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The “Layer Cake” Deep Draw

In late 2014, we were approached by a major connector company searching for the right fabrication process for a newly designed connector sleeve. In addition to the blueprint, they had one piece created from a 3D Printer, and a handful of no-quotes from various suppliers.

In essence the component was a series of stacked shapes, much like a layer cake, hence the “layer cake” deep draw.The top section of the part was spheroid in shape and  was mounted on two rectangles, each with different dimensions. We believed we had the deep draw stamping skills to design the tools and make this part.

With uniform round or rectangular shapes, the deep draw process is well defined and repeatable, and this was the challenge of this connector: the deep drawn shape was not uniform.  It was a combination of  rounds and rectangles.

But round shapes reduce differently from rectangular shapes.  Round shapes more or less reduce uniformly, while reduction for rectangles occurs in the corners, which can weaken the wall. So we chose to blend the two deep draw reduction theories and proceed with our tooling design.

The linchpin of the design would be the initial flat blank created as the strip entered the transfer press.  We had a good feel for the blank’s dimensions, but we were uncertain as to its final shape.  If the blank is incorrectly shaped, then the flow of the metal might not remain uniform and lead to work piece deformities rather than stable deep draw reductions. The final design for the blank would only be achieved through a trial and error process within the press.

3D CAD models were also a challenge to a new standard for this complex deep drawn shape. Concepts like sweep, loft, or derived parts aren’t necessary modeling techniques for round parts. After countless hours of brain storming, conceptualizing, drawing, and revising, we  were able to provide our tooling supplier with files they could import directly into their 5 axis CNC machining centers and EDM wire equipment.

We delivered good parts on time. The end use of the component will serve as part of an assembly for the control of a robotic surgical device.  We look forward to deep draw production of this component by mid-2015. And we have a new customer….