Every time a fastener is used to form a joint between two parts, torque control is a key element of that formula. Ensuring a well-tightened fastener is installed properly to the pre-defined torque specification will determine the success or failure of a product. Torque testing is key to identifying and reducing fastening failures.
A lack of monitoring and measuring torque is a lack of quality control. Insufficient torque can cause a screw or bolt to loosen from vibrations. Excessive torque can cause fasteners to overstretch and break. After a torque specification is determined for a joint, it is a good practice to perform periodic audits to verify proper torque is being achieved.
There are three common torque testing methods that have been established to provide an accurate reference to the applied torque. The video below will demonstrate the “Loosening” test method using a torque analyzer and torque sensor. It can also be accomplished using a dial torque wrench, a digital torque wrench or a dial torque screwdriver.
Loosening Torque Test
This test is also known as the “breakaway” test. It is similar to the “first movement” method, with one basic difference. Instead of applying torque in the tightening direction of the fastener, this test uses force in the direction that loosens the fastener.
To conduct this test, take a screw or bolt that is tightened down and begin to loosen it. When the fastener breaks loose, record the torque reading. The torque value to loosen the fastener is the approximate torque that was applied to the joint. This method is considered the easiest to perform, but it may not always correlate to the torque applied to the joint.
From low-cost tools to sophisticated fastening systems, all assembly equipment need to be audited. The objective is to verify accuracy and repeatability performance goals are being maintained. Eventually, torque tools begin to drift out of tolerance. An auditing technique to detect and prevent fastening failures is vital.
Using quality torque testing equipment makes a safer world through accuracy and precision. Measuring 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 fastened can vibrate loose and excessive torque can strip threaded fasteners.
A torque testing program is imperative for any manufacturer. It provides valuable information and helps identify the root cause of fastening failures. Knowing how to select and properly conduct a test method is important. To learn more about these torque measuring methods and test equipment, contact us.
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