Processes: Design for Manufacturability/Testability (DFM/DFT)

Design for Manufacturability/Testability is a process whereby certain principles are applied to a product design to make it producible. Some of the benefits of following the DFM/DFT principles are assembly cost savings, fabricated part cost savings, work-in-process (wip) reduction, reduction in overhead material costs, better product designs etc. Manufacturing Engineering and Test Engineering typically spearhead these efforts and work closely with Design Engineering on all new product designs. The guiding principles of DFM/DFT are sometimes viewed as common sense but not always followed. Here are just a few of the DFM principles:

1) Reduce and simplify the number of parts in the design. Every part creates an opportunity for error so the less number of parts, the smaller the chance for error. It also simplifies assembly as fewer parts are used.

2) Use of common parts across all designs reduces inventory, machine setups, assembly operations and material handling.

3) Bulletproof or mistake proof designs so that parts can only be assembled one way.

4) Orientate parts so that minimal effort is used to assemble and non-value added motions are minimized. This also includes machine motion as well.

Design for Testability applies to an electrical or electronic part or device that requires some level of testing to validate the part is acceptable to use or move on to next level. The goal is to have as much test access to the unit as possible so an automatic tester (ATE) can quickly test the board and fault isolate any defect found. In many ways, the DFT logic and methodology applies to software validation as well.

Design Engineering will need to consider DFT as a means to increase the overall quality of the product while reducing cost at the same time even though time spent on the design itself may increase. I think of it this way; an engineer designs a product once but manufacturing builds the product thousands of times. If the product is neither designed with DFM of DFT in mind, production costs will shoot up and quality will drop as a result. The choice is simple here. Here’s a simple DFT ‘cheat sheet’ I developed awhile back that was given to design engineering for them to follow. It was very well received at the time. View DFT form Return to Processes