In product design, mistakes are costly, and the longer it takes to discover a problem, the more costly it becomes.
I came across an article written by Dr. David M. Anderson about Design for Manufacturability where he talks about “The Rule of 10“. He claims that it costs 10 times more to find and repair a defect at the next stage of assembly, and then it costs 10 times more at each subsequent stage of assembly. So following his rule of 10 it goes something like this…
|Level of Completion||Cost to find & Repair Defect|
|the part itself||X|
|at sub-assembly||10 X|
|at final assembly||100 X|
|at the dealer/distributor||1,000 X|
|at the customer||10,000 X|
While you can have your own multiplier, whether it be 10, 6, or anywhere in between, the principle is right on. I would actually take this concept and back up in time to the engineering stages of a product.
You should have a cost target in mind from day one of engineering, and not just a “throw a dart at the wall” cost target, but a true educated guess as to what you believe the product should cost.
As time progresses during the engineering, any items that could/should have been taken care of at a previous stage are just collecting money until they show their ugly head. If these items end up requiring a redesign to any tooling or fixtures, then you could potentially be looking at $1,000’s to change the design.
This isn’t to say that mistakes can never happen. We’re all human, after all. But it is saying that you should catch those mistakes as early as possible. Bring your manufacturing team into the Product Design stage so that concurrent engineering can take place and you will be able to utilize the knowledge that they bring to your team (you chose them for a reason didn’t you?).
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