What Is A Coordinate Measuring Machine?

A coordinate measuring machine (CMM) is used to measure the geometrical characteristics of objects. A CMM can accurately measure the three-dimensional coordinates of points on an object’s surface. In addition, CMMs can measure the distance between two points, the angle between two lines, the radius of a curve, and other characteristics.

The first CMM was developed in the 1950s by British engineer David Ingram. Ingram’s machine was designed to measure the dimensions of small precision parts for the aerospace industry, which required highly accurate measurements of the geometry of aircraft parts.

Since then, many manufacturers of precision measurement equipment have come up. This has created a need to ensure that you purchase your equipment from professionals. The best coordinate measuring machine shouldn’t require error mapping like those found on https://eleymet.com/coordinate-measuring-machines/ and others. Today, CMMs are used in various industries, including automotive, electronics, medical devices, and consumer product manufacturing.

This article will delve deeper into what makes a CMM tick, how to use it, and some of its benefits.

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Understanding A Coordinate Measuring Machine

There are various designs of coordinate measuring machines, including: 

• Portable Models

Portable coordinate measuring machines are small enough to be handheld and are often used in field applications.

• Benchtop Models 

Benchtop coordinate measuring machines are designed for use in laboratory or production environments.

• Floor-Standing Models 

Floor-standing ones are the most significant type of coordinate measuring machine and are typically used in industrial applications.

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Types Of Coordinate Measuring Machines

There are two main types of coordinate measuring machines: contact and non-contact CMMs. Contact CMMs are using a probe that physically contacts the measured object. Contact coordinate measuring machines are more accurate but can damage delicate things. In contrast, non-contact CMMs use a laser or an optical encoder. At the same time, non-contact coordinate measuring machines are less accurate but safer to use.

Components Of Coordinate Measuring Machines

A contact coordinate measuring machine consists of three main components: a measuring head, a measuring arm, and a computer.

• Measuring Head 

The measuring head is mounted on the measuring arm. It contains one or more sensors that measure the coordinates of points on an object’s surface.

• Measuring Arm

The measuring arm is mounted on a base, which may be fixed or mobile. It’s used to position the measuring head relative to the measured object.

• Computer

The computer stores the measurements taken by the sensors and generates a three-dimensional model of the object’s surface.

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How Coordinate Measuring Machines Work

Non-contact coordinate measuring machines use a laser interferometer to measure the coordinates of points on an object’s surface. A laser interferometer consists of a laser, a beam splitter, and two photodetectors.

The laser beam is split into two beams by the beam splitter where one beam is reflected off the measured object’s surface while the other is used as a reference. The two beams are recombined at the photodetectors, which generate electrical signals that are proportional to the difference in the optical path length of the two beams. The electrical signals are used to calculate the coordinates of the points on the object’s surface. 

Other non-contact coordinate measuring machines use optical encoders to measure the coordinates of points on an object’s surface. Optical encoders consist of a light source, a grating, and a photodetector. The light source projects a beam of light onto the grating, diffracting the light into a series of parallel beams.

The photodetector measures the intensity of the diffracted light beams. It generates electrical signals that are proportional to the position of the light beam on the grating. The electrical signals are used to calculate the coordinates of the points on the object’s surface.

Most coordinate measuring machines are controlled by computer software. The software is used to create measurement programs, which specify the dimensions that should be measured and the acceptable tolerances. The software also provides a user interface, allowing you to view the measurement results and adjust the program if necessary. 

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How To Use A CMM

A CMM can measure the dimensions of various objects, including mechanical parts, electronic components, and even three-dimensional objects such as sculptures. It can measure a variety of features such as:

• linear dimensions 
• angular dimensions 
• holes 
• slots 
• circles 
• spheres
  

Here are two easy steps to follow when using a coordinate measuring machine effectively:

• Select The Type Of Measurement

To use a coordinate measuring machine, select the type of measurement to be taken and enter the appropriate parameters into the machine. You then place the object to be measured on the measuring platform, and the probe or laser will be selected. The probe or laser is supposed to be positioned at the start point of the measurement.

• Take Measurement

Then, move the coordinate measuring machine along the measurement path. The data points are collected and processed, and the machine’s software displays your results. The software can also analyze the measurement data and generate reports. These reports can be used to identify trends or to track the performance of the CMM over time.

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Things To Keep In Mind While Using A Coordinate Measuring Machine

There are a few things to remember when using a coordinate measuring machine. First, you should place the measured object on the coordinate measuring machine’s measuring table. The object should be centered on the table. Ensure the object doesn’t move during the measurement process.

Second, you should be familiar with the CMM’s software because the software is used to create measurement programs and generate reports. Third, avoid damaging the CMM’s probes. Probes are delicate and can be easily damaged if they’re dropped or mishandled.

It’s also important to regularly calibrate the coordinate measuring machine to achieve the highest possible accuracy. Calibration is the process of adjusting the CMM to compensate for errors. There are a variety of different calibration methods, including the use of standard objects of known dimensions or the use of software algorithms.

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Pros Of Using A CMM

There are many advantages of using a coordinate measuring machine:

• Accuracy And Process Improvement

Coordinate measuring machines are much more accurate than traditional measurement methods such as calipers and tape measures. This is essential for ensuring that products meet the required tolerances. Using a CMM can also help to improve organizational processes. This is because the CMM can be used to identify areas of non-compliance with quality standards and can be used to monitor the implementation of process improvements.

• Cost Savings

Using a CMM can lead to cost savings for an organization. This is because CMMs can be used to streamline processes and can also be used to reduce the amount of time and resources required to achieve quality assurance. In addition, the use of a CMM can help reduce scrap and rework as well as the need for customer returns.

• Increased Efficiency

Coordinate measuring machines are much faster than traditional measurement methods. They also identify issues early in the manufacturing process. This is important for reducing waste and ensuring that products are produced efficiently.

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Cons Of Using A CMM

There are some disadvantages of using a coordinate measuring machine, including:

• Training

Coordinate measuring machines require operators to have specialized training. If you can’t pay for training, which can be fairly expensive, this may be a disadvantage. 

• Maintenance

Coordinate measuring machines require regular maintenance. This can be difficult if you lack the resources to invest in the proper maintenance of these machines.

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Summary

Coordinate measurement machines are an excellent resource for measuring the characteristics of real-world objects. The procedure of using a CMM is straightforward. There is, however, a steep learning curve involved in operating the apparatus.

Measurements taken with a CMM are more reliable if the user selects a CMM that’s well-suited to the job and then strictly adheres to the manufacturer’s instructions. Use the information in this article, and you shouldn’t run into any snags while using the CMM.

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Frequently Asked Questions (FAQ)

Coordinate Measuring Machine

A coordinate measuring machine (CMM) is a device that measures the geometry of physical objects by sensing discrete points on the surface of the object with a probe.

How to Use a CMM

How to use a CMM: to use a manual CMM the operator would move the probe by hand or using the joystick to the part that requires inspection. The machine will then take the measurements which are transferred to the computer software.

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