Helical Rack Speeds Part Removal on Injection Molding Robot

Customer's Problem

A pick & place robot manufacturer needed an axis drive solution for the Injection Molding industry to reduce their part removal time, thereby increasing the throughput of the injection molding machine.

They tried different drive solutions in the past, but they just couldn’t handle the high speeds and acceleration forces required.

ATLANTA's Solution

Choosing from their wide range of standard rack & pinion drives, ATLANTA offered a high-quality helical rack to handle the high linear speeds that the robot reached. The helical gearing was also quiet, even at the peak speed of six meters per second. To handle the high acceleration forces, reaching six times the rate of gravity (6g), the rack & pinion teeth were hardened and precision ground.

By finding a drive solution that could handle the speeds and accelerations, the manufacturer realized they could eliminate the need for a gearbox. They instead drove the pinion gear directly with their servo motor, which simplified the axis drivetrain and reduced costs. The pinion was attached to the motor shaft with a compression coupling, instead of a keyway, to lock it in place and prevent fretting corrosion.

To lubricate the gearing and reduce contamination of the mold, a felt gear was used to provide continuous lubrication. The felt gear meshed directly with the pinion, ensuring a thin film of grease at the tooth flanks.

At the end of the development process, the part removal time for the robot was reduced to only a fraction of a second, achieving the fastest time in the industry.