S Type Load Cells The Heart of Reliable and Precise Material Testing
When it comes to materials testing, precision is everything. Whether performing tensile testing of a metal wire, compressive testing of a polymer cube, or fatigue testing of a composite material, every test result depends on one key element: the load cell. Among the multiple load cell types available, the S-type load cell has recently become the preferred choice for UTMs because it is more sensitive, stable, and versatile than other alternatives.
What Is an S-Type Load Cell?
The “S” in S-type load cell refers to its capability to measure both tension and compression. It is a type of force transducer designed to measure both pulling (tension) and pushing (compression) loads. The metal body of the sensor also contains bonded strain gauges. When force is applied, the load cell deforms slightly – stretching or compressing the strain gauges. This deformation changes the electrical resistance of the gauges, and this change is converted into an electrical signal that is directly proportional to the strain.
STC Tension Compression Load Cell for Crane Weighing Scale
Due to its symmetrical construction, the S-type load cell can measure forces in both directions with good linearity and repeatability. It is compact, simple to mount, and can accommodate forces ranging from a few newtons to several tons.
Why the S-Type Load Cell Matters in Universal Testing Machines
A UTM is a testing apparatus that works by applying loads and forces to material samples. These machines are commonly employed in both quality control and research and product development applications across industries such as metals, plastics, textiles, composites, and biomedical materials.
At the center of every UTM is the load cell — the component that directly measures the applied force. The UTM is a typical commercial application for the S-type load cell because:
Accommodates both tension and compression testing without sensor changes
Provides high accuracy over an extremely wide range of forces
Remains stable under repeatable loads
Offers a cost-efficient solution that can be easily integrated into vertical or horizontal machine frames
When properly calibrated and conditioned, an S-type load cell enables you to achieve accurate and reliable data for any test — even those with multiple testing stages.
STK S Type Alloy Steel Load Cell for Tank Scales
How S Type Load Cells Are Used in Universal Testing Machines
The S-type load cell has a wide range of applications across many industries, functioning as a transducer for both static and dynamic force measurement.
These force sensors are essential for accurately determining tensile, compressive, and dynamic forces, enabling highly precise and repeatable results in material testing.
Tension Testing Machines
Tensile testing stretches a specimen until it breaks. The gradually increasing tensile force during the test is measured by an S-shaped load cell, and the collected data are used to calculate mechanical properties such as Ultimate Tensile Strength (UTS), Yield Strength (YS), and percent elongation at yield.
These load cells are widely used for materials such as metals, plastics, rubber, and fibers, owing to their ability to accurately capture both static and dynamic loads.
Compression Testing Machines
In compression tests, materials are deformed or fractured under applied force. The load applied to the specimen is measured by an S-type load cell.
Such measurements are useful for characterizing materials like foams, ceramics, and construction materials in terms of compressive strength, modulus, and deformation properties.
STM S Type Stainless Steel Load Cell for Push-Pull Force gauge
Bending (Flexural) Testing Machines
In bending or flexural testing, the specimen is supported at two points while a load is applied at the center.
The S-type load cell measures the force required to bend the specimen, allowing for the determination of flexural strength, stiffness, and modulus of rupture.
These results are commonly used to evaluate the structural integrity of brittle materials, composites, and laminates.
Shear Testing Machines
Shear testing assesses a material’s ability to resist sliding or deformation along an internal plane.
The S-type load cell provides accurate measurement of the applied shear force, allowing precise evaluation of shear strength even under complex loading conditions.
Torsion Testing Machines
Torsion testing involves twisting a specimen, rod, or product to study the stresses and strains generated by torque.
When used in combination with a torque transducer, an S-beam load cell can measure both axial force and torque, providing valuable data for analyzing torsional strength and shear modulus.
STL S Type Alloy Steel Load Cell for Belt Weigh Scales
Peel, Tear, and Adhesion Testers
Peel and tear tests are standard methods used in industries such as adhesives, films, and packaging to measure the force required to separate bonded or laminated materials.
S-beam load cells, a variation of the S-type design, are also widely used in these tests as well as in crane scales and platform scales, especially under harsh environmental conditions.
Indentation and Puncture Testing Machines
Indentation and puncture tests apply localized loads to assess hardness, puncture resistance, or surface strength.
The S-type load cell is sensitive enough to measure very small forces and corresponding minor deflections, making it ideal for thin films, membranes, soft polymers, and biological samples, where high force resolution is critical.
Specimens for Tensile Stress, Modulus of Elasticity, and Elongation
In such setups, an S-type load cell is used to measure force, while deformation is captured by displacement or extensometer sensors.
When used together, they provide the data required to calculate Young’s modulus, stress–strain relationships, and strain rate, especially for samples with non-standard shapes or small dimensions.
Fatigue and Cyclic Loading Machines
In fatigue testing, repeated or alternating loads are applied to a specimen until failure occurs.
The S-type load cell, known for its high accuracy, linearity, and stability, ensures precision during long-term cyclic loading, minimizing drift and improving the repeatability and accuracy of force measurements through millions of cycles.
Machines for Creep and Stress Relaxation Testing
For long-duration experiments where materials are subjected to constant load or strain, the S-type load cell provides excellent stability and low signal drift.
It delivers reliable data for creep rate determination, time-dependent deformation, and stress relaxation behavior over extended testing periods lasting hours, days, or even months.
High-Temperature and Environmental Test Modules
S-type load cells constructed from stainless steel or equipped with temperature-compensated strain gauges maintain high accuracy and repeatability even under harsh environmental conditions.
They remain well-calibrated under high temperature, high humidity, or corrosive atmospheres, making them ideal for use in controlled environmental chambers and specialized test modules.