DFMA Assembly / Shipulski on Design / Lean Manufacturing Assembly

Shipulski on Design: The Power of Constraints

Too many projects, too many tasks, too many deliverables. At every meeting, work is piled onto our full plates with the implication that none will fall to the floor, like an all-you-can buffet but with expandable plates.

Of course, our plates are not expandable. Resources and deadlines are effectively fixed. We may be able to shuffle resources between projects, but the number of resources is a constraint. And the shuffling comes with no schedule extension, so time is also a constraint. (So is the amount of work a single person can do.) No question, these constraints are real, and we all know it. After a while, the all-you-can-eat approach gets to us. We come to loathe the requests for more work (and sometimes the requestors) because our constraints aren’t respected. We get angry and put ourselves in a “no” mindset, where requests are guilty until proven innocent. We use our constraints to justify our negativity.

But there’s a positive side to constraints. Constraints are a powerful mechanism to help us converge on commercialization—they help us focus. In a healthy way, constraints demand we concentrate our resources on the most important problems. We usually get this right, but the challenge comes when there are more problems than resources.

"Constraints are a powerful mechanism to help us converge on commercialization."

Here again, constraints come to our rescue. With constraint-thinking, we bound the problem narrowly to reduce its size and shape. Focusing resources over a smaller area increases the engineering intensity and enables faster problem solving. Most elements of the design are constrained out of the problem, leaving only two elements with a single problem between them. With only challenge to overcome, the problem gets solved quicker. Unfortunately, we usually spend too little time on problem definition.

It makes sense to spend time on problem definition, but practically, it’s difficult. The healthy elements of constraints (constrain the problem) are overpowered by the dark side of constraints, which trick us into trying to make immediate progress on all problems. In the heat of the moment, our highly constrained projects can lead to confusion. From the outside, problem definition does not look like progress (it looks like thinking), but seasoned insiders know tightly constraining the problem is progress and is vital for convergence on commercialization.

Constraints are also helpful for divergence. When things are going well and we’re stagnated by our success, constraints can help us create new thinking. Divergent thinking comes easily when our backs are against the wall and the end of our business is imminent, but there’s no need to let things get that bad. Instead, creative use of constraints can achieve the benefit of a near cataclysmic event without the risk.

Unreasonable constraints can help engineers see their products differently. Instead of solving the usual problems, unreasonable constraints are fabricated to create new problems. The best way is to constrain out a product’s main benefit. A product that does things fast must be slow; a light one must be heavy; a stiff one must be jiggly. The unreasonableness takes the pressure off the engineers (no one can expect real-world solutions to silly problems) and helps them loosen up.

And once loosened, a strange thing happens. By thinking through the implications of the unreasonable constraint, engineers develop novel lines of thinking that can be twisted back onto the real product. The forced divergence flips on itself and converges on new features and even new product lines.

Constraints are real, but we make them what they are. I urge you to take ownership of your mindset, choose how you want to see your constraints, and use their powers for good.

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Mike Shipulski is a leading authority on lean manufacturing, product development, and design for manufacturing and assembly. His column will appear every other month, alternating with Austin Weber’s “On Campus.” E-mail Mike with comments via mike@shipulski.com or follow his blog at www.shipulski.com.

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