In 2009, Dexter Magnetic Technologies introduced a dual-axis robotic manipulator to control sputtering in the manufacturing of computer hard drives for high-density digital recording. The product relied on a sophisticated drive and pulley system consisting of two single-sided timing pulleys configured into two independent drive sections, each of which uses two single-sided timing belts.

During tests at a customer’s plant, the faster of the two compact belt drives required frequent and precise tensioning to eliminate belt stretching and excessive wear. This led Chris Ras, Dexter product development manager, to begin exploring a gear design as an alternative to the belt drive.

Ras contacted Intech Corp. to discuss how their self-lubricating plastic gears might work into his design. The constraints of the application were limited space and a need for high torque and reversing torque. In addition, the gears would have to be retrofitted into existing equipment at the customer’s facility. After reviewing load data through Intech’s proprietary gear calculation program, Tody Mihov, Intech’s engineering manager, determined that the company’s self-lubricating Power-Core plastic gear would work well in this application.

The Power-Core is machined from stable nonhygroscopic composite material cast around a metal, stainless steel or aluminum core. Besides resisting corrosion and chemicals, the gear is lightweight (0.037 pound per cubic inch), runs without lubrication up to 1,200 feet per minute, and reduces noise up to 6 decibels.

The plastic gear is for applications where lubrication, noise, shock, vibration, moisture or chemicals present problems for gears made of metal, nylon or Delrin. It is available in spur, helical, bevel and worm designs, with ODs of 3/4 inch and up.

For Dexter’s application, Mihov improved the gear’s load-carrying capacity by applying a plus-plus gear mesh modification to the gear train. This addition assured the smooth manipulator motion that Ras desired. In addition, a special idler gear shaft made field-ready retrofit easy.

An in-house test by Ras determined that hard-drive efficiency increased by 15 percent. Gone were the radial stresses that belt tensioning had transferred to the bearing. The only force transmitting onto the mating gear teeth was the torque, which traveled on a precision-machined pitch line. To further increase drive-and-pulley system reliability, Dexter has retrofitted the system’s rotary axis with the plastic gear.

For more information on self-lubricating plastic gears, call 201-767-8066 or visit www.IntechPower.com.