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DFSS Instructor Prep · Module 9
Layer B — Tier 2 Domain Depth
Materials, Processes & DFM
Where the design becomes a part. DFM (Design for Manufacturing) is the engineering layer that converts drawings into producible product — and the place where most “process-induced” failure causes in a DFMEA (Module 3) actually originate. This module covers Yazaki’s core manufacturing processes (injection moulding, stamping, plating, SMT), the DFM rules each demands, materials reporting compliance (IMDS), and how tolerance design connects DMADV’s Design phase to manufacturing reality.
What’s in this module
- What DFM is and why DFSS lives or dies on it
- The Yazaki process portfolio at a glance
- Injection moulding — the dominant polymer process
- DFM rules for injection moulded parts
- Stamping & progressive die — the terminal process
- Plating processes & control
- SMT & PCB assembly
- DFA (Design for Assembly) — the harness perspective
- Tolerance design & stack-up analysis
- Materials compliance — IMDS, REACH, RoHS
- DFSS linkage — DMADV through DFM
- Instructor facilitation pattern
- Self-check (10 questions)
1. What DFM is — and why DFSS lives or dies on it
Design for Manufacturing (DFM) is the discipline of designing products specifically to be manufactured well — within the capabilities and tolerances of the production processes that will actually make them. DFM is distinct from, but tightly linked to:
- DFA (Design for Assembly) — designing for ease and reliability of assembly
- DFx (Design for X) — umbrella term that also includes DFT (Test), DFS (Service), DFE (Environment), DFC (Cost)
The simplest framing: DFM converts “what the engineer wants” into “what the factory can repeatedly make”. Without it, even a brilliant design becomes a manufacturing nightmare with high reject rates, high warranty cost, and erratic capability.
Why this is the keystone of DFSS Design phase
DMADV’s Design phase produces the detailed design specification + DVP&R — and DFM is what makes those specifications producible. A specification with a tolerance the factory cannot achieve (Cp < 1) is a recipe for either a Phase 4 capability failure (Module 4) or a long warranty tail. Reviewing every CTQ in Measure for “manufacturability before tolerance” is one of the highest-leverage interventions an instructor can make.
~70%
of total product cost is locked in during design — DFM acts on this 70%
20–30%
Typical tooling-cost reduction from good DFM in moulded plastics
15–25%
Cycle-time reduction achievable from DFM optimisations
2. The Yazaki process portfolio at a glance
Yazaki Pune touches most major manufacturing processes for automotive electrical and electronic products. Knowing which process produces which part — and which lives at which level of the harness BoM — lets you speak to participants in the language of their factory floor.
Injection moulding
Thermoplastic resin melted, injected into mould, cooled, ejected.
Yazaki: Connector housings, junction boxes, BFT shells, HV connector bodies, grommets, protectors
Stamping & progressive die
Metal strip fed through multi-station progressive die; punches, bends, draws into terminal shape.
Yazaki: Female/male terminals, bus bars, junction-box stampings, ground straps
Electroplating
Electrolytic deposition of metal layer (tin, silver, gold over nickel) on stamped terminal.
Yazaki: All terminal platings — high-volume reel-to-reel selective plating
Crimping
Mechanical compression of terminal wings around stripped wire (Module 5).
Yazaki: Every wire-to-terminal joint, both in plant and at customer JIT lines
Wire processing
Cutting, stripping, twisting, marking, applying seals — high-volume automated equipment.
Yazaki: Komax / Schleuniger automation in WH plants
SMT & PCB assembly
Surface-mount components placed onto solder paste, reflowed; for EI products with electronics.
Yazaki EI: HUD driver boards, BMS slave boards, sensor PCBs
Soldering / welding
Ultrasonic / resistance / laser welding for HV joints and battery cell tabs; reflow / wave for PCBs.
Yazaki: HV bus-bar joints, BMS sense lines
Wire-harness layboard assembly
Manual / assisted layout of wires on a board following 1:1 drawing; tape, conduit, connector loading.
Yazaki: The defining final-assembly process of every WH plant
Why this list matters in DFMEA review
In Module 3 we noted that PFMEA failure modes flow from DFMEA causes that are process-induced. Each item in this list is a source of those process-induced causes. When a DFMEA failure cause says “improper crimp” or “insufficient plating thickness”, the corresponding PFMEA must address the specific process in this list — and the Control Plan (Module 4) must define a monitoring point at that operation.
3. Injection moulding — the dominant polymer process
Almost every plastic part on a Yazaki product is injection-moulded. Understanding the process is critical to DFM literacy.
3.1 The injection moulding cycle
- Clamping — mould halves close under thousands of tons of force
- Injection — molten plastic forced from barrel into closed mould cavity at high pressure (hundreds of bar)
- Cooling / packing — plastic solidifies, with continued pressure to compensate for shrinkage
- Mould opening — clamp releases, mould halves separate
- Ejection — ejector pins push the part off the moving half
- Repeat — full cycle typically 10–60 seconds depending on part size and material
Each step has signature failure modes:
- Short shot — incomplete fill (cause: pressure / temperature / venting)
- Flash — excess material at parting line (cause: insufficient clamp force, worn mould, excessive pressure)
- Sink marks — surface depressions over thick sections (cause: insufficient pack, uneven cooling)
- Warp — distorted part shape (cause: uneven cooling, anisotropic shrinkage)
- Weld lines — visible lines where flow fronts meet (cause: gate placement, flow imbalance)
- Voids — internal bubbles (cause: gas, moisture, insufficient pack)
- Ejector marks — pin imprints (cause: ejection force on thin walls)
3.2 Mould flow simulation — the digital DFM tool
Modern DFM doesn’t wait for a physical first-article to find problems. Mould-flow simulation predicts fill pattern, weld-line locations, shrinkage, warp, and gate-pressure requirements before the mould is built.
Autodesk Moldflow — industry standard
Moldex3D
Sigmasoft
DFMPro — DFM rule-checking
The DFSS hook
Mould-flow simulation produces predictive outputs — “this corner will see weld line”, “warp will be 0.3 mm”. These predictions are essentially simulated CTQ outcomes for the Analyze and Design phases. A robust DFSS project for an injection-moulded part runs mould-flow simulations as part of Analyze; manufacturing trials in Verify should match the simulated predictions.
4. DFM rules for injection-moulded parts
The classic checklist. Most senior designers know these intuitively; the discipline is applying them with full awareness of their interactions.
Wall thickness uniformity
Thick + thin sections cool differently — sink marks, warp, voids.
Target: uniform 1.5 – 3.0 mm
Draft angle
Vertical walls won’t release from mould without draft (taper).
Typical: 0.5° – 2° per side, more for textured surfaces
Avoid undercuts
Undercuts require side-actions (slides, lifters), increasing mould cost & cycle time.
Eliminate where possible; use snap-fits with cleverer parting lines
Rib design
Ribs add stiffness without adding wall thickness. Excess thickness creates sink marks on the visible face.
Rib thickness ≤ 60% of base wall thickness
Radii on corners
Sharp internal corners cause stress concentration; sharp external corners are mould-wear sources.
Internal radius ≥ 0.25× wall thickness
Gate location
Gate placement controls flow pattern, weld-line location, and packing efficiency.
Choose based on flow simulation; avoid visible / functional surfaces
Parting line strategy
The parting line is where the two mould halves meet. Affects appearance and dimensional accuracy.
Place on stepped flat surfaces; avoid on critical functional surfaces
Achievable tolerance
Injection-moulded parts have inherent tolerance limits.
Typical ± 0.1 mm; tighter possible with cost
The DFMA Boothroyd–Dewhurst tradition
The systematic study of DFM/DFA goes back to Boothroyd and Dewhurst’s work in the 1970s–80s. Their methodology produces a numerical “DFA index” that quantifies how easy a part is to assemble. The takeaway for senior leaders: DFM has been a measurable, quantifiable engineering discipline for 40 years — not a soft “design review” topic.
5. Stamping & progressive die — the terminal process
Every Yazaki terminal starts as a flat metal strip and ends as a 3-D shaped contact through a progressive die — typically 12–20 stations punching, bending, drawing, and forming the strip into final terminal shape, with the part still attached to a carrier strip for reel-to-reel handling.
5.1 The stamping DFM checklist
- Material selection — copper alloys (C194, brass, phosphor bronze). Different alloys have different formability vs spring vs conductivity trade-offs.
- Strip thickness — typical 0.2–0.6 mm for signal terminals; thicker for power terminals.
- Grain direction — strip rolling direction affects formability. Bends should be perpendicular to grain.
- Minimum bend radius — typical ≥ 1× strip thickness; tighter bends can crack.
- Burr direction — punched edges have a burr side and a clean side. USCAR-21 (Module 5) specifies burr height limits (≤ 0.1 mm for ≤ 0.8 mm strip).
- Hole-to-edge distance — typically ≥ 2× strip thickness from hole centre to edge.
- Die wear — gradual edge degradation produces burr increase, dimensional drift; must be monitored.
- Process capability — terminal critical dimensions need Cp/Ppk ≥ 1.67 typical.
Stamping is where mechanical metrology lives
For terminal-critical dimensions (contact-zone height, lance angle, crimp barrel dimensions), the production measurement is typically optical (vision system) on stamped strip, then on crimped terminal. Sample frequencies, MSA, and Cpk per PPAP Element 11 (Module 4) all live here. The Testing Center Manager’s metrology capability for terminal stamping is one of the most-audited Tier-1 quality systems.
6. Plating processes & control
Module 5 introduced the tin/silver/gold plating selection. This section covers how the plating physically gets onto the terminal.
| Plating step | What happens | Failure modes |
|---|---|---|
| Cleaning | Strip oils & oxides via alkaline / acid baths | Inadequate cleaning → peeling, blistering |
| Nickel underplate | Electrolytic Ni deposition (1–3 µm) — diffusion barrier against copper migration | Insufficient thickness → Cu diffusion to surface → Au/Ag tarnish over time |
| Top-layer plating | Tin (3 µm), silver (1–3 µm), or gold flash (0.05–0.5 µm) — electrolytic or selective reel-to-reel | Thickness variation → premature wear; pinholes → corrosion; whiskers (tin) |
| Reflow (tin only) | Re-melt of tin to consolidate structure | Excessive reflow → tin redistribution off contact zone |
| Drying / packaging | Final cleaning, dry, reel up | Humidity exposure → tin oxide; handling damage → contamination |
Plating thickness measurement
X-Ray Fluorescence (XRF) is the standard production technique — non-destructive, fast, gives layer-by-layer thickness. Sample frequency typically per reel.
The selective plating economics
Plating is expensive — particularly silver and gold. Yazaki plates selectively — only the contact zone gets the noble plating; the crimp section gets tin (cheaper, more formable). This is the canonical example of “manufacturing engineering as cost control” — but requires careful registration to ensure the right plating ends up at the right location. Mis-registration is a real failure mode in DFMEA.
7. SMT & PCB assembly
For Yazaki EI products (HUD driver boards, BMS slaves, sensor PCBs), the dominant assembly process is Surface Mount Technology — components glued onto solder paste, then reflowed in a temperature-profile oven.
7.1 The SMT process flow
- Solder paste printing — stencil deposits paste on PCB pads
- Solder paste inspection (SPI) — vision system checks paste volume/shape per pad
- Pick & place — high-speed machine places components on pads (often 50,000+ components per hour)
- Reflow oven — 5–8 zone temperature profile heats PCB to ~245 °C (lead-free), then cools — solder melts and forms joints
- Automated Optical Inspection (AOI) — vision system checks joint quality, component presence/orientation
- X-Ray inspection (AXI) — for hidden joints (BGAs, QFNs) where AOI can’t see
- In-Circuit Test (ICT) / Functional Test — electrical verification
SMT failure modes that link back to Module 2
The dominant SMT-related field failure is solder fatigue under thermal cycling (Module 2 #2 — Coffin-Manson). Common assembly defects: tombstoning (small components stand on end), solder balls, voids, head-in-pillow (worst — looks soldered but isn’t connected), insufficient solder, bridging. AOI/AXI catches most of these in production.
7.2 PCB DFM rules
- Pad sizes per IPC-7351 — different package families have well-defined pad geometries
- Component spacing — minimum 0.5 mm typical to allow placement & rework
- Thermal relief on planes — pads connected to large copper planes get spoke-pattern relief to prevent uneven heating during reflow
- Avoid components too close to board edges — depanelisation stress damages joints
- Orient polarised components consistently — reduces AOI false-positives and operator confusion
- Fiducials at known positions for pick-and-place machine alignment
- Test points for ICT — accessible on bottom side, away from components
- Stencil aperture design — solder paste volume controlled by stencil thickness × aperture area
8. DFA — the harness assembly perspective
Design for Assembly (DFA) addresses how easily the part can be put together. For Yazaki’s WH business, this is the dominant cost driver — the harness assembly board is largely manual, and every minute saved per harness multiplies across hundreds of thousands per year.
8.1 DFA principles for harness assembly
- Reduce part count — fewer connectors, fewer terminals, fewer splices wherever circuit logic permits
- Reduce variant count — same connector body across multiple positions on the harness reduces operator confusion and mis-assembly
- Standard insertion forces — operators tire of high-force connector mating; spec ≤ 75 N typically
- Mistake-proof through asymmetric keying — physically impossible to mate wrong-to-wrong (Module 5 connector polarisation)
- CPA / TPA on critical connectors — error-proofing as physical features (Module 5 §6)
- Colour code for differentiation — even when keying makes mis-mate impossible, colour reduces operator confusion at the layboard
- Provide locating features — wire identification marks, layboard positioning aids
- Self-aligning — connectors mate cleanly with modest misalignment
The Yazaki WH-specific DFA opportunity
A harness with 80 connectors that takes 14 minutes to assemble vs one with 60 connectors taking 9 minutes is a meaningful cost story at scale. DFA opportunities live in DFSS Analyze and Design — they’re rarely revisited after launch. Bringing DFA-quantified savings into the Define phase is one of the strongest ways to get senior commercial sponsorship for a DFSS project.
9. Tolerance design & stack-up analysis
The mathematical heart of DFM. When five plastic and metal parts assemble together, their individual tolerances combine into a stack-up that determines whether the final assembly works.
9.1 Worst-case vs statistical stack-up
Two competing methods:
Worst-case stack-up
Total tolerance = Σ |Ti| (linear sum of individual tolerances)
Statistical (RSS) stack-up
Total tolerance = √(Σ Ti²) (root-sum-square — assumes independence and central tendency)
| Method | Logic | Use when |
|---|---|---|
| Worst-case | Every dimension at its worst extreme simultaneously | Safety-critical interfaces; very low volume; one-off engineering |
| RSS (statistical) | Recognises that simultaneous worst-case is statistically unlikely | High-volume production with process capability data; recommended for most cases |
| Monte Carlo | Numerical simulation using actual distributions, not just ±T | Complex non-linear stack-ups; when actual process distributions known |
The DFSS tolerance-design workflow
- Identify the critical assembly dimension (a CTQ — Module 5 §11)
- List contributing dimensions through the stack chain
- Apply RSS stack-up assuming Cp = 1.33 minimum on each contributor
- Compare to assembly tolerance budget — does it fit?
- If not, either tighten the contributing tolerance (driving cost) or redesign the assembly to reduce stack chain length (DFA improvement)
- Validate using Monte Carlo with measured process distributions in Verify
9.2 GD&T — the language of tolerance
Geometric Dimensioning & Tolerancing (per ASME Y14.5 / ISO 1101) is the standard notation for engineering drawings. GD&T conveys not just “size ± tolerance” but the geometric character of the tolerance (form, profile, orientation, location, runout) and the datum reference frame.
Key concepts your room should be fluent in:
- Datums (A, B, C primary/secondary/tertiary) — the reference frame for all other features
- Form tolerances — flatness, straightness, circularity, cylindricity
- Profile tolerances — surface and line profile
- Orientation tolerances — perpendicularity, parallelism, angularity
- Location tolerances — position, concentricity, symmetry
- Runout — circular and total runout
- MMC / LMC modifiers — Maximum / Least Material Condition — allow bonus tolerance based on size
An instructor red flag in DFMEA / DVP&R review
When a DFMEA function statement references “the dimension X” without specifying the GD&T characteristic, the DFMEA is incomplete. “Diameter 5.00 ± 0.05” is clearer than “5 mm hole”; “Position Ø0.1 to A|B|C” is clearer still. Senior DFMEA reviewers — and you — should expect this rigour on critical dimensions.
10. Materials compliance — IMDS, REACH, RoHS
Materials reporting is the regulatory layer that crosses every Yazaki part. Three frameworks dominate.
| Framework | Origin | What it requires |
|---|---|---|
| IMDS (International Material Data System) | Automotive industry, hosted by Eurofins (formerly DXC) | Every supplier reports the complete material composition of every part. Master DB used by all OEMs. Required as part of PPAP Element 1 (Design Records) — see Module 4. |
| REACH (Registration, Evaluation, Authorisation of Chemicals) | EU regulation 1907/2006 | SVHC (Substances of Very High Concern) list — must declare if present above 0.1% by mass. List updated twice a year. |
| RoHS (Restriction of Hazardous Substances) | EU Directive 2011/65/EU (RoHS 2) | Restricts lead, mercury, cadmium, hexavalent chromium, PBB, PBDE, four phthalates above defined limits. Automotive has specific exemptions (ELV directive 2000/53/EC). |
| ELV (End-of-Life Vehicle Directive) | EU 2000/53/EC | Recyclability targets; restricts heavy metals (lead, mercury, cadmium, hexavalent chromium) with exemptions. |
| India BS-VI / AIS | Indian regulations | Materials provisions echo EU frameworks; specific Indian regulations on battery materials (post-2022 fire incidents). |
Why this affects every DFSS Design decision
A material chosen during Analyze for cost or performance can hit a REACH-SVHC trigger later. Switching halfway through a programme is expensive. Materials compliance is a Define-phase constraint, not a Verify-phase surprise. The Shared Service Advance Materials specialist owns this clearance; bring them into Design early.
11. DFSS linkage — DMADV through DFM
| DMADV Phase | DFM content that lands here |
|---|---|
| Define | Materials compliance constraints (IMDS / REACH / RoHS / ELV); manufacturing-method choice (injection mould vs alternative); volume vs tooling investment trade-off; production-site selection |
| Measure | Operationalised manufacturability CTQs — tolerance budget (e.g. ±0.05 mm critical, ±0.1 mm secondary); process Cp/Ppk targets (1.67 typical); cycle-time target; DFA index improvement target; first-time-right (FTR) yield target |
| Analyze | Concept selection across manufacturing routes; mould-flow simulation; tolerance-stack-up analysis (worst-case + RSS); supplier capability assessment for sub-tier sourced parts |
| Design | GD&T applied to all functional features; DFM rule application (wall thickness uniformity, draft, radii, etc.); DFA optimisation; tolerance design with statistical methods; PFMEA driven by DFMEA process-induced causes (Module 3) |
| Verify | First-article inspection (FAI); mould trials with sample parts; production validation run (300+ parts per PPAP); MSA on production gauges; Cpk demonstration; IMDS / REACH compliance submission |
A DFM-anchored cross-module worked example
Consider a new 0.64 mm signal-class female terminal (Module 5) for an EI sensor application (Module 2 reliability physics + Module 8 EMC immunity):
- Materials compliance (M9 §10): Cu alloy C194 substrate; Au-flash / Ni / Cu plating — IMDS reported; gold thickness halogen-free; REACH-clear
- Stamping DFM (M9 §5): 0.25 mm strip; bend radius ≥ 0.25 mm; burr direction defined; Cp 1.67 on contact-zone height
- Plating control (M9 §6): Nickel barrier 1.5 µm minimum; selective gold plating on contact zone only — saves cost
- Crimp (M5): 15–20% compaction ratio per USCAR-21 Rev 4; CFM in production (M5 §9)
- Connector body (M9 §3-4): Glass-filled PA66, 1.5 mm wall, 1° draft, no undercuts; weld lines simulated and confirmed to avoid critical-strength regions
- Tolerance stack-up (M9 §9): Critical interface mate-engagement depth; RSS stack of housing molding ±0.1 + terminal lance ±0.05 + retainer ±0.05 → predicted ±0.13 mm; design margin 0.4 mm budget — comfortable
- DFMEA (M3): Process-induced failure causes from stamping, plating, moulding all mapped; PFMEA addresses each; Control Plan (M4) monitors at each step; PPAP Element 11 capability data demonstrates Cpk on every critical dimension
12. Instructor facilitation by function
| Function | DFM angle that lands |
|---|---|
| Shared Service — Advance Materials | This is their core scope. Treat as cohort SME on material selection, plating chemistry, IMDS reporting, REACH/RoHS clearance. |
| WH (LV/HV) Manager / Dy. Manager | DFA in harness assembly — part-count reduction, variant rationalisation, layboard cycle time. The single biggest cost lever in WH. |
| CDDC — Connectors / JB / BMS / PDU AGM | Injection mould DFM for connector housings; stamping DFM for terminals; tolerance stack-up for mated assemblies. |
| CDDC — Grommet/Protector Sr Manager | Rubber and TPE moulding — different process from rigid plastics; shrinkage, compression set, polymer ageing (Module 2). |
| CDDC — Fuse/JB/Relay Box Manager | Mixed plastic + bus-bar + relay assembly; complex tolerance stack-up; welding processes. |
| EI — Sensor Developer / AR HUD PM | SMT for sensor and HUD-driver boards; PCB DFM; thermal interface materials. |
| EI — Optical / Mechanical Designer | HUD housing injection mould DFM; freeform mirror manufacturing tolerances; tolerance stack-up driving image-position accuracy. |
| Testing Center Manager | Metrology equipment — XRF for plating, vision systems for stamping, GD&T inspection; MSA capacity for PPAP. |
| SD Coordination / Project Mgmt | Make vs buy decisions; supplier capability assessment; tooling-investment phasing within APQP (M4). |
| Innovation Cell / Tech Assistant | New process introduction — additive manufacturing, laser welding, advanced moulding (gas-assist, MuCell). |
A high-leverage question for any DFSS project
“What’s your tolerance stack-up on the critical assembly dimension, and have you done it RSS or worst-case? What Cpk did you assume on each contributor?” A team that can answer fluently is operating at DFSS-Design-phase rigour. A team that hasn’t done the stack-up has Phase 4 capability problems waiting.
Instructor self-check
Ten questions calibrated to the DFM literacy you’ll need in the room.
Q1. The typical achievable tolerance for an injection-moulded plastic part with good DFM is:
A. ±0.0001 mm
B. ±0.1 mm (tighter possible at cost; ±0.05 mm achievable for small precision parts)
C. ±10 mm
D. ±1 m
Correct — ±0.1 mm is the comfortable default; tighter is possible but each step costs tooling complexity and cycle time. Designs that demand ±0.01 mm on a moulded part are a DFM red flag.
Q2. A participant’s design has zero draft angle on a 50 mm tall vertical wall. The implication is:
A. Manufacturing cost will be lower
B. The mould will last longer
C. The part will not release cleanly from the mould — ejection will scrape and damage the wall, or require complex mould features. Typical draft angle: 0.5° – 2° per side
D. The part will be stronger
Correct — draft is a fundamental moulding constraint. Zero draft on a vertical wall is a DFM violation.
Q3. For a stack-up of 5 independent dimensions each with tolerance ±0.1 mm, the RSS (statistical) total is:
A. ±0.5 mm (worst-case)
B. ±√(5 × 0.1²) ≈ ±0.22 mm
C. ±0.0 mm
D. ±5 mm
Correct — RSS gives a smaller, more realistic stack-up than worst-case for high-volume production where all dimensions being at extremes simultaneously is statistically improbable.
Q4. Why does Yazaki use selective plating on terminals (gold/silver only at the contact zone, tin elsewhere)?
A. Regulatory requirement
B. Aesthetic reasons
C. Plating thickness limits
D. Cost — noble metals are expensive; selective plating delivers contact-zone reliability where needed while using cheap tin in the crimp section. Mis-registration is a real DFMEA failure mode.
Correct — selective plating is the canonical example of “manufacturing engineering as cost control” alongside risk (mis-registration).
Q5. IMDS (International Material Data System) is:
A. An ISO standard for crimping
B. A quality management framework
C. The automotive industry’s materials reporting database — every supplier reports complete material composition of every part, required as part of PPAP submission
D. An EMC standard
Correct — IMDS feeds OEM compliance with REACH, RoHS, and ELV. PPAP Element 1 (Design Records) typically requires IMDS submission with the approved reference number.
Q6. A senior participant’s PFMEA addresses “improper crimp” as a failure mode without addressing which prevention/detection actions in production. What’s the most likely instructor diagnosis?
A. Their PFMEA is disconnected from the DFMEA causes and from the Control Plan; CFM (Module 5 §9) should be a detection action; tolerance & inspection plan need direct linkage
B. The DFMEA is irrelevant to PFMEA
C. “Improper crimp” is not a valid failure mode
D. The Control Plan is optional
Correct — PFMEA must address DFMEA process-induced causes; detection actions live in the Control Plan. Disconnected documents are a top-tier audit finding.
Q7. For a Yazaki harness with 80 connectors taking 14 minutes to assemble, reducing to 60 connectors taking 9 minutes saves:
A. Nothing
B. 5 minutes per harness × hundreds of thousands per year — meaningful cost, captured during DFSS Analyze/Design as a DFA opportunity
C. Only the time per harness, not money
D. Only valid if quality is reduced
Correct — DFA savings are real, scalable, and best captured in DFSS Analyze and Design. They’re typically the strongest commercial story for Yazaki WH-focused DFSS projects.
Q8. In SMT assembly, “head-in-pillow” is:
A. A type of pad design
B. A reflow oven setting
C. A serious defect where the solder paste and ball appear to join but never form a true metallurgical bond — looks soldered but isn’t connected. Detected by X-ray (AXI), not optical (AOI)
D. A type of solder
Correct — head-in-pillow is one of the most insidious SMT defects because it survives basic visual inspection. The detection requires AXI; the prevention requires solder-paste profile and component placement control.
Q9. The relationship between DFSS and DFM in DMADV is best described as:
A. DFM is unrelated to DFSS
B. DFM replaces the Design phase
C. DFM provides the manufacturability constraints that DFSS Design must satisfy — Analyze concept-selects across manufacturing routes; Design applies GD&T, tolerance stack-up, and DFM rules; Verify proves capability per PPAP
D. DFM only applies post-launch
Correct — DFM and DFSS are tightly coupled. The DMADV Design phase outputs are the place where DFM rules and GD&T are applied to the design.
Q10. The most diagnostic three-part question for any DFM-relevant DFSS project is:
A. What colour, what material, what process?
B. Plastic or metal?
C. Domestic or imported?
D. What’s your tolerance stack-up on the critical assembly dimension, RSS or worst-case, and what Cpk did you assume on each contributor?
Correct — these three questions test whether tolerance design has been done at all, what statistical method was used, and what process capability was assumed. A team that can answer fluently is operating at DFSS rigour; one that can’t has Phase 4 problems waiting.