Manufactured components that go into higher level assemblies need numerous dimensions verified to be sure that they will fit together properly later in the manufacturing process. Stand alone parts must be of proper size and shape with appropriate radii, thicknesses, and feature relationships for proper appearance and functionality. Modern manufacturing processes and computer aided design (CAD) allow the manufacture of parts with complex curves, intricate features, and critical relationships. Injection molding and five-axis machine tools produce threedimensional parts with important dimensions on every surface and in every opening, hole, or recess.
The manufacturing engineer determines which features and dimensions to measure. For example, the diameter of a through hole in a machined metal part may not be critical,but the position of
its center relative to a datum might be. Or the converse might be true. Or both the diameter and its location may be critical . In addition, with today’s CAD software, it can be tempting to put tight tolerances on dimensions that do not warrant those tolerances.
Those needs can vary, depending on where the part is in its life cycle, and where it is in the manufacturing process. For example, a new part typically goes through a detailed first-article inspection. This measurement process not only verifies that the part dimensions are in specification, it also verifies that the manufacturing process is capable of producing the part properly. Later, when the manufacturing process is stable, a smaller set of measurements may be performed during audit inspections on samples from the production run.
Those measurements are attributed to other parts in the same batch or production run. Dimensional measurements are also performed as final inspection and at incoming inspection on the customer’s side. Where, when, and to what degree measurements are made depends on the value of the part. Only when properly dimensioned and toleranced drawings calling out particul ar features or dimensions are available can the capabilities of available measuring devices be assessed so that the proper tool is used for the job. Quality, reputation, and costs are all affected by part measurements.
Most manufacturing companies have some number of measuring devices available from the day that they start operation. These range from hand gauges, micrometers, and calipers, up to a coordinate measuring machine (CMM) and maybe an optical comparator. Those tools are purchased to support a particular level of manufacturing, with its associated tolerance and accuracy requirements. Over time, new manufacturing equipment may be purchased to machine more complex parts that need to meet tighter tolerance requirements. It can be tempting to do all the new measurements with the available tools already on hand. However, it’s easy to reach a point where the measuring capabilities simply can’t keep up with the latest requirements.
Even if the existing measuring tools are determined to be capable of the new measurements, there can be cost implications. Certain measuring devices are good at particular measurements. Verifying all the necessary dimensions may require using several measuring devices that may be located in different parts of a shop, or in use for other parts, or that require a particularly skill ed operator who may not be available. Shops striving for lean operations can encounter bottlenecks in any of those places. Time wasted in moving a part to different measuring machines or waiting in a queue until a machine is available contribute to the total cost of that part (time is money). In addition, the delay in getting the measurements may increase scrap if the process continued and the delayed measurements determine that the process was out of control.
Multisensor Metrology Technology - SmartScope, CMM machine and 3D CT scanner & laser scanner. Our range includes OGP SmartScope CNC 670, OGP SmartScope ZIP 250, OGP SmartScope ZIP Lite 300, OGP SmartScope MVP 200, OGP SmartScope FLASH CNC 200, OGP SmartScope FLASH CNC 300, QVI SNAP, SHAKE SHR CT 50, ShapeGrabber Ai310 and many more. There will be one that suits your measurement or inspection needs.
Optical Gaging (S) Pte Ltd (OGS) is a Division of Quality Vision International Inc. Our devotion to innovation and quality has become industry standards relied on by major manufacturers. At OGS, we believe that each sales signals the beginning of a new friendship.
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