Delphi's Wet/Dry door modules - WIP - modularization design

Automotive Design & Production, Dec, 2002

Although the virtues of modularization are widely touted by automakers, to realize the true potential savings that modularization promises, module suppliers must simplify designs and reduce parts and assembly time. Delphi (Troy, MI) has done just that with its Wet/Dry door module. Delphi pioneered the door module concept in the 1980s (when it was Inland Fisher Guide) and has been honing the concept ever since. Over the last ten years, Delphi's door module has gone from a consolidated sheet metal assembly, to a component dubbed "SuperPlug" which utilized injection molded parts to simplify assembly, to the current Wet/Dry product. As the module has evolved, Delphi has been able to increase efficiency and reduce costs by cutting both the number of parts and the required assembly time. The original sheet metal module was a big step forward over conventional doors, It slashed the number of components from 16 to 9 and cut assembly time from 12 to 9.4 minutes. Similarly, the SuperPlug brought the number of component s down to 8 and shaved an additional 1.4 minutes off of assembly time. The Wet/Dry module continues this trend by halving the number of components to 4 and further reducing assembly time to 6.6 minutes.

Delphi is able to achieve greater efficiency with its Wet/Dry product by incorporating the entire window lift and guidance system, the handle and latching system, door wiring, audio components and water barrier into one unit, Including the water barrier is especially important since the part's installation is currently one of the most labor-intensive door processes on the assembly line. Also, the thin Mylar sheets now used for the barrier, which keeps water from reaching the vehicle's interior, are easily damaged during installation. The Wet/Dry system eliminates the separate Mylar sheets and integrates the water barrier into the module carrier. This integrated design also routes all connections where assemblers can see them, as opposed to conventional modules, which require that many operations are carried out entirely by feel. And unlike older designs that move along a line on vertical racks, it can be assembled in a horizontal or tilted position that is optimized for better eraonomics. "This is a key benef it of modular design," says Delphi engineer Brian Staser. "Operations that previously were completed on a moving door, or were done blindly, are now performed efficiently in a subassembly process." How much more efficiently? Compared to a conventional door module, the Wet/Dry unit requires only 10 assemblers as opposed to 18, reduces the overall assembly time by 45% and saves the OEM an estimated $24 per vehicle.

Delphi engineers were able to achieve such savings partly by utilizing Design for Manufacture and Assembly (DFMA) software from Boothroyd Dewhurst Inc. (Wakefield, RI). DFMA examines structural efficiency, ease of assembly and overall manufacturability of the module. With the information from the software in hand, Delphi's team was able to anticipate part and manufacturing costs and optimize designs to be both low-cost and multifunctional. A major goal of DFMA analysis is to reduce the number of parts needed for an assembly, but Delphi also used the tool to get engineers to think more deeply about the best way to design systems. "The concepts behind DFMA are among the greatest engineering strategies that can be applied to core design issues," says Staser, "And the program trains engineers to think in ways that facilitate lean design and manufacturing. DFMA brings engineers to a realization of how to get higher content in a design beyond merely adding pieces."