Although the waterfall model is a useful tool for introducing design controls, its usefulness in practice is limited. The model does apply to the development of some simpler devices. However, for more complex structures or devices, a concurrent engineering model is more representative of the design processes in use in the industry and is key to success in any industry, where design and manufacturing come together “and stay together” from concept to finished parts, systems, and vehicles, reporting from both the manufacturing and engineering perspectives.
In a traditional waterfall development scenario, the engineering department completes the product design and formally transfers the design to production. Subsequently, other departments or organizations develop processes to manufacture and service the product. Historically, there has frequently been a divergence between the intent of the designer and the reality of the factory floor, resulting in such undesirable outcomes as low manufacturing yields, rework or redesign of the product, or unexpectedly high cost to service the product.
One benefit of concurrent engineering is the involvement of production and service personnel throughout the design process, assuring the mutual optimization of the characteristics of a device and its related processes. While the primary motivations of concurrent engineering are shorter development time and reduced production cost, the practical result is often improved product quality.
The objective is to eliminate multiple design revisions, prototypes, and re-engineering efforts and create an environment for designing right the first time. The major perceived disadvantage of concurrent engineering is that it increases the time spent in preliminary design, when the design staff is anxious to finalize details and release drawings. Design for manufacturability is the process of proactively designing products to optimize all the manufacturing functions: fabrication, assembly, test, procurement, shipping, delivery, service, and repair, and assure the best cost, quality, reliability, regulatory compliance, safety, time-to-market, and customer satisfaction. An unbalanced view leaning too far towards Concurrent Engineering will produce a surfeit of activities involving teams, quality circles; ISO 9001, process modeling, QFD, and the DFX acronyms (Design for Manufacture), Assembly, Decommissioning, etc.