What is the difference between a VMM and a CMM?

Measuring is an essential part of the production process. It ensures the consistency and conformity of parts, and ensures they fit smoothly into larger assemblies. Lack of an adequate measurement solution can result in high costs and, if a product fails, can even be life-threatening.

However, if you work on a shop floor, you know that measurement is often not a quick or easy task. It often requires tedious and repetitive work, and only requires specially trained technicians.

Although the abbreviations sound similar, these measuring machines use very different methods. Below we'll discuss the differences between CMMs and VMMs, and when to use each.

What is a VMM?

A vision measuring machine is a device that uses optical imaging to perform non-contact measurement of an object. Its main components include an optical system, an image acquisition system, measurement software, and a control system. During the measurement process, the optical system projects an image of the object being measured onto the image acquisition system. The measurement software then processes the image to calculate the object's geometric parameters.

Working Principle

The imager uses surface light, contour light, and coaxial light for illumination. The image is then captured by a camera lens through a variable-focus objective lens and transmitted to a computer screen via an S-terminal terminal. Software commands then capture the desired elements, generating an image on the display that automatically measures the object being measured. The worktable drives an optical scale, moving in the X, Y, and Z directions. A multi-function data processor processes the data, and software performs calculations to complete the measurement.

Technical Features

High Precision: The image measuring instrument utilizes non-contact measurement, eliminating friction errors associated with contact measurement and improving measurement accuracy.

Fast Measurement: The image measuring instrument boasts high measurement speeds, significantly improving production efficiency.

High Degree of Automation: Equipped with an advanced control system, the image measuring instrument automates the measurement process, reducing the operator's workload.

Adaptability: The image measuring instrument can be configured with the appropriate measurement software and optical system to meet the measurement needs of different industries, offering high adaptability.

Environmentally Friendly: The image measuring instrument utilizes non-contact measurement, minimizing environmental pollution during the measurement process.

Application Areas

Manufacturing: Image measuring instruments are widely used in the manufacturing industry for product quality inspection, product development, and other fields.

Aerospace: The aerospace industry requires high precision and reliability in measuring equipment, and image measuring instruments are widely used in this field.

Precision Instruments: Image measuring instruments are primarily used in the precision instrumentation field for instrument inspection and calibration.

Electronics: Image measuring instruments are primarily used in the electronics industry for dimensional and appearance inspection of products such as mobile phones and computers.

Pharmaceutical Industry: Image measuring instruments are primarily used for high-precision measurement of medical devices and pharmaceutical packaging.

Precautions

1. It is important to select an appropriate workpiece fixation method and orientation.

2. The workpiece lighting method is also very important and should be designed based on the features being measured.

3. Determine the workpiece coordinate system based on the drawing and define the workpiece datum within the coordinate system.

4. Image measuring instruments without an automatic zoom system require image calibration, and the appropriate magnification must also be determined.

5. The measurement path and method are crucial and must be determined accurately.

6. Programming and recording annotations on vision measuring machines can make data more accurate and facilitate data maintenance.

The importance of vision measuring machines in modern science and technology cannot be ignored, and their technological breakthroughs and application prospects are promising. With the continuous advancement of science and technology, vision measuring machines will play a vital role in even more fields. To promote the high-quality development of my country's manufacturing industry, we must vigorously strengthen the research and development of vision measuring machine technology to improve product quality and open up new application areas. At the same time, we should actively seek exchanges and cooperation with internationally advanced technologies to enable our vision measuring machine industry to shine globally.

What is a CMM?

CMM stands for coordinate measuring machine (CMM). A CMM uses a probe to measure coordinates and applies mathematical operations to generate dimensional data and geometric tolerance (GD&T) features. Some portable CMMs, such as the KEYENCE XM series, do not require a workbench or dedicated measurement area. Their portable design allows for greater freedom of movement during measurement, which is particularly useful for measuring large or heavy parts.

Its emergence stems, in part, from the need for fast and reliable measuring equipment to support the high-efficiency machining of automated and CNC machine tools, as well as the increasing number of complex-shaped parts. Furthermore, advances in electronics, computers, digital control, and precision machining technologies have provided the technological foundation for the development of coordinate measuring machines (CMMs).

Coordinate measuring machine (CMM) systems use portable contact probes that can be moved around the shop floor, extending their measurement range beyond parts on a specific workbench.

In addition to dimensional data, CMMs can also collect geometric dimensioning and tolerancing (GD&T) data, such as angles, flatness, and parallelism. This additional data has led to CMMs being widely used for 3D part inspection. They can generate real-time data reports and pass/fail analysis to ensure that measured parts meet quality assurance standards.

Applications

Automotive Manufacturing: The automotive industry is a key application area for CMMs. During the automotive production process, CMMs are used to measure the size and shape of engine components, ensuring engine performance and safety. It can also be used to detect wear and fatigue in automotive parts, identifying potential failures in advance. Coordinate measuring machines (CMMs) meet the automotive industry's demand for high-precision measurement and have become indispensable testing equipment on automotive production lines.

Mechanical Manufacturing: CMMs can be used to measure the machining accuracy and assembly quality of mechanical parts, improving the performance and reliability of mechanical equipment. Whether measuring large mechanical parts or small precision parts, CMMs provide highly accurate measurements, ensuring product quality and performance.

Electronics and Semiconductor Industry: In the electronics industry, CMMs can be used to measure the size and shape of electronic components. High-precision measurements of electronic components, integrated circuits, and semiconductor materials ensure product performance and quality, meeting stringent industry standards.

Aerospace Industry: In the aerospace industry, CMMs can measure the size and shape of aircraft parts, ensuring that product quality and performance meet design requirements.

Scientific Research and Applications: In addition to their industrial applications, CMMs are also widely used in scientific research and applications. For example, in fields such as materials science, physics, and chemistry, precise measurement and analysis of various materials and samples are required, and coordinate measuring machines provide powerful tools for researchers.

Additionally, coordinate measuring machines can also be used in fields such as medical devices, mold manufacturing, and optoelectronics. In the medical device field, coordinate measuring machines can be used to measure the size and shape of medical devices such as artificial joints and implants, ensuring their safety and effectiveness. In mold manufacturing, coordinate measuring machines can be used to measure mold processing accuracy and assembly quality, improving mold life and product quality. In optoelectronics, coordinate measuring machines can be used to measure the size and shape of optical components, ensuring the performance and precision of optical equipment.