Turning 3-dimensional product models into manufacturing process designs is no easy task. Kevin Marseilles, senior process designer with Delphi Corp.’s Saginaw Steering Systems Division, used to spend hours breaking down 3D solid models created by Delphi’s product designers into different manufacturing steps. He would then manually put each step into a process drawing.
“Product and process designers encounter problems when using the existing CAD/CAM (computer-aided design and computer-aided manufacturing) programs
in the vendor-suggested ways,” says Jeffrey Solash, licensing executive with Delphi, a $28 billion global supplier of transportation components, headquartered in Troy, Mich. “These problems result from the way CAD/CAM software creates parent/child relationships in the design feature trees. We asked the vendors to help us find a solution, but they were unresponsive, so we decided to do something ourselves.”
That something was the development of two new methodologies—one used to design 3D CAD models, called Horizontal Modeling (HM), and another, which uses the CAD files to create manufacturing process models, called Digital Process Design (DPD).
Michelle Drage, director of technology commercialization and licensing for Delphi, explains, “When you look at the variety of CAD/CAM tools in the marketplace, we wanted to get to a method of utilizing these tools in a consistent, common way in plants across the organization. Regardless of the CAD/CAM product being used, designers would use the same methodology.” Adds Solash, “Change always occurs. If designers don’t have a common method, this can create havoc. Everyone in the organization has to speak the same language. You can then send a design from Saginaw, Mich., over to Mexico, India or China, and everyone can respond.”
Vertical vs. horizontal
In the vendor-suggested methods for CAD modeling, says Solash, the designer chooses a basic shape, such as a cylinder, and attaches digital shapes and features as required. Parameters, such as length, width and angle, can be ascribed to the shape. In the standard methodology, each feature is positioned to one or more of the previous features in a vertical chain, creating a parent/child relationship. This process works relatively well—until the designer needs to make a change. A change made in a feature often wipes out the steps made subsequently by removing the dependent geometry, which forces the designer to redo steps and features.
“There is a huge impact on morale when this happens,” says Solash, “And, far more important issues result, such as increased time to design, manufacture and market.”
In Delphi’s Horizontal Modeling method, the CAD features are laid out horizontally. Features are not tied to each other, but rather are tied to coordinate planes that are placed in the model. The designer starts with an x-y-z reference system, and attaches features to those coordinates, making the geometry independent of the placement of previous features. “I want to emphasize,” says Solash, “that we are using the same vendor programs as before. It doesn’t matter if it’s CAD software from Dassault (such as Catia or SolidWorks), or (UGS PLM’s) Unigraphics—the same methodology works with them all.” Adds Drage, “We created no new code in developing these methodologies.” This is important for two reasons. First, CAD programs are already very expensive, costing tens of thousands of dollars. Second, the programs are quite complicated, and adding even a bit of new code would involve years in testing for compatibility.
After the product designers create 3D models with Horizontal Modeling, process designers build manufacturing process sheets. These sheets go directly to the shop floor to tell machinists what to do, as well as to other engineers for stress and material analysis. There is change throughout this process, for example, when Computer Numerical Control (CNC) machines are updated, or the product design needs to be modified to streamline manufacturing flow.
During the transition, the manufacturing process designers must interact with the product design engineers, which means the CAD/CAM system must be flexible enough to accommodate changes. Delphi’s Digital Process Design methodology is set up to extract the individual process steps from the 3D CAD model created by the product designer. It allows the process designer to automatically create shop-floor process sheets that are attached to each extracted step in the manufacturing process.
Any changes are updated in both the product design model and the manufacturing process design. Because the design is constructed horizontally, the user can cut-and-paste changes into the process design, and updates occur automatically. This is critical in a complicated design, which may require more than a hundred process sheets.
Big Payback
Delphi has documented big benefits in applying the HM and DPD methodologies. Marseilles, the senior process designer at Delphi’s Saginaw Div., says that when he gets a 3D model created with HM, he can build the process sheets with DPD in one-fourth of the time he previously spent. “I can go directly from a 3D model to a process model. Everything is 100 percent usable.”
In addition to reducing process sheet creation time by 75 percent, Delphi cites productivity improvements in product design with the HM methodologies. The time to create 3D models, which Delphi says accounts for 20 percent of the CAD product design activity, has been reduced by 20 percent, while the time to edit models, which consumes 50 percent of the designer’s time, has been reduced by 65 percent. For one design team, Delphi says these savings added up to $2.4 million, by eliminating the need for outside design contractors.
Delphi engineers and designers have used the HM and DPD methodologies to create more than 2,500 manufactured parts. The methodologies have been tested and proven within the Delphi organization for the last five years and are now in production at 14 Delphi and partner plants worldwide, including in the United States, Mexico, Spain, Poland and Brazil. As well, Delphi has applied for a number of patents on the methodologies. One patent has been allowed and will shortly be issued by the U.S. Patent Office; about 15 other patents are in process.
Last Fall, Delphi Technologies, Inc. (DTI), a subsidiary of Delphi Corp. established to own and manage Delphi’s intellectual property, announced the commercial availability of the methodologies. DTI, which is based in Troy, Mich., has licensed Cadpo to provide certified training on HM and PDP. Cadpo, headquartered in Westminster, Colo., offers training and services to industrial clients such as Boeing, GE, GM and 3M.
Delphi compares its HM and DPD methodologies to such well-known strategies as Six Sigma and Shainin. Says Drage, “There’s no reason why our methodologies for horizontal modeling and process design couldn’t be accepted in much the same way as Six Sigma.” Perhaps in the not-too-distant future, your manufacturing organization will have trained “black-belts” in the Delphi method, doing battle to reduce the design-to-manufacturing cycle.
