Your equipment for precise measurements is only as good as the results it gives. That is why there is no doubt that skilled technicians should appropriately calibrate your equipment. The question is – how often should you do it?
There is no one-size-fits-all answer to this question, but reading this article will give you some guidelines you should follow and explain what equipment calibration is and why it is essential.
All measurement instruments lose their ability to provide accurate readings over time and with use and wear. Ensuring that devices are correctly measuring is vital to maintaining your processes, product quality, and reputation.
With a procedure for periodic re-calibration, you can avoid many costly problems:
- In product development, inaccurate measurements can distort findings and slow or stall progress.
- In manufacturing, improperly calibrated measurement instruments can result in shoddy work and a less than the optimum product for customers.
- During quality inspections, items could incorrectly fail inspection resulting in costly rework or discard of good articles.
- For companies in industries or with customers that require a regular calibration regimen for instruments used in the production of their products or parts, the penalty for non-compliance could be fines or loss of business.
Regular recalibration and adjustments will ensure that readings taken from measuring instruments are consistent and accurate and within the specification limits or tolerance.
What is a calibration interval?
A calibration interval is a period established for a test instrument to be returned for recalibration. We recalibrate instruments to be confident they perform as good as, or better than, described in the manufacturer’s specifications.
Over time, the equipment stops working the way it was supposed to. Mechanical parts wear, electronic components drift, so instruments that have mechanical parts (like the material that makes the diaphragm type sensors in a pressure gauge) or electronic components (like every digital multimeter made) will also drift and perform differently over time.
For some devices, governmental regulations dictate calibration frequency, particularly for medical and pharmaceutical instruments or other devices that can affect public safety.
In these cases, flexibility is not allowed in setting up a calibration cycle. However, it could be more profitable in other situations to find the best balance between calibrating too often (pricey) and calibrating too little (inaccurate measurements).
So, how often should you calibrate your equipment?
Here are the essentials you should consider when deciding on how often to calibrate:
A good starting point is the recommendation of the instrument’s manufacturer. Many measuring equipment types will come with an owner’s manual giving approximate guidance for how often it should be calibrated.
This recommendation should be treated as the baseline standard, with your analysis determining whether something should be calibrated more frequently.
The criticality of measurement
You should calibrate the instruments installed in critical locations more often than those in less critical areas.
In regulated industries like pharmaceuticals and food and beverage, you should be more careful when deciding to decrease an instrument’s calibration frequency. It would be wise to compare first the cost of calibration to the cost of an out-of-tolerance calibration.
In case of a shock
If a piece of measuring equipment undergoes any mechanical or electrical shock, it should always be recalibrated to ensure its accuracy. Even if nothing appears to be wrong with the instrument, these instruments’ exact tolerances mean that even microscopic changes can alter their efficacy.
Before a major critical measuring project
This is extremely important. If you are making decisions or taking actions based on the measurement results, you’ll want to ensure a high degree of confidence that the standards used remained in tolerance.
An instrument used in extreme environmental conditions should be calibrated more often than one in stable conditions. You can update the calibration frequency depending on how often you use a tool and whether it is under extreme environmental conditions.
If an instrument is transported frequently, you should consider calibrating it more often.
If an instrument is dropped
Suppose the piece of equipment has been dropped or accidentally hit. In that case, you need to check its calibration or send it immediately for its calibration to be checked. Every device will react differently when dropped but it always pays to have it reviewed, especially if it’s a precision tool.
After a specific number of uses
As technology continues to advance, it is becoming easier to track how often a piece of equipment is used. This gives you a significant advantage in being proactive when it comes to scheduling your recalibration.
Over time, you can track how many uses it takes to fall out of tolerance on average for different types of equipment. Once a good baseline is established, it is as simple as recalibrating each piece of equipment before it hits this usage limit.
As you have seen, there is no magic answer about how often you should calibrate. However, you can make your calibration schedules based on the conditions, the circumstances, and the stability history of your instruments.
In most cases, the requirements vary depending on the application, QA requirements, industry standards, performance, or safety regulations. There can be regulatory requirements for specific industry measurements based on a standard or rule that stipulates the calibration period’s accepted length.
Other than that, only you can determine what interval is best for your needs and risk management practices. But don’t worry. Once you start diving in, you will see that the process is relatively easy.
It should, of course, be possible for you to change your quality system if needed. Test different options and see what works best for you and your specific needs. The process to determine which interval is best is not complicated. It is merely a matter of analyzing your calibration results to see where small improvements can be made. If a large percentage of your equipment fails, you may want to shorten your interval, and vice versa – if most everything passes, but certain pieces of equipment always fall, shorten the gap on those pieces of equipment.