Usually there are 12 categories which are bolt , stud, screw, nut , selftappingscrew, wood screw, gasket, retainer ring, pin, composite member, bolting, and soldering lamp.
A section bar of a selftappingscrew for saving drilling hole is provided with high-tightening force, which belongs to the design preparation technical field of the section bar.
可免钻孔上自攻螺丝并具有高紧固力的型材，属型材的设计制造技术领域。
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This company mainly produces various series of drilling screw with tappingscrew dry wall screw fiber board screwself - tappingscrew machine screw all kinds of non-standard goods.