Our fasteners for standard parts are usually in 7-10 days，If it is non-standard fasteners, it takes 20-35 days.
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1, the spring washer expansion ring phenomenon, generally not the spring washer itself.
2, the spring washer that produces the expansion ring must be subject to a radial external tension, and the external tension comes from the tightening axial force generated by the tightening torque.
3, the outer chamfer of the nut supporting surface causes the radial component of the axial clamping force, which makes the opening of the spring washer expand. The smaller the diameter of the chamfer, the more likely it is to swell.
4. Adding a flat washer between the nut and the spring washer helps to slow down or prevent the expansion of the ring, but the flat washer is too thin or too soft to prevent the expansion of the ring.
5, spring gasket hydrogen embrittlement fracture is generally caused by unreasonable heat treatment process, and there is no timely hydrogen removal treatment after electric galvanizing.
The specification model of the bolt is usually expressed by M, and the number behind M indicates the diameter of the bolt, in mm.
For example, M8 indicates a bolt with a diameter of 8mm, and M10 indicates a bolt with a diameter of 1.0mm. The length of the bolt is generally expressed in L, and the unit is mm.
For example, L50 indicates a bolt whose length is 50mm. The type of bolt can also be expressed in the form of "M circular diameter length (CM)".
Where M represents the metric thread, for example, M81.25.50 means that the nominal diameter is 8mm. The pitch is 1.25. The screw length is 50mm bolt.
The performance grade of the nut varies according to different use occasions and bearing requirements, and the common performance grades are 4.8, 8.8, 10.9 and so on.
For example, the common nut grades in the ISO standard are 4, 5, 6, 8 and 10, where a class 4 nut is a low-strength general purpose nut and a Class 10 nut is a high-strength special nut.
In addition, the performance grades of the nuts used for steel structure connection are more subdivided, including 3.6.4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, 12.9 and other grades.