When it comes to Coordinate Measuring Machine (CMM for short) inspection, it’s important to understand what the capabilities of these machines are and what an inspection can deliver. Fortunately, CMM technology has been around for over 30 years and has advanced (and still is advancing) a great deal. A CMM is capable of a number of different types of inspection with incredible detail.
When it comes to the types of inspections, a CMM is generally capable of 4 generic types of data gathering: dimensional, profile, angle, and depth.When we think about a dimensional inspection, we are using a CMM to capture data across multiple axes of the object to be able to determine the exact measurements and dimensions of all aspects of an object. Profile inspections deal with capturing the profile and form data for 2D or 3D objects and parts. Depth inspections use techniques, often involving stereographic imaging, to capture the depth(s) of any object.
With a number of different methods for gathering data, CMM’s have become extremely versatile. Some types of CMM’s require contact with the object such as a touch probe that takes measurements by making multiple points of contact or a scanning probe that keeps continuous contact with the object while moving across or around. In at least one study, these two methods were found to be equally as accurate when more than 2 points of contact were used. Some objects might be easily scratched or deformed by contact from a probe, so optical and x-ray computed tomography (CT) CMMs can be used. X-ray CT is currently gaining popularity for dimensional analysis because it has the capability to capture both internal and external geometries in one scan. (You can read more here about this trend.)
When it comes to accuracy, any CMM is hard to beat. Tactile and non-tactile CMM’s are able to take measurements as accurate as a picometer (0.1 micron) or less than 1 millionth of an inch. Most of these measurements are gathering data in optimal conditions of 20C/68F, but fortunately, a trained technician can use computed regression analysis to obtain equally as accurate measurements in non-optimal conditions. This is extremely important as portable CMM’s have been developed to be taken to sites to do measurements of large, heavy objects or small delicate objects without them having to be moved while still maintaining the same accuracy.
Industry needs for greater accuracy due to tighter tolerances has really driven development in CMM’s. In return, international standards have been set for calibration of CMM’s to ensure repeatability and precision around the globe. This requires a large amount of training to ensure CMM’s are maintained and used properly. Without these experts and their skills, detail and accuracy would be compromised. Fortunately, the experts at Engineered Mechanical Systems are here to help you get the most accurate data possible. Contact us today to discuss how your needs can be met.