How to Choose a CMM

Coordinate measuring machines (CMMs) are efficient and accurate measuring tools that outperform measuring alternatives like rulers, micrometers, and vernier calipers. These versatile machines measure the 3D dimensions, GD&T features, and compare to CAD in industries like healthcare, automobile, aerospace, and more.

However, not all CMMs are created equal– but that’s good news! CMMs have different measurement areas, software, and accuracy. Each of these factors should be taken into account when choosing the right CMM for your inspection or measurement needs.

With that said, if you are wondering how to choose a CMM, the following post will help.

What are the Different Types of Coordinate Measuring Machines?

There are three conventional CMM machine types: bridge/gantry, cantilever/horizontal, and arm.


Bridge/Gantry CMMs are a type of CMM that is made up of a bridge-like structure supporting the probe’s movement across the stage. Gantry style CMMs are a type of bridge CMM built for larger parts and are floor-mounted. While a classic “bridge” style CMM is not always floor-mounted.


Horizontal and Cantilever CMMs both use a side mounted “arm” that moves a probe either up and down (cantilever) or side to side (horizontal) to inspect parts.


Arm-type CMMs are jointed machines that use encoders to track the angle of each joint and use math to determine where in space the probe tip is.

At KEYENCE, we offer non-conventional portable handheld CMMs that work to replace conventional CMMs. In this blog, we’ll discuss CMM options in relation to accuracy, part size, and software.

CMM Considerations


When discussing accuracy, we aren’t discussing whether a CMM is accurate or not; rather, how a CMM aligns with an industry’s accuracy spectrum. All CMMs are accurate, but analyzing the comparison of the accuracy is crucial for deciding which is best for you or job.

Bridge CMMs are generally used in environmentally regulated quality control rooms which require; air-conditioning for temperature and humidity control, air filters for dust and particulate control, vibration isolation equipment, and other factors for situations where high accuracy measurements are required. It typically requires a dedicated and certified CMM programmer who has specialized training to operate the system. On the other hand, arm CMMs are also used on the production floor, and are often used in cases where accessibility is a higher priority than accuracy.

Out of the two CMM options that KEYENCE has, the most accurate CMM is KEYENCE’s XM Series Handheld Probe. The XM’s accuracy is +/- 7μm and repeatability is +/- 3μm. It can be used on the shop floor, or in a quality room, making it extremely versatile for everyday use.

Secondly, we have KEYENCE’s WM-3500 Wide Area Coordinate Measuring Machine. The WM’s accuracy is +/- 28μm and repeatability is +/- 10μm. This CMM is ideal for anyone performing large part or equipment inspection, machine alignment, and manual measurement processes that require multiple inspectors, since the WM only requires one user to measure 50ft parts.

Measurement Area

Small Parts

Do you manufacture parts that could fit in a 6x4x3 ft (X,Y,Z) area? If this resonates with you, the XM Series handheld CMM is the best CMM machine for your parts.

You can place parts directly on the stage of the KEYENCE’s XM-5000 for measurement, or use the tripod and bring the XM to your parts for in-machine measurement. If you choose to use the XM stage, it has a built-in fixture plate to make it easy to secure parts quickly for inspection. Conventional bridge CMMs use an overhead probe, require a temperature controlled clean room, and cannot be moved on the shop floor, but KEYENCE’s XM Series is a versatile CMM that can be operated anywhere needed, by anyone, making quality checks a breeze.

Large Parts

Do you measure auto body parts, aerospace equipment, or construction machines? No matter what type of large parts or equipment you measure, you’re all too familiar with the restricted measurement area, high maintenance costs, and difficulty of single-person inspection that comes with large parts. These parts can’t fit on a bridge CMM stage, and are a pain to move around the shop floor, so a portable CMM is your best CMM machine option.

Portable CMM machine types are handheld and transportable across shop floor locations. These CMMs are brought to the part in which the operator touches the device probe to the part. The CMM instantaneously records measurements and creates inspection reports. KEYENCE offers a wide variety of handheld CMMs, with maximum measurement ranges to suit many applications.

If you’re looking for something to handle these larger jobs, the WM Series is your best CMM machine option. The WM Series reaches a maximum measurement size of 15m. The system can be freely moved around the shop floor, even coming with a mobile roller case for easy transportation, allowing you to travel to those large parts and equipment for measurement and inspection.

CAD Software

Using a CMM for comparisons with molds and castings is a common practice, but it can be time-consuming without up-to-par types of CMM software. If you’re looking to use a CMM for inspection, choosing a CMM with CAD comparison functions is an ideal choice.

All of KEYENCE’s CMMs provide CAD software, so the material or part size you’re using is the determining factor for which CMM is the best fit.

Ready to Try a CMM?

Different types of CMMs each have specifications that make them ideal for particular measuring or inspection needs.

If you are measuring or inspecting parts under 6ft, the KEYENCE XM-5000 Series is the choice for you, and for anything larger, be sure to check out the KEYENCE WM-3500 Series.

Still need help with how to choose a CMM? Contact KEYENCE today and our team will get back to you immediately for a scheduled demo!

Related Downloads

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