Articles
The most accurate method of determining what torque is correct for a joint is to run the actual joint or an exemplar assembly. While this method is pure science, the real world condition is that there is neither time, money, nor labor to do this on most joints. Many Fastener Engineers rely on the use of a torque table (or tables) to give a value for the most general of conditions. What are the conditions and what things affect them? Why is torque used? What is actually needed is tension in the joint. Tension, another term for ‘stretch’ is the force that tends to pull the attachment apart. This counterbalances the external forces affecting the attachment that loosen the components. However, it is almost impossible to measure tension in a joint by any practical method. Bolts can be strain-gaged, a costly process (almost US$150 per bolt on the average), then instrumented and measured in the joint. Then what? Leave the bolt there with wires hanging out?
