In the grand scheme of a manufacturing plant, torque wrenches may seem like small potatoes. But failing to properly calibrate and maintain them can lead to big problems, according to San Jose, Calif.-based toolmaker Mountz Inc.
"In the maintenance and manufacturing world, tightening, controlling or measuring torque of fasteners is imperative for production efficiency and quality control," Mountz explains.
"With inadequate torque, a fastener can vibrate or work loose. Conversely, if the torque is too high, the fastener can break, strip or adjoining parts may fail, causing premature malfunction, warranty or other liability."
The bottom line, according to Mountz: "Precise torque control can mean the difference between a safe, reliable, economical product and complete disaster."
In a new whitepaper, Mountz offer some basic tips to help manufacturers get the most out of their torque wrenches:
- Not all torque wrenches are alike. Before using a torque wrench, read all instructions to fully understand the working features and manufacturer's recommendations. Also, test the tool to make sure it functions properly and has a current calibration sticker or calibration certificate indicating its validity.
- Most torque wrenches have a scale that can be adjusted. Externally adjustable scales typically have a master scale and sometimes a micrometer scale. Internally adjustable (preset) tools do not have an external scale and typically are used in a production environment or for one-torque setting.
- Determine if the torque wrench will provide the accuracy needed for the application. Accuracy can be stated in terms of full scale (FS) or indicated value (IV). FS accuracy indicates the allowable error over the full-scale range of the tool; IV accuracy indicates allowable error at the set point on the wrench. IV-stated wrenches are more accurate, especially on the lower end of the range.
- Establish a verification and calibration interval. Because torque wrenches go out of calibration with use, verifying the accuracy of a torque wrench is a key quality measure. Any operator can verify if a wrench is in or out of calibration by connecting it to a suitable torque tester/checker and pulling the wrench.
- Establish a preventive-maintenance program. The more often a wrench is used, the faster it will wear or go out of calibration. Consequently, Mountz recommends monitoring the number of cycles per day or total hours that a tool is used to establish proper maintenance intervals. Torque wrenches should be serviced based on the manufacturer's recommendations; or no longer than 100,000 cycles; or when a visual inspection reveals old or dry grease, parts that show signs of excessive wear, or loose or unstable components.
"A torque wrench is a precision tool and should be treated and maintained like a measuring instrument," Mountz points out in the whitepaper.
For more detail on these maintenance tips, download the Mountz whitepaper "Understand, Maintain and Service Your Torque Wrench."