Machine Design

Better bundles with leadscrews

Replacing a pneumatic actuator with an intelligent lead-screw system let a company that makes shrink-bundling machinery avoid difficulties when changing product lines.

A recent upgrade of the shrink bundler from Omega Design Corp. reduced changeover times and lowered maintenance demands. The upgrade employed a Kerk Motion Products RGS 10000 screw-driven slide adapted to be an actuator assembly. The servo-driven leadscrew slide combines greater push power with high-resolution motion control.


The "Classic" Series of shrink bundlers is the flag-ship product of Omega Design Corp., Exton, Pa. These machines move glass, metal, or plastic containers into bundles and then shrink -wraps or stretch-wraps them in an outer plastic cover.

The "pusher" in the shrink bundler is a pneumatically driven actuator that pushes the product into the film or packaging material. But the air-driven cylinder in the original design caused an excess of play and uneven motion. The typical result was lengthy setup time and continual maintenance for alignment and timing.

Additionally, it was difficult to accommodate new package designs, sizes, materials, and configurations with the pneumatic pusher. Frequent changeovers on a packaging line forced production to stop for retooling and realignment — sometimes for several hours.

Omega replaced the original actuator with a Kerk RGS (Rapid Guide Screw) 10000, a screw-driven slide with linear-speed regulation from Kerk Motion Products. Though technically not an actuator, the new assembly was a direct swap-out for the old air cylinder, making an easy retrofit.

The RGS includes an aluminum guide and carriage driven by a precision-rolled stainless-steel leadscrew. The moving surfaces contain Kerkite high-performance polymers running on a Kerkote TFE coating. The compact profile provides high torsion stiffness and stability for its size and weight. The integral mounting base supports the RGS over its entire length and comes standard with a wear-compensating antiback-lash carriage.

The old design could run only at a constant rate. The new system now adjusts the speed at which product moves through the machine. Changeover times between products dropped as recipe-driven settings stored in the controller easily adapt the bundler to the differing shapes and weights of products. The new RGS 10000 can generate over 150 lb of force, almost twice that of the original pneumatic actuator.

Kerk Motion Products, (603) 465-7227,
Omega Design Corp., (610) 363-6555,

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