Why do some nuts and washers, and some nuts without washers
This is according to the requirements of the guests. Some need to add, some do not need to add
If the diameter of the screw and the diameter of the fixed parts of the hole size difference is relatively large, if not washers, nuts and parts of the contact area is relatively small, it is necessary to increase the contact area of the gasket. In addition, the pressing oblong hole, also need to add washer. The same reason is to increase the contact area, making the connection more reliable.
General screw diameter and the diameter of the fastening parts of the hole is not large, the nut and parts of the contact area is relatively large, you can not add a gasket
