As the world continues to shrink and companies from around the world compete for the same business, it's more important than ever before to get the most value from your measurement system purchase. Whether you already own or are preparing to purchase a measurement system, remember to evaluate all aspects of the system before you buy in order to get maximum value.
Before making a major capital expenditure in a measurement system, make sure you get the right equipment. Video measurement systems, such as RAM Optical's DataStar and OMIS families, meet the measurement needs for many manufacturers, particularly those that need to take field-of-view measurements and manufacture parts with features too small to touch. Small, precise parts can usually be measured faster on video measurement systems than with traditional contact measurement systems. Plus, video measurement systems' programmable zoom optics offer a wider range of measurement options.
Get the right system
Bob Donaldson, president of RDR Inc., consults for several measurement system manufacturers and helps companies make their measurement system purchases. "People make the mistake of looking at how much they're going to spend rather than how much it's going to cost them to get the wrong machine," says Donaldson. "If you increase scrap rates by 5 percent because the uncertainty on the system is too large, imagine what that costs you. Compare that to what you saved by buying cheaper equipment." It's even more costly if the system is used in process or gage control, and you adjust your manufacturing based on the results from the measurement system.
Donaldson also recommends purchasing equipment that complements your existing measurement system. The focus needs to be on getting the right equipment for the job, not necessarily buying a whole new system.
Location is everything
Placing the system in the right environment is just as important as purchasing the right equipment. The manufacturer's specifications mean very little if you don't take reasonable steps to control the environment. Contact measurement systems manufacturers take great pains to control temperature and part movement. In addition to these variables, video measurement systems must consider the effect of light when measuring parts. External light sources can adversely affect measurements on video systems that use programmable lights.
ACTCO Metrology in Meadeville, Pennsylvania, specifically designed a new building without windows to accommodate its 11 video systems. Despite the lack of windows, the company made sure the work environment was large and open to make it a comfortable place to work. Some companies darken the lights in the room or provide enclosures to block external light in critical measurement applications.
Take advantage of your system
In addition to the specific application you purchased your system for, your video equipment may have other uses that you're not taking full advantage of. Video systems combine the strengths of an optical comparator, toolmaker's microscope and noncontact coordinate measurement machine into one system.
With the ability to see more than just a profile, video systems allow users to visually inspect their parts at very high magnification. Add to that the ability to make Polaroid prints, video-captured images for documents, and e-mail and videotapes for training, and you have a very powerful documentation system.
Video measurement systems allow users to create programs that automatically measure the complete part and provide quantifiable pass/fail results. Much more than simple go/no-go gages, these results can be used for process feedback, trend analysis and other statistical evaluations. Results can be collected and charted over time or recorded for historical or regulatory purposes.
Most video measurement systems will allow you to install a network card, which allows you to perform data analysis at a computer workstation instead of tying up the inspection equipment. Charlie White, vice president of engineering at Datum Inspection has six CMMs and two video measuring systems. "We never ask the machine to act as a report generator," he says. "I can't remember the last time I printed a report from one of my systems."
Importing computer-aided design files and creating programs offline is another great way to extend the value of your video measurement system. Working on a $2,000 computer to make part programs instead of on a much more expensive measurement system increases the time that the system is available for measuring.
Reverse engineering offers another opportunity to take full advantage of your video measurement system. If an original blueprint gets lost or destroyed or if a customer supplies a part but not a blueprint, the ability to export CAD data from your measurement system can be very helpful. Many companies take machined-to-fit prototypes and document their measurements using a measurement system.
Video systems can also collect edge information and compare measurement points to your CAD model to evaluate form errors on manufactured parts with complex geometric shapes. IQ-Formfit, a software package from Integrated Quality in Columbus, Ohio, provides fast 2-D and 3-D best-fit capabilities to help accurately align parts with CAD models. Its graphical user interface and powerful graphics engine allows users to manipulate and visualize their CAD model, measurement data and analysis results. Best of all, it makes form-tolerance analysis much faster and easier.
Calibrating and maintaining your system
If you don't keep your equipment calibrated, you'll get representative but inaccurate measurement data. It's also a good idea to keep your calibration standards in good repair and calibrated. It's simply good insurance in case you ever need to prove traceability.
Regardless of whether you calibrate your equipment internally or have the factory come out to calibrate the system, it's a good idea to do preventive maintenance at the same time. Have the optics and rails cleaned, and perform any other maintenance recommended by the factory. Keeping the system in top mechanical condition will extend its life and increase its resale or trade value.
It's easy to justify the expense of purchasing equipment, but sometimes it's difficult to sell management on the benefits of a comprehensive training program for operators. Measurement systems offer a wide range of capability, and learning to use them well helps users make better and more accurate measurements.
Most companies have one or two "experts" and several operators for each of their measurement systems. Unfortunately, on-the-job training or peer training only goes so far. Even the resident experts need refresher training to get the most out of the system. Most video measurement manufacturers offer factory or on-site training. While training at the manufacturer's site involves additional travel costs, it is sometimes the only way to get away from interruptions.
Many companies offer training on a wide range of systems. Some companies, such as ACTCO Metrology, have dedicated systems and classrooms. Be sure to check any training company's credentials with the manufacturer and with previous clients.
"In any computer-aided measuring device, software is everything," says White. "Anybody can put together hardware if they try hard enough. The power to meet future needs is in the software. Make sure that your purchase is going to run on a software platform for the future."
The ability to work on a network is a must, and your software should work with other applications. "That should be a standard ingredient for any forward-thinking platform," explains White. "It allows your measurement software to leverage off of the best efforts of other applications. The days of only using algorithms embedded in the software are dead." New measurement applications, such as RAM Optical's Galaxy 3.0, have the ability to integrate the customer's existing analysis applications into a complete solution.
Keeping the software on your video measurement system current is as important as staying calibrated. Software upgrades often add new time-saving functions, fix bugs and should ensure that your software is Y2K-compliant.
If you're considering purchasing a new video measurement system or adding to your existing system, there are a number of issues to consider to make the investment more profitable and more useful to your company. Selecting the right system can improve accuracy, increase throughput and reduce defects. Just be sure to carefully consider equipment location, establish an effective calibration and maintenance system, train personnel in the system's use, and choose state-of-the-art software.
About the author
Matthew Haag is product manager for RAM Optical Instrumentation, a division of Newport Corp. For more information, e-mail email@example.com .
©1999 RAM Optical Instrumentation.
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