What Is a CMM Machine: Components, Uses, and Benefits

What Is a CMM Machine? Components, Uses, and Benefits of CMM Measurement

Strong manufacturing depends on the precise measurement of parts and components. Every part needs to be identical to ensure correct functionality, but sometimes, irregularities in fabrication and production can lead to discrepancies in the dimensions of manufactured parts. Without accurate measurement, dimensional errors can result in products failing to operate properly.

Traditionally, quality assurance checks have been performed by manufacturing professionals using handheld metrology instruments like gages and calipers. But while some trained experts can be quite good at quality assurance measurements, the process can be slow and subject to mistakes.

That’s where coordinate measuring machines can make a difference.

What is a Coordinate Measuring Machine (CMM)?

A coordinate measuring machine (CMM) is a device used for measuring length, width, and depth of an object using coordinate processing technology. There are multiple types of CMMs with their own specialties, but all CMMs essentially perform the same crucial measurement function.

Coordinate measuring machines can be distinguished by their structure. The main types of CMMs include:

• Bridge
• Cantilever
• Horizontal Arm
• Gantry

Broadly speaking, a CMM uses either touch probes or contactless measurement equipment. In touch probes, the probe contacts the surface of the object being measured. Contactless CMM measurement uses cameras or laser scanning to perform dimensional inspection with optical triangulation methods. While most coordinate measuring machines are made to analyze relatively small components, some can accommodate larger objects.

Uses of Coordinate Measuring Machine

Coordinate measuring machines are some of the most useful quality assurance tools available today. For complex parts and prototypes with tight tolerances, CMMs are indispensable instruments in modern design, engineering, and manufacturing.

Each type of CMM has different advantages that make it more suited for particular applications. The main purpose of a CMM is, of course, to perform measurements, but the uses of a CMM vary with each type.

Bridge CMMs are usually designed for use in a manufacturing environment. They can stand up to repeated daily use but may only be able to inspect small to medium-sized parts. The size of the objects that a bridge CMM can measure is usually restricted by the size of the granite table.

Cantilever-type CMMs are similar to bridge CMMs in that they are designed to measure precision components and parts. But cantilever CMMs are only supported from one point and allow a part to be analyzed from three sides, rather than one or two.

Gantry coordinate measuring machines don’t require a part or component to be set on a table for measurement, making them perfect for inspecting larger objects. Gantry-type CMMs are often used in the automotive space and other industries where heavy machine parts must be measured.

Horizontal Arm CMMs are useful for measuring irregular objects that wouldn’t fit the range of other coordinate measuring machines. This type of CMM takes advantage of its horizontal orientation to measure longer, more slender parts.

CMMs are used in a wide variety of industries to measure parts of all shapes and sizes. From heavy machinery in automotive, aerospace, and aviation to precision parts in medical and biotechnology fields, coordinate measuring machines are essential for ensuring consistent, accurate dimensions.

Benefits of Coordinate Measuring Machine

Using a coordinate measuring machine has a host of benefits. Not only will CMM systems provide the most accurate measurements of parts but they can drive improvements in overall manufacturing operations as well.

Better Quality Assurance

While human operators can accurately perform diagnostic measurements, even the best-trained specialists are still subject to error. People can become tired, distracted, or even negligent when performing repetitive quality assurance tasks, resulting in inaccurate measurements.

A coordinate measuring machine eliminates room for human error. It can be programmed to perform automated inspections without constant operator input. Once calibrated for dimensions, an automated CMM can measure as many parts as needed without rest.

Improved Efficiency

Once a CMM is set up, it can drastically reduce production time. The inspection stage of the manufacturing process can be streamlined to the utmost speed while retaining measurement accuracy.

And depending on the particular model, a coordinate measuring machine can also save valuable space on the shop floor. Not to mention, a quality CMM can help to reduce scrap and manufacturing waste by providing accurate measurements that prevent errors down the production line.

Customizable and Compatible

A CMM can be outfitted with specialized software programs to operate the machinery. The software can then be continuously updated for maximum efficiency. CMM probes and other hardware can also be modified and upgraded to adapt to manufacturing needs.

Improved Reputation

Every manufacturing organization strives to provide their customers and clients with the highest quality products. By using coordinate measuring machines, manufacturers can produce consistently better parts, resulting in a stronger reputation distinct from the competition.

Parts of a Coordinate Measuring Machine

While there are at least four main types of CMMs, most are designed with similar parts. Understanding how these parts work can provide insight into the CMM needs of a particular manufacturing operation.

The parts of a coordinate measuring machine include:

• Structure
• Probe (or Probes)
• Controller
• Software

The structure of a CMM refers to the overall form of the machine. This includes the type of material the machine is made of and its specific design. As previously mentioned, CMMs can come in several different types

Measuring arms, tables, fixtures, and even air compressors can all vary depending on the structure of the model.

The probe, or probes, may use direct contact to measure an object or use lasers, lights, or cameras to perform contactless measurements. The probe tip may be composed of different materials but the most popular type is a ruby ball.While CMMs can differ in structure, all CMMs use probe movement to accomplish their measurement tasks.

The controller determines the output of the machine. It directs commands to motors and scanning probes and can be adjusted to accommodate different parts. While direct computer control can be performed manually, CMM controls are usually automated in larger operations.

And while it’s not necessarily a physical part, metrology software is indispensable in a quality CMM system. The software collects, analyzes, and displays measured data in real-time. And when metrology software used artificial intelligence elements, the software can actually learn over time and more easily recognize irregularities.

How to Use a Coordinate Measuring Machine

Using a coordinate measuring machine properly takes training and experience. While the machine can be programmed to operate on its own, calibration and other setup needs must be accounted for first.

In the simplest terms, measurements on CMMs can be performed by directing the measuring probe to the designated location, at which point the machine will take the dimensional coordinates of the object.

But there are necessary steps to take before recording measurements.

First, the object being measured should be allowed to acclimate to room temperature. This will prevent any irregularities in shape and size due to temperature changes, especially for parts or prototypes that have come from different departments or facilities. While changes caused by temperature may be small, they can make a big difference in the dimensions of precision parts.

The probe should be calibrated to accurately measure target objects. While calibration processes differ, it generally involves analyzing an object at predetermined dimensions and comparing data points against known dimensions.

The object chosen for calibration should resemble the intended target object as much as possible in terms of material hardness and size. Some popular choices include:

• End Bar
• Ball and Cone
• Hole Plate
• Ball Plate

A laser interferometer may be used for the highest level calibrations, which measures a CMM’s movement using light.

It may also be necessary to replace, lubricate, or clean components of the machine before use to ensure the best outcomes.

3D Engineering Solutions and CMMs

At 3D Engineering Solutions, we’re dedicated to providing state of the art engineering metrology services to partners in virtually every industry. Anywhere that precision 3D modeling is required, our team’s detail-oriented approach and abundant experience will deliver the highest quality results.

We’re happy to work with you to expand your CMM capabilities. Whether you’re installing new CMM equipment or adopting the latest CMM software, our staff of degreed engineers will support you at every step of the process.

Contact us today for CMM Machine Services.