[Case studies] 7 QC Tools IATF , Example

matrix datasheet linking IATF 16949 Core Tools (APQP, PPAP, FMEA, MSA, SPC) with the 7 QC Tools, including 5 automotive case studies, key actions, and results:

IATF 16949 Core Tools × 7 QC Tools Matrix

Objective: Reduce defects, improve process control, and ensure compliance.

Case Study	Core Tool Used	QC Tool Applied	Key Actions	Results
1. Paint Thickness Variation	APQP	Pareto Chart	- Identified 80% of variation from 2 spray guns (Pareto). - Updated APQP control plan.	Paint uniformity improved by 65%; PPAP approved.
2. Weld Crack Defects	FMEA (PFMEA)	Cause-Effect Diagram	- Mapped root causes (machine, material, method). - High RPN (512) → Updated welding parameters.	Cracks reduced by 75%; RPN lowered to 85.
3. Dimensional Variability	MSA	Histogram	- MSA revealed gauge variation (GR&R = 28%). - Histogram showed skewed data.	Upgraded gauges (GR&R <10%); CpK improved from 0.8 to 1.5.
4. Supplier Bolt Failures	PPAP	Check Sheet	- Tracked defect types (check sheet). - Rejected supplier batch (PPAP re-submission).	PPM dropped from 1,200 to 150; supplier process improved.
5. Stamping Press Overload	SPC	Control Chart	- X-bar R chart detected abnormal tonnage spikes. - Adjusted maintenance schedule.	Downtime reduced by 40%; no overloads in 6 months.

How QC Tools Support Core Tools

Core Tool	Linked QC Tools	Purpose	Example
APQP	Pareto, Check Sheet	Prioritize risks and track progress.	Pareto charts for Phase 3 (Process Design) risks.
PPAP	Histogram, Scatter Diagram	Validate process capability and correlations.	Scatter plot: Bolt torque vs. tensile strength.
FMEA	Cause-Effect, Stratified Analysis	Identify root causes and segment risks.	Fishbone for high-severity failure modes.
MSA	Histogram, Control Chart	Ensure measurement system accuracy.	Histogram of gauge variation pre/post-calibration.
SPC	Control Chart, Stratified Analysis	Monitor process stability and segment data.	X-bar R chart for hood thickness by shift.

Detailed Case Breakdown

Case 1: Paint Thickness Variation (APQP + Pareto)

• Problem: 30% of hoods failed thickness specs.

• QC Tool: Pareto showed 80% defects from Gun A (misaligned nozzle).

• APQP Action: Updated Process Flow Diagram and Control Plan.

• Result: PPAP approval; $50K/year savings in rework.

Case 2: Weld Cracks (FMEA + Cause-Effect)

• Problem: Cracks at hinge joints (Severity = 9).

• QC Tool: Fishbone revealed poor electrode maintenance (Machine) and low current (Method).

• FMEA Action: Revised welding SOPs and added poka-yoke for electrode checks.

• Result: RPN reduced from 512 → 85; no field failures in 12 months.

Case 3: Dimensional Issues (MSA + Histogram)

• Problem: 15% of hoods out of tolerance.

• QC Tool: Histogram showed bimodal distribution (gauge error).

• MSA Action: Replaced calipers; GR&R improved to 8%.

• Result: CpK 1.5; eliminated sorting.

Case 4: Bolt Failures (PPAP + Check Sheet)

• Problem: Supplier bolts shearing during assembly.

• QC Tool: Check sheet logged failure modes (threads, hardness).

• PPAP Action: Required supplier to re-submit with updated Process FMEA.

• Result: 0 defects in next 5 batches.

Case 5: Stamping Overloads (SPC + Control Chart)

• Problem: Random press shutdowns.

• QC Tool: X-bar R chart flagged tonnage spikes (Operator B shifts).

• SPC Action: Trained operators; added IoT sensors.

• Result: 40% fewer breakdowns; OEE improved by 15%.

Regulatory Alignment (IATF 16949)

• APQP: Mandates Pareto charts for risk prioritization (Phase 3).

• PPAP: Requires histograms/scatter plots for capability proof.

• FMEA: Uses stratified analysis to segment failure modes.

• MSA: Relies on control charts for gauge stability.

• SPC: Demands CpK >1.33 (Control Charts for monitoring).

Quick-Reference Guide

Defect Type	Start With This QC Tool	Core Tool to Resolve
Chronic high defects	Pareto Chart	APQP/FMEA
Measurement errors	Histogram	MSA
Process instability	Control Chart	SPC
Supplier quality	Check Sheet	PPAP
Complex root causes	Cause-Effect Diagram	FMEA

Visual Workflow

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Problem → QC Tool Diagnosis → Core Tool Solution → Standardize (IATF 16949)  

Example: Weld cracks → Fishbone diagram → PFMEA update → Revised Control Plan.