Considerations for Water Cooled Injection Molding Machine Motor Repair

The plastic industry relies on injection molding machines to produce part after part. To endure the high demand, the motors on injection molding machines are manufactured to withstand extreme environments. The motors are water cooled and are unique compared to a standard motor. When repairing these motors, you should consider how your repair shop strips the motor of its coils, how it is rewound and how the windings are varnished.

Disassembled Water Cooled Motor

The stripping methods used by standard motor shops can be detrimental to water cooled motors. These shops use the Burnout Oven method where the motors are placed in an incineration oven to heat up the varnish to make the coils pliable. Burnout oven temperatures exceed 680°F which compromise the integrity of the core with frame damage & distortion. While distortion of any motor housing is unacceptable, a unique problem with water cooled motors is the warping of the motor housing causing a leak in the water jacket. A faulty water jacket can allow the coolant to leak and contaminate other components of the motor.

Similar to the issues with a distorted water jacket, water cooled motors may have rubber o-rings that are susceptible to the high heat of the Burnout Oven. When introduced to high temperatures, the o-rings can melt causing leakage of the coolant. This leakage can contaminate the windings, bearings, electronic components and etc. This contamination can result in a slew of problems including but not limited to damaged bearings, imbalance of rotating equipment, and breakdown of insulation. To learn more about the effects of contamination and how to prevent it, read our article Electric Motor and Generator Failures from Contamination.

Unlike other motor repair shops, Dreisilker uses its MotorSafe Stripping method in place of the Burnout Incineration Method. In our MotorSafe Stripping method, we gently warm the outside diameter of the laminations to 400 degrees F with induction or non-contact natural gas. Once heated, we hydraulically remove coils preserving 3 phase groups for data. Our method of motor stripping protects the motor housing and specialized elements of a motor such as a water jacket or o-rings.

After stripping of a motor, rewinding the motor is a critical step of the repair process. We make sure to wind the motors back to OEM specifications or better using computer-controlled technology. The original wire size and wiring data are recorded so that we can replicate the motor’s winding with uniformity and accuracy. Other shops may change specifications, substitute with inferior materials, or modify the original design.

When a motor is rewound, the windings need to be varnished to protect the motor windings from contamination and ensure electric conductivity. The typical repair shop method for varnishing a motor is the dip and bake method. While we use this method for common motor applications, we trickle varnish water-cooled motors to match the OEM standards (for water-cooled motors).

Trickle varnishing is accomplished by connecting the windings to a rotating table and using electrical resistance to heat the windings during rotation. Once at temperature, a tiny stream of varnish is trickled onto the winding head. The varnish follows the wire into the entirety of the slot, eliminating chances for partial discharge in random windings. Once fully saturated, the current is increased in the windings, resulting in the varnish curing while on the machine. This process is faster and better than the traditional dip and bake process because it cures on the machine – making it ideal for emergency repairs. Check out more varnishing techniques in our article 4 Types of Motor Winding Insulation Methods.

How your water cooled injection molding machine motors are repaired is very important to the reliability and lifetime of your motor. If you need your water cooled motor repaired, make sure you consider which method is used for stripping the motor, how the motor is rewound and how the windings are varnished. If you have any questions on how our repair method for water cooled motors is different, feel free to call us today.