December 2011 / Volume 63 / Issue 12
A smooth transition into microparts—continued
Contributing Editor Bill Kennedy’s interview with Bob Savitzky, president of RS Precision Industries, included additional information about the shop’s transition from a traditional tool and die operation to a manufacturer of microscale parts, as well as Savitzky’s philosophies about customer relations. That extra material is presented here:
Kennedy: What role did your adoption of CNC technology play in the transition of your shop’s operational focus?
Savitzky: Prior to CNC we had four Bridgeport machines and three or four machinists, as well as horizontal mills and multi-spindle drill presses for rough machining parts prior to heat treatment. The CNC mill displaced almost all of the manual machines. We discovered that we were able to finish machine details that in the past had to be finished by EDM. This was because manual machining couldn’t efficiently produce irregular shapes. Not only did we make the parts quicker by CNC, but also more precisely and consistently. This also tremendously facilitated finish grinding, because the stock left on the parts for finishing was much smaller and more consistent. The CNC machine probably eliminated about a third of our internally generated EDM work.
Kennedy: Did your workholding experience with EDM translate directly to micro machining?
Savitzky: The difference is that in EDM there is no mechanical force between the EDM electrode and the workpiece; you can hold the parts very lightly in V-blocks with very delicate clamps, but when you try to machine the parts they need to be held securely to prevent spinning or slipping.
Kennedy: So how did you develop workholding for machining?
Savitzky: We came up with clamping and fixturing schemes that would hold the parts very uniformly around their entire circumference. This might involve multiple jaws that moved in unison or an equivalent method that kind of hugged the parts and supported them. As an example, if you take a paper cup and hold it uniformly around its circumference, the clamping is fairly secure. But if you put it between flat palms and press them together it will surely collapse. If the part was thin walled we might put a pin inside and clamp over it.
Kennedy: How do you balance use of conventional machining versus EDM?
Savitzky: We try to optimize the mix between conventional machining and EDM. EDM should be used strictly for finesse. Its ability is to create features with exquisite tolerances and surface finishes, complex configurations, and with fragile walls that would buckle and distort under conventional machining. It should never be used as a bulk metal-removal process. We conventionally machine parts as close to finished as possible, then use EDM for finishing.
Kennedy: EDM has a reputation of being slow. How do you overcome that?
Savitzky: For years we were able to successfully control the process tightly enough only by producing the parts one at a time. Modular tooling, very high accuracy electrode making, and innovative multiple parts fixturing enabled us to improve processes to meet customer demands to be more competitive. Now the costs of many EDM operations are completely competitive with conventional machining. Moreover, because the EDM process is entirely burr free, it produces a better part.
Kennedy: Beyond providing machining, partmaking, inspection, and product delivery services, in what other ways does RS Precision assist its customers?
Savitzky: We always talk to our customers and their engineers to learn how the part will be used, and which features are critical and not so critical for the ultimate function of the part. Engineers usually are very good designers and draftsmen, but don’t always understand the impact of their designs on manufacturability. We work with them to understand what the part is supposed to do. If we can make their parts more easily, it often makes their end product better. We call this aspect of our work ethic and service to our customers “Going Beyond the Blueprint.” It helps us produce the best possible part at the lowest possible cost.
Kennedy: Any closing comments?
Savitzky: We have come very far from the tool-and-die mentality to where we are today. We are all about producing small precision parts with EDM. And it is a continually evolving process.
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