Motor Lamination Tool Qualification Checklist: PPAP-Style Guide for New Motor Core Tooling

What Is a PPAP-Style Lamination Tool Qualification Checklist?

A PPAP-style lamination tool qualification checklist is a structured approval method used to verify that a new stamping tool can repeatedly produce motor laminations and lamination stacks that meet dimensional, material, magnetic, assembly, and production requirements.

It is not just a dimensional report.

That is where many launches get thin.

A single lamination may pass inspection. The stack may still lean. Burrs may face the wrong way. Coating damage may create electrical contact between laminations. Stack height may drift after the tool heats up. The press may run fine at trial speed and misfeed at production speed.

So the real approval question is simple:

Can this lamination tool produce acceptable motor core stacks at production conditions, with controlled variation, traceable evidence, and clear reaction plans?

This checklist is built for that question.

Copy-Ready Motor Lamination Tool PPAP Checklist

Use this table as the working structure for a new lamination tool qualification package.

A checklist works only if the evidence is real. “Checked” is not evidence. A report, sample, record, or signed decision is evidence.

Lamination Tool Design Record Verification

Before the formal trial, freeze the design record.

For motor lamination tooling, the design record should include:

• Lamination profile drawing
• Finished stack drawing
• Material grade and thickness
• Coating requirement
• Burr limit and burr direction rule
• Slot, tooth, bridge, bore, OD, and key feature tolerances
• Stack height requirement and measurement pressure
• Lamination count
• Stacking method: interlock, weld, bond, rivet, skew, or loose stack
• Magnetic or motor performance requirements, if applicable
• Critical and special characteristics
• Packaging and corrosion protection requirements

Do not treat the flat lamination drawing as the full requirement. The motor uses the stack. The tool must be qualified against the stack.

Small detail, large consequence: if the drawing controls slot width but not slot alignment through the stack, winding may become the first real inspection station. That is late. And expensive.

Material and Electrical Steel Requirements

Material must be verified before the tool is judged.

A new lamination tool can look unstable when the real issue is coil variation. It can also look good during trial and fail later when production material changes.

Check:

• Steel grade
• Nominal and actual thickness
• Thickness tolerance
• Coating type and coating condition
• Coil width
• Camber
• Surface condition
• Edge condition
• Lot traceability
• Storage condition
• Lubrication compatibility

For motor laminations, material thickness affects stack height. Coating affects interlaminar insulation and stacking factor. Surface condition affects feeding and burr formation. This is not background data. It belongs in the approval package.

Progressive Die Trial and Run-at-Rate Validation

A lamination tool should be qualified under production-intent conditions.

That means:

• Intended press
• Intended feed system
• Intended coil width
• Intended lubrication
• Intended stroke rate
• Intended stacking or collection method
• Intended inspection method
• Intended operator instructions

A slow trial can hide problems. Feed stability, slug pulling, sensor faults, scrap movement, heat growth, and burr formation may change when the tool reaches real speed.

During the formal trial, record:

• Press number
• Tool number and revision
• Coil lot
• Lubrication setting
• Stroke rate
• Start and stop times
• Scrap quantity
• Downtime reasons
• Adjustments made
• First-piece, mid-run, and last-piece results
• Stack build results
• Parts held for approval

If the tool requires repeated adjustment to make acceptable parts, do not approve it as stable. It may still be fixable. Different thing.

Lamination Dimensional Inspection Criteria

The dimensional report should cover both the individual lamination and the finished stack.

Individual lamination inspection

Measure features such as:

• Outside diameter
• Inside diameter or bore
• Slot width
• Slot opening
• Tooth width
• Tooth tip geometry
• Bridge width
• Keyways or locating features
• Hole position
• Profile tolerance
• Flatness
• Material thickness
• Burr height

Stack inspection

Measure or verify:

• Stack height
• Lamination count
• Stack parallelism
• Slot alignment
• Bore alignment
• OD alignment
• Stack lean
• Twist
• Skew angle, if applicable
• Interlock height or weld/bond condition
• Loose lamination movement
• Stack weight, if used as a process check

Do not rely only on the best-looking stack. Pull samples across the run. Early, middle, late. After stops. After coil change, if the trial includes one. After adjustment, if any adjustment occurred.

That is where the truth usually sits.

Burr Height, Burr Direction, and Edge Quality Control

Burr control is one of the main reasons lamination tool approval needs its own checklist.

A stamped lamination edge is not neutral. Burr height, burr side, rollover, and edge tearing can affect stack height, coating contact, assembly fit, and magnetic behavior.

Define:

• Maximum burr height
• Burr measurement locations
• Burr side or direction
• Number of readings per part
• Sampling frequency
• Tool sharpening trigger
• Reaction plan when burr exceeds action level
• Containment rule for parts made since last good check

Use two limits if needed:

Waiting until the reject limit is reached is poor control. The process should react before parts fail.

Coating Damage and Interlaminar Contact Review

Electrical steel coating is functional, not decorative.

During qualification, inspect for:

• Scratches
• Smearing
• Bare metal
• Pickup marks
• Drag marks
• Local burnishing
• Damage near slots or bridges
• Damage caused by stacking, interlock, or ejection

Create a simple visual standard. Good. Acceptable. Reject.

Do not leave coating judgement to memory. Operators change. Lighting changes. People get used to damage when they see it every day.

If coating damage is linked to performance risk, include additional testing or engineering review before approval.

Lamination Stack Height and Stacking Factor Validation

Stack height is more than a dimension. It reflects material thickness, coating, burr, flatness, interlock behavior, and compression method.

Define the measurement method before collecting data:

• Number of laminations
• Compression pressure or load
• Measurement points
• Gauge type
• Whether oil must be removed
• Whether interlock areas are included
• Temperature condition, if relevant
• Acceptance tolerance

Stacking factor, sometimes called lamination factor, should be reviewed when the motor design depends on effective steel content. It can be influenced by coating thickness, burr, waviness, surface condition, and compaction.

A stack that is tall because of burr is not the same as a stack that is tall because material thickness shifted. Both may fail the same number. The fix is different.

MSA Requirements for Lamination Tool Qualification

Measurement system analysis should be completed before process capability is trusted.

Prioritize MSA for:

• Burr height
• Slot width
• Tooth width
• Bore diameter
• Profile or true position
• Stack height
• Interlock height
• Skew angle
• Coating visual judgement, when used for release
• Core loss or magnetic test, if part of approval

If the measurement system cannot separate good parts from bad parts, the process study is weak. This is especially true for burr height. A burr gauge study done on easy, flat features does not prove the burr method is acceptable on narrow teeth or slot edges.

Process Capability Study for Critical Lamination Features

Capability studies should be used on measurable, stable characteristics.

Good candidates include:

• Slot width
• Tooth width
• Bore diameter
• OD
• Key feature position
• Stack height
• Interlock height
• Burr height, if measurement repeatability is acceptable

Do not force capability studies onto subjective defects. For coating scratches, slug marks, and occasional cracks, use defect tracking, inspection frequency, and reaction plans.

For formal approval, capability data should come from the production-intent run. Not hand-selected samples. Not prototype press conditions. Not after sorting out the bad pieces.

PFMEA and Control Plan Requirements

The PFMEA should reflect real lamination failure modes.

Include risks such as:

• Misfeed
• Pilot wear
• Slug pulling
• Burr growth
• Coating damage
• Mixed material
• Wrong lamination orientation
• Stack miscount
• Interlock loose
• Interlock too high
• Weld or bond defect
• Stack lean
• Tool insert wear
• Sensor bypass
• Rust during storage
• Damage during packaging

The control plan should then answer:

• What is checked?
• How is it checked?
• How often?
• By whom?
• With what gauge?
• What is the limit?
• What happens when the limit is missed?
• How far back are suspect parts contained?

A control plan that says “adjust process” is not enough. It should say what happens to the parts already made.

Tool Maintenance and Requalification Triggers

A lamination tool is not approved once forever. It is approved under known conditions.

Define maintenance controls for:

• Punch sharpening interval
• Die wear limits
• Insert replacement rules
• Sensor checks
• Scrap chute cleaning
• Lubrication checks
• Guide and pilot wear
• Interlock punch condition
• Post-maintenance inspection

Define requalification triggers, too.

Partial or full requalification may be needed after:

• Major tool repair
• Tool transfer to another press
• Material grade change
• Material thickness change
• Coating change
• Design revision
• Stacking method change
• New lubrication
• Unexpected burr trend
• Repeated misfeeds
• Customer or internal quality escape

Not every sharpening requires full PPAP. But every maintenance event should have a release check. The scope depends on risk.

Final Approval Criteria for Motor Lamination Stack PPAP

Approve the new lamination tool only when these statements are true:

• The design record is released and matches tool output.
• Production-intent material was used.
• The trial was run at intended production conditions.
• Individual laminations meet dimensional requirements.
• Finished stacks meet stack requirements.
• Burr height and burr direction are controlled.
• Coating condition is acceptable.
• Measurement systems are suitable.
• Capability or stability evidence supports production.
• PFMEA risks are covered by the control plan.
• Reaction plans are clear.
• Tool maintenance limits are defined.
• Master samples are retained.
• Packaging protects the product.
• Open issues are closed or controlled with written approval.

Approval should not mean “the last sample looked good.”

It should mean the process is understood well enough to run.

Advanced FAQ: Motor Lamination Tool Qualification