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What are CMMs?
Coordinate Measuring Machines (CMM) are mechanical systems designed to move a measuring probe to determine coordinates of points on a work piece surface. CMMs provide the tools to precisely inspect critical dimensions, thus dramatically increasing the number of acceptable parts for our clients and decreasing the occurrence of errors.
CMMs are useful in nearly every industry due to their capabilities in dimensional measurement, profile measurement, angularity or orientation measurement, depth mapping, digitizing or imaging and shaft measurement. Consequently, CMMs reduce the incidence of nonconforming parts by providing exceptional inspection abilities. Furthermore, their ability to accurately reverse engineer existing parts is extremely helpful when prints are no longer available.
How does a CMM work?
CMMs move a measuring probe to obtain the coordinates of points on an object’s surface. Often these parts have tolerances as small as .0001". The machine uses an X-Y-Z grid to determine its position on a worktable. The probe is used to touch different spots on the part being measured. The machine then uses the X,Y,Z coordinates of each of these points to determine size and position. The probes drag along the surface of the part taking points at specified intervals. This method of CMM inspection is more accurate than the conventional touch-probe method and often faster as well. Many thousands of points can then be taken and used to not only check size and position, but to create a 3D image of the part as well. This "point-cloud data" can then be transferred to CAD software to create a working 3D model of the part. This procedure is often used to facilitate the "reverse engineering" process. This is the practice of taking an existing part, measuring it to determine its size, and creating engineering drawings from these measurements. This is most often necessary in cases where engineering drawings may no longer exist or are unavailable for the particular part that needs replacement.