Newsletter # 45 – What is your DFM process?

The last newsletter was about designing impossible features. This time we are going to talk about the DFM process.

The concepts of DFM and DFMA seem to be getting more attention and traction across the engineering and manufacturing sectors. They are even teaching it in some of the more forward-thinking universities. More engineers are using the concepts in their designs and collaborating more with manufacturers to head off problems at their design stages. This is all wonderful and great stuff. Yet I get the impression from working with all the hundreds of companies that we serve that very few companies actually have a process for how they implement DFM. The practice seems to be haphazard at best in many companies. Some engineers have embraced it wholeheartedly and seek out our advice on nearly every design they work on. Others at the same company never do. There doesn’t seem to be a cohesive plan coming down from engineering management about how DFM should look at their company. This lack of structure and process yields very different results across the organization and leaves much waste to be removed. We have seen that the parts which have the most problems, the most ECO/ECNs, and are the greatest hassle in general are from engineers who don’t seek out help early on in the design process.

So what is the process at your company? Has it started with discussions within the engineering and manufacturing groups of the need to include DFM in the design process? Has engineering management gotten behind the idea that it is a crucial step in the design process to reduce lead time and cost of your company’s product? If not, let us recommend that your company fully embrace the idea of implementing a robust and thorough DFM process. Here are a few suggestions for what this process could include.

– Start out by making sure that all your design engineers and drafters/checkers have a familiarity with the manufacturing process that will be used to make your parts. Go visit your vendors, watch videos, read articles and newsletters, and bring in trainers. This is money well spent.
– Get feedback early on in the concept stage if it is needed. It is always good to get started in the right direction with making sure that you have the right process, materials, and rough design concepts for your needs. Is it going to be a machined part when a stamped part would suffice? A 10 minute discussion can potentially save many hours, days or even weeks of work later if you headed down the wrong path.
– Get more feedback once your design is 80% done. Are there any red flags that jump out at the manufacturer? Talk about what type of machine it will be made on and if it will flow well in production. The manufacturing process can begin to be designed at this stage with rough concepts for work holding, inspection, cutting tools, etc.
– Once your design is complete and is getting checked, this is where you really want to go through it with a fine tooth comb.
Check for the following things at a minimum:

Part geometry – Are there any overly difficult features or features that require more complicated work holding for the type of machine or process that will be used? If it is a machined part, have you maximized all your radii so stiffer tools can be used?
Drawing templates – Ensure all your best DFM standards improvements made it on to the company template.
Material callouts – Ensure that the material type and form is appropriate. Have you specified any long lead time items with no alternates? Are there expensive minimum buys for a small volume of parts? (Extrusions, paint, and hardware can often fall into this category.)
Tolerances – Make sure that all your tolerances have been reviewed and are not just a default three decimal places. Make sure your title block tolerances are correct. Ensure that any GTOLs used are appropriate and not driving cost.
Finishing notes – Choose the least expensive finish option that will satisfy the requirements for the application. Ensure any plating thicknesses will work with the tolerance scheme.

While the specifics are important, perhaps the most important idea to take from this newsletter is that building DFM into your process is critical. What may seem like burden and expense at the outset is guaranteed to have an enormous positive impact and immediate ROI if done properly. If your company needs assistance with this, we would be honored to help.

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