2021 Satra STM512 Repeated Compression Tester

The Satra STM 512 is a two-station repeated compression tester designed to simulate the forces applied by repeated heel strikes during walking. This machine evaluates whole shoe constructions, heel components, and midsole materials for structural fatigue and compression set, which is the permanent loss of material thickness. The mechanism utilizes a pneumatic plunger equipped with a domed striker to represent the human heel. It features adjustable loading forces to replicate the specific impacts attributed to men, women, or children. The cycle limit is programmable, with a standard test typically running for 500,000 cycles. Additionally, the strike rate can be increased to accommodate accelerated testing or the assessment of running shoes. The equipment requires a clean, dry compressed air supply for operation. Key metrics measured include failure due to collapse or splitting, material thickness loss, and the degradation of shock absorption over time. It can also be utilized to produce material ageing prior to further assessments.