Overview
The DIN 9021 standard describes a flat standard body washer called an enlarged washer. The purpose of the DIN 9021 washer is to reduce the deformation of the materials to be joined. It is also often used to increase the support part of the screw and increase the strength of the formed connection.
DIN 9021 fastening group
The fastening group to which DIN 9021 belongs directly depends on the material of its manufacture:
- If the washer is made of steel with a strength class above 140HV, it belongs to high-strength fasteners.
- If made of stainless steel - stainless steel fastener
- If made of brass - brass fastener
- And of course, polyamide - polyamide fasteners
Materials used to manufacture the washer DIN 9021
The materials from which the DIN 9021 washer is made are very diverse:
- Steel, which can optionally be coated with zinc, hot-dip galvanized zinc and plate zinc, as well as Delta-MKS.
- Stainless steel, steel grades A2 and A4. This material does not require any additional treatments
- Brass. This material does not require any additional treatment
- Polyamide. This material does not require any additional treatments
Areas of application
DIN 9021 is best used with materials that are characterized as thin-walled, soft, and brittle. When working with these materials, it is important to distribute the torsional load over a larger area than that of the bolt or nut head. After all, thin-sheeted materials can be spun even when screwed in by hand, and will be pushed through and thus deformed.
With soft materials, the situation is the same: if the load on the material is not properly distributed, it will be deformed.
Brittle materials include plastic, which will crack if used improperly.
Read more about sizing in din 9021 pdf.
The scope of application also directly depends on the material of manufacture:
- Galvanized steel is a good protection against corrosion if the fastener is to be used in an aggressive environment.
- Brass is used if the system is subjected to frequent dynamic, vibration loads.
- Stainless steel allows the fasteners to be used at significant temperature changes and in aggressive and humid environments.
- Polyamide hardware withstands mechanical shocks, does not crack or break at the permissible load factor.
