You don’t want to be surprised by a torque tool that is out of calibration. After all, torque tools are precision instruments used to tighten critical, often safety-sensitive fasteners. When these tools are out of calibration, products can be made incorrectly, possibly even failing in the field. So, when a torque wrench is out of calibration, you need to know about it as soon as possible, to prevent product failure and liability.
While you might be able to take a guess when you observe a spike in your rate of lost product, the only way to know for sure that your torque tools remain in calibration is to test them. To prevent tools from slipping through the cracks, your testing program should be organized, detailed, and documented. By developing and following a plan for your torque tool calibration procedure, your company can lower your liability risk and establish greater oversight over the production process.
Make a Plan for Your Torque Tool Calibration Procedure
While general guidelines can help you organize your calibration plan, the details of your torque tool calibration procedure will depend on factors unique to your company. The best way to come up with a calibration plan is to start by answering general questions to assess the needs of your company. Ask yourself:
- How many torque tools do you need to calibrate?
- Are you using different types of torque tools?
- What amount of tolerance is permissible for each tool type?
- Is your industry subject to specific regulations regarding tool calibration?
- How frequently must each tool type be tested in order to mitigate risk?
- Will you calibrate your tools in-house or ship them to a certified laboratory?
- If calibrating in-house, how will you test your inspection equipment?
By answering these questions, you can identify your company’s needs and priorities—the first step when creating a standard testing procedure for your torque tools. Knowing how many torque tools you have allows you to create a testing schedule while understanding their permissible tolerances makes it possible to establish calibration standards. Regulations serve as a guide to the standards for your industry that must be met or exceeded.
Risk can be estimated as a function of cost and time. As a baseline, torque wrenches should be tested once every six months or once a year. Some must be tested much more often if merited by the risk of product failure. The cost of risk can be estimated based on the percentage of revenue each tool is responsible for between calibrations. After all, the purpose of calibration is to certify that each product made by a given tool stands up to quality standards. If a tool fails its calibration test, then the products it made will fail their quality control inspections. Ask yourself, how many products am I willing to risk on each tool?
Additionally, risk is complex and not limited to the direct cost of lost materials and time. Instead, risk is amplified by extra costs resulting from the repercussions of product failure, such as legal fees, fines, and increased insurance premiums. As the cost of risk increases, so should the frequency of calibration inspections.
Testing Torque Tools In-House Improves Productivity and Mitigates Risk
Inspection frequency must be balanced against productivity. In other words, if all you do is test your tools, then you won’t build any products. Productivity loss per inspection depends on the tool’s turnaround time. If each tool can be tested in seconds, you can test every tool, every day, with minimal productivity loss, almost entirely eliminating the potential of improper calibration. If each tool takes two weeks to travel to and from a certified laboratory and you inspect each tool once a month, you’ve lost 50% of that tool’s productive capacity. If tests take two weeks and you test once a year, you’ve only lost 4% of capacity (assuming 50 working weeks per year).
Calibration plans, then, are a balancing act between risk and productivity. The more you test, the less you work. The longer you go without testing, the greater the risk of product failure and costly repercussions. The best way to improve the equation is to reduce testing turnaround times by investing in in-house torque testers. If you can reduce tool turnaround from weeks to seconds or from days to minutes, then you significantly increase your tool availability while also decreasing your risk. However, expanding your testing program will require additional investment in training, equipment, and employee compensation, which should be weighed against your potential gains.
If you do choose to invest in torque testers for your company, you’ll also need to test the calibration of your testing equipment. Again, you can send it to a certified laboratory or invest in in-house testing equipment. To decide whether to invest in calibration equipment for your torque testers, consider how much testing productivity would be lost to turnaround times.
Torque tool calibration plans organize your company’s torque tool testing procedures. They safeguard against product loss and liability due to unnoticed calibration errors in torque tools and compartmentalize your risk into discrete segments of time per tool. The simplest way to decrease risk while maintaining productivity is by using in-house torque testing equipment. Owning your own calibration equipment allows you to test more often, in less time.