English 
In 2014, Longking Group's dust bag project needed a clip spring, which required strong elasticity and high strength. Many suppliers could not achieve the requirements for flexibility with ordinary iron, manganese steel and carbon steel The project was in a state of stagnation. At the requ
A US customer proposed an idea of a nylon rope fixing device for household trucks (with a coil spring retracting box), but he could not accomplish it. Our R&D Department completed the design and achieved the goal, independently.
