{"id":1050,"date":"2014-08-19T15:04:04","date_gmt":"2014-08-19T15:04:04","guid":{"rendered":"http:\/\/proqc.com\/blog\/?p=1050"},"modified":"2025-07-01T09:02:18","modified_gmt":"2025-07-01T09:02:18","slug":"cmm-testing","status":"publish","type":"post","link":"https:\/\/proqc.com\/blog\/cmm-testing\/","title":{"rendered":"Coordinate measurement machines (CMM): What are they and who needs it?"},"content":{"rendered":"

Within our testing laboratory in Ningbo, China, our engineers perform mechanical, electrical, environmental and other special testing as required by our clients. Experienced engineers use applicable and regionally specific standards, such as ASTM, IEC or ANSI specifications, to conduct a variety of in-house and on-site testing.\u00a0One of our most common testing procedures involves the use of either a portable or in-house CMM. \u00a0<\/span><\/p>\n

What is a coordinate measurement machine?\u00a0<\/strong><\/h2>\n

“A\u00a0<\/span>coordinate measuring machine\u00a0(<\/span>CMM) is a device for measuring the physical geometrical characteristics of an object.”\u00a0<\/span><\/p>\n

“Dimensional inspection is used in process control; its results adjust the parameters of
\nthe manufacturing process to achieve the desired outputs. Computer controlled
\ndimensional inspection is typically performed with a Coordinate Measuring Machine
\nor CMM, which is a very precise mechanical system designed to move a measuring
\nprobe to determine coordinates of points on a work piece surface. A CMM consists
\nof a workspace in which parts are fixed, a sensor for detecting the part surfaces, a
\nmechanical assembly for moving the part sensor around the workspace, and a
\ncomputer with software used in calculating the part dimensions based on the sensor
\nmeasurements.” (Source: http:\/\/www.engr.sjsu.edu)<\/p><\/blockquote>\n

How does it work?<\/strong><\/h2>\n

“A coordinate measuring machine (CMM) works in much the same way as your finger when it traces map coordinates; its three axes form the machine’s coordinate system. \u00a0Instead of a finger, the CMM uses a probe to measure points on a workpiece. Each point on the workpiece is unique to the machine’s coordinate system. \u00a0The CMM combines the measured points to form a feature that can now be related to all other features.”\u00a0(Source: http:\/\/www.hexagonmetrology.us\/applications\/technical-resources\/metrology-101\/727-intro-to-coordinate-metrology)<\/p><\/blockquote>\n

The CMM’s dimensional capabilities generally includes position, roundness, perpendicularity, parallelism, flatness, angularity, profile of surface, profile of a line, symmetry, concentricity, straightness and datum quantification.<\/p>\n

Who needs CMM testing?<\/strong><\/h2>\n

Measuring the physical geometrical characteristics of an object allows for comparison to approved product specifications. Evaluations include first article and first piece evaluation and critical dimensional profile measurements. \u00a0Determining if products meet specification requirements prior to production and\/or shipment can reduce costly rework and delays later.<\/p>\n

As noted, CMM testing can be performed on-site or in-house. \u00a0Accuracy is a considerable factor with CMM testing, so many clients prefer to partner with a third-party (3PQ) rather than using equipment that may be on-site at the factory. \u00a0The machines themselves vary where accuracy is concerned, but equally important is the experience and skill of the operator. \u00a0“Incorrectly defining or failing to define a part alignment is the single most influential factor in gage repeatability errors and incorrect measurements.” (Quality Magazine posted an article<\/a> related to this\u00a0and discusses it in more detail.)<\/span><\/p>\n

Our CMMs:<\/strong><\/h2>\n