Standard_Parts_Catalogue

Page 1089 | 3.2 Mounting, Positioning, Leveling with Screws, Clamping and Supporting Elements 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 GN 6339 Heavy Duty Washers continued Outside diameter d 2 The outside diameter d 2 of the lower type refers to washers DIN 125 / ISO 7089, and the higher type to washers DIN 7349. Chamfer face diameter d 3 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 d 3 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 d 1 The inside diameter d 1 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 cham- fer diameter d 3 and the max. contact area diameter of the bolt head. Technical information Chamfer angle α = 70° ± 2° This relatively large angle is necessary when using hexagon headed bolts to avoid interference with the chamfer face diameter d 3 of the washer. Chamfer edge F The extended chamfer edge F, as seen from d 3 , and d 1 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 d 1 , 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 d 3 , a minimum height is established which ensures that the bolt thread will not be damaged when the bolt is tightened.