A coordinate measuring machine (CMM) is used to measure the physical geometrical characteristics of an object. It takes readings in six degrees of freedom, then displays the data in mathematical form. Measurements are defined by a probe that is attached to the third moving axis of the machine. A CMM may be operated manually or by a computer and can be free-standing, portable, or handheld. It has three axes (X, Y, and Z), and when the machine gets the readings from the probe, it uses the X, Y, and Z coordinates to determine position and size with micrometer precision. This is why coordinate measuring machines are very accurate.
A CMM is usually used in the assembly and manufacturing process to test a part or assembly against the design intent. It is also considered as an industrial robot because it can be programmed to repeatedly measure identical parts.
It was in the 1950s when the first CMM was developed in Scotland by the Ferranti Company as a direct need to measure precision components in their products for the military. That machine had only 2 axes, and it wasn’t until the 1960s that 3-axis devices were developed, while computer-controlled machines came out in the 1970s. Since then, the CMM has become an even more accurate and reliable device.
List of Advantages of a Coordinate Measuring Machine
1. The hardware lasts for a long time.
If the machine is properly maintained, it will not wear out during its useful life. It may require a change of motor or a few parts, but its fundamental machine is guaranteed to last for several years. This means you won’t have to keep on replacing your CMM.
2. The software continuously gets better.
Today, there is great improvement in graphically driven software and its ability to retrieve and store a wealth of information. Metrology experts also say that the software will continue to become more affordable, accurate, user-friendly, and standardized.
3. You can upgrade the machine by upgrading only the software.
Most coordinate measuring machines can have software upgrades for five times and they will still give the same performance. Most owners of CMMs will ask for a software upgrade more times than asking for an upgrade in hardware.
4. Newer models are now resistant in less controlled environments.
Most would want to have a CMM in on the shop floor in order to increase efficiency, and the measuring machines of today allow you to do just that. They are now more resistant to most shop floor influences, such as vibrations and temperature changes.
List of Disadvantages of a Coordinate Measuring Machine
1. There is no standardization yet.
Today, there are hundreds of different kinds of CMMs, dozens of manufacturers, and various software programs to run the machines. This means that it is more difficult to interchange software between coordinate measuring machines.
2. CMM systems can be complicated to operate for some.
Not all users of CMMs are knowledgeable about the principles of coordinate measuring machines. It is mostly manufacturing and production experts who operate these machines, and they need to work fast because they need to make more parts to make money. They don’t have as much time as quality engineers so they need systems that are simpler.
Natalie Regoli is a child of God, devoted wife, and mother of two boys. She has a Master's Degree in Law from The University of Texas. Natalie has been published in several national journals and has been practicing law for 18 years.