Written by Muqi Wulan
Design for assembly (DFA) means the design of the product for the ease of assembly (Boothroyd, Dewhurst & Knight 2011: 1). A product design for ease of assembly depends on whether the product is to be assembled manually, with special-purpose automation, with general-purpose automation (robots), or a combination of these. There are three types of assembly methods:
• Manual assembly;
• High-speed automatic assembly;
• Robot assembly.
Figure 1 shows the comparison of these three assembly method in terms of assembly cost and production volume.
Figure 1 – Assembly cost versus annual production volume for 3 assembly methods (El Wakil 1998: 435)
According to each assembly method, general design guidelines are developed for designers to follow and consolidate manufacturing knowledge into a design. These guidelines are provided in the form of simple design rules.
Design guidelines for manual assembly
The process of manual assembly falls into two assembly operations:
• Handling – acquiring, orienting and moving the parts;
• Insertion and fastening – mating a part to another part or a group of parts.
In terms of the assembly operation, the design guidelines will be presented in the following two tables (Boothroyd, Dewhurst & Knight 2011: 74).
Table 1 – Design guidelines for insertion and fastening
Table 2 – Design guidelines for insertion and fastening
Summary
Design for manufacture and assembly (DFMA) is systematic approachs to bridge the gap between design and manufacture, and take manufacturing considerations into product design in an effective way. Design for assembly (DFA) aims at improving the product design for the easy and low-cost assembly. It is an assembly-conscious design approach. The first step toward a rational design for assembly is the selection of the most appropriate method for assembling the product under consideration. Design rules or guidelines to implement design for manual assembly generally include (Dieter and Schmidt 2009: 598):
• minimise the number of parts,
• minimise the assembly surfaces,
• minimise handling in assembly,
• minimise assembly direction,
• and provide unobstructed access for parts and tools.
Selected References
Boothroyd, G., Dewhurst, P., Knight, W. A. (2011) Product design for manufacture and assembly. 3rd edn. Boca Raton: CRC Press, Taylor & Francis Group
Dieter, G.E., Schmidt, L.C. (2009) Engineering design, 4th edn. New York: McGraw-Hill
El Wakil, S. D. (1998) Processes and design for manufacturing. 2nd edn. Boston: PWS Publishing Company
Back to DFX
Back to Embodiment Design
Back to MAE Design Model