Chapter 5: Design for ManufacturabilityAssembly (DFMDFA or DFMA)


OVERVIEW

When we talk about design for manufacturability/assembly (DFM/DFA or DFMA), we describe a methodology that is concerned with reducing the cost of a product through simplification of its design. In other words, we try to reduce the number of individual parts that must be assembled and ultimately, increase the ease with which these parts can be put together.

By focusing on these two items we are able to:

  1. Design for a competitive advantage

  2. Design for manufacturability, assembliability

  3. Design for testability, serviceability, maintainability, quality, reliability, work-in-process (wip), cost, profitability, and so on.

This, of course, brings us to the objectives of DFM/DFA, which are:

To maximize

  1. Simplicity of design

  2. Economy of materials, parts, and components

  3. Economy of tooling/fixtures, process, and methods

  4. Standardization

  5. Assembliability

  6. Testability

  7. Serviceability

  8. Integrity of product features

To minimize

  1. Unique processes

  2. Critical, precise processes

  3. Material waste, or scrap due to process

  4. Energy consumption

  5. Generation of pollution, liquid or solid

  6. Waste

  7. Limited available materials, components, and parts

  8. Limited available, proprietary, or long lead time equipment

  9. Degree of ongoing product and production support

Therefore, one may describe the DFM/DFA process as a common-sense approach consistent with the old maxim , "Get it done right the first time." In DFM/DFA, we strive to get it done right the first time with the most practical and affordable methods in order to meet the customer's expectations in terms of time, process, costs, value, needs, and wants. This approach is quite different from the old way of doing business. Figure 5.1 shows the old and new ways of design.

click to expand
Figure 5.1: Trade-off relationships between program objectives (balance design).

So, in a formal way we can say that design for manufacturing and assembly is a way of focusing on designing the product with manufacturability and assembliability in mind, to ensure the product can be produced with an affordable manufacturing effort and cost and also, after the manufacturing process, to ensure that the original designed product reliability can be maintained , if not enhanced. This approach may seem time-consuming and not value added, but if we consider the possible alternatives available we can appreciate the benefit of any DFM/DFA initiative. For example, consider the following:

  • What good is the design, if nobody can produce it?

  • What good is the design, if nobody can produce it with an affordable effort (in terms of manufacturing cost, scrap, rework , production cycle/ turn -around, wip, and so on)?

  • What good is the product, if nobody can afford it?

  • What good is the product, if we cannot market it in time?

  • What good is the product, if it does not sell?

  • What good is the product, if it is not profitable?

  • What good is it, if it does not work?

By doing a DFM/DFA, we are able to take into consideration many inputs with the intent of optimizing the design in terms of the following characteristics:

  • Design/development lead time vs. marketing time

  • Customer needs/wants vs. field application/performance vs. engineering specifications

  • Production launch efforts

  • Manufacturing cost

  • Flexibility and obsolescence of process and equipment

  • Maintainability/serviceability of product

  • Profitability

Specifically, we are looking for the:

  1. DFA to minimize total product cost by targeting:

    1. Part count ” the major product cost driver

    2. Assembly time

    3. Part cost

    4. Assembly process

  2. DFM to minimize part cost by:

    1. Optimizing manufacturing process

    2. Optimizing material selection

    3. Evaluating tooling and fabrication strategies

    4. Estimating tooling costs




Six Sigma and Beyond. Design for Six Sigma (Vol. 6)
Six Sigma and Beyond: Design for Six Sigma, Volume VI
ISBN: 1574443151
EAN: 2147483647
Year: 2003
Pages: 235

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