CMM & VMM: Differences and Advantages of Both Services

CMM, or Coordinate Measuring Machine, and VMM, or Vision Measuring Machine, are both measuring instruments used for high-precision measurements. These instruments are used in the aerospace, automotive, medical, manufacturing, and quality control industries, where precision measurement is crucial. However, they are unique in their measuring method and results. Both of these methods have some shortcomings and advantages. 

In this article, we will provide an overview of the CMM and VMM inspection services, their key differences, and the advantages of each.   

What Is CMM Inspection Service?

In simple terms, CMM inspection service is a measuring method using a Coordinate Measuring Machine that has probes and robotic arms attached to it for measuring objects by touching specific points. This measuring process is complex and time-consuming. It needs well-trained people to operate it adequately. However, the accuracy of the measurement is high.

What Is VMM Inspection Service?

VMM inspection services are a measuring method using the Visual or Video Measuring Machine. Unlike CMM, this machine measures the object with data captured by the lenses attached to it. This is a contactless method. Instead of probes, this machine uses powerful optical components that can efficiently capture every small detail of the object it is measuring. 

Differences Between CMM and VMM Inspection Service

Despite being measuring machines, CMM and VMM are different in their work process.

‍

Measurement Method

CMM inspection provides measurements with high accuracy by touching the object with its probes. In addition to measurements, CMMs are versatile for collecting other 3D GD&T data as well. VMM inspection services utilize built-in cameras to capture and produce high-resolution images of the structure of the object with high accuracy. The VMM inspection method doesn’t involve touching the object.

‍

Applications

CMM inspection is useful for measuring small, large, and complex-shaped objects. It is useful for industries and applications where dimensional accuracy is crucial. Such as engine components, chassis parts of the automotive industry, medical implants, prosthetics, surgical instruments, reverse engineering, quality control, etc.

‍

VMM inspection services, on the other hand, can measure small, critical dimensions with accuracy. VMM is also capable of measuring the dimensions of transparent objects or other objects that cannot be measured by CMM. VMM inspection is useful for industries like electronics, aerospace, automotive, and medical to measure delicate and small components for its ease of use and accuracy.

‍

Limitations

VMM inspection services require less time than CMM inspection for measuring any object. The dependency on the expertise of the operator is less in the VMM inspection services, whereas the accuracy of CMM inspection mainly depends on the efficiency of the operator.

Advantages Of CMM Inspection Services

CMM inspection provides high-precision measurements of complex objects. It is capable of measuring small as well as large objects. CMM inspection is especially known for its high accuracy and repeatability. This method is ideal for getting precise geometric measurements like diameter, depth, etc.

• Collect data on objects with different surface conditions
• Match original designs with desired tolerance levels
• Catch issues before large-volume runs are executed
• If CAD data is supplied before parts physically arrive, programs can be written in advance to improve throughput

Advantages Of VMM Inspection Services

VMM inspection services use powerful cameras and lights to capture the measurement details for statistical reports. This helps in getting maximum measurement data, providing accuracy, and making the whole process quicker than CMM. 

‍

Besides this, VMM inspection services can be used for measuring transparent objects and objects with fragile or untouchable surfaces. This is only possible for VMM inspection, as it uses high-resolution cameras to record the measurements of objects without touching them.

• Capture highly accurate measurements without physical contact, ideal for delicate or soft parts
• Measure extremely small features, edges, and profiles that may be difficult to probe with a CMM
• Advanced optics and lighting to enhance surface contrast for consistent results
• Clear visual documentation can be generated of part features for easier reporting and validation

Considerations of CMM vs. VMM

CMM and VMM inspection services are unique in their measuring process. CMM uses touch probes to measure the dimensions, and VMM uses powerful cameras to measure objects without touching them. However, both are capable of providing measurements with high precision.  While choosing one of them, you must consider the purpose of measurement and the kind of object you are measuring. 

‍

If you are considering either service, contact Nel PreTech for more information.

‍