Quality Scan: Optical Measuring Systems Can Keep Up with Production
By Keith Vince
Detroit Precision Hommel
Rochester Hills, MI
Manufacturers, especially those in the production business, are looking for flexible gaging that can collect all relevant information on a part and report it - from the plant floor - without adding time to the production cycle. As product life cycles shrink and new products are designed and manufactured, inspection technology must keep up.
Critical components to be measured in the manufacturing world include shafts, spindles, and other cylindrical parts. They are literally the key to precision, durability, and function of assemblies from engines and transmissions to motors, pumps, and compressors. Attributes of geometry, and features such as cams, must be inspected, often 100%. Yet time for inspection is limited, and operators may not be trained adequately.
Technology exists that can enable manufacturers to achieve their inspection goals. Optical CNC shaft-gaging systems combine length and roundness measurement with digital image technology, making it practical to rapidly scan the part, and inspect up to 150 different features on a shaft in less than a minute.
With no practical limit to the number or the size of features that can be measured, these systems are highly accurate, high-speed measurement tools that can confirm production quality instantly. Manufacturing checks, automatic tool correction, initial sample measurement, and machine setups, are typical applications for this type of gage.
Flexible optical gaging systems can move inspection into the future if they can measure a wide variety of part designs and part features with minimal changeover, limited only to selection of a specific part measuring program. These systems are handling a wide range of shaft sizes to nearly 480-mm diam and 2500 mm in length with measuring resolutions to ±1 µm. Filters ensure highly reliable measuring results, and reduce sources of error, including dirt and swarf.
Contour, diameter, length, and roundness are just a few characteristics that can be recorded in submicron detail during a single pass of an optical measuring head. Driven by Windows-based measuring software, these systems provide an alternative to conventional shaft-measuring techniques that can be more accurate and more complete with comparable cycle times. Once the workpiece has been scanned, data can be stored, graphed, or transferred for later reference.
Optical gaging systems have become flexible inspection solutions that allow the part inspection function to keep up with changing specifications, part designs, and production rates through consistent use of traceable standards, digital measurement technologies, and standard operating systems.
These types of systems are adaptable to manual, semiautomatic, or fully automatic gaging, horizontal or vertical installations, stand-alone operation, and universal measuring. Optical gaging systems are also suited to installation in a production line or cell - next to the machine tool - and can help reduce machine qualification times while providing the ability to assure 100% quality control within the machining cycle.
Dedicated gages are still required for some high-volume production applications, but the era when manufacturers were prepared to buy, store, and maintain dedicated gages is winding down. The inherent limitations of dedicated gages are costly to accept in a time of scarce capital dollars and frequent product changes.
The trend to high-volume, flexible gaging is being accelerated by limited capital dollars and the need for rapid, complete, and accurate measurements. Flexible, high-speed, reprogrammable gaging will be a key tool to ensure manufacturing quality of vital components.
This article was first published in the May 2005 edition of Manufacturing Engineering magazine.