Design for Manufacture and Assembly (DFMA) is a technique that helps identify, quantify and eliminate waste or inefficiency in a product design. It is a component of Lean manufacturing and the combination of two methodologies – design for manufacturing (DFM) and design for assembly (DFA).
Designing for manufacture is about designing for ease of manufacturing – efficiently producing the parts that will form the product after assembly. The method aims to reduce the overall part production cost as well as minimise the complexity of the manufacturing operation. Designing for assembly is the method of designing for ease of assembly, reducing product assembly cost and minimising the number of assembly operations.
If the principles of DFMA are followed then the consumer should receive a product they desire, but at a lower cost to the producer. The principles of DFMA are to:
- Minimise the number of parts
- Create modular assemblies
- Minimise reorientation of parts during assembly or machining
- Specify acceptable surface finishes for functionality
- Avoid difficult components
- Avoid special tooling/test equipment
- Standardise parts and materials
- Design for efficient joining
- Simplify and reduce the number of manufacturing operations
- Use cross-functional team working to optimise design for cost-effective manufacturing
- Use self-locating features
- Provide accessibility
- Minimise operations and process steps.
The benefits of DFMA are many but are the principles truly enough?
Why use DFMA?
I realised the importance of DFMA a couple of weeks ago when a desk I ordered for my home office arrived. I ordered it from a store I visit regularly and as a result, I already had certain expectations about the product. My primary expectation was that it would arrive preassembled and would be high quality. However, when it arrived it wasn’t preassembled as I had expected it would be. Feeling disappointed, I grabbed my toolbox and set about building the desk.
But putting the pieces together was no easy feat. The instructions were complicated and unclear, and there were a vast number of pieces – many of which were similar and hard to differentiate based on the instructions. As a result, the DFA element didn’t delight me. The store failed to set clear expectations – if you are supplying something that is not preassembled then obviously the customer needs to be made completely aware. However, the manufacturer of the desk could have overcome this issue if it had:
- Given clear instructions – pictures are helpful but not when they are small. I was given an A5 booklet and the pictures were more than half the size of the paper
- Used clear labelling – this allows for easy identification of components, particularly when some items are similar
- Itemised parts – all nuts, bolts, screws and fixings need to be itemised and linked to a component to make assembly easier
- Reduced the number of parts – I had more desk pieces, drawer parts, handles, runners, side panels, modesty panels and legs than I knew what to do with
- Made it mistake-proof – I spent hours trying to align the drawer runners with the pre-punched holes in the pedestal sides, unable to work out what hole matched with what.
Do the principles work?
So, how did my desk compare to the principles of DFMA? I’m certain that whoever designed it was talented and capable but I don’t think the product was created with an eye on the customer. Whether your customer is a global multinational or someone like me looking for a new desk, the voice of the customer is more valuable at the beginning of the design process than after the product has been delivered.
Susannah Clarke, Managing Partner at Process Management International