Injection Molding: get the right motor
While the motors of hydraulic injection molding machines are the largest energy users in the complete system, much progress has been made in controlling this over the past 20 years. These developments mainly concern slowing the motor down when hydraulic oil is not needed or reducing the need for oil by other methods. In some cases, this means that new hydraulic machines are not far away from achieving all-electric standards of energy use.
However, there are still many older machines in service that use old technology (fixed speed pump/fixed volume pump) and these have very high energy demands. Fortunately, motor and control system developers have produced a wide range of solutions using variable-speed motors, variable-volume pumps and now servo motors with fixed speed pumps. These are available for many older machines and can dramatically reduce energy use if retrofitted to older machines.
Actions:
- Examine all the motors used in the injection molding machines.
- Produce a list of the motor/pump types used and find out what the options are for retrofitting new motors and control systems to reduce energy use.
- Consider retrofitting older machines with electric screw drives (if available) to reduce the peak power needed and downgrading the main motor (if possible).
- Consider retrofitting older machines with servomotor pumps/fixed speed pumps
Dr. Robin Kent — ©Tangram Technology Ltd.
Note: Dr. Robin Kent is the author of Energy Management in Plastics Processing, published by Plastics Information Direct, and managing director of Tangram Technology Ltd., consulting engineers specializing in energy management in plastics processing. rkent@tangram.co.uk.