Calibration to Ensure Measurement Accuracy
Calibration is the process of determining the performance limitations of a measuring tool or instrument by comparing its measurement readings with a known value from a reference instrument or a standard. Standards are prepared by various organizations, agencies and governing bodies and are universally used by testing laboratories. A “traceable” calibration means that the reference instrument’s known value can be traced back to a national standard, held by an organization such as NIST (National Institute of Standards and Technology). Routine calibration helps ensure that a measuring instrument will produce results which meet or exceed defined criteria with a specified degree of confidence.
Calibration looks at the measurement concepts of accuracy and precision. Accuracy is how close a measurement reading or result is to the known value or correct measurement. Precision is the consistency or repeatability of the measurement readings. Manufacturers generally state expected accuracy and precision of their instruments as a designated percentage or value.
Why Calibrate
Calibration ensures that readings taken from measuring instruments are consistent and accurate, and within the specification limits or tolerance. The main reason for calibration is that all instruments lose their ability to provide accurate measurements over time and with use. A calibration procedure may reveal an underlying problem that could be costly, if left unattended.
- In manufacturing, items could incorrectly pass or fail inspection resulting in inferior products going to market or costly rework or discard of good items.
- In product development, inaccurate measurements can distort findings and slow or stall progress.
- For companies in industries or with customers that require a regular calibration regimen for instruments used in production of their products or parts, the penalty for non-compliance could be fines or loss of business.
In general, commerce depends on globally agreed upon standards of weights and measures. Only traceable calibration can ensure adherence to these standards.
When to Calibrate
Calibrating your instruments prior to use is often a good policy. That way you’ll have a measurement history from the beginning. When determining the calibration frequency, take into consideration factors that can effect accuracy, such as how often the instrument is used, the environmental conditions where the instrument is stored and used, and the required uncertainty in measurement. Shorter intervals between calibrations may reduce the risk of questionable measurements.
Types of Calibration
Calibration services are performed on a wide-range of measuring instruments and are typically named for the type of measurement the instrument performs, such as dimensional, mechanical, pressure, force, torque, electrical, temperature, mass, vacuum, humidity and flow calibration. Most measuring standards, gages and hand tools including micrometers, parallels and calipers, require dimensional or mechanical calibration.
Calibration at LTI
All calibration is performed by our department known as LTI Metrology, including a wide-range of A2LA and NIST-traceable calibration services both at our lab and in the field. We provide dimensional/mechanical, pressure, torque, force, electrical, temperature, mass and vacuum calibration services. Humidity and flow calibration orders are subcontracted to our approved vendors.
Field service is available for surface plates, optical comparators, hardness testers, balances, measuring tools and more. LTI also supplies new instruments and replacement parts from leading manufacturers, and provides repair services.