Machining 101: What Are CMMs?

Optimized bases, drives, probes, software and more make coordinate measuring machines the most accurate tools for measuring part dimensions. To learn more about these marvelous machines keep on reading!

What is a CMM Machine?

A CMM (coordinate measuring machine) is a measurement tool that consists of a motion system, a probing system, a computer and measurement software. This tool can measure the dimensions of machine or tool parts using coordinate technology. The dimension open to measurements include the height, width and depth in the X, Y, and Z axis. Depending on the CMM machine’s sophistication, you can measure the target and record the measured data all at once.

How does a CMM Machine Work?

The part that is to be measured is placed on the CMM’s base. The base is the site of measurement, and it’s made from a dense material that is stable and rigid. Although aluminum and granite are both common, granite’s superior thermal stability and vibration damping makes it the most effective option. Its stability and rigidity also ensure that the measurement is accurate. Also, mounted above the CMM plate is a movable gantry that is equipped with a touching probe. The CMM machine then controls the gantry to direct the probe along the X, Y, and Z axis. By doing so, it replicates every facet of the parts to be measured.

On touching a point of the part to be measured, the probe sends an electrical signal which the computer maps out. By doing so continuously with many points on the part, an accurate measurement can be obtained. After the measurement, the next stage is the analysis stage, after the probe has captured the part’s X, Y, and Z coordinates. The information obtained is analyzed for the construction of features.

CMM Components

Knowing about a CMM machine also comes with understanding the functions of its components. Below are the important components of the CMM machine.
  • Probe – Probes are the most popular and important component of a traditional CMM machine. Due to their nature, the probes’ tip comes from a rigid and stable material. Common materials used are ruby and zirconia. The tip can also be spherical or needle-like.
  • Table – The table is an important component of the CMM machine because it must be very stable. It should also not be affected by temperature, and be able to withstand normal wear and tear. Granite is ideal for highly accurate measurement because its shape stays the same over time.
  • Software – The software is not a physical component but will be classified as a component. It’s an important component that analyzes the probes or other sensitivity components.

CMMs on the Shop Floor

The CMM collects data faster than manual measuring instruments, and offers great flexibility and operational swiftness in the right hands. Because of this CMMs are starting to become integrated into measurement stations on shop floors. These stations might be physically attached to a production line or integrated through a transfer device like a cart or conveyor belt. Machine tool operators can usually carry out shopfloor CMM applications with the aid of intuitive software, thus eliminating the need for additional, specialized personnel.

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