DIN 125 Flat Washers Form A/B

DIN 125 flat washers are metric plain washers used between a bolt head or nut and the mating surface. Their primary function is to provide a defined bearing surface, distribute the applied clamping load over a larger area, and reduce localized contact stress on the joint. Common market names include flat washer, plain washer, and metric flat washer.

The DIN 125 designation is associated with two principal geometric forms. Form A has a flat outer edge without a chamfer, while Form B has a chamfered outer edge. The distinction is primarily geometric and should not be confused with the “Product Grade A” terminology used in ISO washer standards. DIN 125 Form A corresponds to the dimensional concept covered by ISO 7089, while the chamfered Form B corresponds to ISO 7090.

The washer is selected according to the mating fastener diameter and the required outside diameter and thickness. These dimensions determine the available bearing area and the way the washer interacts with the joint surface. DIN 125 A and ISO 7089 dimensional series are commonly available across a broad metric range, including sizes extending from small metric fasteners to large-diameter applications.

DIN 125 is now a legacy designation, but it remains widely recognized in fastener specifications and commercial product descriptions. For current standard references, ISO 7089 and ISO 7090 are the relevant international standards for the corresponding plain and chamfered washer forms.