The screw size in the cross recessed pan head combination screw has various main technical requirements: the material requirements are iron and stainless steel, iron has low, medium and high carbon steel, and the materials of stainless steel combination screws are stainless steel 201, stainless steel 304 and stainless steel 316. The thread tolerance is 6G, and the mechanical property grades of iron combination screws are 4.8 and 8.8. The 4.8 combination screw is ordinary steel with a maximum allowable hardness of 255HV. The 8.8 combination screw is generally made of wire 10B21 pier, and then hardened, and then dehydrogenated after hardening.
Hydrogen removal is to prevent hydrogen embrittlement of the spring washers in the combination screws. Prevent the spring washers from breaking. The tolerance grade of the combination screws is A. The cross slot is H-shaped. The surface treatment of the combination screws is environmentally friendly and non-environmentally friendly. For example, environmentally friendly blue zinc, environmentally friendly colored zinc, black zinc, colored zinc, white nickel, etc. The technical requirement for the combination screws to the spring washers is that the washers should be able to rotate automatically without falling off.
