ADVANCED MATERIALS & PROCESSES | JANUARY 2026 29 The purpose of performing materials testing is to ensure that the properties of the examined materials will meet specific requirements. Proper testing on a material testing/ force stand ensures that the material will respond appropriately when placed under the expected usage conditions, or meet the standards required for product development. For rubber materials, the properties are often found by testing the raw component before it is made into the final product. Tests range from elasticity to hardness, tear resistance, and even relaxation of forces, or creep. These tests can provide insight into the qualities of the materials, allowing for analysis in product development, materials processing, and/or materials handling so that adjustments can be made as necessary at any stage of manufacturing. COMPRESSION TESTING For certain rubber products, deflection under compression loads is a significant aspect of the material quality that ensures a finished part’s longevity. A good example is the soles of shoes. Soles are designed to support weight, and as a result, the soles of the shoe need to deflect appropriately to ensure functionality and comfort. Compression testing would enable the observation of how much the material deflects while load is applied—for example, applying 100 pounds to an approximately 1-inch square section yields 100 pounds per square inch (psi). Afterward, the comparison of the change in height subsequent to the load being applied to the sample will inform on the deflection TECHNICAL SPOTLIGHT RUBBER MATERIALS TESTING: A PRIMER Proper elongation and break testing of rubber materials ensures the most accurate assessment of a sample’s properties. be observed and measured. The changes may include modulus of elasticity or the ultimate tensile strength when placed in variable thermal conditions. This is valuable information for finished products while operating in a wide range of temperatures, such as rubber automotive parts in all-season vehicles. When testing tensile elongation, accurate measurements are critical. Often, standards will require the usage of an extensometer, which measures the deformation of material under stress, to accurately track the changes in the material sample’s length relative to its starting length. In performing tensile testing, using an extensometer allows for repeatable, consistent measurements based on a fixed starting length. It also enables the determination of elongation to be based on the changes in at 100 pound-force (lbf), or 100 psi for the sample. TENSILE TESTING Tensile testing on rubber materials can be used for determining tear forces, or for determining the inherent properties of the sample, such as modulus of elasticity or ultimate tensile strength. Often, tensile testing is used to test the longevity of a sample by repeatedly working the material to the same load application, or elongation length. Additionally, depending on the force equipment used, environmental conditions can be altered to affect the properties of the material. These adjustments will enable the changes to the properties to Fig. 1 — A Starrett MMS-5000 test stand with built-in extensometer, testing an elastic band. The extensometer is set to travel the full vertical test space as the contacts separate. Fig. 2 — This extensometer is designed for use in both single- and dual-column test stands.
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