Calibration is the cornerstone of quality when it comes to torque application. Unless the torque wrench has obviously been damaged, you can't look at a tool and know it is not within tolerance. It must be tested.
Some companies employ a daily torque tool verification program. They "bump test" every tool, every day, to ensure that the intended torque value is the value that is being applied at every fastener.
At one time, quality was viewed as a cost center. It really isn't. We see quality as a revenue center. There is likely a line item in your P&L for warranty and repair work.
You probably don't have a line item for lost reputation, delayed or lost orders, or even lost customers. But the reality is, those items exist. Quality drives that number. The lower your quality score, the higher those invisible numbers for losses tend to be.
Calibrating your torque wrenches, torque screwdrivers, and power tools is an important part of quality assurance.
How important is calibration? In 2001, a company making a medical device had a lapsed calibration program. The scientists did not want to give up their instruments, and as a result, they were not calibrated within prescribed times.
The result? Devices were designed based on inaccurate readings. The FDA came to the company with guns drawn. The company paid $60,000,000 in fines. And, if the entire issue was not fully remediated, the FDA promised that executives would be jailed and the company would be shut down.
While this real-life situation does not include torque tools, it does highlight the importance of maintaining the integrity of a calibration program.
As members of the ISO torque committee, we support the ISO standard for calibration intervals. Typically that is every 5,000 cycles or once a year, whichever comes first.
Yet, we frequently hear the question, how often should I calibrate my torque tools? Some companies are concerned about the costs of calibration. The cost of the warranty and repair work along with delayed or lost orders, or lost customers far outweigh the cost of calibrating torque tools.
Look at it this way. How long does it take to regain your reputation for quality? How much does that cost?
In today's economy, it costs ten times as much to acquire a new customer as it does to keep an existing customer.
Remember, torque wrenches can be taken out of tolerance when they are used as a hammer, dropped, thrown, or are taken over their rated capacity.
Recently, we had a 400 foot-pound Exacta 1200 Series digital torque wrench come back to us with a note stating that the wrench wasn't working.
At first glance, the wrench looked fine. On deeper review, we found the protective plate for the radio was bent, and the entire electronics housing was bent.
A quick look into the results log showed that the last use of that 1200 Series digital torque wrench had taken the transducer up to 960-foot-pounds.
The tool needed calibration. Without that tool being within the specified tolerance, quality would be significantly impacted.