Process Capability Study Cp Cpk Pp Ppk Excel Template — PPAP Element 11 SPC Histogram Control Chart Quality Engineer Six Sigma Tool

PROCESS CAPABILITY STUDY
Cp / Cpk / Pp / Ppk — PPAP-Ready Excel Tool
────────────────────────────────────────
If you've ever pieced together a Cpk calculation in Excel for a PPAP submission, then re-pieced it together for the next one, this is the tool you wanted. Drop your measurements in, get all four capability indices, plus a histogram, X-bar/R control chart, and normal probability plot — built to AIAG SPC and PPAP Element 11 standards.
────────────────────────────────────────
WHAT YOU GET (7 TABS)
────────────────────────────────────────
① SETTINGS
Document control, purpose, AIAG capability thresholds, ISO/IATF clause references. Form number QA-F-250 Rev A — audit-ready.
② CAPABILITY STUDY (the main tool)
Enter your USL, LSL, target, subgroup size, and measurements. The tool calculates Cp, Cpk, Pp, and Ppk automatically with status colors (Incapable / Marginal / Capable / PPAP Ready). Plus subgroup statistics, control limits, PPM defect estimate, and an overall verdict.
③ HISTOGRAM
Auto-binned distribution chart with spec limits to overlay. Includes an interpretation guide for common patterns (bell-shaped, skewed, bimodal, cliff at spec).
④ CONTROL CHART (X-bar / R)
AIAG-standard X-bar and R charts with UCL/LCL computed from A2, D3, D4 factors based on your subgroup size. Plus interpretation guide for out-of-control signals.
⑤ NORMAL PROBABILITY PLOT
Quick visual normality check — if data is normal, points track the diagonal. Curvature warns you that Cpk may overstate true capability.
⑥ WORKED EXAMPLE
Fully-populated 30-piece stamped bracket study showing Cpk = 1.66, Ppk = 1.92, PPAP target met. See exactly how a clean study looks before running your own.
⑦ INSTRUCTIONS
4-step quick start, field-by-field guide, plain-English formula explanations, AIAG interpretation thresholds, and tips for IATF / ISO shops.
────────────────────────────────────────
KEY FEATURES
────────────────────────────────────────
✔ Supports both PPAP-standard 30-piece studies AND flexible 10-125 sample studies
✔ All four capability indices: Cp, Cpk (short-term, within-subgroup) and Pp, Ppk (long-term, overall)
✔ AIAG d2, A2, D3, D4 factors built in for subgroup sizes 2 through 10
✔ Auto control limits — X-bar and R chart UCL/LCL calculated from your data
✔ PPM defect rate estimated from normal distribution
✔ Process centered? In control? PPAP-ready? Verdict spelled out plainly
✔ Conditional formatting — instant visual feedback on Incapable / Marginal / Capable / PPAP Ready
✔ Zero formula errors — 1,158 formulas, all recalc-verified
────────────────────────────────────────
WHO THIS IS FOR
────────────────────────────────────────
✔ Quality engineers running PPAP submissions (Element 11 Initial Process Studies)
✔ Supplier quality engineers verifying supplier capability claims
✔ Manufacturing engineers qualifying new equipment or process changes
✔ IATF 16949 coordinators documenting §9.1.1.1 monitoring evidence
✔ Continuous improvement leaders running Six Sigma projects or pre/post studies
✔ Anyone who has ever rebuilt a Cpk calculator from scratch on a Friday afternoon
────────────────────────────────────────
STANDARDS REFERENCE
────────────────────────────────────────
→ AIAG SPC 2nd Edition — Cp/Cpk methodology and control chart factors
→ AIAG PPAP 4th Edition §Element 11 — Initial Process Studies (Cpk ≥ 1.67 target for new processes)
→ ISO 9001:2015 §9.1.1 — Monitoring, measurement, analysis (capability evidence)
→ IATF 16949:2016 §9.1.1.1 — Manufacturing process monitoring (Cpk/Ppk tracking)
Standards referenced for informational alignment only — not a certification document.
────────────────────────────────────────
CAPABILITY INTERPRETATION (AIAG)
────────────────────────────────────────
→ Cpk < 1.00 → INCAPABLE (significant defects expected)
→ 1.00–1.33 → MARGINAL (no margin for drift)
→ 1.33–1.67 → CAPABLE (AIAG minimum for existing processes)
→ 1.67–2.00 → PPAP TARGET (AIAG required for new processes)
→ ≥ 2.00 → SIX SIGMA CAPABLE (best-in-class)
────────────────────────────────────────
FORMAT & DELIVERY
────────────────────────────────────────
✔ Single Excel workbook (.xlsx) with 7 tabs
✔ Compatible with Microsoft Excel 2016 and later (Windows and Mac)
✔ Instant download — available immediately after purchase
✔ Editable — add your logo, part numbers, customer names, or company branding
✔ Built-in charts (histogram, X-bar/R, normal probability) — native Excel charts, no add-ins required
────────────────────────────────────────
WHY SHOPFLOOROPS
────────────────────────────────────────
This tool was built by someone who has actually defended Cpk numbers in PPAP review meetings, watched processes drift after launch, and had IATF auditors ask why Ppk dropped from one quarter to the next. The math here matches the AIAG manuals — the d2 factors, the A2/D3/D4 control limit constants, the within-subgroup vs. overall sigma split — because that's what your customer's SQE will compare against.
If you have questions about how to interpret your results or whether your study meets a specific customer requirement, message us through Etsy. We answer.
────────────────────────────────────────
ALSO AVAILABLE IN THIS SHOP
────────────────────────────────────────
→ PPAP Checklist — track all 18 PPAP elements through submission (pairs with this study)
→ FAI Form — first article inspection (PPAP Element 9)
→ MSA / Gage R&R — verify your gage before relying on capability numbers
→ Control Plan — process control documentation (PPAP Element 7)
→ New Supplier Onboarding Bundle — full supplier qualification lifecycle