Metrologia
Metrologia
Computer Gaging: Doing More With Less
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Computer Gaging: Doing More With Less

George Schuetz, Mahr Inc.

When you think about it, a lot of data has become available to the process engineer on the shop floor. Starting 50 years ago with in-process charting, data has grown exponentially with the digital revolution in electronics and gaging. Almost all gaging types now have a digital version—and once you go digital you have the ability to send measuring results to "something" that can collect and manage them. In fact, this has become the de facto method for the collection of gaging data: the operator takes a measurement and sees the results on the gage, but "the system" takes his results and puts them into their proper bins.

The proliferation of personal computers and the fact that everyone is now pretty much comfortable using them has made the PC available in almost every manufacturing, assembly and quality area. PCs are rarely necessities for standard dimensional measurements, although almost any application can be enhanced through the use of PC-based gaging software. And while the use of "gaging computers" cannot serve as a substitute for sound gaging practice, the potential benefits they offer are greater, and the barriers to entry lower than ever before.

Gaging computer systems are now handling many of these individual gaging points by integrating all the different gage interface types into one base computer. Now, instead of having a number of standalone air gages and LVDT style bench amplifiers, the gaging computer has the interfaces available to configure all these input types. This is where less becomes more for the gaging process. The computer now provides the visual indication for the operator to look at these individual displays, and watch the changing tolerance colors and the data being acquired. Thus, the gaging computer has become the display, data collection device, results classifier, and overall guide to the measuring process. This is a much more cost-effective solution to dealing with multiple gage input requirements.

Automating the gaging process is another benefit of the gaging system for both the operator and the process engineer. For complex measuring functions—say measuring 20 features on an engine block after a complex machining operation—the gaging computer will provide a "guided sequence" which leads the operator through the gaging routine. The routine can instruct the operator on what gage to use, where to place it, as well as provide an indication of the results and what to do if the results are not as they are supposed to be. All the time, in the background, the results of the measurements are being stored for continuous review and analysis of the process almost anywhere in the world.

It is fairly easy to see how the centralization of gaging into one place can reduce the cost of the gaging station by reducing the number of standalone signal processing units, and this trend will certainly continue.

But what about those other gaging stations that are complicated in their own right and need their own dedicated computer to run and analyze the results? These gaging stations could be those for surface finish, shaft and/or form measurement. It has always been a challenge to integrate these various systems into the guided sequence when each has its own unique operating system. But advances are being made to affect this integration. PCs now have enough horsepower to run multiple very complex applications quickly on the same platform. What this will do is eliminate the need to have separate computers running their own special gaging software.

The concept is this: There is an overall gaging program running a guided sequence, leading the operator through the gaging routine, collecting the data and analyzing the results. Rather than tell the user to walk over to the surface finish system and do his task and transmit the results, there is no separate surface finish station. Instead, the surface finish system is integrated into the same gaging computer system with the surface finish software running in the background. The gaging software "calls up" the surface finish program and activates one of its application programs. When the guided sequence calls for a surface check, it links to the software, the check is made by the operator, and the results collected. Then it's back to the rest of the sequence, transparent to the operator and all using the same style of user interface. Now there's one computer, doing more and eliminating the cost of multiple computer systems; even more being done with less.

With the person on the shop floor taking responsibility for so much today, from producing parts, running the machine, programming parts, doing preventative maintenance and making good/bad decisions about his parts, it's important to make his or her job as easy and efficient as possible. By giving operators a single-user interface that implements all their gaging, from calipers to complex surface systems, and does it in a way that leads them through the measuring routine, it makes life easy, reduces the potential for error, and provides a cost-effective way to monitor the gaging process.

Gaging computer systems are now handling many individual gaging points by integrating all the different gage interface types into one base computer. Now, instead of having a number of standalone air gages and LVDT style bench amplifiers, the gaging computer has the interfaces available to configure all these input types.