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Quality Scan: Product Design to Inspection: The Missing Link

Joe Zink




It is no secret that companies of all sizes are looking to improve their efficiency in order to improve their profitability. And there's no better place to start than by investigating the information flow between product design and inspection. Most manufacturers hope they will discover an information superhighway where information flows freely both ways. However, many find a one-way, narrow road full of potholes. Product design does provide inspection with a CAD model of the part. But in too many cases, the validation information is still supplied on a printed, marked-up, and highlighted 2-D drawing. Some companies feel they have filled a few of those potholes by sending these 2-D drawings electronically. In either case, this inadequate "information link" causes the inspection department to do a lot of rework and, unfortunately, they must try to interpret design intent.

Let's face it. Technology may not always be the answer, but in this case, technology is emerging as a new class of products aimed at providing the missing link between product design and inspection.

A typical inspection planning product may reside on the product designer's CAD computer. The design engineer uses this tool to translate his part design into an inspection plan. Because he's not concerned about, or may not even know about the measurement technology that will be used for the inspection (a CMM, vision system, articulating arm), the plan typically only specifies the datums, features, and dimensions that he feels are critical for the part. By leaving the technology of measurement to the inspection department, the designer has created an inspection plan that is general enough to be used on a variety of measurement devices. At the measurement device, however, the inspection plan needs to be converted into an inspection program. Coordination between the inspection software and the planning software is key to making the translation easy, complete, and straightforward.

To address this information link, progress is being made through three types of activities. First, some inspection software companies are creating planning-software products. This is one way to solve the coordination problem. Because they are creating both halves of the solution, they make sure that their planning software and their inspection software work well together. They can also add additional tools to manage the process and make the inspection program more efficient as well.

Secondly, partnerships are being created. For example, Chrysler has an internally created software product called eTool, which the designer uses to create a part design. A new module of eTool allows the designer to also create an inspection plan. A special software development project with our company now enables Chrysler to directly import this inspection plan into their inspection software product and automatically create a part program (see the September 2009 edition of Manufacturing Engineering magazine for more information).

And, finally, all of the players in the manufacturing information highway—NIST, users, and vendors—are coming together to explore the possibility of a standard definition for this inspection-plan file. If this standardization is possible, then vendor A's software can be used to create a plan, and vendor B's software could be used to convert the plan into an inspection program. Since XML is used so widely to transmit information across the Internet, it seems likely that an XMLlike format may emerge as a proposed standard.

Each of these initiatives is aimed at addressing the initial flow of information from design to inspection. But what happens when the part design changes? Even simple modifications to a feature's nominal location, or a change in a dimensional tolerance, can end up being another one of those potholes that needs to be fixed.

Information flow should not be a one-way street from design to manufacturing. Manufacturing modifications should also be sent "upstream" to the designer. With new advancements in inspection software, technology has finally advanced to the point where it can convert the inspection program back into an inspection plan, in a format that the designer can use. This file can be compared to the inspection plan to see what additions, deletions and/or modifications were made by manufacturing.

With bidirectional data flow allowing collaboration between design, manufacturing, and inspection, companies are seeing the benefits of their own information superhighway. With a formalized communication process in place, this missing link will become a thing of the past.


This article was first published in the May 2010 edition of Manufacturing Engineering magazine. 

Published Date : 5/1/2010

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