Design for process optimizes a product for its manufacturing process, design for assembly makes components quicker and easier to put together, and design for disassembly makes them easier to separate later. Each strategy reduces impacts at a different stage of the product life cycle.
These strategies belong to C4.1 Design for manufacture strategies (HL only). Designers may apply all three to the same product, but each has a different primary objective.
| Strategy | Main objective | Typical design decisions |
|---|---|---|
| Design for process | Ensure that the design suits the selected manufacturing process | Select compatible materials; avoid shapes that are difficult to manufacture; specify realistic tolerances; reduce processing steps, waste, and tooling complexity |
| Design for assembly | Reduce the time, cost, and difficulty of assembling components | Minimize part count; standardize components; use self-locating parts; design one-way insertion; reduce or eliminate separate fasteners |
| Design for disassembly | Allow components and materials to be separated efficiently | Use reversible fasteners; provide access to joints; avoid permanent adhesives; label materials; separate hazardous or valuable components |
For example, consider an injection-moulded electronic casing. Designing a consistent wall thickness and suitable draft angles is design for process because these features support injection moulding. Using snap-fits and self-aligning components is design for assembly because it shortens assembly time. Using accessible screws instead of permanent adhesive is design for disassembly because the casing can be opened for repair, component reuse, or material recycling.
A common misconception is that design for assembly and design for disassembly are opposites. They can create tension, because permanent snap-fits may enable rapid assembly but obstruct separation, yet a well-designed reversible fastening system can support both.
Exam technique: If asked to distinguish these strategies, identify the relevant life-cycle stage, state the strategy's objective, and give a specific design feature. Do not merely say that each strategy “makes manufacturing easier”; explain whether it improves the production process, component assembly, or end-of-life separation.