Electric Motor Repair Case Study Part 1 - Inspect, Measure, Disassemble
When a damaged motor makes its way to the shop, a few things need to happen before any lamination cutting or rebuild can occur. Our process begins with a detailed inspection, measurement, and disassembly of the motor core to assess the extent of damage, document the overall design and prep for reverse engineering. This process ensures optimal outcomes because every motor is unique, the extent of damage can vary greatly and thus, in this critical first step, we create a game plan for the rebuild.
To begin, we closely examine the motor core to assess damage and wear that would require replacement. Here are a few indications of wear often seen in a damaged motor core:
- Damaged laminations
- Bent or loose teeth
- Missing or worn material
This first step ensures our engineers understand how the motor was damaged and anticipate any challenges that will need to be addressed in the manufacturing and rebuild process.
Once the initial inspection is complete, detailed measurements of the motor core are taken. We will measure the core length and mark the positioning of the core within the frame. If the core includes vent plates, we will also make sure to measure and record each individual pack length. Slot and width depths are also measured as well as overall stack length. These measurements will go onto the final drawing and is what the replacement core will be manufactured to match. All measurements are taken from multiple locations on the core using certified precision measuring equipment to ensure accuracy.
The next step is removing the stator core. This is often done by heating the motor frame to expand the housing and allow for pulling the core out of the frame. Each motor is unique, so it’s essential to document how each core is designed so that it can be properly disassembled. For example, if pins hold the core to the frame, a drill press may be used to remove the pins so that the core can be removed from its frame.
After disassembly, the core is separated and a few representative lamination samples are taken to the engineering lab where they are placed on a coordinate measuring machine, or CMM, for accurate measuring so that a CAD drawing of a replacement lamination can be produced.