4 Factors In Choosing The Right CMM Machine |
Posted: September 19, 2017 |
Used coordinate measuring machines are an easy, low-risk way for shops to introduce more advanced inspection processes. You can save as much as half off the price of a new machine when you buy used from a reputable metrology dealer. When you’re deciding on what CMM machine to purchase, there are four key factors you need to identify first. Volume Volume is your first and last test of a CMM machine – a machine’s volume is the maximum size of the component that the machine can measure. As with so many aspects of metrology, there is generally a trade off, where equipment with higher volumes, such as portable arms, offer lower accuracy in exchange for higher volume, but bigger and more expensive equipment, like a gantry coordinate measuring machine, can provide both accuracy and large volumes. While the bridge-style CMM machine is the most common metrology equipment out there, gantry, vertical, and horizontal coordinate measuring machines can all be used to accurately measure very large parts, such as car bodies. Portable ROMER arms, the tool of choice used by contract metrologists at Canadian Measurement Metrology Inc. (CMM), can measure components well-beyond its reach, as you can integrate multiple parts set ups, allowing you to measure oversize components. By contrast, bridge coordinate measuring machines are some of the best tools for small components. Accuracy, Uncertainty & Tolerance Accuracy, uncertainty, and tolerance go hand in hand in metrology; accuracy is the degree of conformity of the measured coordinates to the values of specified coordinates, i.e., the original design of a component compared to the built product. Uncertainty is, according to the ISO, a parameter of the dispersion of values that could be attributed to the measurement, while tolerance is the range of permissible variation from specified values. It can be difficult to figure out which measurement is more important and what this all means. However, you should know what your accuracy needs are, as they’re often specified by your client. An independent metrology dealer like Canadian Measurement Metrology can help you identify the machine that suits your accuracy and tolerance requirements. Repeatability Repeatability refers to a machine’s ability to repeat the same measurements at the same level of accuracy. If you plan to automate your inspection or reach 100% inspection, a highly repeatable device like a Renishaw Equator is a must. Typically, a higher repeatability means a lower accuracy, but you can compensate for this by measuring a master component with a more accurate CMM machine. Speed Finally, you have to consider the speed at which your metrology equipment will measure and collect data, or else you could wind up facing long wait periods for your inspection to be complete. If you need to collect millions of data points on a single component, laser trackers and other optical solutions can help you achieve 100 percent inspection. An independent metrology dealer will offer you the best selection of used CMM machinery to choose from at an affordable price. Independent dealers offer used equipment from all major metrology brands, leaving you free to choose the most effective for your shop without being stuck with a single OEM. They will find the machine that best suits your measuring requirements.
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