ASTM A125 covers spring compression testing for helical heat-treated springs. These types of springs are typically used in the transportation industry for suspension systems and can also be seen in certain types of industrial machinery. Springs are often used to store or dissipate energy in a simple and efficient manner.
Most spring testing is done in the compression mode.
Springs are manufactured in many different varieties. Some key measurement characteristics include the diameter of the bar, the height of spring, the number of coils as it relates to height, coil diameter, and whether the end of the spring is squared or round. ASTM A125 specifies a deflection loading of up to 85% of the original height.
Platens are used to compress the spring to the required amount of deflection. Industrial springs can be quite robust and therefore a high capacity compression tester is often needed. When springs are compressed, they can store a considerable amount of energy. Proper safety precautions must be taken and many spring testing machines will feature some sort of mechanism to attach the spring to one of the platens. A safety cage may also be used for maximum protection.
There are several calculations cited under A125. Solid Capacity is represented in lbs. and is a measure of the capacity of the spring to withstand and store a compressive force. The solid height is defined as the total height of the spring when it is subjected to a compressive load that causes all adjacent coils to touch. Once all of the coils touch, the spring cannot be compressed any farther, therefore solid height is a maximum value.
For more information, please use the spring calculator.