Engineering expertise has taken on an increasingly important role in being able to meet the fast-paced needs of OEMs for metal stampings and springs. Prototyping parts to test and prove design concepts, suggesting ways to reduce secondary operations to reduce costs, and providing value engineering consulting expertise are all key to ensuring the success of projects. This initial phase set the scene for CSS to complete a successful project for Aragon Surgical, a Palo Alto, CA-based startup medical device firm.
CSS worked with Aragon Surgical to significantly reduce its costs by converting a fully machined jaw housing for a laparoscopic surgical device to a stamped part with machined features. Brandon Loudermilk, Aragon Surgical's senior research and development engineer, explained that the company was looking to reduce the overall cost of its previously released laparoscopic surgical device by decreasing costs on as many parts as possible. The jaw housing was one of the higher priced parts for Aragon, and the company also faced challenges with receiving sufficient parts from its existing supplier.
Engineers at CSS began the process by examining at the part and discussing ways that it could be stamped instead of machined from a solid tube. "When we started, I thought there was no way anyone could stamp this part to be perfectly round and make it function properly," said Loudermilk. CSS engineers then engaged in conversations with Aragon and went through numerous steps to arrive at the most important features on the part and determine how it could be stamped within the necessary tolerances. In a few short weeks, they came to an agreement and were able to begin working on production tooling.
CSS showed Aragon a lock barrel for a high end commercial door lock that was similar in many ways to the jaw housing. "When I saw how they could produce that part, how round it was and how good the finish was, it made me consider talking to them more about stamping this part," Loudermilk affirmed. Engineers at CSS went over the Aragon part print with a fine-toothed comb, adjusting the 3-dimensional CAD model and marking up the original drawing with their initial ideas. The groups discussed the tight dimensions, stepping through each feature to see if they could hold the tolerances. They examined the mating parts to see what the critical features were and how the mating parts interacted, discussing which features were critical and agreeing on which other features could be machined out, and how the part would have to be aligned.
The Aragon Surgical part requires a unique rotary head used on milling the portion of the part that gets machined after it is stamped. After the part is formed, it goes into the milling operation to finish mill certain surfaces that need a particular surface finish and accuracy. The tooling costs were significant, but the high per part savings made the investment worth it.
When the part was made as part of a tube, it was held to a tolerance of plus or minus 1/1000th of an inch. The stamped part is capable of plus or minus 2/1000th of an inch. Even though the tolerance is 1/1000th more, the part is fully functional in the design, at a significant savings. The startup firm was conservative with its capital, and went through numerous discussions to arrive at an agreement, which included amortizing the tool costs used to stamp the part.
"We paid up front for a certain quantity of parts, with the additional cost going towards paying for the tool costs. This enables us to get cheaper parts quickly, without putting out our capital up front. After the initial run was consumed, the tooling comes out of the piece price, making it that much more attractive and profitable." Loudermilk estimates that the initial run was 20-30 percent cheaper; when the tooling costs come out the new stamped jaw housing is 50-60 percent cheaper than the machined version, while still meeting all the design specifications.