Why calibrate?
The main reason for calibration is that even the best instruments drift and loose their ability to give accurate measurements. This drift makes calibration necessary.
What is calibration
What time is it? What time is it exactly and how do you know it?
Calibration can be briefly described as an activity where the instrument being tested is compared to a known reference value. The keywords here are ‘known reference’, which means that the known reference used in the comparison should be traceable to recognized standards.
In this case, calibration would be comparing the time an alarm clock shows to a wristwatch, which has been synchronized with a known time signal (e.g. with the radio time signal).
Calibration in industrial applications
Calibration is about understanding the value of accurate measurement results.
When process measuring instruments age and experience physical stress or temperature variations, critical performance gradually declines. This is called drift.
As a result of this, the measurement results become unreliable and ultimately the production quality can suffer.
Drift cannot be eliminated, but it can be discovered through calibration. Calibration is the comparison of instrument performance to a standard of known accuracy.
Calibration assures that the measurements are accurate and within the required specification limits of the process instrument.
Why is calibration important
The main reason for calibration is that even the best instruments drift and loose their ability to give accurate measurements. This drift makes calibration necessary.
Specific reasons for calibration include:
- To keep high and consistent product quality
- Industry regulations/quality systems require calibration
- Optimize process and increase capacity
- Safety reasons
- Check quality of measurements
- Direct economic benefits (e.g. from proper billing)
- Controlling emissions
The consequence of poor calibration has severe financial impacts. According to studies made by Nielsen Research and ATS (2006 & 2008), the average cost of poor quality calibration costs manufacturers $1,734,000 each year. When considering solely large companies with revenues of more than $1 billion, the cost balloons to an average of $4,000,000 annually.
The cost and risk of not calibrating
- Neglecting calibration can lead to unscheduled production downtime, quality problems and product recalls.
- Risking employee safety.
- Risking customer/consumer safety.
- Loosing licence to operate due to not meeting regulatory requirements.
- Direct economical losses in businesses where invoicing is based on process measurements (e.g. energy industry).
How often you need to calibrate
After a period of time, instruments drift and can no longer give accurate measurement results. To resolve this issue, instruments must be calibrated at regular intervals. But how often?
Calibration interval can be determined by:
1. Following manufacturer’s recommendation
2. According to criticality of the instrument
3. Quality standard guidelines (e.g. ISO)
4. Based on history trend analysis (e.g. using that functionality in calibration software)