Problem
The Client requested a simple review of Design for Manufacture (DFM). The product was a 3-inch long torque wrench for a product facing FDA evaluation. The Client presented me with an exact working prototype of their wrench. It was a break-over torque wrench with a single fixed value for torque break-over, including a ratcheting capability. The special feature of this wrench was that it was inexpensive and therefore could be sold as a disposable part of the kit containing the entire device.
- My initial evaluations of the wrench during the quoting process revealed that the initial design would not be able to address Client needs. It could neither exert the required torque nor ratchet as desired. It was completely non-functional.
- Since this wrench was a key part of the new products innovation, its absence threatened the entire project.
- Also, torque wrenches currently used in this application could cost $500, due to the dozens of precision-machined and assembled parts in it. But the target price for the previous wrench COGS (Cost of Goods Sold) was only a few dollars.
- And finally, my searches would reveal that, while someone had created a ratcheting mechanism in only 2 pieces, no one had ever designed a 2-piece break-over torque wrench.
Action
- I reviewed the Client’s request for Design for Manufacture (DFM) adjustments to the product.
- Since maintaining product performance is critical to any Design for Manufacture (DFM) effort, I performed some performance tests on the torque wrench. I discovered that the wrench could neither exert the required torque nor ratchet as desired.
- I informed the Client of my results. I asked if they would like me to try to invent a solution for them.
- Developed a theory of a 2-piece assembly which, if it worked, would provide both ratcheting and torque-limited break-over.
- I designed several concepts, created and developed prototypes. Consulted with a metallurgist and dynamic analyst, created a design for large scale production, and met the Client’s new cost requirements. (Patent: US 2017 /0334046 A1)
Result
Though the design of the critical marketing-advantage part (the wrench) had to begin all over again, the Client was able to bring their product to market, and the new torque wrench was ready in time for them to begin production.
Project Notes
- It is important for a designer to carefully evaluate each proposal, and consider what actions will best support the Client, especially if these actions impact risks of which your Client may not be aware.
- It is also important to have the intellectual tools to tackle a design task which has no current solution.
