The full form of CMM is a Coordinate Measuring Machine. Read more Its types, components, working principles, prob system and current vacancies.
What is CMM and its full form?
The full form of CMM is Coordinate Measuring Machine.
It is an advanced measurement machine that works to measure complex and large components.
CMM is a device for measuring the physical characteristics of an object. The machine is controlled by a computer or an operator.
CMM consists of 3-axis namely X-axis, Y-axis, Z-axis. Measurement is done by the prob attached to a third moving axis.
This prob could be mechanical, optical, laser or white light.
So, the machine that takes reading in 6 DOF(Degree of freedom) is known as CMM.
Types of CMM Machine
There are four basic types of stationary CMM:
- Bridge type CMM
- Cantilever CMM
- Horizontal Arm CMM
- Gantry CMM
Bridge type CMM
Bridge CMMs are the most common type of coordinate measuring machine. It is used for inspection of High accuracy, moderate flexibility, for medium-sized components.
Cantilever CMMs differ from the bridge style in that the measuring head is only attached on one side of a rigid base. This type of CMM is used for the inspection of the Highest Accuracy, Lowest Flexibility, for small-sized components.
Horizontal Arm CMM
Horizontal arm CMMs are less accurate than the other types of CMM. because of their design. However, it also makes them useful for measuring large workpieces or components.
Gantry CMMs are designed similar to bridge-type CMMs but tend to be much larger. Gantry CMM is used for High accuracy, Moderate flexibility for large components.
Components of CMM Machine
The main 3 components of CMM are
- The machine itself (includes its 3-axis)
- Probing System
- Controllers & Softwares
Here are the main parts found in every CMM machine
- Air Bearing
- Scales & Encoders
- Prob system
- Servo motors
- Machine control system
The air bearing is responsible for the movement of the machine along all its 3 axes.
Scales & Encoders help CMM to locate and read the movement of the axis.
Working Principle of CMM machine
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. Instead 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.
The CMM combines the measured points to form a feature that can now be related to all other features.
CMM probs convert physical measurements into electrical signals. CMM probes have a wide classification for direct and comparative measurements.
CMM probes are available in three main forms:
- Touch-Trigger probes
- Displacement Measuring CMM probes
- Proximity or Non-contact Probes
Learn more in CMM Certification Course