An out of calibration or out of tolerance equipment can have serious implications on the quality of product and eventually on the reputation of your company. So, what exactly does calibration out of tolerance mean? Sometimes, during calibration of equipment, certain point or points fail to meet the required tolerance level. This results in a failed calibration. A specific tolerance level or maximum permitted error level is used for comparing the test result. If the equipment being calibrated fails to meet the required tolerance level, it becomes out of tolerance.
If you handle out of tolerance equipment correctly, you will be ready to deal with and even be capable of avoiding the related implications.
In case you find that your equipment is out of calibration, here is what you need to do:
- Quarantine the equipment.
- Take note of the quantity of product inspected and tested by such equipment.
- Review the calibration data to find out whether there were any past discrepancies in calibration. Also determine whether the equipment was in really bad shape or way out of tolerance.
- Ensure that correct range or tolerance is used for calibration. This is important because mostly the calibration process is inherited wherein the accuracy is predefined by the calibrating company. Whether the calibration of equipment is done by you or by a calibration lab, ensure that the calibration range or tolerance used should be perfectly suited as per your usage.
If you aren’t confident about the results of such out of tolerance equipment, you may have to segregate or recall and re-inspect the suspected product batch with good calibrated equipment. You need to have a solid plan of action to be followed after the product batch is retested and the results are found to be erroneous.
It should be noted that the process of handling out of calibration equipment should be properly planned and documented. This should be done as required by the Control of Nonconforming procedure or a similar process required by the ISO 9001 standard.
Calibration Certificate: Important Points to Keep in Mind
You need to decide what kind of information you want on the calibration certificate of your equipment. This is important because the data reported on the certificate needs to be reviewed frequently in detail so that you can assess as to whether:
- It is being calibrated at the correct range
- It is in good condition after every calibration
- It is found marginally out of calibration
- The duration between two consecutive calibrations can be increased
You need to continually review calibration data to ensure that the equipment received is always in tolerance. The calibration data records help you decide whether or not you can increase the span between two consecutive equipment calibration sessions. This also depends on the type and frequency of usage of the equipment. The objective is to be economical and still have the confidence that the equipment is delivering precise results.
Now let’s see what type of information should be included in a calibration certificate:
- Accurate description of equipment including its ID
- Location, owner and user details
- Date on which it is calibrated and next due date for calibration
- Condition in which it is submitted for calibration to determine if it was out of calibration or not at the time of submission
- Specific calibration readings which give a clear idea that if the equipment was brought in an ‘out-of-tolerance’ condition, by how many points was it out of range
- Procedure used for equipment calibration
- Name of person in-charge for conducting calibration
- Details regarding the Standard used for calibration including the name, ID, description, last calibration date and whether it is traceable to NIST or other national standard organization.
You can make sure that you have all the necessary information handy in case of an out-of-tolerance situation, if you plan well.
Now that you are aware of how to handle an out of tolerance equipment and the importance of calibration data, you can get the most from the calibration of equipment.
Author Bio: Edward Simpson works for RS Calibration Services and has a knack for finding faults in machines and does not rest until they are rectified to perfection. He lives in Pleasanton, California and loves to write about how machines work and about the importance of proper care and calibration of equipment.