A Collaborative Design Strategy for PWA's Involving Suppliers Presentation Abstract
Scholand, A. J.; Peak, R. S.; Fulton, R. E.(1997), IMAPS Advanced Technology Workshop, Jun 10-12, 1997, Hilton Head, SC.
The development of major engineering products such as automobiles, aircraft, energy and electronic systems, although managed by one major corporation (the 'Prime'), to a large extent depends on work done by a fan-out network of contractors, sub-contractors, and their suppliers. In the end, small manufacturing enterprises (SMEs) account for over 50% of the design/manufacturing effort in such complex systems. However, because of the separation between the Prime, who controls the design specifications, and the SMEs, who have the domain-specific expertise, many delays are introduced into the product development cycle. In addition, the SMEs are not able to fully leverage their process and product expertise because they cannot perform sophisticated 'what-if' analyses to study the product-wide effects of cost saving measures or other product enhancements.
A recent project, TIGER- Team Integrated Electronic Response, was sponsored by the Department of Defense and funded through the National ECRC Program to improve the process by which products are developed in this multi-tiered business environment. TIGER focused on reducing time-to-market times and design revisions by bringing the various companies together to form a collaborative concurrent engineering team using standards-based design, analysis, and manufacturing tools.
The TIGER project focused on three organizations representing the three levels of a typical large-scale product development program. The Boeing Defense & Space Group, headquartered in Seattle, Washington, represented the Prime contractor. The Defense & Space Group designs, produces and maintains avionics and other aviation-related electronics. Examples include radio communication equipment, audio equipment, and attendant and navigation panels. It also furnishes secondary flight controls and specialty avionics products and services such as interface electronics, controllers, build-to-print items and associated test and support equipment unique to Boeing airplanes.
The electronics designed by the group primarily are produced at the company's commercial electronics manufacturing facility in Irving, Texas. This wholly-owned Boeing subsidiary represented the First Tier Supplier.
Boeing-Irving in turn subcontracts out to a vast array of specialty fabrication and component suppliers. Holaday Circuits, Inc. of Minnetonka, Minnesota represented a typical SME. Holaday Circuits is a Printed Wiring Board (PWB) supplier.
The TIGER scenario involves the evolutionary development of a Printed Wiring Assembly/Board (PWA/B) design through interactions with the Prime (Boeing Defense & Space), the Assembly Factory (Boeing Irving), and Holaday Circuits.
The scenario starts with Prime designers at Boeing Defense & Space viewing the TIGER system user interface (SUI), a graphical tool to manage design versions and inter-tool information exchange. From the SUI, the Prime designers complete a preliminary PWA design in the Mentor Graphics Corp. board layout tool. They export it as a neutral file, and then convert this file to a STEP AP210 file. This file is made accessible to Boeing's First Tier Supplier, Boeing Irving via the Boeing Intranet.
Production engineers at Irving analyze the PWA described in the AP210 STEP file for obvious manufacturability problems, using a producability expert system called the Rule Execution Facility. After some initial iterations with the Prime, the First Tier Supplier offers the PWB fabrication work to several SMEs. The PWB design information is sent to these suppliers in a standard STEP format, along with electronic request for proposals (RFPs).
PWB fabrication engineers at one of the SMEs, Holaday Circuits, receive the STEP file after an electronic RFP process that formalizes them as members of the IPT. As the STEP file contains PWB design details in a neutral form, fabrication engineers can use it to drive internal tools such as layup design. In the TIGER case, they upload this design file to an engineering service bureau (U-Engineer) over the Internet using encryption to ensure privacy. At the bureau they have access to TIGER Tools similar to those located at the Prime and Assembly Factory, including process-specific thermomechanical analysis modules that they execute themselves in a highly automated manner.
From the TIGER SUI, they launch DaiTools-PWA/B, a specialized CAE design-analysis integration toolkit developed at Georgia Tech. The fabrication engineers use DaiTools to read in the STEP file. This step combines it with other information to form an analyzable product model (APM) that includes idealizations to drive a variety of analysis modules. As layup details affect PWB thermomechanical behavior, SME engineers first design a layup, selecting specific laminates, prepregs, and copper foils to physically realize the requirements specified by the Prime designers in the AP210 model. Once the fabrication engineers have utilized their manufacturing experience to make a first attempt at meeting the design specifications, they can use graphical interfaces to drive a range of analyses directly from the product model they have just defined. The TIGER project utilized warpage as an example figure of merit to be analyzed, since warpage affects many other process problems (chip/component surface cracking, solder joint failure, edge deformation, poor connectivity, and misregistration), however, given a refined computer-processable analysis model in virtually any discipline, in all likelihood it can be routinized and turned into an analysis module like those highlighted here.
By selecting a formula-based Thermal Bending Model from a catalog of PWB warpage modules, the fabrication engineers can perform quick checks and design comparisons. If more accurate results are desired, they can select an FEA-based Plane Strain Warpage Model which uses idealized attributes from the analyzable product model (APM) for each stratum. Each module automatically extracts the idealized attributes it needs and creates any tool specific inputs required, such as a finite element job file. It further handles the file transport and job control aspects of automated execution of computer-aided analysis tools. The fabrication engineers receive results back in PWB-specific terms that are then checked against design limits. These results aid the engineers in refining their product to meet or exceed the specified figures of merit, as they can change the layup and then rerun the analyses with a push of a button. Essentially, by using a product data-driven approach to automate tedious data inputs and model creation, DaiTools-PWA/B enables a convenient form of manual design optimization.
If the analysis results indicate a potential problem or design improvement opportunity in the design specifications (as opposed to the product instance which conforms to those specifications), the fabrication engineers instruct DaiTools to create an issue (containing a summary of results from the analysis) and submit it to the Negotiation Facility. This tool coordinates IPT membership and tracks issues, comments, and resolutions to aid collaborative design evaluation and improvement. The Prime designers change the design based on this feedback, and re-issue design data to the Assembly Factory and SMEs. The SMEs can re-run analyses in the same manner if needed, thus illustrating the iterative collaborative engineering loop enabled by TIGER
In the TIGER scenario, these analyses did in fact suggest that a lower cost material than the initially specified material will meet the product requirements, enabling Holaday to make a cost-savings recommendation to the product development team.
The TIGER collaborative engineering scenario demonstrates how a large manufacturer can provide suppliers early PWA/B information in a standard format for early design feedback. This scenario highlights how PWB fabrication engineers utilize this design model and their expertise to drive thermomechanical analyses such as PWB warpage in a highly automated manner. The Georgia Tech CAD/CAE integration techniques utilized to create representative analysis modules have been extended and confirmed in TIGER. Accomplishments include the world's first usage of AP210 DIS (the STEP draft standard for PWA/Bs) to automatically drive finite element analyses (in Ansys) - all using live data that originates in a commercial circuit board layout tool (Mentor Graphics). A demonstration Internet-based engineering bureau delivers these capabilities to suppliers on a basis ranging from self-service (for highly automated routine analyses) to full-service (for challenging new analyses). This paradigm provides suppliers advanced capabilities without requiring expensive in-house tools and analysis expertise. As seen at a recent live demonstration, the advantage of TIGER techniques is the effective inclusion of suppliers in the product team, enabling timely, cost-saving design improvements.