A dial indicating torque screwdriver is designed for torque evaluation and torque verification. It is a low cost tool that can be 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 measuring tool on the actual material and fastener to be joined. An evaluation is usually conducted with ten parts, ten fasteners, and a torque measuring instrument. 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.
Torque Measurement with a Dial Torque Screwdriver
Once a torque specification is determined, the joint should be audited to verify the product has been fastened to the specified torque. It is important to audit the joint for accuracy and to ensure your product’s quality, safety and reliability isn’t compromised. A dial indicating screwdriver can perform these two common torque testing and verification methods.
1) First Movement Test – Once the fastener has been tightened, employ the use of torque measuring tool. Mark the tightened fastener and surrounding application. In the tightening direction, begin to slowly apply force to the tool until the first movement in the fastener is noted. The reading recorded is a good indication of the original torque applied to the joint. This is the best way to determine residual torque.
2) Loosening Test – This is a similar process to the first movement test described above, except instead of the tightening the fastener, the torque is applied in the direction that loosens the fastener. At the point the fastener breaks loose, the torque reading is recorded. The torque value to loosen the fastener is the approximate torque that was applied to the joint.
Torque measurement is utilized in all three areas of the assembly process. Controlling torque is essential for companies to ensure their product’s quality, safety and reliability isn’t compromised. The failure of a three-cent fastener that isn’t properly tightened can lead to catastrophic or latent failures. Fasteners that are insufficiently torqued can vibrate loose and excessive torque can strip threaded fasteners. It is important for many companies to ensure that proper torque is being applied and maintains gauge requirements associated with the ISO 9001 Quality Standard.
When it comes to measuring torque, Mountz is the torque expert. Need assistance with a torque testing application? Contact us .
