When the tightness of a screw or bolt matters, your torque wrench must be able to help you apply the precise amount of torque needed to match the specifications required; this means making sure it is properly calibrated at all times. Not only will this make sure you are not over-tightening a bolt or leaving it too loose, it will also help you extend the life of the instrument, help you avoid costly repairs, and keep your customers happy. The problem is that there is no single answer to the question, “how often do I need torque wrench calibration?” Calibrating too frequently can be expensive and unnecessary; but not calibrating frequently enough can lead to safety issues, quality problems, and associated costs of its own.
Here are 8 things to consider when planning your torque wrench calibration schedule:
- Try and pinpoint when the readings begin to change, example, if they have a tendency to change between 2500 and 2800 repetitions, schedule calibration for 2500 repetitions.
- Even though calendar-based calibration is not considered a best practice, every six months is at least a starting point until you can pinpoint a better schedule to fit the needs of your tool.
- If the error on the torque goes beyond the acceptable limit you should recalibrate.
- Frequency of use- the more you use it, the more it will need calibrated.
- Setting of the wrench as a percentage of full scale is something to think about.
- General care both in use and in storage of the torque wrench (ex. if it is beat up or dropped you will want to check the calibration).
- Ambient conditions – again, both during use and while being stored.
- If the wrench is subjected to an overload equal to or more than 25% the maximum it should be recalibrated.
While calendar-based calibration schedules is a good place to start with your planning (every 12 months for example), that does not always keep your instruments operating at their best. It all comes down to the factors explained above, so be sure to factor them in.