Do not use self tapping screws
Flat head screws, etc. also does not require the use of gasket. In many applications, the force of the screw is not large, often do not disassemble, there is no need for gaskets. And the existence of the gasket, affect the appearance, does not apply to the use of countersunk head screws.
No provisions of self tapping screws without gasket, but because the self tapping screws are often used in non regular removal of the place, and will not force big place, so unless there is a need to increase the stress area of the nut, generally do not have to use the gasket.Self tapping screws also have a flat head, in this case, the general should be smaller than the top of the back, or else they can not get into the hole in the ah.
Flat washer is generally used in the connecting piece is a soft texture, a hard brittle, its main role is to increase the contact area, pressure distribution, to prevent the soft texture of the crush. The basic function of the spring of the spring washer is to tighten the nut after the nut to a force, increasing the friction between the nut and bolt! The material is 65Mn (spring steel), heat treatment hardness is HRC44 ~ 51HRC, through the surface oxidation treatment.
Self tapping screws are needed to use the gasket.A part between a connector and a nut. A flat metal ring is generally used to protect the surface of the connecting piece from the nut.
