Case Study: Paperless Inspection Unqualified Success at Chrysler
Advanced Metrology Group improves productivity.
In 2009, Chrysler Group LLC implemented its proprietary eTool for the paperless management of inspection plans-electric documents, which transmit the critical design intent information for creating CNC measurement programs. This new system allowed the Sheet Metal team in Chrysler Group’s Advanced Metrology Group to improve productivity by approximately 40%.
A major test of this solution appeared in 2010, when Chrysler re-implemented its eTool solution in conjunction with the launch of a totally different CAD package, Unigraphic’s NX TeamCenter. The change to NX TeamCenter, which is Fiat S.p.A’s corporate design environment, allowed Chrysler and Fiat to share design elements, parts and assemblies as the two automakers become more closely integrated.
This changeover was made to reduce costs and improve design and manufacturing flexibility. Chrysler’s Advanced Metrology Group, which had already reached a 40% improvement in productivity with the CATIA-based eTool, was faced with developing a completely new version and adding this task to their pre-existing workload. “It was overwhelming to even think about starting over again from scratch.” says Howard Casey, team leader. Casey’s group did a mental shift and thought of this new situation as an opportunity to further improve a tool that was already working well.
Paper Chaos Tamed
Before Chrysler implemented its eTool in 2006, CMM programmers received design intent information from design engineers from handwritten notes, on drawings, spread sheets, PowerPoint presentations and even by word of mouth. With each of these methods, the link between manufacturing and the original design data was broken. Therefore, there was no easy way to confirm that the parameters used to inspect the parts were current. Today, designers create inspection plans with eTool, which are electronically associated with the CAD model throughout the part’s life cycle. The potential for misinterpretation and data entry errors has been dramatically reduced. CMM programmers import these plans into PC-DMIS metrology software (from Wilcox Associates, a Hexagon Metrology Company) where almost complete CMM programs with optimized probe paths are automatically generated and only minor refinements are needed.
Throughout the product development process, inspection plans continue to change and evolve. At Chrysler Group manufacturing facilities, measurement specialists sometimes alter programs to deal with fixturing issues and other concerns not previously anticipated by the measurement system programmer. CAD models also change to accommodate manufacturability issues. In the past, detecting these changes was a very tedious and time-consuming process. Advanced Metrology Group’s master part program would have to be compared against the latest CAD model and also against the measurement programs modified at the plant level.
To reduce these issues, Wilcox Associates developed a Change Manager for Chrysler. This module automatically compares changes made to the inspection plans by designers and part programs at the plant level so that the programmers can quickly identify which changes need to be made in the master part program to reconcile the differences. This improvement had eliminated hours of sorting through anomalies in measurement data to find disconnects between the CAD model and measurement programs. However, now the Advanced Metrology Group was being asked to port all of these improvements over to a completely different CAD environment.
Unfrozen In Time
“The Engineering and the Advanced Metrology Teams worked together to develop a list of all of the positive and negative aspects of the existing eTool for the CATIA system in addition to the functionality that should be added,” Casey says. “Then this information was relayed to the IT team who had developed the eTool for CATIA. Four months later, a test software was developed, tested and debugged. Six months after that, a NX eTool tool that did everything the CATIA eTool did and more was 95% complete.”
The main advantage of the eTool in NX TeamCenter compared to the eTool in CATIA is that NX TeamCenter is not frozen in time. The CATIA eTool was embedded in the CAD program as part of the release model. When the model was released it was “frozen” and any potential errors made in the assignment of GD&T information within eTool were permanently embedded as well.
“Specifications are continually being changed or fine-tuned,” Casey says. “However, once the CATIA eTool model was frozen, it was no longer capable of recording these changes. It was cumbersome. Fortunately, the NX eTool is not embedded in the release model. It is an accessible overlay that follows the model and may be modified as needed. The NX eTool can recognize changes in the geometry of parts or assemblies and can update the PC-DMIS measurement program to validate those features,” Casey says.
While a considerable amount of work was involved in designing and troubleshooting eTool for NX TeamCenter, integrating the new concept with PC-DMIS metrology software required very little effort. From the onset of eTool’s development, PC-DMIS software engineers at Wilcox Associates worked closely with Chrysler to insure seamless integration of the eTool’s inspection plans with the metrology software. This development work has progressed in parallel with Wilcox’s analogous Inspection Planner product and many of the features developed in conjunction with Chrysler have found their way into the Inspection Planner.
In this case, a new interface was needed between eTool and PC-DMIS. The Advanced Metrology Group decided to use a highly stable DataLog file format that Chrysler had been using. DataLog is a stand-alone file containing GD&T and other information that sits outside of NX TeamCenter. All Wilcox had to do was develop a utility capable of importing the information from DataLog, and the measurement and analysis side of Chrysler’s inspection planning system was up and running.
As a result, the Change Manager, which has improved productivity for Chrysler’s Advanced Metrology Group for the past two years, now feeds its data from the DataLog file. Everything works the same, however, the eTool is no longer frozen. The part program always maintains a link to the inspection plan and metrologists can automatically track the latest changes to the model as well as the design intent information. This results in an even greater time-savings and increases inspection program integrity.
60% Productivity Gain
In spite of all the extra work to transition to the NX TeamCenter, the Advanced Metrology Group has already achieved its goal of an approximately 60% improvement in productivity due to the use of paperless inspection.
“We have a lot less problems because everything is clear cut. It’s all digital data and everything follows corporate standards,” Casey says. “Now every time you make a hole, it’s made the same way and the standards for evaluating it are the same. We have clearly improved our productivity, based on how much we get done everyday, and it continues to improve.”
As a result, the Advanced Metrology Group has been asked to take on additional responsibilities. It is now writing inspection programs, not only for sheet metal, but also for stamping plants owned by Chrysler Group in the United States, Mexico and Canada.
While all of this is happening, the group will also find the time to stay current with the latest versions of mission critical software. In 2011 Chrysler, along with Fiat, will transition over to the latest version of NX TeamCenter. Plans are also in effect to update all of the CMM’s in its plant to PC-DMIS 2011 measurement software which will contain many features advocated by Chrysler to make inspection planning functionality more stable and easier to use. Q
eTool For Everybody Else
Chrysler’s proprietary eTool software module resides inside their CAD software. It collects design intent information that allows PC-DMIS inspection software to generate measurement programs automatically. This technology is only available to Chrysler plants and their suppliers. If you are not a Chrysler supplier, you can find the same capabilities in PC-DMIS Planner from Hexagon Metrology. This software facilitates the automatic generation of inspection programs based on data collected from any CAD product.
This stand-alone application provides a paperless method for transforming design intent into inspection routines. Using PC-DMIS Planner, part designers record their requirements for validating or verifying a part without getting involved in the technology of the inspection process or measurement device. It is simply a matter of defining datums, identifying what needs to be measured, and establishing the relationships and tolerances among features. Subsequently, PC-DMIS uses this plan along with the associated CAD model, as the basis for automatically generating a measurement program.
Much like Chrysler’s eTool system, PC-DMIS Planner includes a full range of tools for developing plans, optimizing paths and generating clearance moves. It also includes a Change Manager feature to keep the inspection programs, the inspection plans, and the CAD drawing in sync.