Calibration of pins and plugs

Calibration services ensure that readings taken from measuring instruments and masters are consistent and accurate, and within specification limits or tolerances.

Why Calibrate?

The main reason for calibration of instruments is that all masters, tools and other items 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 regular calibration of 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. This means that all equipment used to perform calibration services must also be calibrated to ensure an unbroken traceability back to the standard kept at a national metrology institute.

Calibration of gage blocks

The calibration of measuring tools, instruments and masters is a comparison of a measurement reading from the item being calibrated with a known value from a reference instrument or standard. Variations between the reading and the known value determine the performance limitations of the tool, instrument or master.

Inception of Calibration

It is often a good policy to calibrate measuring instruments prior to the first use. This will establish a measurement history from the beginning for future reference and comparison. Tracking the history on the instruments to make sure that they have been within the specifications will help in making decisions about calibration frequency or intervals.

Frequency of Calibration

Shorter intervals between calibrations may reduce the risk of questionable measurements. When determining the frequency of calibration, consider factors that may affect measurement accuracy:

• How often the instrument is used
• Environmental conditions (e.g. humidity, temperature, vibration) where the instrument is stored and used
• The required uncertainty in measurement
• Requirements of your company’s quality program

Calibration of length standard

Calibration services compare a measurement reading from a measuring instrument or tool with a known value from a reference instrument or standard to determine the performance limitations of the tool or instrument. Standards are prepared by various organizations, agencies and governing bodies and are universally used by testing laboratories. A traceable calibration is performed using a reference instrument with a known value that can be traced back to a national standard, held by an organization such as NIST (National Institute of Standards and Technology). Routine calibration services help ensure that measuring instruments will produce results which meet or exceed defined criteria with a specified degree of confidence.

Calibration services look at the measurement concepts of accuracy and precision. Accuracy describes 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.

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 standards and masters, gauges and measuring hand tools including micrometers, parallels and calipers, require dimensional or mechanical calibration services.