K Factors
Bolt Condition K
Non-plated, black finish 0.20 - 0.30
Zinc-plated 0.17 - 0.22
Lubricated 0.12 - 0.16
Cadmium-plated 0.11 - 0.15
The torque wrench is a relatively inexpensive means of giving a rough estimate of the bolt’s preload. For most practical applications, the torque wrench will provide the degree of accuracy desired. However, even perfect input torque can give a variation of preload by as much as 25 - 30 %. The following example will demonstrate some complications that can be involved in calculating torque.
