Combining the Resource Consumption Model (RCM) and the Cambridge Engineering Selector (CES) to Analyze Product Design

Abstract

It has been reported that as much as 70 to 80 percent of the cost to produce a product is determined during the conceptual product design stage; therefore, product decisions made at this point are critical [1]. Inherent part design features, such as material, shape and features, quality, and functional specifications influence product cost. Additionally, manufacturing strategies and manufacturing process parameters such as production resource requirements, production volume, capacity, and cycle time affect product cost. Product design and manufacturing process selection are often separate functions within many industrial organizations. Engineers need systematic ways to concurrently address both product design and manufacturing process selection. The Cambridge Engineering Selector (CES) is a tool that focuses on material, process, and shape combinations of product design. The Resource Consumption Model (RCM) is a tool that focuses on production process resources, resource costs, production volume, production capacity, and manufacturing cycle time. Both tools help identify viable manufacturing process alternatives to meet stated manufacturing objectives. A product design scenario is identified and analyzed using both CES and RCM. RCM methodology complements CES, providing a powerful approach toward computer-aided process planning. The combination of these tools lead to better product design decisions. PRODUCT DESIGN AND MANUFACTURING PROCESS SELECTION The manufacturing process involves a transformation of raw materials into finished goods. Customers express their needs, product designers transform customer needs into product and part specifications, manufacturing selects the processes and produces the products, and the customers purchase the products. The goal in the transformation process is to derive the best methods to produce the best product while maintaining customer and marketing functional requirements. It is sometimes assumed that product design and process design are sequential decisions. In fact, these decisions need to be considered simultaneously. The way a product is designed affects how it is to be manufactured and its cost, which affects product pricing and how many people buy it, which affects production capacity, which affects process costs, which again affects product pricing and how many people can afford to buy it. Better decisions can be made if product design, process design, and cost analysis can be considered concurrently. If these decisions are not viewed as a whole, a decision in product design that might offer the best technical solution could cause the product to fail because it makes the product less attractive to customers or increases the cost of the product beyond the affordable reach of most consumers. Computer-aided process planning tools (CAPP), computer-aided design tools (CAD), and computer-aided engineering tools (CAE) are improving to offer a computer-integrated manufacturing (CIM) environment. Much more work, however, remains. Developing integrated tools is a complex problem. Many design and analysis functions must be done which often requires specialized engineering knowledge and training. Today’s solution is to hire a variety of engineers,