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How to do strength torsion test for combination screws?

The combination screw is a tool that uses the physical and mathematical principles of the oblique circular rotation of the object and the frictional force to fasten the machine parts step by step. In use, it often occurs that the teeth cannot be closely adhered to each other, the screw head of the combination will be broken off if the screw is locked too hard, or the tooth pattern cannot be locked tightly, etc., which are all problems of quality accuracy. So today I will tell you how the combined screw does the strength torsion test.

Combined screw strength torsion test:
1. Turning force test: The changing power of a product is the ability to demonstrate its ability to resist being changed into two halves. Various specifications have the minimum requirements for the changing force of self-tapping combination screws. This test is to clamp the combination screw in a chuck with a tapping center cut on the changing force test tool, and then apply force with a torque wrench until the combination screw is twist off. If the torque does not exceed the minimum requirements of the rules, the product is unqualified. Unqualified shows that the combination screw is too soft or the diameter of the thread is too small.

2. Locking test: This test is to lock the combination screw to a test board, which has regular hardness/thickness and hole diameter. If the combination screw is locked through the test board, but the thread is deformed, the product is not qualified. Unqualified shows that the surface hardening of the combination screw is too shallow or too soft.

3. Locking torque test: This test is only required for screw-rolled combination screws. When performing the locking test, the minimum locking torque of the test board was observed. If the torque exceeds the specified standard value (the standard value depends on the size/surface treatment of the combined screw), the product is not qualified. The failure shows that the surface of the hinge screw does not have enough lubricity, or the thread is improperly formed and requires more torque.