GN 6339 Heavy duty washers high type

Outside diameter d₂
The outside diameter d₂ of the lower type refers to washers DIN 125 / ISO 7089, and the higher type to washers DIN 7349.

Chamfer face diameter d₃
This dimension is, together with the chamfer angle α 70 and the inside diameter d°1°, the most important dimension of these heavy duty washers. Diameter d°3°° is actually, even in the lower tolerance range, larger than the max. contact under head diameter on a bolt.
This will ensure that the chamfer of d₃ of the hardened washer will not be pressed into the underhead radius causing an indentation on the bolt which would damage the bolt.

Inside diameter d₁
The inside diameter d₁ is kept as small as possible ensuring that the bolt is inserted centrically into the washer. The choice of a matching pair of bolt and washer with least radial clearance is important in order to avoid a mismatch between chamfer diameter d₃ and the max. contact area diameter of the bolt head.

Chamfer angle α = 70° ± 2°
This relatively large angle is necessary when using hexagon headed bolts to avoid interference with the chamfer face diameter d₃ of the washer.

Chamfer edge F
The extended chamfer edge F, as seen from d₃, and d₁ create an edge that provides the smallest radial clearance towards the transition from bolt shank to head. Even with the minimum chamfer angle of α = 68 and the smallest dimensions for d°1° and d°3°°, this radial clearance is sufficient for all bolts according to DIN EN.

Lead height h
This is the height of the cylindrical part of the internal diameter d₁, h should be as high as possible in relation to the pitch of the thread of the bolt.

Washer thickness s
Washers GN 6339 are higher when compared with DIN washers (exception: DIN 7439 which is equal to the high type).
A larger thickness leads to a stronger washer. As a result, bearing in mind the chamfer d₃, a minimum height is established which ensures that the bolt thread will not be damaged when the bolt is tightened.