|Chamfer angle α = 70° ± 2°||
This relatively large angle is necessary when using hexagon headed bolts, which usually have a tapered transfer from shank to head (the so-called trumpet) to avoid fouling of the washer.
|Chamfer edge F||
The extended chamfer side F as seen from d<SUB>2</SUB> creates with d<SUB>1 </SUB>an edge the so-called trumpet of the transfer from shank to head of the bolt, so that the smallest radial clearance prevails. Even with the smallest angle of 68° and the lower dimension of d<SUB>2 </SUB>and d<SUB>1 </SUB>the radial clearance of all bolts to DIN EN is still sufficient.
|Chamfer face diameter d2||
This dimension is, together with the chamfer angle α 70° and the inside diameter d<SUB>1</SUB>, the most important dimension of these heavy duty washers. Diameter d<SUB>2</SUB> 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<SUB>2</SUB> of the hardened washer will not be pressed into the underhead radius causing an indentation on the bolt which would damage the bolt.
|Features and applications||
The influence of a washer on the quality of the screwed connection is very often understimated. With washers GN 6339, high quality preloaded screwed connections can be established. A high static clamping force can be reached avoiding loss of tension.<BR>At a specified preloaded clamping force it is often possible to use thinner bolts. This can result in a better ratio between clamping distance and bolt diameter to minimise the danger of failure.<BR>The case hardened smooth bolt head/screw contact face leads to a lower and more constant friction coefficient even when continuous clamping and releasing operations are required.<BR>Washers GN 6339 are only suitable for machine construction bolts of classes 8.8 / 10.9 / 12.9, and not for steel bolts DIN 6914.
|Inside diameter d1||
The inside diameter d<SUB>1 </SUB>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 d<SUB>2 </SUB>and the max. contact area diameter of the bolt head.
|Lead height h2||
This is the height of the cylindrical part of the internal diameter d<SUB>1</SUB>, h<SUB>2</SUB> should be as high as possible in relation to the pitch of the thread of the bolt.
– Version <STRONG>BT</STRONG>: case hardened black oxide steel, material-no. 1.7227, fine machined and fine ground, tensile strength Rm = 1220 – 1400 N/mm<SUP>2</SUP>.<BR>- Version <STRONG>GO</STRONG>: case hardened steel treated GEOMET 500, material-no. 1.7227, fine machined and fine ground, tensile strength Rm = 1220 – 1400 N/mm<SUP>2</SUP>.
|Outside diameter D||
The outside diameter D of the lower refers to washers DIN 125 / ISO 7089, and the higher type to washers DIN 7349.
|Washer thickness L||
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<SUB>2</SUB>, a minimum height is established which ensures that the bolt thread will not be damaged when the bolt is tightened.