A realistic playbook for PPM, DPPM, OTD, and COPQ in iron castings (foundry quality KPIs). Get clear formulas, target ranges by industry/complexity, and YB Metal quality gates—even before you RFQ.
TL;DR — realistic targets you can buy against
- PPM (external) after stabilization:
- Industrial (non-auto): 800–2,500 PPM typical; ≤800 PPM for simple parts.
- Automotive (PPAP L3, mature): ≤500–1,000 PPM common; best-in-class ≤300 PPM.
- DPPM (delivered defect parts, often “line-stop” level): target ≤200–500 DPPM (industrial), ≤50–200 (auto).
- OTD (on-time delivery): ≥95–98% (define window, e.g., −0/+3 days).
- COPQ (cost of poor quality): track internal + external; agree unit costs for returns/rework upfront.
Definitions & formulas (agree the math first)
| KPI | What it measures | Formula | Notes |
|---|---|---|---|
| PPM (Parts Per Million) | Nonconforming parts shipped per million | PPM = (Nonconforming parts ÷ Parts shipped) × 1,000,000 | Use customer-found defects; log time window (30/90/12-mo) |
| DPPM | Defective parts per million (failed at customer) | Same as PPM but exclude minor concessions | Often stricter—ties to line-stops/field returns |
| DPMO | Defects per million opportunities | DPMO = (Total defects ÷ (Units × Opportunities)) × 10^6 | Use when one part has multiple defect opportunities |
| OTD | % of shipments on or before promise | OTD = On-time shipments ÷ All shipments × 100% | Define window (e.g., ReqDate −0/+3 d); partials count? |
| COPQ | $$ impact of poor quality | COPQ = (Scrap + Rework + Returns + Warranty + Expedite) | Agree cost table: handling, freight, sorting, line-stop fee |
Benchmarks by segment & complexity
| Segment/part type | Complexity example | Stabilized PPM | DPPM | OTD |
|---|---|---|---|---|
| Industrial iron castings | Pump/valve bodies, brackets | 800–2,500 | 200–500 | 95–98% |
| Auto powertrain (PPAP) | Machined housings | ≤500–1,000 | ≤50–200 | 97–99% |
| New ramp-up (first 3 months) | Any | 2,000–5,000 | 500–1,000 | 90–95% |
| Thin-wall / many cores | Compressor covers, complex housings | 1,500–3,500 | 300–700 | 94–97% |
Use these as starting targets; lock the final numbers after pilot + PPAP/FAI.
What drives the numbers (and how to move them)
- Design window: uniform sections, adequate fillets, min wall per process → fewer inherent risks.
- Process capability: controlled melt/sand KPIs, robust gating/feeding, ISO 8062 CT realism.
- Inspection depth: FAI + CMM/3D scan on criticals; sampling scaled to risk.
- Supplier logistics: stable batch sizes, pull signals, route lead times → better OTD.
- Feedback speed: 8D discipline on escapes; closed-loop corrective actions within 10 working days.
YB Metal quality gates (what we commit to)
- Incoming/base: spectrometer per heat; sand KPIs (AFS GFN, moisture, LOI); nodule count/shape for ductile.
- In-process: pour temp window; inoculation logs; yield/scrap Pareto; SPC on critical dims where needed.
- Final: FAI + CMM on PPAP lots; Brinell per batch; leak/NDT as specified; traceability (heat/batch/serial).
- KPI reporting: monthly PPM/DPPM/OTD dashboard; 24-h containment on escapes; 5-Why/8D with evidence.
Minimize movement with the right machining order
- Symmetric removal when feasible; avoid finishing around trapped stress.
- Criticals last: sealing faces/bores after bulk hog-out.
- Probe checkpoints mid-cycle; alarm if drift exceeds control limits.
Sample KPI targets you can copy into the SQA
- Scope: Gray/grey & ductile iron castings, green/resin/shell processes
- Window: Rolling 90 days; reset upon engineering change or new tool release
- Targets:
- External PPM ≤ 1,200 (industrial); DPPM ≤ 300
- OTD ≥ 96% (Required Date −0/+3 days; partials pro-rated)
- COPQ reporting monthly; escape response: 24h containment, 10-day 8D
Verification: - PPAP L3 at SOP; FAI + CMM on criticals; sampling per AQL/RQL agreed
Converting KPIs into cost (COPQ quick math)
| Scenario | Example assumption | Rough cost impact |
|---|---|---|
| Sorting at customer | 1,000 pcs / 2% suspect / $0.25 per piece sort | $500 |
| Return freight + rework | 200 pcs × $4 freight + $6 rework | $2,000 |
| Line-stop fee | 1 hour stop @ $5,000/hr + team time | $5,000+ |
Data hygiene (so KPIs are fair)
- Separate engineering change fallout vs process escapes.
- Freeze denominators (what counts as “shipped” or “on-time”).
- Keep one source of truth (shared dashboard), one calendar for holidays/Incoterms.
FAQs
Ready to Start Your Iron Casting Project With YBmetal?
Send us your drawings or part photos, and we’ll prepare a tailored sourcing plan, including foundry recommendations, a cost estimate, and a sampling lead time.