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Why should I use DFMA?

Why should I use DFMA?

Design for manufacturability and assembly (DFMA) is, simply put, the proper way to design equipment.

The products designed that used proper DFMA have these benefits:

  • They are faster to assemble

  • Have a less expensive overall cost to manufacture

  • Are easier to maintain

  • Have fewer parts

You may ask, why doesn’t everyone apply this technique?  Frankly, I think it is because the acronym used sounds complicated – DFMA.   The acronym implies that there are a lot of complicated steps needed (and there can be).  When you google it, lots of long presentations and societies pop up all wanting to educate you on this tool.

Or maybe it’s because it’s not taught in an easily applied way at a foundational level in engineering or design school.

The best introduction I had to this was a one-week class I took about one year after I started my first design engineering job, fresh out of college. I remember the class vividly, as it challenged my current home-grown approach to design.  At the time, I didn’t feel very creative at my work, so this tool was something I could leverage and apply to the design work I was doing every day.

Did it make me a better design engineer?  Absolutely.  Did I apply every aspect of Design for Manufacturability and Assembly in my everyday projects?  Not a chance.

I just didn’t have enough time.  I had deadlines, CAD models to produce, design problems to solve, and drawings to release.  At the end of a project, there was barely enough time to apply a complicated equation and evaluate all the parts.  Much less, to redesign and consolidate all the parts.

I remember having it all come together and make sense one day.  I asked a senior designer named Stan to review my product that was ready to release. I knew it would meet the specs and perform well, and I wanted the job done.  Stan was notoriously stubborn. He was working in Creo/Pro E on a Sun Unix Desktop and the entire department of 50 people was working in AutoDesk Mechanical Desktop or CATIA, so he had some clout.

He did something unexpected.

He didn’t red-mark my detail drawing to AISC Y14.5 as the other designers were doing, day in, day out.  He looked at my design, took a step back, and in about fifteen min redesigned the entire thing I was working on.  He combined a few parts, and made my design much simpler, but still met the appropriate requirements.

I was dumbfounded.

Mostly because I was so focused on my goal to release the drawings! I did not have the perspective or experience to take a step back during my design process and re-evaluate the direction I was going.

It wasn’t too hard to accommodate Stan’s ideas.  I also had half the amount of parts to release, so in the end, it only took me about 10% overall on the project, and I still met my deadline.

After that I realized something.  I could apply Design for Manufacturability to all my designs if I simply applied a core technique – TO REDUCE THE NUMBER OF PARTS IN MY DESIGN.

It did a number of things to the way I approached my designs:

  • I evaluated the parts individually.

  • I questioned the need for more parts.

  • I instead tried to incorporate the feature into some existing sheet metal, machined, or plastic item that was already existing.

  • I re-evaluated my overall design regularly, instead of only at the end.

Despite all of the benefits of DFMA, there are some other, management-level, perceived reasons to not choose DFMA, such as higher design cost and too short a design time.  However, there are good counter-arguments:

  • DFMA creates savings in manufacturing, shorter assembly time, fewer parts to purchase, fewer parts to stock in inventory, and fewer parts to fix if they break.

  • If the team is trained in DFMA first, and in project planning, you can REMOVE time from the prototype build and ADD to the design phase.

  • DFMA training is short and can provide benefits to the team for a full career for the engineer.

So, bottom line, if you are a designer or design engineer, you need to take a course on Design for Manufacturability and Assembly.  Get some training in it, and learn from a creatively un-hindered designer like Stan on how to really apply it efficiently.

Design is fun. Really fun.  Make your designs better by making them simpler.

About the Author: Willem Mast is the owner and operator of WMD Squared.  He loves mechanical design of all types, optimizing engineering systems, and bicycles.  Orginally posted here: