Why is DF(x) so Important?

  • Multiple layers of feedback from customers and partners create some of the best practice guidelines you will ever see. Never stop learning, never stop improving and never stop listening.
  • The principle of DF(x) is simple, listen, learn and apply.
  • The engineering world has a reputation for sharing feedback, views and ideas. While not unique in the world of business there are few communities which gel together like the world of engineering.

DF(x) is a term you will likely hear quite often as an engineer. In product development parlance it means “design for X”, where “X” can be “manufacturing”, “assembly”, or some other focus area. Designing for “X” means focusing the design to take into account all considerable factors of “X”. The most common uses include:

  • Design for Manufacturability
  • Design for Assembly
  • Design for Testability
  • Design for Usability
  • Design for Serviceability
  • Design for Reliability
  • Design for Transportability
  • Design for Safety
  • Design for Accessibility
  • And so on…

So what is DF(x)?

DF(x) is not an event; rather it is a set of best practices, and hopefully a mindset for every design engineer.  Designing for “X” requires forethought.  It’s always useful to remember the famous Benjamin Franklin quote:  “An ounce of prevention is worth a pound of cure”.   In design engineering, especially in the modern age of high technology product development, a gram of prevention is worth a metric ton of cure!

Sharing feedback is vital

In order for DF(x) to be useful, design engineers must be aware of the various lessons learned from previous development efforts.  In order to do this, design engineers need to solicit cross-functional input from all areas of the business, including its customers, in order to gather the relevant data to determine what to do differently or better for the new development effort.

In other words, DF(x) principles should be considered pro-actively and reviewed at every stage of product development as a pre-emptive measure, but only after observing the reactions from previous efforts and actually learning the lessons!

DF(x) and plastic injection moulding

From a mechanical engineering standpoint, let’s take plastic injection moulding as an example and focus on Design for mouldability.  First, the engineer might gather reactive feedback from the tooling & moulding vendor.  How difficult was the last enclosure to get right the first time?  What changes were required after first analysis of the 3D model?  Why were those changes needed?

Lessons to learn

To further illustrate, we’ll say that perhaps the structural ribs inside wall of the part were causing sink marks on the cosmetic front wall of the part.  The toolmaker just made the tooling exactly to the 3D model files provided.  The moulder then suggested to add a “moat” around the ribs to prevent sinking, as they had seen this help with previous cosmetic sink mark issues with another customer’s design.  The toolmaker then had to make severe changes to the tooling, having to add material by welding and then regrinding the existing tooling.  Ultimately, the toolmaker ruined the existing tooling and had to remake the core side tooling, adding considerable cost and time delay to the project.  A very hard lesson to learn indeed.

Re-visit the project

Now the mechanical engineer is tasked with a new project, to design a new enclosure industrial.  The engineer can draw upon that hard lesson and have a much better informed discussion about the 3D model geometry at the peer design review.

Further, drawing from another lesson learned in communication, the mechanical engineer can pro-actively discuss the part design with the toolmaker and moulder together to convey concerns from the previous catastrophe, and take measures to avoid making the same mistakes again.  Perhaps designing moat features around all structural ribs that are adjacent to cosmetic surfaces becomes a new best practice. Then the entire design team can add this to their design review checklist going forward, along with earlier collaboration with both the toolmaker and moulder before any steel is cut.  Now we’re getting somewhere!

Listen, learn and apply

This is a small but classic example of DF(x) in action – the team has learned a lesson and applied that key learning to future designs to avoid repeated mistakes. To get the most from this mindset, it is important that a team includes time for extra reviews and lessons learned in the original project charter.

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