Enlarged Washer A fastener that has the appearance of a flat disk with a smooth cylindrical hole in the middle, the diameter of which is larger than the diameter of the metric product with which it is used. Materials from which they are made: steel 140, 200.
Scope DIN 9021 is effectively used for joining materials with a soft structure, such as wood, plastic, etc. The people also have the name "rivet washer", which indicates its appropriate use. Also often used with self-tapping screws DIN 571 and threaded studs DIN 975 when installing wooden structures. A characteristic feature of this washer is that the outer diameter is equal to 3rd of the inner diameter, which helps to take these parameters into account during calculations and installation.
Material Stainless Steel. The A4 steel grade allows you to use fasteners with significant temperature changes and in an aggressive and humid environment.
No coating.
Analogs GOST 6958-78, ISO 7093-1. ISO 7093-2.