Molded urethane parts have so many beneficial properties that are useful in a wide variety of applications. Today, we will look at a few of the common properties found in polyurethane parts. When your business or industry needs quality, custom-molded urethane parts, be sure to contact ESCO Plastics and let us know what we can create for you.
The hardness of molded urethane parts is measured with a scale called a durometer. The full name, Shore Durometer, comes from its creator Albert Ferdinand Shore. He developed a device to measure hardness in the 1920s. The higher the number on the scale, the greater an object’s resistance to indentation, which indicates that it is a very hard object. The lower the number, the less resistance, and therefore softer material. There are several scales of durometer which are used for materials with different properties. The two most commonly used scales are the ASTM D2240 and the ASTM D412 — commonly referred to as Shore A and Shore D.
The word tensile refers to the ability of a material or object to be drawn out or stretched without breaking or tearing. The ability to sustain higher stresses than other materials is one of the great qualities of polyurethane products. It is, therefore, crucial for you to know the tensile strength requirements of your molded urethane parts so that they can perform their job well. As a result, when ESCO Plastics tests our products before shipment, we test for tensile strength, which is the maximum strength of the urethane product before failure.
A modulus is the force at a specific value of elongation. In connection with molded urethane parts, this refers to the stress in pounds per square inch that is required to produce elongation. Typically, this is done using a cross-section of the original product. A modulus test is similar to a tensile strength test, however, the sample is stretched to a predetermined percent larger than the original size so that the force needed to stretch it can be determined. The resulting force will be measured in PSI.
Elongation is measured by applying tensile force — stretching the molded urethane material and determining the change in length from the original product. The stretching is done using a dumbbell-shaped piece of the material that is placed between the grips of a tensometer. This machine then steadily pulls the material apart until it reaches its breaking point, or point of failure.
Due to their high load-bearing capabilities, urethane products can handle more stress without failing than most other materials. It is essential to determine just how high the load-bearing capabilities of your product are before they are put into use. One way that this can be done is with a compressive set test. The urethane product is put under a compressive load that minimizes its thickness to a predetermined measurement. While the product is in contact with the two compressive plates, it typically spreads out laterally, which increases the effective load-bearing area. Once it has reached the predetermined measurement of thickness, the test will continue for a certain period of time at which point the material will be released and re-measured.
At ESCO Plastics, we take the quality and performance of our polyurethane products very seriously. We run industry-standard tests to make sure that your parts meet the specifications you need before they are put into applications where they need to perform under all manners of stress. When you need the best custom-molded urethane products available, be sure to contact ESCO Plastics.