Inspec Insights

CMM vs. Vision System - Four Questions to Ask When Choosing Your Measurement Method

We’re often asked how our contract inspection department chooses which measurement system to use for the jobs we handle in our in-house lab.  It usually comes down to a decision between our CMMs or our Vision Systems however, now that CMM style probing has become a more commonly used tool for vision systems, deciding which system to use becomes less cut and dry.  This article will provide some things to consider to, hopefully, make the decision of what equipment to use to measure your products a little easier.

Four factors to consider when deciding on your inspection system:

  1. Speed
  2. Size  
  3. Number
  4. Variety

  1. Speed: Is your inspection a one-time event or an ongoing sampling?
    Since vision systems are less dependent on moving probes and probe approach speeds, they have the potential to be much faster, 5-10 times faster in many cases.

  2. Size: What size is your smallest feature?
    Both CMMs and Vision systems can handle larger features.  As features get smaller than 3-5mm, we start leaning toward using a vision system, they are more accurate for smaller features. 

  3. Number: Do three of your datums appear in one view of your print? 
    In the past, vision systems have been assigned to 2-D applications, however, the newer ability to use vision and CMM probing interchangeably and on the same machine, makes vision systems a more common choice in 2½-D and 3-D applications.  In any event, if the main datums appear on one view of your print, we would consider the part 2-D in nature and would lean towards the vision system. 

  4. Variety Do you need probing and vision capabilities on the same part?
    The nature of the characteristics you need to measure is a key consideration.  Visions systems can be equipped with full probing, making it in effect a CMM.  If you need both vision and CMM capabilities, a vision system with probing may be your best option.

So it’s not always obvious which system to use.  If you’re still unsure, contact us and we’ll be happy to talk with you about it.

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