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:
Design for a competitive advantage
Design for manufacturability, assembliability
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
Simplicity of design
Economy of materials, parts, and components
Economy of tooling/fixtures, process, and methods
Standardization
Assembliability
Testability
Serviceability
Integrity of product features
To minimize
Unique processes
Critical, precise processes
Material waste, or scrap due to process
Energy consumption
Generation of pollution, liquid or solid
Waste
Limited available materials, components, and parts
Limited available, proprietary, or long lead time equipment
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.
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:
DFA to minimize total product cost by targeting:
Part count ” the major product cost driver
Assembly time
Part cost
Assembly process
DFM to minimize part cost by:
Optimizing manufacturing process
Optimizing material selection
Evaluating tooling and fabrication strategies
Estimating tooling costs