Background:
A current KOMAREK customer using a non-KOMAREK screw-fed MS300 briquetting machine had requested an upgrade for their current feed screw drive system. The machine’s feed screw system was driven by an electric motor rated for 460 V, three-phase, 60 Hz service, delivering a maximum speed of 1,200 rpm. The motor was coupled to a 25:1 gearbox, reducing the output speed to a maximum of 48 rpm at the screw auger. This speed proved insufficient to deliver adequate material to the roll set for consistent briquet formation.
To address this limitation, the user installed a 120 Hz variable frequency drive (VFD), effectively doubling the motor speed and increasing the maximum screw speed to 96 rpm.
In addition to the motor and gearbox, a flanged spool incorporating thrust bearings was installed on the gearbox output shaft to accommodate the thrust and side loads generated by the screw auger. While functional, this configuration increased the overall installation height and introduced additional complexity to the feed screw system design.
Challenge:
Feed screw drive systems that utilize separate motors—and in some cases multiple gearboxes—are common on briquetting machines but can be costly to users due to increased maintenance requirements, repair expenses, and production losses associated with downtime.
In this case, operating the feed system at twice its rated speed significantly accelerated wear on the drive components, including the electric motor, gearbox, and motor couplings. Running an electric motor beyond its 60 Hz rating also reduces available torque, negatively affecting overall system performance and reliability.
Solution:
The customer partnered with KOMAREK to implement a KOMAREK designed gearmotor to upgrade their feed screw drive system. Incorporating a gearmotor, the motor and gearbox are integrated into a single unit, simplifying the drive system and significantly reducing the overall footprint. In addition, the gearmotor assembly can be equipped with the required support bearings to accommodate the thrust and side loads present in this application.
KOMAREK also customized the motor speed (maximum 1,780 rpm), gear ratio (13.4:1), and shaft length to ensure the gearmotor operates within the desired speed range while seamlessly integrating with the existing screw auger.
Results:
The gearmotor simplified operation of the feed screw drive system and provides greater reliability compared to the separate motor and right-angle gearbox configuration. Machine downtime is reduced from five or more days—previously required to remove and send the gearbox out for repair—to less than one day by swapping in a replacement gearmotor.
With the revised motor speed and gearbox ratio, the new gearmotor achieves a maximum output speed of 133 rpm. Under the original configuration, the user operated at 100% of the available speed (96 rpm). With the new system, the same screw speed is achieved at only 72% motor output. This operating margin further improves reliability while also providing additional headroom should higher screw speeds be required in the future.
Additionally, the gearmotor’s compact footprint significantly increased the available clearance above the briquetting machine, resulting in a safer and more accessible working area.