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Coordinate measuring machines (CMMs) precisely and accurately measure the geometry of objects – but how exactly do these machines get exact measurements down to the micron?

There are various parts, data, and retrofits that help these machines measure objects with precision. The reality is that these exact measurements make it easy to reproduce products and automate processes to streamline production.

To get exact measurements from a CMM, you can buy a new or used CMM machine or invest in measurement services. It is most convenient to work with a CMM retailer that offers a full spectrum of services; for example, CMMXYZ measures on-site and off-site to accommodate the varying needs of different businesses and sells both new and used equipment.

Consider all the moving parts and factors that contribute to a CMM’s ability to obtain exact measurements:

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The Parts

CMMs are composed of intricate parts that enable them to provide exact data. However, the parts most essential to the accuracy of data collected by a CMM are the probes that directly measure a given object.

DigitalEngineering247 explains that these probes “gather the points through a human operator or via automation through a process called direct computer control (DCC). The DCC CMMs can assess identical objects over and over through programming.”

There are also CMMs that use lasers or sensors to measure items. These machines measure objects that are delicate and could be compromised by direct contact.

The intricate parts of a CMM that contribute to its overall functionality and ability to measure objects include:

  • Air Bearings
  • Scales & Encoders
  • Probe system
  • Servo motors
  • Joystick
  • Machine control system
  • Software

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Thorough Measurements

CMMs can provide exact measurements because they don’t only measure the length and width of an object; they measure its entire geometry. CMMs measure objects based on:

  • Straightness
  • Flatness
  • Roundness
  • Cylindricity
  • Conicity
  • Angularity

Calibration

Manufacturers and retailers provide CMM calibration to ensure that your metrology machine is up to standards. Calibration ultimately compares your machine’s findings with the results of a machine that is proven accurate.

Calibration allows professionals to look at the data collected by both machines to identify discrepancies and make any necessary adjustments.

Software

CMMs use advanced software to obtain and report precise measurements. This software collects all data in one place to make it easy to monitor and automate CMM use. The good news is that there are often software updates that can help you ensure that your machine is always reporting accurate measurements.

Verifications & Certifications

The accuracy of CMMs is verified based on their ISO certifications. The ISO 10360 is the standard CMM certification that verifies the capabilities and accuracy of a machine.

The ISO site explains that an ISO 10360 certification “specifies the acceptance tests for verifying the performance of a coordinate measuring machine (CMM) used for measuring linear dimensions, as stated by the manufacturer. It also specifies the verification tests that enable the user to periodically reverify the performance of the CMM.” This certification was first established in 1994 and has since become the industry standard.