Start your PFMEA right: this Process Snapshot maps the Electric Water Pump (EWP) final assembly and end-of-line testing flow, transfers critical risks from DFMEA, defines stations, characteristics, gages/MSA, traceability, and constraints—ready for AIAG-VDA PFMEA 7-Step execution.
🧭 Why a Process Snapshot? #
Before PFMEA Step 1 (Planning & Preparation), you need a single, shared picture of what process you’re analyzing: flow, scope, constraints, risk handoffs, characteristics, and how quality is verified. This prevents scope creep, missed interfaces, and orphan risks.
🔁 Handoff: DFMEA ➜ PFMEA (What we inherit) #
Carry over special characteristics and high-AP risks so the process can control them.
| DFMEA Risk / Function | SC Tag | What Process Must Control | Where (Process Station) |
|---|---|---|---|
| Deliver coolant flow (no/low flow) | 🔺 Safety / 🎯 CTQ | Impeller press-fit depth, rotor/impeller torque retention, leak & flow verification | Op06 Press-fit, Op14 Flow Test |
| Prevent leakage (seal integrity) | 🔧 Regulatory | Seal installation method, surface finish cleanliness, early leak screening | Op09 Seal Install, Op13 Pre-Leak, Op14 Final Leak |
| EMC robustness of PCB | 🎯 CTQ | ESD controls, handling, potting/curing discipline | Op08 PCB Handling & Potting |
Tip: Create a “Handover Matrix” tab in the PFMEA workbook and reference these row IDs in your Control Plan.
🗺️ High-Level Line Map (12–18 steps) #
(Example; rename/merge steps to match your plant)
- Incoming & Kitting — Verified parts kit (impeller, shaft, bearings, seal, PCB, housing, screws, O-rings)
- Bearing Press — Bearings to housing/shaft (depth & alignment)
- Shaft Sub-Assembly — Shaft prep, lubrication/cleaning checks
- Stator Into Housing — Seating depth, orientation
- Rotor/Impeller Press-Fit — Interference fit to spec with depth/force control
- Mechanical Seal Install — Orientation, lip protection, cleanliness class
- PCB Handling & Potting — ESD controls, potting volume/time, cure profile
- Connector Fit & Solder/Crimp Verify — Pull test/vision check (if applicable)
- Housing Closure & Screw Torque — DC tool strategy & traceability
- Pre-Leak Screening — Early air decay or pressure hold test
- Electrical Spin Test — Basic run-up sanity, current draw
- Final Leak & Flow/RPM Test (EoL) — At defined ΔP, duty, temp; results to MES
- Final Inspection — Labeling, visual, packaging checks
- Pack & Ship — Traceability closure
📦 Process Scope & Boundaries #
- In scope: Final assembly from kitting to pack-out, including EoL testing and in-line inspections.
- Out of scope: Supplier manufacturing of components (unless flagged “special supplier process”), vehicle integration, logistics post-shipment.
- Lifecycle considered: Normal production, changeover, maintenance restart, environmental extremes (humidity/temperature in cell), and run@rate.
⏱️ Constraints & Targets (fill with your plant’s numbers) #
- Takt time: 36–48 s (target), station balancing within ±10%
- Capacity: 2 shifts × 8 h, OEE ≥ 85%
- Cleanliness: ISO 16232 class X at seal station; particle monitor at cell entry
- ESD: ANSI/ESD S20.20 compliant; <100 V HBM equivalent at PCB station
- Traceability: Full serialization; torque & test curves tied to unit ID in MES
- PPM/FPY: FPY ≥ 98% at EoL; line PPM < 500
⚙️ Special Processes (need extra control/validation) #
- Press-fits (bearing, rotor/impeller): depth/force windows, fixture hard-stops, LVDT
- Seal installation: guided tooling, chamfers, lubricants, cleanliness
- Potting/curing: time-temperature recipe lock, mass/volume verification
- Screw tightening: DC tool with strategy, angle control, socket ID sensing
- Leak/flow testing: recipe lock, daily master part, GR&R on benches
🧪 Key Process Characteristics & Targets (starter grid) #
Replace X/Y with your nominal/limits; mark SCs with 🔺/🔧/🎯
| Op | Characteristic (What) | Target / Tolerance | SC | Verification (How/When) |
|---|---|---|---|---|
| 05 | Impeller press-fit depth | 12.00 ± 0.05 mm | 🎯 | In-station LVDT 100% + SPC (X̄-R) every 30 pcs |
| 05 | Press peak force | X–Y kN window | 🎯 | Force–distance curve 100% (signature match) |
| 06 | Seal orientation | Correct key/face | 🔧 | Vision 100% + poke-yoke nest |
| 06 | Shaft surface finish (Ra) | ≤ 0.30 µm | 🔧 | Incoming cert + random audit daily |
| 09 | Screw torque | 4.0 ± 0.3 N·m | 🎯 | DC tool trace 100% with OK/NOK interlock |
| 10 | Pre-leak (air decay) | ≤ X ml/min @ 1.0 bar | 🔧 | 100% test; daily master part check |
| 12 | Final leak | ≤ 0.5 ml/min @ 1.5 bar | 🔧 | 100% test; auto-lock in MES |
| 12 | Flow @ ΔP 20 kPa | ≥ 35 L/min @ 80% duty | 🔺 | 100% test; store curves & limits |
| 07 | ESD point-to-point | < 100 V | 🎯 | Wrist strap & mat tester: start-of-shift |
🧰 Gage & MSA Plan (excerpt) #
| Gage / Tester | For | Type | MSA Plan | Status |
|---|---|---|---|---|
| LVDT depth probe | Press depth | Variable | GR&R ≥ 10 parts × 3 appraisers × 3 trials (target ndc ≥ 10) | Planned |
| Press force signature | Force window | Attribute/Curve | Discrete decision + periodic correlation study | Active |
| DC torque tool | Torque/angle | Variable | Built-in audit + annual GR&R | Active |
| Leak bench | Leak rate | Variable | GR&R with masters at 3 points | Scheduled |
| Flow bench | Flow/ΔP | Variable | GR&R quarterly; temp compensation check | Active |
| ESD tester | ESD path | Attribute | Daily verification log | Active |
🧮 SPC & Reaction Plan (starter) #
- SPC on: press-fit depth (X̄-R), leak rate (I-MR), torque (X̄-R)
- Rules: Nelson/Western Electric; auto-hold after 2 consecutive rule breaks
- Reaction: stop-ship for SC excursion; quarantine last OK lot; initiate 8D; verify fixture/tooling; retrain if method cause; calibration check for measurement cause
🧲 Poka-Yoke & Interlocks (examples) #
- Vision orientation for seal & connector
- RFID socket sensing for torque tool; recipe lockout in MES
- Fixture hard-stop for press depth; no-go gauge for sub-components
- Two-hand start & door interlock on moving tooling
- Barcode/serial scan at each critical station; no pass → no progress
🌡️ 6M Baseline (environment & interfaces included) #
- Man: certified operators; job instruction sheets; refresh every 6 months
- Machine: PM schedule; MTBF/MTTR tracking; spare kit on site
- Method: WI rev-controlled; photo standards; changeover checklist
- Material: FIFO; lot control; incoming COA for seals/bearings/lube
- Measurement: MSA plan approved; calibration matrix synced to MES
- Mother Nature (Environment): humidity 40–60% at PCB/Seal ops; temp 20–26 °C; particle counter check per shift
🔐 Traceability & Data Strategy #
- Unit serialization from Op01; scan at each gate
- Store torque curves, press signatures, leak/flow curves per unit in MES
- Recipe control: only approved parameter sets downloadable; passworded roles
- Analytics hooks: FPY, top-N defect codes, trend SPC alerts, PFMEA row ID tags in MES
🧾 Draft PFD (you’ll finalize in Lesson 5.2) #
- Symbols: Operation ▢, Inspection ◯, Transport ➝, Storage ▤
- Show part flow + data flow (MES), rework loops, quarantine points, and SC checkpoints.
📋 What to Prepare for PFMEA Step 1 (next lesson) #
- Current PFD (rev A) and layout
- Latest DFMEA Summary with SC list
- Characteristics Matrix (this lesson’s table → spreadsheet)
- Gage List + MSA status
- Work Instructions (draft) and Control Plan shell
- Lessons Learned from prior lines/products
🔗 Internal Linking Suggestions #
- Lesson 5.1: Step 1 — Planning & Preparation (+ 5T)
- Lesson 5.2: Step 2 — Structure Analysis (PFD & Process Tree)
- Template Hub: PFD, Characteristics Matrix, MSA Plan, SPC Pack, Traceability Map
🧠 Pro Tip #
Make the Process Snapshot a living artifact in your MES/PLM. When anything here changes (tooling, limits, WI), it should trigger PFMEA/Control Plan review—that’s how you keep process risk controlled.
