https://www.jinzen.cc/product/jinzen-sewing-machine-spare-parts/
Industrial sewing machines contain many moving parts that work together at high frequency. Hooks, feed dogs, presser feet, needle-related components and other mechanisms repeatedly contact or move against surrounding parts.

With continuous operation, friction and mechanical contact become important factors in component selection. The suitable material, surface condition and dimensional accuracy depend on how the part interacts with the rest of the mechanism.

A component designed for frequent movement should not be evaluated only by whether it can be installed. Its behavior during sustained operation is equally important.