A Coordinate Measuring Machine (CMM) is a device that measures the geometry of physical objects by sensing discrete points on the surface of the object with a probe. The machine specifies the probes position in terms of displacement from an origin point in a three-dimensional coordinate system (XYZ axes) . Various types of probes are used in CMMs, the most common being mechanical and laser sensors, though optical and white light sensors also exist. Depending on the machine, the probe position may be manually controlled by an operator or it may be computer-controlled. CMMs typically specify a probes position in terms of its displacement from a reference position in a three-dimensional Cartesian coordinate system. The points can be measured either manually by an operator or automatically via Direct Computer Control (DCC) or automatically using scripted programs; thus, an automated CMM is a specialized form of industrial robot.

CMMs are most often used to test a part or assembly to determine whether or not it respects the original design intent. The measured points can be used to verify the distance between features, and they can also be used to construct geometric features such as cylinders and planes for GD&T such as roundness, flatness, and perpendicularity. CMMs are integrated within quality assurance or quality control workflows to check the dimensions of manufactured components to prevent or resolve quality issues. The advantages of using CMMs over manual inspections or checks performed with conventional metrology instruments, such as micrometers and height gauges, are accuracy, speed, and the reduction of human error.

There are several different types of CMMs, and they are categorized based on their structures. Each structure has its pros and cons. The most common types of CMMs are:

• Bridge CMM: This type of CMM has a bridge-like structure with two columns and a horizontal arm that spans the gap between them. The probe is mounted on the horizontal arm and moves along the X, Y, and Z axes.

• Cantilever CMM: This type of CMM has a single vertical column with a horizontal arm that extends out from it. The probe is mounted on the end of the horizontal arm and moves along the X, Y, and Z axes.

• Portable measuring arm CMM: This type of CMM is a coordinate measuring machine that can take measurements of parts right on shop floors, allowing for quick results and real-time analysis. Technicians use an articulated arm, with either a six- or seven-axis system, to measure components wherever required.

• Optical CMM: This type of CMM uses optical sensors to measure the geometry of physical objects. It is often used for measuring the surface of com...