A terminal drawing approved by your design team with zero springback compensation data looks good on screen. At stroke 50,000, the bend angle drifts 0.05 mm. Your supplier blames the material.
In this checklist, you will audit flat blank layout decisions, bend radii compliance, material grain alignment, and carrier web design before a single pound of tool steel is ordered.
Go through every item.
Geometry Sign-off
- Confirm the flat blank layout achieves material utilization above 70 percent with the strip carrier design reviewed and approved.
- Verify all bend radii meet or exceed 1× material thickness for the specified copper alloy grade.
- Audit springback compensation in the die design for every bend angle exceeding 30 degrees from the forming plane.
- Check that the terminal contact zone maintains a minimum radius of 0.1 mm at all edge transitions to avoid stress concentration.
- Validate that the progressive die tooling punch-to-die clearance is specified at 5 to 8 percent of material thickness per side.
- Confirm all critical-to-function dimensions are flagged on the drawing with bilateral tolerance bands — not reference dimensions.
- Review the coplanarity specification for multi-leg terminals and confirm the inspection datum scheme matches the assembly condition.
- Ensure that coined features — embossments, contact dimples, or locking tabs — have defined depth and radius tolerances on the drawing.
[Gate Condition]: Do not proceed to material preparation until the flat blank layout, all bend radii, and springback compensation values have been signed off by both the design and tooling engineering teams.
Strip Layout
- Confirm the material grain direction runs parallel to all bend axes — perpendicular bending across grain direction risks micro-cracking.
- Verify the pilot hole diameter is at least 1.5× material thickness and positioned within 2 mm of the strip edge for stable progression.
- Audit the carrier web width to confirm it meets or exceeds 1.5× material thickness on both sides of the terminal profile.
- Validate the pitch progression accuracy tolerance of ± 0.02 mm between consecutive stations across the full strip.
- Check that idle stations are placed between critical forming and coining operations to isolate punch forces and prevent interaction.
- Confirm the strip layout accommodates the specified copper alloy temper — harder tempers require wider carrier webs and larger bend radii.
- Review the slug management plan to confirm slug pulling prevention features — slug retention pins or die button relief — are designed in.
[Gate Condition]: Do not proceed to die build until the strip layout drawing — showing grain direction, pilot hole positions, carrier web dimensions, and idle stations — is stamped approved by tooling engineering.
Tolerance Stack
- Build a tolerance stack-up analysis for the full terminal profile — blanking, bending, and coining combined — against the assembly interface drawing.
- Confirm that the worst-case stack-up across all three forming stages stays within 75 percent of the total tolerance band on the assembly drawing.
- Verify that the stamped electrical terminals dimensional layout report format matches the customer PPAP requirement before first-article submission.
- Audit the datum reference frame to confirm primary, secondary, and tertiary datums are accessible on the finished terminal — not blocked by formed features.
- Ensure that the inspection plan defines measurement points at the contact zone, the crimp barrel, and the mounting feature — three locations minimum.
- Confirm the CMM or vision system measurement uncertainty is less than 10 percent of the smallest tolerance band on the drawing.
- Validate that the first-article inspection sample size follows the customer requirement — typically 5 to 10 pieces per cavity for progressive tooling.
[Gate Condition]: Do not release the die for production until the full tolerance stack-up is documented, the datum scheme is validated, and the first-article dimensional report is reviewed against the assembly drawing.
Audit to PO
A strip layout omitting idle stations transfers punch vibration into coining stations at stroke 300,000. Kravzik validates every DFM checklist item before die steel enters the wire EDM, running digital strip simulations with springback compensation so the die hits Cpk ≥ 1.33 from the first shift.
Send us your terminal drawing for a complete DFM analysis with springback simulation data and tooling cost breakdown, delivered within 48 hours.
