A dial indicating torque screwdriver is designed for torque evaluation and torque verification. It is a low cost tool that can utilized for QC, R & D and assembly operations. The Mountz dial indicating torque screwdriver can be used to monitor torque as it increases or decreases or display peak torque applied. The dial torque screwdrivers, by Mountz, measure torque through the use of known twisting force needed to distort a torsion bar. The amount of torque applied is measured on a dual scale dial display. This tool can be used in two ways, it can either be set in track mode so it can constantly track the applied torque or set in memory mode, which is done by withdrawing the slider and resetting the bezel ring to zero before using. This tracks the applied torque as before, but leaves the memory pointer at the maximum torque position.
Determine Torque Requirements in R & D
When determining correct torque specifications, the engineer must consider the maximum load placed on the fastener, the strength of the material joined, and whether the joint is hard or soft. A hard joint connects materials directly. In this case, the fastener rotates very few degrees to develop full clamping force after it encounters the material. Since a soft joint contains a gasket or involves compressible materials, it requires additional tightening after the fastener makes contact, to achieve full clamping force.
One recognized method is to perform a destructive test with a calibrated torque control tool on the actual material and fastener to be joined. An evaluation is usually conducted with ten parts, ten fasteners, and a calibrated torque control tool with a transducer. First the fastener is tightened to the point of failure, then repeated several times to verify the consistency of the failure point. Now another series of tests is begun whereby the joint is torqued to 75% of the failure point. Depending on how the parts will be used, the tightening can be reduced by any degree necessary. If parts on a machine are subject to heavy vibration, maybe 85% of the total force is necessary for good torque control.