Why Calibrate?
In industry and science, it is important to measure parameters accurately in order to design processes or experiments that get repeatable results. In some cases slight changes in the initial condition of a parameter can cause large changes in results, so accurate measurement is critical. Accuracy ensures repeatable quality in the production of products. Customers will gravitate toward products that are reliable and meet their expectations. Product accuracy is a measure of compliance with those expectations and it is the key component used to communicate the quality of a product.
The reasons to calibrate are simple. Calibration of components, equipment, and products can:
- Save Money
Cost and waste reduction through standardization will increase profits. - Ensure Safety
Calibrated products and components perform as expected and are safe to use. - Ensure Quality
Calibrated components and equipment will produce standardized products reliably. - Shorten Production Time
When quality components are available, no time is wasted replacing out of tolerance components. - Assure Compliance to Certifications
Compliance to industry regulations and company certifications is assured. - Determine Accuracy
Calibration will allow reliable reporting of product accuracy. - Provides Traceability
Calibrations may be performed with traceability to national standards, if necessary. - Increase Consistency and Reliability
Products built to the proper specification perform better and last longer. - Compensate for Drift
Drift error is corrected by regular calibration. - Prevent and Predict Process Failures
Reliable and accurate sensors can detect gradual movement toward out of tolerance process conditions.
How Often Should You Calibrate?
All sensors drift, some more than others. Manufacturers usually have a good idea of how long it will take for a sensor to drift to an out-of-tolerance condition. A manufacturer will recommend a "calibration interval" based on their experience and a sensor's inherent calibration stability. This calibration interval is usually found in the sensor's specification. The "recommendation" implies some leeway to extend or reduce the interval based on the ongoing history of an individual sensor. Some sensors may remain in tolerance longer than other. In practice it is up to the user to determine when to re-calibrate based on experience with each sensor.
By process, calibration also includes repair of the device if it is out of calibration. For external calibration services, a report is generally provided by the calibration service, which would show any errors in measurements with the measuring device before and after the calibration. Depending on your application, calibration verification could be an option to verify instruments by comparing measurements using calibrated equipment to measurements of equipment that has had their calibration expire. Expired Calibrated Instruments that do not produce the same measurements as the Calibrated Instruments would need to be sent to a calibration service expert for repair.
As an example, to show how calibration is performed we can use an external micrometer as an example. For a mechanical measuring device, accuracy of the scale is the main parameter for calibration. In addition, these instruments are also calibrated for zero error in the fully closed position and flatness and parallelism of the measuring surfaces. For the calibration of the scale, a calibrated slip gauge is used. A calibrated optical flat is used to check the flatness and parallelism.
Why calibration is important?
Calibration of measurement equipment is highly important because it ensures the reliability of the device. There are two [2] main objectives to calibration of measuring devices and instrument. First, calibration checks and verifies the accuracy of the measuring device. Secondly, calibration also creates traceability of the measurements to ensure they are consistent with other measurements.
When should you calibrate your measuring device?
The accuracy of all measuring devices erodes over time. This is typically caused by normal instrument usage. However, changes in accuracy can also be caused by electrical or mechanical shock or exposure to hazardous manufacturing environments like a machine shop or chemical lab. Depending on the type of measurement instrument and the environment in which it is being used, it may degrade very quickly or over a long period of time. Calibration improves the accuracy of the measuring device which leads to improved product quality.
A measuring device should be calibrated:
• According to recommendation of the instrument manufacturer.
• After any mechanical or electrical shock.
• Periodically [annually, quarterly, monthly]
Hidden costs and risks associated with a non-calibrated measuring device could be much higher than the cost of calibration. Calibration is extremely important whenever measurements are critical. Therefore, it is recommended that the measuring instruments are calibrated regularly to ensure that errors associated with the measurements are in the acceptable range. This ensures that businesses can have great confidence and reliance in the results they control.
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