Design for manufacturing vs design for assembly

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Design for manufacture (DfM) and design for assembly (DfA) are two complementary approaches for reducing the costs associated with the production of goods. Both approaches recognize that a large proportion of the cost of an item is embedded early in the design and development stage of an item. Both approaches seek to minimize this production cost through design – engineering out production costs. 

Design for manufacturing

Design for manufacture is an approach to actively take manufacturing considerations into account during the design stage of a product. The approach looks to make it easier, quicker, and cheaper to manufacture the product by specifically designing the product with manufacturing in mind. Key principles within design for manufacture include:

  • Adjusting the design to remove manufacturing steps
  • Reduced the machining tolerance requirements, so that the product can be manufactured quicker
  • Changing the materials to materials that are easier to machine

Design for assembly

While design for manufacture seeks to reduce manufacturing costs by making components easier to manufacture, design for assembly is specifically concerned with reducing assembly costs. This approach recognizes that a large proportion of the overall production cost is often associated with assembling the good. Key design for assembly principles include:

  • Reducing the number of components that need to be assembled in the product
  • Adding chamfers, or increasing tolerances, so that the components are easy to slot together
  • Avoiding using lots of different sized fasteners
  • Reducing the number of fasteners – potentially with built-in fasteners that can be easily clipped together

Final thoughts: Look to balance savings from both design for manufacture and design for assembly

While design for manufacture and design for assembly both seek to minimize production costs, the approach taken is slightly different. While the approaches are not inherently in conflict with one another, there may be elements that are not necessarily aligned. 

Rather than seeing DfM and DfA as alternative approaches, it may be best to consider how best to optimize the overall production process. To consider how you can make the product easier to manufacture and also easier to assemble. The ultimate aim is to draw from both methodologies to reduce the overall cost of production.