DFM principles (DFM Design for Manufacturing)

With the heat of the global competition intensifying, companies have now started to seriously think as to how their products could remain competitive in a dynamic market. The Japanese companies such as Toyota, Honda, Mitsubishi and several others have been the forerunners in manufacturing products that were of high quality, yet inexpensive and available at short notice. They have done this consistently over the years have been quite profitable all through and growing in the international markets, notably in the Western markets. They achieved this despite the fact that it was the West that had been the harbinger of computer technology and automation. While it was Whitney and Henry Ford who had initiated the concept, their message was lost because of the preoccupation with technological superiority. The Japanese have much automation in their factories too; however, they seem to have grasped the value of simplicity in the plants – fewer parts, same or similar parts, and parts that are simpler to manufacture.

DEM Principles for Assemblies:

1. Minimize the number of parts
*Design the product in such a way that it consists of very few parts
*Use a different technology, if necessary
2. Combine parts where feasible parts can be combined with other parts when:
*They are of the same material
* They do not move relative to other parts in the assembly
* Their combination would not affect the assembly of other parts
* After sales service does not require these to be separated.
Standardize designs
Standardize wherever possible
*Parts, modules, sub assemblies, manufacturing processes and systems may be standardized
* Where the parts cannot be the same, see if they can be similar
* Apply ‘group technology’ concept of ‘families’ of parts
* Where possible use standard catalog components
Minimize number of operations in the assembly
Modify the parts with simplification of assembling in mind
Even minor modifications yield greater Assembly simplification

Slight changes in a part’s geometry can reduce the difficulty in grasping, positioning and inserting a part. The effort and time taken can reduce significantly. Human errors of putting a wrong part or of orienting it wrongly can be reduced.

Use modules
*This allows for more standardization and speeds up the assembly process.

Minimize ‘newness’


*new parts
*new processes
*new suppliers
*new machines
New things—particularly too many new things – introduce many imponderables and increase uncertainty and, consequently, errors resulting in unacceptable quality and time delays in assembling.

Use ‘Poka Yoke’ or fool proofing

Design in such a way that the parts cannot be assembled in correctly.

Much of the direct cost of manufacture is incurred in making components. The cost of assembling these parts is comparatively small. Then, why is Design for Assembly made an important issue? As can be seen, the Design for Assembly effort results in reducing the number of components and in standardizing them. In fact, most of the suggestions made above for Design for Assembly are about the components. Reducing the number and variety of components has considerable cost time- resource effort economies combined with the economies associated with simplicity. Processes, systems, or parts made simple have a considerably high probability of improved quality and productivity.

Advantages of Minimizing the number of parts

1. By reducing the variety, the time to make the assembly (or the sub assembly) is reduced, because, there are less number of operations/movements of the workers
2. BY reducing the number of components to be produced, there can be longer production runs and economies of scale.
3. Each eliminated part means that much less costs of producing, moving, handling, buying, storing, monitoring, inspecting, repairing, maintaining, reworking and paperwork.
4. Lesser the number, lesser is the complexity, cost, effort and confusion. Confusion is the biggest impediment to productivity. Confusion and waste are synonymous.

The DFM concepts emphasize simplicity and standardization everywhere. Some may feel this is contradictory to the very objective of a new product design. After all, a new product is supposed to open up hitherto untapped markets. Therefore, a new technology, a new process, a new resource and a new system may have to be used. While no one may have any issue against simplifying things, standardization may mean as much of the old as possible.

The reply to this dilemma is that DFM attempts to strike an optimal balance change and standardization. It is about how to introduce change harmoniously into the production system. The required change, if obtained with several hiccups while producing, would only lead to undesirable delays, increased flow times and enhanced cost. Whether a company has same old products or new, the objective behind DFM is to have such a product design which would impart manufacturing/operations competitiveness to the organization.

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