The first number is the ultimate tensile strengths (UTS) in MPA divided by 100, & the second numbers are the ratio of yield strength to UTS.Ĭommon classes are 5.8, 8.8, & 10.9.

The points are not decimal but act as a denominator. This grade is often stamped on the heads. Using two numbers separated by a point, the bolts are classified according to their strength. The bolt is inserted through the parts that all have unshielded holes, & a nut is then screwed onto the bolt to provide a clamping force & prevent axial motion.Ī screw my first pass through the first part with an evacuation hole, but its threads are being fastened with threads in one part. By some definitions, whether a thing is a bolt or a screw depends on how it is used. This type of fastener is usually inserted through two parts, which have aligned holes. The bolts are closely related to screws, which are also mechanical fasteners with threaded shafts.