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Apr 28, 2011

Design For Manufacturability

Design for Manufacturability (DFM) is a proven design methodology that works for any size company. By using DFM techniques companies can design products right the first time by utilizing concurrent engineering design teams to optimize manufacturability, quality, reliability, serviceability, cost, flexibility, market acceptance, and time-to-market.

The intense competition in today’s market place has raised customers’ expectations to unprecedented levels. The “throw it over the wall”, or “I designed it you build it!” motto can no longer be used to deliver flawless products in a timely manner. The objective of any organization is to make the product better, faster, and cheaper than the competition can. In the past, products have been designed that could not be produced. Products have been released for production that could only be made to work in the model shop where prototypes were built and adjusted by highly skilled technicians. Effective product development must go beyond the traditional steps of implementing product and process design technology as the solution. Management practices must be used to design the customer’s requirements into the product and ensure that both the factory and the company’s suppliers have the capability to produce the product. Therefore, many companies search diligently for real life solutions to smoother new product introduction.

A designer’s primary objective is to design a functioning product within the given economic and schedule restraints. The designer will work within the context of an existing production system that can only be minimally modified. However, research has shown that decisions made during the design period determine 70% of the products cost while decisions made during production only account for 20% of the products cost. Further, decisions made in the first 5% of product design could determine the vast majority of the products cost, quality and manufacturability characteristics. This indicates the great leverage that DFM can have on a company’s success.

One way that manufacturability can be assured is by developing products in multi-functional or Concurrent Engineering teams. The success of these teams require early and active participation from Manufacturing, Marketing, Finance, Designers, Design Engineers, Quality, Service, Purchasing, Vendors, Regulatory, Compliance, and Technicians. The team works together to not only design for functionality, but also to optimize cost, delivery, quality, reliability, ease of assembly, testability, ease of service, shipping, human factors, styling, safety, customization, expandability, and regulatory and environmental compliance. Some organizations make a weak effort at DFM by throwing the Design Engineer, Designer, Manufacturing Engineer and Quality Engineer in a room to review a product design. The personnel involved in product development need to understand the customers’ requirements to effectively develop products to meet these requirements. Product developers need to be brought into contact with the customer through a representative group of prospective customers. Marketing and program management functions need to be involved in product development to provide this type of customer/market input. Concurrent Engineering is based on the integrated design of products and manufacturing and support processes. It is not a matter of assessing manufacturability of the product after it has been designed and making appropriate changes to the product design to enhance its producibility. This approach extends the design cycle time, increases product development cost, and may not result in the most optimum way to produce the product. Instead, manufacturability must be considered from the very start of product development and designed into the product. Concurrent engineering involves many basic principles and concepts but a good rule of thumb is to follow the “Ten Commandments of Concurrent Engineering.”

1. Understand your customer.

2. Use product development teams.

3. Integrate process design.

4. Involve suppliers and subcontractors early.

5. Use digital product models.

6. Integrate CAE, CAD, and CAM tools.

7. Simulate product performance and Manufacturing processes electronically.

8. Use Quality Engineering and Reliability techniques.

9. Create an efficient development approach.

10. Improve the design process continuously.

While basic training in DFM principles is a starting point for a DFM program, further steps are required for developing producible products. An organization must begin considering its unique process capabilities and developing company specific design guidelines. While the design of a custom part or selection of a new part may be the most optimal approach to meet product requirements from the designer’s point of view, it may not be the best overall approach for the company. Product cost and quality may be negatively affected by the proliferation of specialized items that require specialized capabilities or prevent efficient manufacture procurement. Minimizing the number of active or approved parts through standardization not only simplifies product design, but can also result in operational efficiencies and lower inventories. A formal policy of parts standardization and emphasis on use of parts from an approved parts list for certain commodities provides management direction to the designer. Product development teams need to understand basic DFM principles that are applicable to a wide range of products. Some basic principles to follow are:

Simplify and reduce the number of parts.
Standardize and use common parts and materials.
Design for ease of fabrication.
Mistake proof product design and assembly. (poka-yoke)
Design for parts orientation and handling to minimize nonvalue-added manual effort.
Minimize flexible parts and interconnections.
Design for ease of assembly.
Design for efficient joining and fastening.
Design modular products to facilitate assembly with building block components.
Design for ease of service.
Design “robustness” into products.
Avoid tight tolerances.

While design automation technology has significantly advanced, DFM concepts are not radically new and different. In many ways, these practices reflect the smaller, less formal organizations of the past, where people knew each other, communicated effectively between the various functional departments, and coordinated their activities with relatively little effort. However, since technology has advanced and become more complex, a return to yesteryear is not feasible, particularly in large organizations with complex products. DFM concepts reflect a modern-day approach to addressing the complexity and technology associated with today’s new product development. An understanding and application of principles, techniques, and tools related to design for manufacturability will further facilitate the development of high quality, low cost, producible designs quickly.

DFM may require additional effort early in the design process. However, the integration of product and process design through improved business practices, management philosophies and technology tools will result in a more producible product to better meet customer needs, a quicker and smoother transition to manufacturing, and a lower total program/lifecycle cost.

The greatest challenges exist not in implementing new techniques, business practices, or technology, but in overcoming the organizational barriers and the resistance to changing the way things are done. As new products and time to market become crucial in achieving competitive advantage, the use of DFM concepts as a basis for new product development will become essential.