Torque tools go out of calibration with use. To maintain consistent accuracy, torque tools must be checked periodically for wear or defective parts. A power or hand torque tool is a measuring tool that must be properly calibrated and maintained. Regular torque tool calibration and re-calibration guarantees the operator repeatable accuracy and adherence to international standards. Torque testing also ensures torque equipment is operating to peak performance and can highlight potential tooling problems before they arise perhaps due to tool wear or broken components.
How do you measure torque? Mountz, “the Torque Tool Specialists,” has over 50 years of experience providing torque tool solutions to industries like medical, aerospace, electronics, energy, automotive and others. We are an ISO 9001 certified company and ISO 17025 accredited company.
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. Torque measurement should occur in three facets of the assembly process.
1. Prior to Assembly
Torque measurement tools, like torque analyzers and torque sensors are used prior to the assembly process. The equipment is used for tool setup or conducting tool capability studies. For tool setup, the tool crib or lab will want to set the torque tool according the torque specification required for the application. For tool capability studies, technicians need to ensure that the torque tool can provide the necessary torque and repeatability that’s required for a potential application.
2. During Assembly
For pneumatic and electric assembly tools that are being used in the production area, many manufacturers like to audit the tool and verify the actual torque being applied to the application or if the tool is starting to fall out of specification. A rotary torque sensor is the ideal torque-auditing tool for testing the actual torque being applied on the assembly application. By connecting a rotary torque sensor between an electric or pneumatic tool and an assembly application, an engineer can measure torque being applied from the tool to the fastener or bolt. This type of torque reading is called a dynamic torque measurement. The rotary sensor is connected to the torque analyzer, which records and stores the data.
Manufacturers also use this auditing process to validate the torque setting of the tool and the data collected during a capabilities study are in sync. Since each assembly application has a different joint rate and tolerances, the performance of the tool on the application may differ from the tool crib or lab results. Using a rotary sensor connected to a torque analyzer, technicians can see if there are any differences with the torque readings between the assembly area and the tool crib or lab. Then the technicians can make any necessary adjustments to the tool or the assembly process.
For hand tools like torque wrenches and hand torque screwdrivers, manufacturers might utilize a torque tester on the production floor and require their assemblers to verify the torque setting daily or weekly to ensure the tools aren’t falling out of calibration. The torque tester will display a result that must be compared to the allowable tolerance of the torque tool. Some torque testers offer a tolerance-setting feature that provides a GO/NG result (RED or GREEN) when the torque tool is tested. If the verification result is OK then the torque tool is deemed in tolerance. If it is NG then calibration or adjustment of the torque tool is required.
3. After Assembly
As a final check, manufacturers may select to verify the torque after an assembly process, so they can verify adequate torque was delivered to the fastener and detect any missed or loose fasteners, or joint relaxation.
What is Residual Torque?
It is the amount of tension that remains in a joint after fastening a threaded fastener. The best way to determine residual torque is by performing a “just move” test. Mountz offers two best practices solutions for measuring residual torque. A digital torque & angle wrench will measure torque applied after 3 degrees of movement, it will also show the final torque measurement and angle applied.
An economical counterpart to a digital wrench is the Mountz dial wrench or dial screwdriver. The dial tool will capture the finishing torque applied to a fastener with memory indicators.
The equipment used for conducting this type of testing would be:
• Dial wrenches and dial screwdrivers
• Digital torque wrenches
• Torque wrench sensor or torque screwdriver sensor mated with a torque analyzer