Design for Manufacture (DFM)

Competing on time has much to do with the manufacturing/operations flow times. It is obvious that a proper planning of the production processes, their workload distribution, the scheduling decisions, planning of the required and men, and removing bottlenecks would result in improved throughputs. However, what s not obvious is the fact that a good product design can help substantially towards the reduction in the manufacturing flow time.

A good product design would be such that it makes many or all of the manufacturing related functions to be done in less time, less effort, and with less cost. Such a product design would facilitate the manufacturing function. The manufacturing related operations include:

1. Material procurement,
2. Material handling,
3. Product conversion (e.g. machining processes).
4. Changeovers and set-ups and
5. Quality control procedures.

All of these, if not handled properly, could lead to increased lead times. A good product design takes the facts or realities of these operations into consideration, incorporates them into the design and thereby facilitates these operations.

What is DFM?

The idea behind a DFM effort is to modify the existing product’s and / or its components’ design or have a new product designed in such a way that the processes to manufacture the same are easier, quicker and / or less expensive. Reducing the manufacturing time is major considerations. This, of course has to be achieved without compromising on quality.

DFM, as a concept, is not new although its huge importance has dawned on the manufacturers only lately because of the intensity of competition in the present times. It was Eli Whitney (and Le Blanc) in the Western pat of the world who had developed a system 200 years ago for manufacturing muskets that incorporated the concept of interchangeable parts. Earlier, all muskets were handmade. This was cumbersome in addition to being expensive. It was also terribly time consuming and made the immediate availability in large numbers a difficult task. Whitney redesigned each part to a specific dimension with a limited tolerance. This paved the way for mass manufacture of muskets. Thus, he designed the musket (and its components) for large scale manufacturability.

Henry Ford seemed to have grasped the concept of DFM about 90 years ago. The following statement by him, about Model T succinctly expresses the idea behind DFM.

‘… it was up to me, the designer, to make the car so completely simple… The less complex the article the easier it is to make, the cheaper it may be sold. We start with the consumer, work back trough the design, and finally arrive at manufacturing’.

Product design influences the efficiency of manufacturing. Thereby it influences the flexibility of marketing strategies and the organization’s success in a competing business world.

Cultural barrier: It is indeed surprising that despite the emphasis during the last several decades on increasing efficiency in manufacturing, the importance of product design for manufacturing efficiency has not been appreciated. A majority of the organizations have had the design department and the manufacturing department ever interacting. Product designers in some manufacturing industries have been sitting in ivory towers. They are highly respected, as their job is perceived to be creative like that of an accomplished artist, whereas, the manufacturing is seen as a rough-and-tough person who has risen from the ranks, and therefore lacking in such finer abilities. A culture barrier seems to separate the designer of the product and the person manufacturing the product.

Over the Wall’ Syndrome: Product designers believe that their job is over once they release their drawings. They, so to say, throw their designs ‘over the wall’ for the manufacturing person to do the next job of producing it. Manufacturing engineers then struggle to produce the product that is, ‘dumped into their laps’. At their best, design and development have been more concerned with how a particular feature requested by marketing may be translated into a physical parameter. How it may be produced, what it may cost and in what time, have not been much of their concern.

As a result there are several engineering changes after the design has been released, because the design gives multitudinous problems when taken up for manufacture. The solution of these problems wastes precious time, and by the time the company has made the product it is too late as the market has shifted. It would have been so much better if the two departments – design and manufacturing – had sat together during the early stages of product design and exchanged notes.