Firing a custom injection molding company is a divorce, not a breakup: there are assets in custody (your mold), a settlement to negotiate (your data, your inventory, your open POs), and a prenup you’ll wish you’d signed years ago. Most buyers stay in bad marriages far too long — not from loyalty, but because the exit looks scarier than the status quo.

So this article does two things. First, it replaces gut feeling with five measurable “irreconcilable differences,” each with a numeric threshold so you know exactly when the marriage is over. Second, it hands you the custody plan: a 30-day evidence log, a 10-week switch playbook that never stops your line, and the prenup clauses to demand from the next partner. The goal isn’t a dramatic exit. It’s a boring, documented, zero-downtime one.

💔 The 5 Irreconcilable Differences — With Numbers, Not Feelings

SIGN 1 · Quality drift that never closes

The symptom: the same defect returns in new clothing; 8Ds are written beautifully and reopened quietly.

The threshold: DPPM trending above ~1,000, or Cpk below 1.33 on key dimensions, or any repeat escape within 90 days.

The good marriage: DPPM under 500 and falling; Cpk ≥1.33 (1.67 for automotive); corrective actions verified effective, then closed.

SIGN 2 · The communication blackout

The symptom: ECNs vanish for weeks; quality escapes get no 24-hour acknowledgment; process changes happen without notice (the silent 4M change).

The threshold: ECN quote over 5 business days, no PCN policy, or one unauthorized material/machine/method change discovered.

The good marriage: 24-hour acknowledgment, 48–72h ECN quotes, written PCN before any 4M change.

SIGN 3 · Cost creep without a ledger

The symptom: annual increases above inflation with no breakdown; change-order fees for everything; “the price is the price.”

The threshold: two consecutive unexplained increases, or refusal to show a line-item cost structure.

The good marriage: open-book line items, resin indexation clause, amortization math you can audit. (Run your own math with a Injection Molding Cost Calculator↗.)

SIGN 4 · Delivery chaos you subsidize

The symptom: chronic expedites; air freight “to protect your launch” billed to you; capacity excuses with no capex plan behind them.

The threshold: OTD below 95%, more than two customer-paid expedites per quarter, or air freight appearing twice a year.

The good marriage: OTD ≥98%, published capacity plan, expedites caused by the molder are molder-paid.

SIGN 5 · Hostility over custody

The symptom: mold release “needs discussion”; CAD and process sheets called proprietary; audits declined; no project isolation.

The threshold: any delay over the contractual release window, any refused audit, any missing ownership letter.

The good marriage: ownership letter on day one, no-lien release in 14 days, audits welcomed — including live video. (See who owns the mold ↗.)

🗄️ Before You File — The 30-Day Evidence Log

Divorce courts love documents; so do negotiations. Spend 30 days collecting, quietly and legally, before anyone knows you’re looking.

🧳 The Switch Playbook — 10 Weeks, Zero Downtime

💍 The Prenup — What to Demand From the Next One

Vet the candidate against the same discipline as our seven red flags audit↗ — the prenup is only as good as the signer.

🗂 Case Files — Six Exits, Executed

❓ FAQ (Snippet-Optimized)

Q1: How do I switch injection molding suppliers without stopping production?
Build 4–8 weeks of safety stock, dual-qualify the new molder with a pilot lot and FAI/PPAP before serving notice, then transfer the mold against a checklist and re-qualify at the new site. Ten weeks, line never stops.

Q2: Can my current molder legally keep my mold?
Only if your contract lacks an ownership letter and no-lien release clause. With both in writing, release is a logistics event, not a negotiation.

Q3: How long does a supplier switch take?
Typically 8–12 weeks: 2 for evidence and contract review, 3–4 for qualification, 2 for stock bridge, 2 for transfer and re-qualification.

Q4: Do I need new PPAP or FAI at the new molder?
Yes — same mold, new home: run first-article inspection, a capability study on key dimensions, and EOL test correlation before ramping.

Q5: What if the old molder refuses process parameters?
Re-develop the window at the new site with scientific molding and a short DOE — typically 1–2 trials. It hurts once; then you write the data clause into every future contract.

🎯 CTA — Free Supplier Scorecard Second Opinion

Not sure if it’s a rough patch or a divorce? Send your 12-month DPPM, OTD and price history. Within 48 hours Ulite returns a free Supplier Scorecard Second Opinion: benchmarked against the five thresholds, plus a dual-qualification plan and the prenup template — whether or not you ever hire us. Ulite — the custom injection molding company you interview last, so you never interview again.

💬 Real-time: The online chat window in the lower-right corner

📧 Email: inquiry@ulitemech.com

🌐 Visit: https://ulitemech.com

📍 Headquarters: Shenzhen, China ( China plastic injection molding company)

     Factory 1: Dongguan, China ; Factory 2: Hung Yen, Vietnam

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