1. Identify from the gap of the screw

If it is the first time to contact and use a non-standard screw, under normal circumstances, they think that the screw is relatively smooth, it should be a good screw, but it cannot be judged like this, because if the gap of the screw is too large, although the screw The rod is relatively smooth to use, but it cannot reach the required accuracy.

2. Identify from the material

If it is a low-quality non-standard lead screw, it will generally be made of relatively cheap 45# steel. In order to achieve a relatively low production cost, the rigidity and hardness basically cannot meet the standard requirements, and the normal import The non-standard screws are all made of Scm420H alloy bearing steel, so the hardness is between HRC58-62.

3. Distinguish from appearance

Non-standard screw manufacturers, because the imported screw is relatively good in material, the metal luster of the surface is relatively uniform, and the weight is relatively heavy; if the material is impure, then relatively speaking The gloss will be darker, because many use polishing to cover up.