Punched edge
Track burr height and direction at specified critical features.
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Vincent@vanguard-tech.cn
Stator Manufacturing Quality
Control the punched edge, protect sheet insulation and verify the finished core before winding masks a costly defect.
Engineering Overview
Electrical-steel laminations are insulated from one another to limit circulating eddy currents. During stamping, a raised burr or damaged coating at a cut edge may bridge adjacent sheets when the stack is compressed. The risk depends on where the contact occurs, how many sheets it connects and the motor's magnetic operating conditions. Burr control must therefore cover the entire route from tool condition to stacked-core verification, not just one visual check on a loose lamination.
Track burr height and direction at specified critical features.
Protect the insulation film through handling and stacking.
Review welds, interlocks or bonds for unintended electrical bridges.
Use an agreed core test to validate assembled behavior.
Image Gallery
Failure Mechanism
Stamping creates a rolled edge, shear zone, fractured region and burr. If a projecting burr pierces the insulating coating and touches a neighboring sheet, it can create an unintended conductive path. Multiple bridges can allow circulating currents and localized heating. Tool wear, clearance, sheet orientation and stack pressure all influence whether a cut-edge feature becomes an electrical problem.
Do not assume every visible mark is a functional short. Define the allowable condition for the actual material, coating, geometry and joining method, then validate it on assembled cores. Conversely, a visually neat edge does not prove that all interlaminar contacts are absent.
Control Plan
| Check | Question Answered | Typical Stage | Important Limitation |
|---|---|---|---|
| Edge microscopy or profilometry | How large and where is the punched burr? | First article and periodic die checks | A local sample may miss another feature or tool station |
| Coating inspection | Is sheet insulation intact after processing? | Incoming sheet and stamped parts | Sheet results do not prove assembled-stack behavior |
| Tool-condition monitoring | Is wear or clearance drifting toward a burr problem? | During stamping production | Requires correlation with actual part measurements |
| Stack electrical/core test | Has assembly introduced abnormal losses or shorts? | After stacking and joining | Test result may need localization and reference comparison |
| Dimensional stack check | Are compression, height and skew within plan? | After joining or bonding | Good dimensions alone do not verify insulation |
Manufacturing Route
Mark slot mouths, teeth, back iron and other high-risk features.
Control clearance, tool wear, feed and material orientation.
Record burr size, direction and coating damage by location.
Control alignment, pressure, handling and joining parameters.
Compare the assembled stack with a qualified reference and limits.
Connect steel coil, die condition, stack lot and test result.
Troubleshooting
| Finding | Potential Contributors | First Investigation |
|---|---|---|
| Loss increases across a production run | Die wear, clearance drift or coating damage | Trend edge measurements against tool-life records |
| Localized hot spot after stacking | Interlaminar bridge or join-related contact | Locate the region before reworking the whole stack |
| Loose sheets pass; stack fails | Compression, interlock, weld or handling effect | Compare pre- and post-stack process conditions |
| High burr at one feature only | Local punch wear or die misalignment | Inspect the corresponding tooling station |
| Inconsistent core test results | Fixture, excitation, temperature or test setup variation | Repeat with reference core and fixed settings |
Engineering Decision
Deburring or secondary processing can alter dimensions and may damage the coating if it is not validated. A better response may be to restore die condition, adjust clearance, change handling or revise the joining method. Where deburring is part of the approved process, recheck both the edge and electrical behavior after treatment.
Ningbo Vanguard Technologies can support lamination material review, stack design, prototype builds and manufacturing process control. For a new motor, agree on a sampling plan and core-test acceptance basis before tooling release; for an existing motor, retain failed cores and correlated tool records for root-cause analysis.
FAQ
Practical answers for design, sourcing and production teams.
No. The electrical effect depends on contact, coating condition, stack compression and the number of sheets bridged. Measure the edge and verify the assembled core.
No. Stack height checks geometry and compression; it does not establish that the sheets remain electrically separated.
No. Set project-specific limits and measurement locations based on material, coating, feature geometry, assembly method and validation data.
Yes. An unqualified process can change dimensions or damage insulation coating. Reinspect after any added operation.
After the joining and compression steps that could create bridges, and before winding if the build sequence allows access. The exact method should match the core design and acceptance plan.
Share your lamination drawing and inspection goals for a stamping and stack-quality review.
