Load Cells

Load Cells for Universal Testing Machines

Load cells are the primary force-measurement devices used in universal testing machines (UTMs). In tensile, compression, peel, shear, and flexural testing, the accuracy and repeatability of the measured force directly determine the quality of the test results. For this reason, modern UTMs overwhelmingly rely on strain-gauge load cells configured in a Wheatstone bridge, a technology that delivers high accuracy, excellent linearity, and long-term stability across a wide range of loads.

How Strain-Gauge Load Cells Work

A strain-gauge load cell converts applied mechanical force into a measurable electrical signal. The core sensing element is a precisely machined elastic metal body—often steel or aluminum—designed to deform predictably when a load is applied.

Bonded to this elastic element are strain gauges, thin resistive foils that change electrical resistance in proportion to mechanical strain. These gauges are wired together in a Wheatstone bridge configuration, typically using four active gauges arranged so that:

• Two gauges experience tensile strain

• Two gauges experience compressive strain

When force is applied, the bridge becomes unbalanced, producing a small differential voltage output (usually expressed in mV/V) that is directly proportional to the applied load.

Key advantages of the Wheatstone bridge configuration include:

• Temperature compensation – opposing gauge placement minimizes thermal drift

• High sensitivity – small strains produce stable, measurable signals

• Excellent linearity and repeatability – critical for standards-based materials testing

This analog signal is then amplified and interpreted by the testing machine’s controller or by a standalone digital indicator.

Why Load Cells Are Essential in Universal Testing Machines

Universal testing machines are designed to apply controlled forces while precisely measuring the response of a material or component. The load cell is therefore the defining sensor in the entire measurement chain.

In a UTM, the load cell:

• Measures applied force during tension, compression, peel, shear, and flexure tests

• Enables compliance with ASTM, ISO, DIN, and other international standards

• Ensures traceable, repeatable, and auditable test results

• Protects the system from overload through defined capacity limits

Selecting the correct load cell capacity and accuracy class is essential. An undersized load cell risks overload damage, while an oversized load cell reduces resolution at low forces. For this reason, many laboratories use multiple load cells optimized for different force ranges.

Load Cells from Universal Test Machine Co.

Universal Test Machine Co. supplies precision strain-gauge load cells engineered specifically for universal testing machine applications. Our offering includes:

• Replacement load cells for Chatillon & Lloyd Instruments systems
  Ideal for maintaining legacy or current test frames without costly OEM upgrades.

• Load cell and digital indicator packages
  Designed for customers building their own tensile or compression testing systems, R&D rigs, or custom automation setups. These matched packages ensure electrical compatibility, stable signal conditioning, and straightforward integration.

• Wide range of capacities and form factors
  From low-force testing of films, fibers, and medical devices to higher-capacity testing of metals, fasteners, and assemblies.

Calibration and Traceability

Every load cell supplied by Universal Test Machine Co. is delivered with a detailed ISO/IEC 17025 calibration certificate, ensuring full traceability to national and international standards through accredited laboratories aligned with International Organization for Standardization requirements.

This calibration documentation supports:

• Laboratory accreditation and audits

• Compliance with ASTM and ISO test methods

• Confidence in long-term measurement accuracy

Product Families and Load Cell Selection

This page serves as the foundation of our load cell offering. From here, we break down into individual load cell families, capacities, geometries, and application-specific product lines, helping you select the optimal sensor for your testing requirements.

Whether you are replacing an existing load cell, upgrading an older universal testing machine, or designing a custom test system from the ground up, Universal Test Machine Co. provides reliable, calibrated force-measurement solutions built for precision materials testing.