The flat pad, which is mainly punched out with an iron plate, is
generally a flat washer with a hole in the middle. This hole size
specification is generally based on customer requirements.
Flat washers are usually thin pieces of various shapes to reduce
friction, prevent leaks, isolate, prevent loosening, or distribute
pressure. This material is used in many materials and structures to
perform a variety of similar functions. Due to the limitations of
the material and process of the threaded fasteners, the bearing
surfaces of the fasteners such as the bolts are not large, so that
the surface of the parts to be joined is protected to reduce the
compressive stress of the bearing surface, and washers are used. In
order to prevent loosening of the connection pair, loose-proof
spring washers and multi-tooth lock washers, round nut stop washers
and saddle-shaped, corrugated, conical elastic washers are used.
Flat washers are mainly used to reduce the pressure. When some
parts are tightened with large axial forces, the washers are easily
pressed into a dish shape. In this case, the material can be
changed and the hardness can be improved.
According to flat washer performance level, recommended materials
are used:
For the 100HV class available with ST12, ST13 and Q235, Q215, Q195,
etc., the surface hardness can reach about 110HV;
For the 140HV class with optional 08F, 08Al and 10, 10F, etc., the
surface hardness can reach about 140HV;
For the 200HV and 300HV grades, 45, 50, 60, 70 or 65Mn steels
should be used. They can be quenched and tempered by heat treatment
to 200-300HV and 300-400HV technical requirements.
