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What is CMM: Types & Components

What is CMM: Types & Components
Austin Peng
Published 14 Jan 2025
Table of Content

Industrial components, once manufactured, need a thorough quality inspection to ensure that they are precise and have the appropriate geometry.

CMM is one of the very commonly used measuring tools that offers a look at the geometrical dimensions of the objects. If you are inclined to learn about what is CMM and its different types, the guide below can help you.

What is CMM?

CMM stands for a coordinate measuring machine. It is a type of equipment that measures the geometry of objects. It uses a probing system and detects the discrete points on the component's surfaces.

CMM tests the component and helps with assembly. These systems have quality control so that the dimensions of the components can be checked to avoid issues of quality. They are highly advantageous compared to manual checks and reduce human errors.

Main Components of a CMM

Components of a CMM

The main components of a CMM are discussed below:

Probe: It is responsible for collecting the data points from the surface of the objects.

Structure: It offers stability and has all the moving parts assembled within it.

Software: It conducts the programming of measurement routines, generates reports, and carries out data analysis.

Control System: It is responsible for coordinating the CCM movement.

Why Do I Need a CMM?

CMM is required for quality control and precise measurement of the objects. By using a CMM, manufacturers can measure the parts and ensure that the design specifications and tolerances are met.

The precision tends to minimize errors and improves the consistency required in applications like medicine, aerospace, and automobile. It also streamlines the process of inspection, reducing the cost of labor and time.

Types of Coordinate Measuring Machines

There are different types of CMM, and they are discussed below:

Bridge CMM

Bridge CMM

Bridge CMM is a probing system that can move through the X, Y, and Z axes in a cartesian coordinate system.

Every axis has a sensor that measures the position of the probe and detects the points on the surface of the component. These points create a point closure that provides for the inspection of the surface area.

Pros

  • It helps in measuring components that have tight tolerance
  • Suitable for small to medium-sized components
  • It is a highly accurate measuring system

Cons

  • It is expensive
  • Fixed measurement volume
  • Lacks portability
  • It is challenging to operate

Gantry CMM

Gantry CMM

Gantry CMMs are similar to bridge CMMs, but they are larger in size. They offer accuracy levels the same as bridge CMM, but they eliminate the requirement of lifting parts on a table. They are suitable for larger parts and are mounted directly on the floor.

Pros

  • Highly accurate outcomes
  • Measures large and heavy parts
  • Easy to load and unload parts

Cons

  • They are expensive
  • Cannot be moved easily
  • Cover a lot of floor area
  • Sensitive to vibration
  • Requires skilled team to operate

Cantilever CMM

Cantilever CMM

Cantilever CMM is different from bridge CMM. It has its measuring head on one side of the rigid base. It allows users to inspect from the three sides and is very easy to operate.

Pros

  • Offers high accuracy
  • Works well with small-sized parts
  • Easy to operate
  • Easy to load and unload components

Cons

  • They have a fixed measurement volume
  • They need a rigid setup
  • Expensive

Portable Measuring Arm CMM

Portable Measuring Arm CMM

A portable measuring arm CMM is a machine that can take measurements of the components on the shop floors directly and offer immediate results.

They do not need to be brought to the lab, and they are composed of a six- or seven-axes system. Hence, the components can be measured anywhere.

Pros

  • They are lightweight and portable
  • They have an extendable measurement volume
  • They have measurements with multi-sensors
  • They are very affordable
  • Portable CMMs are easy to operate

Cons

  • Lacks accuracy
  • Sensitive to vibrations
  • Need rigid setup

Optical CMM

Optical CMM

Optical CMMs are machines that are portable and non-contact. They have an arm-free design and consist of an optical triangulation method for scanning the objects.

However, they lack accuracy and are mostly used in combination with other types of CMMs. Hence, it is not suitable for such components that need a critical accuracy level.

Pros

  • Performs the measurement in very little time
  • Extendable measurement volume
  • Doesn’t need a rigid setup
  • No programming required
  • Affordable
  • It has multi-sensor measurements

Cons

  • They lack accuracy in measurement

What is a Coordinate Measuring Machine Used For?

What is a Coordinate Measuring Machine Used For

Coordinate measuring machines are used in many industries for a lot of purposes, and some of these are the following:

  • CMMs are opted to ensure quality control in manufacturing industries so that components that require high accuracy can be manufactured.
  • The exactness of the components and their dimensions can be assessed as the tool provides accurate lengths, points of measurement, and geometry.
  • CMM also determines cycles so that computerized models can be made in the absence of CAD models.
  • CMMs are meant to perform statistical process control, which consists of analyzing and collecting data. It helps to analyze what tools need replacement or which controls require optimization.
  • CMMS also helps align different tools and devices to obtain precise estimations when assembling the components.

Ensuring Quality with a CMM: DEK Can Help

The accuracy of dimensions is one of the crucial aspects when it comes to manufacturing components. If the components are not geometrically accurate, they may not be useful for the applications.

We at DEK use CMMs to ensure the quality of each and every component we manufacture. So, if you are looking for components of high accuracy and dimensions, get in touch with us.

Conclusion

Understanding everything about CMM plays a vital role in creating components for a project. Moreover, it also gives an insight into measuring the dimensions of components.

As you have read the detailed guide above, you must have understood how the dimensions can be measured for each and every component and its significance.

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Austin Peng
Co-founder of DEK
AUTHOR
Hello! I'm Austin Peng. I manage a factory that specializes in CNC machining, injection molding, and sheet metal fabrication for small quantity production and rapid prototyping solutions. When I'm not immersed in work, I love diving into football matches, exploring new travel destinations, enjoying music, and staying updated on the latest tech trends. Feel free to chat with me about anything, whether it's work or life!

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