Producibility Elements Highlighted:
Understand Current Process Capabilities (Company and supplier)
Perform Trade Studies on Alternative Product and Process
Error-Proof the Design
Understanding manufacturing capabilities during the earliest design phases can significantly reduce program costs, cycle times, and defect rates. At Raytheon TI Systems in Dallas, Texas, emphasis has been placed on early identification of defect drivers through analyses such as Process Capability Analysis (PCA) and Process Failure Mode and Effects Analysis (PFMEA).
PCA is based on a series of process capability models that accurately predict manufacturing labor costs, cycle times, and defect rates for the processes required to assemble or fabricate the components of a design. PFMEA uses the traditional FMEA techniques, but incorporates manufacturing, assembly line workers, process engineers, as well as design engineers, into a formal review of the assembly or fabrication process. PCA supports the Process FMEA analysis by identifying the critical defect drivers in the process and providing recommendations for eliminating their resultant defects.
Program X, a major program at Raytheon TI Systems, has been using PCA as an interactive design tool to minimize defects during design. PCA has proven successful in providing valuable inputs to design engineers while their designs are still in progress. This enables trade studies to be evaluated to yield the optimal design, balancing performance requirements with manufacturing process capabilities.
Program X had been working a Pre-Engineering Manufacture/Design concept primarily to develop a product that met its performance requirements at the lowest possible cost. Using PCA, the program was able to closely look at defect drivers and identify how to eliminate defects before going into production. Through Program X's PCA, the elimination of defects was directly linked to reducing program costs and cycle times.
As the design team conceptualized various subassembly designs, PCA was used to evaluate the design for Six Sigma / variability reduction purposes. Sixteen of the system's 20 subassemblies were identified as critical feature sets and were targeted for analysis. By applying PCA models, the design team got immediate feedback on the effects their design decisions would have in manufacturing. In some cases, the design decision was made real-time to adopt the approach recommended by the PCA model. Following the complete analysis, PCA recommendations were documented and submitted as part of the design technical package. Included in this report were the PCA results based on the current design, recommendations for changes, and projected results with those changes incorporated. For the 16 assemblies analyzed, incorporating PCA recommendations resulted in an overall defect-per-million-opportunity reduction
of 3,400. Extended across the program life-cycle and production quantities, the resulting cost avoidance was over $42M.
Recommendations based on the PCA models included items such as moving rubber stamp symbolization of part numbers from the assembly level to incorporate a better methodology at the fabrication level. Other recommendations were increasing screw sizes and incorporating orientation configurations to prevent mirrors, lenses, and components from being incorrectly installed. Additionally, changes in the wire sizes for interconnect cables and the methods of inserting the wires into the connectors generated significant improvements.
Program X performed a PFMEA on the designs to further identify the processes used in the assembly of the hardware, the potential process failure modes, and the potential effects of those failure modes. This analysis took the PCA analysis a step further to ensure the processes used to assemble the hardware would be well understood before the hardware was built. Results from the PFMEA and PCA analyses were iterated until the team eliminated defects and manufacturing risks from the product or identified contingency plans for those issues or defects which could not be eliminated.
As proven by the significant cost avoidance realized by Program X, development programs have greatly benefitted from PCA and PFMEA. PCA and PFMEA provide valuable information to support critical tradeoffs required to ensure product performance and meet process objectives while addressing customer needs. To fully understand the cost impact that design decisions make on defect rates, it is imperative to consider manufacturing process capabilities during the earliest possible design phase.