Picking CDs to Duplicate

Simplified motion assembly yields cost, production advantages

John Klein is a design engineer with Amtren Corporation’s Optical Systems Group, Montgomery, AL, one of the largest volume manufacturers of CD/R & DVD/R automated recording systems, primarily for customers with low- to moderate-volume duplication requirements. One day, Klein and several other Amtren representatives were visited by Tom Solon, an applications engineer at Kerk Motion Products, Hollis, NH, who had brought along the company’s latest product.

“The ScrewRail was still a very new product for us; we didn’t even have any documentation for it yet,” recalls Solon. “Still, it sounded like it might provide the type of motion Amtren was looking to create. When I first showed them the device, they were fabricating their own actuation mechanism. Within an hour of my arrival, their design was being revised to incorporate the ScrewRail. Within six weeks, Amtren shipped the first units.”

Rather than being used in an ancillary function, this component is employed by the machine’s pickarm assembly in one of the duplicator’s most critical operations. Other than the actual CD/DVD trays, the pickarm is the only moving component — the pickarm rotates into position, picks up a CD/DVD from a stack of blanks, rotates it into position, and drops it into the CD/DVD drive. The pickarm then picks up the CD/DVD out of the drive and rotates it to an output stack. In some models, the CD/DVD may also be transferred to an accompanying printer.

This application uses ScrewRails from the 4000 series standard configuration, all of which feature a TFE coating that increases lubricity and typically extends the normal nut life by more than 300%. The motion device combines both drive and support/guidance functions into a single, compact, coaxial component. A single unit delivers three-dimensional motion, allowing it to simultaneously lift and rotate when mounted vertically, as in the Amtren application. External rail-to-screw alignment is eliminated in the component, producing substantial cost savings over typical two-rail systems.

Kerk also assisted with an extensive redesign effort, changing the structure of the gear that is a significant part of the duplicator pickarm assembly. In the previous design, Amtren would purchase a machined gear, place it on the duplicator, put in the setscrews, after which they would painstakingly determine exactly where they needed to put the flag, drill holes, then align the entire assembly. It was a difficult and sometimes imprecise process. Consequently, the design was streamlined with an injection-molded gear with some custom machining, incorporating features that align to the rail and already including the flag positioning. To mount the gears, they only need to be pressed onto the rail, and then additional parts are snapped into place. This simplified assembly process eliminates gear alignment requirements.

“I’m convinced the ScrewRail has taken our product up a notch,” said Klein. “We had other designs that performed the same basic function, but I’m certain they would not have had the consistency and smooth performance. Ultimately, we’ve been able to reduce the cost of the motion system by 40-50% over the cost of the alternate design.”

“I’ve got to give kudos to Amtren for their flexibility and responsiveness,” said Solon. “I have never seen a new design implemented so quickly anywhere else. Certainly, there are companies that, for various reasons, would have been reticent to embrace new technology so quickly, particularly in such a critical part of their product.”

Kudos aside, Klein contends that the greater risk would have been to stand pat. “We’re always looking for ways to improve the quality of our products while lowering costs,” he said. “The instant we saw the Kerk ScrewRail, it was evident that we had a way to achieve both objectives. Along with Kerk’s design capabilities, ScrewRail has enabled our equipment to produce millions of CDs or DVDs without any maintenance or adjustment. We can’t afford to let opportunities like that go by.”

—RM

Kerk Motion Products
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