN/mm.
Tensile strength The maximum stress a material can withstand while being stretched before breaking. Expressed in N, kN, MPa, or psi depending on the standard. Governed by ASTM D790 (films), ISO 6892 (metals), ISO 527 (plastics).
Elongation at break The percentage increase in a specimen’s gauge length at the point of fracture. A key measure of material ductility and flexibility.
Peel force / Seal strength The force required to separate two bonded or heat-sealed surfaces. Critical for packaging integrity testing. Governed by ASTM D638 (flexible packaging seal strength).
Crosshead speed The rate at which the crosshead moves during a test, expressed in mm/min. Test standards specify required speeds. The UTM range offers speeds from 0.0017mm/min to 1,016mm/min with 0.1% average accuracy.
ASTM E8 The ASTM International standard governing the calibration and verification of force-measuring instruments used in tensile and compression testing. All UTM machines from United Testing Systems are certified to ASTM E8.
Extensometer An optional accessory attached directly to the specimen to measure strain more precisely than crosshead displacement alone. Used when direct strain measurement is required by the relevant test standard.
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FAQs
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All UTMs in the United Testing Systems range deliver an average crosshead speed accuracy of 0.1% — consistent across the full speed range of 0.0017mm/min to 1,016mm/min (UTM 5–10kN) and 0.0017mm/min to 508mm/min (UTM 100–600kN).
Accuracy in a UTM is determined by several factors: load cell quality and calibration, frame stiffness (which governs how much the machine itself deflects under load), optical encoder resolution for position tracking, and the software’s control of the servo loop.
United Testing Systems machines use a dual feedback loop — a DC tachometer for coarse motor speed control, and microcomputer-controlled precision management of position, speed, strain, and load rate. This architecture ensures stable, repeatable results whether you’re running a single specimen or a high-volume QC batch.
Frame stiffness is particularly important in low-force applications. The UTM 5–10kN delivers 35kN/mm stiffness, meaning crosshead displacement closely reflects actual specimen deformation. Where even greater precision is required, an extensometer can be attached directly to the specimen for direct strain measurement.
A 15-minute warm-up period is recommended before testing begins, and the A/D board standardisation runs automatically at start-up to maintain calibration integrity.
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The three hero configurations in the United Testing Systems UTM range are distinguished primarily by their load capacity, which determines the type and weight of specimens they can test accurately.
The DSTM 5–25kN is designed for low-force applications. It’s the machine of choice for testing thin flexible packaging materials, plastic films, adhesive tapes, foils, and fibres — where sensitivity and accuracy at low force values matter most. With a frame stiffness of 35kN/mm and crosshead speeds up to 1,016mm/min, it is well-suited to laboratory testing environments performing ASTM D790 and ASTM D638.
The UTM 50–100kN provides greater force capacity for mid-range applications. It’s suited to rigid packaging substrates, thick plastics, woven materials, and rubber compounds where more force is needed without stepping up to full industrial-scale capacity.
The UTM 100–600kN is engineered for high-force industrial applications — metals, composites, structural components, and heavy-duty assemblies. With a frame stiffness of 140kN/mm and a crosshead travel of 1,525mm, it handles demanding test programmes in both quality control and R&D settings.
Choosing the right machine comes down to matching load capacity to your specimen type. Our team can help you identify the right configuration for your application. Contact us here.
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UTMs from United Testing Systems are certified in accordance with ASTM E8 — the standard governing the calibration and verification of force-measuring systems used in tension and compression testing. This is the foundational compliance requirement for any UTM operating in a quality or R&D environment.
Depending on your application, UTM testing programmes typically reference the following standards:
- ASTM D790 — Standard Test Method for Tensile Properties of Thin Plastic Sheeting
- ASTM D638 — Standard Test Method for Seal Strength of Flexible Barrier Materials
- ASTM F1140 — Standard Test Methods for Internal Pressurization Failure Resistance of Unrestrained Packages
- ISO 527 — Plastics: Determination of Tensile Properties
- ISO 6892 — Metallic Materials: Tensile Testing
The UTM range’s A/D board is automatically standardised each time the system initialises, ensuring the machine is always operating from a calibrated baseline — supporting audit readiness and the production of standards-compliant test records.
→ See our UTM Glossary for definitions of key standards and terms
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