Overview
Control Plan Item custom fields implement the IATF 16949 / APQP control plan structure within Polarion work items. These fields define what to measure, how often, how to control, and what to do when something goes wrong — essential for statistical process control (SPC), manufacturing quality assurance, and continuous improvement workflows.
- Link design characteristics to manufacturing process controls
- Document measurement system analysis (MSA) and gage R&R methods
- Define sampling plans per AIAG statistical guidelines
- Trace control plan actions to PFMEA risk mitigations
- Track control effectiveness metrics on dashboards
Core Control Plan Custom Fields
| Name | Type | Default | Description |
|---|
measurementTechnique | Text | (empty) | Specific measurement or inspection method used to verify a process characteristic meets specifications. Examples: caliper measurement, coordinate measuring machine (CMM), visual inspection per workstandardization, hardness test, tension test. Often references MSA or gage R&R study documentation. |
sampleSize | String | (empty) | Number of parts to be inspected per sampling event. Examples: 5, 30, first+last, AQL 2.5 (per ANSI/ASQ Z1.4). Works with sample frequency to define the complete inspection regime. Critical for statistical process control calculations. |
sampleFrequency | String | (empty) | How often inspections occur during production. Examples: every shift, 100%, every 4 hours, per lot, continuous. Complements sample size to fully specify the sampling strategy. Higher-risk characteristics (high PFMEA severity or detection scores) typically require more frequent inspection. |
controlMethod | Text | (empty) | Control technique used to keep the process within specification limits. Examples: SPC control chart (X-bar R, I-MR, p-chart), poka-yoke (error-proofing), visual control, fixture design, parameter lock, tool wear compensation, environmental control (temperature, humidity). Often derived from PFMEA risk mitigation strategies and preventive controls. |
reactionPlan | Text | (empty) | Corrective actions to take when a process exceeds control limits or produces nonconforming product. Includes immediate containment (sort, rework, scrap), root cause analysis methodology (5 Why, 8D, A3), permanent corrective action, and verification of effectiveness. Critical for containment, traceability, and continuous improvement cycles. |
Field Usage Patterns and Integration
Measurement Technique
Purpose: Documents the verification method for process characteristics. Essential for manufacturing process capability, product quality assurance, and regulatory compliance.
Integration Points:
- Links to Characteristic work items via PowerSheet expansion (Characteristics Sheet)
- Referenced in Verification Evidence when test reports document measurement system analysis
- Influences Control Method design — must have corresponding inspection capability
Examples:
Brake Pad Thickness:
Measurement Technique: Digital caliper (±0.02 mm) per workstandard WS-42
Reference: MSA Study 2025-Q1 (Gage R&R: 15% variation)
Injection Molding Cavity Pressure:
Measurement Technique: Pressure transducer + data logging per ANSI B88.3
Reference: Calibration certificate CAL-2025-0847
Solder Joint Visual Inspection:
Measurement Technique: Optical microscope (100x magnification) per IPC-A-610 Acceptability
Reference: Inspector certification IPC-CIS-2024
The measurement technique must be capable of distinguishing conforming from nonconforming product (Gage R&R ≤ 30%, ideally ≤ 10%). Document measurement system capability in supporting evidence. If measurement uncertainty exceeds process tolerance, the control plan effectiveness is compromised.
Sample Size
Purpose: Specifies inspection quantity per sampling event. Drives statistical sampling plan selection and cost-risk tradeoffs.
Integration Points:
- Works with Sample Frequency to define inspection regime cost and risk coverage
- Influences Risk Priority — higher-risk characteristics typically require larger samples
- Referenced in PFMEA severity and detection ratings (post-mitigation detection improvement)
- Used in Control Plan Cost Analysis calculations
Common Sample Size Patterns:
| Pattern | Usage | Risk Level | Cost Impact |
|---|
100% | Every part inspected | Highest control | Highest cost |
5 | Small subgroup (SPC) | Medium | Moderate cost |
30 | Statistical adequacy | Medium-High | Moderate cost |
AQL 2.5% | ANSI/ASQ Z1.4 single-sampling | Medium | Variable |
first+last | First and last part per lot/shift | Low-Medium | Low cost |
1-per-shift | One part per production shift | Low | Minimal cost |
Sample size should be justified by control plan design principles: SPC subgroups typically use n=5 (rational subgrouping); acceptance sampling plans select sample size from ANSI/ASQ Z1.4 based on AQL target; and 100% inspection is reserved for high-risk characteristics where statistical sampling is insufficient.
Sample Frequency
Purpose: Defines inspection timing — how often measurement occurs during production. Balances risk coverage with cost.
Integration Points:
- Combined with Sample Size to define total inspection volume
- Driven by PFMEA Risk Assessment (high ASIL or severity → higher frequency)
- Influences Cost of Quality metrics on dashboard
- Referenced in SPC Control Limit Calculations (frequency affects rational subgrouping strategy)
Frequency Strategies:
| Frequency | Trigger | Characteristics |
|---|
continuous / 100% | High-risk, critical safety characteristics | Every part; real-time feedback |
every 4 hours | Medium-risk characteristics with process instability history | Production shift-based |
per lot | Batch manufacturing environment | One measurement per production batch |
per first-piece | New setup or material change | First part after changeover |
weekly | Stable, low-risk, historical process capability ≥ Cpk 1.67 | Reduced inspection in stable state |
Failure Mode: Incorrect Fastener Torque
PFMEA Pre-mitigation: Sev 7 | Occ 6 | Det 5 → AP High
Risk Control: Implement torque verification with statistical tracking
Control Plan Item:
Measurement Technique: Digital torque wrench + data logging
Sample Size: 5 (rational subgroup for X-bar R control chart)
Sample Frequency: every 1 hour
Control Method: X-bar R control chart with ±2σ limits
Reaction Plan: If any point exceeds limits → stop production, adjust wrench calibration, retest 5 parts
Expected Post-mitigation: Det 2 (very high detection capability)
Modern control plans use adaptive frequency: start with high frequency (e.g., every 1 hour), reduce to lower frequency (e.g., every 4 hours) after demonstrating process stability (20+ subgroups with no out-of-control signals), revert to high frequency if instability detected.
Control Method
Purpose: Specifies the control technique that maintains process within specification limits. Implements preventive controls from PFMEA risk mitigation strategy.
Integration Points:
- Derived from PFMEA Risk Controls (Prevention controls that reduce Occurrence rating)
- Linked to Characteristic specification (target value, tolerance)
- May reference Measurement Technique (inspection) and Reaction Plan (corrective action feedback loop)
- Displayed in Control Plan Risksheet with visual indicators for control type effectiveness
Control Method Types:
| Type | Example | Mechanism | Capability |
|---|
| SPC Control Chart | X-bar R, I-MR, p-chart, c-chart | Real-time process trend monitoring; detects shifts/trends before out-of-spec | Detects early; prevents nonconformance |
| Poka-Yoke (Error-Proofing) | Fixture with go/no-go stop, button interlock, sensor check | Physical or logical design prevents error from occurring | Prevents error; highest reliability |
| Visual Control | Color-coded zones on gage, workstandard display, mistake-proofing visual | Operator reads and confirms visually (requires training) | Depends on operator attention |
| Parameter Lock / Fixed Setting | Machine parameter set once and locked for entire production run | Eliminates variability by removing operator adjustment | Good if process is stable |
| Automatic Compensation | Tool wear offset, thermal compensation, feedback control loop | System automatically adjusts to maintain target | Very effective for drift/wear |
| Preventive Maintenance | Calibration schedule, tool replacement before wear limit, filter changes | Prevents degradation that causes variation | Sustains baseline capability |
| Material/Supplier Control | Incoming material inspection, supplier certification, material test cert review | Controls upstream source of variation | Prevents material-caused failures |
Injection Molding Cavity Pressure Control:
Control Method: Closed-loop pressure feedback control with +/- 5 bar limit bands
Implementation: Accumulator and proportional valve maintain cavity pressure
within setpoint during fill phase; laser displacement sensor
detects mold deflection and adjusts proportional valve
Operator Interface: Pressure trend displayed on HMI; alarms at ±5 bar
Maintenance: Monthly pressure transducer calibration verification
Link to PFMEA: Prevents high-pressure related defects (sink marks, part ejection failures)
Success Metric: Process capability Cpk ≥ 1.33 (±10% of 500-bar setpoint)
The control method must address the root cause of the failure mode. A detection control (e.g., post-process inspection) is not a sufficient control method unless the failure mode is unpreventable — always prefer prevention controls. For high-ASIL risks, combine multiple control methods (primary + backup + verification).
Reaction Plan
Purpose: Defines corrective and containment actions when a process goes out of control or produces nonconforming product. Critical for continuous improvement and regulatory traceability.
Integration Points:
- Triggered by Control Limit Exceedance (SPC out-of-control signal) or Nonconforming Product Detection
- Initiates Problem-Solving Workflow (5 Why, 8D, A3)
- Links to Change Requests for permanent corrective actions
- Tracks containment effectiveness in Quality Dashboard
- Demonstrates Recall Readiness through documented reaction documentation
Reaction Plan Structure:
REACTION PLAN for [Control Plan Item]
IMMEDIATE CONTAINMENT (0-1 hour):
1. STOP production of affected parts
2. Sort produced parts since last OK inspection:
- [Example: sort first 50 parts from last 2 hours]
- [Inspection criteria: measure 5 characteristics per WKSTD-42]
3. Notify [Quality Engineer, Line Supervisor, Supplier Quality if applicable]
4. Quarantine affected lot: [location, label]
5. Document initial reaction:
- Time of detection
- Parts affected (count, serial numbers if applicable)
- Measurement values that triggered reaction
- Photos of nonconforming product
ROOT CAUSE ANALYSIS (1-24 hours):
6. Convene problem-solving team: [roles: Quality, Maintenance, Production, Design]
7. Apply structured problem-solving: [5 Why / 8D / A3 per problem severity]
8. Investigate root cause from control method perspective:
- Is measurement technique functioning? (gage verification, calibration)
- Is sample size/frequency sufficient? (missed detection event?)
- Did control method fail? (e.g., SPC chart not checked, poka-yoke overridden)
- Is setup/parameter correct? (operator error, setup sheet unclear?)
- Is equipment functioning? (wear, calibration drift, sensor failure?)
CORRECTIVE ACTION (24-72 hours):
9. Implement temporary correction:
- Adjust process parameter within design window
- Increase sample frequency or sample size temporarily
- Retest product or restart with new material lot
10. Verify effectiveness:
- Run 20 parts (or equivalent) and measure
- Plot on control chart; all points must be in-control before resuming normal production
11. Document permanent corrective action:
- Update work instruction if process parameter changed
- Update calibration schedule if measurement system degradation detected
- Modify control method if it failed to detect/prevent
- Update training if operator error was root cause
FOLLOW-UP & PREVENTION (ongoing):
12. Verify sustained improvement:
- Monitor control chart for 10 subsequent subgroups
- Audit adherence to reaction plan monthly
- Update PFMEA detection rating if control method modified
13. Share learning:
- Document in continuous improvement log
- Share root cause and corrective action with supplier if material-related
- Update risk control assessment if residual risk changed
Automotive Brake Pad Friction Coefficient:
Reaction Plan:
STOP production immediately
Sort all parts since last OK test (measure friction on 100% of sorted parts)
Quarantine affected parts in QC area with red tag
Notify Quality Manager and Design Engineering
RCA: Apply 5-Why to understand if material lot is suspect or application process changed
Corrective Action: If material lot defect → return to supplier, restart with new lot
If process drift → re-calibrate friction tester, adjust application pressure
Verify: Test 20 sample parts on new process; all must pass friction criteria
Follow-up: Plot control chart weekly for 8 weeks to confirm sustained improvement
Simple Injection Molded Part Color Specification:
Reaction Plan:
STOP production if visual inspection detects color outside tolerance
Audit last 10 parts (visual comparison to color standard)
Notify Line Supervisor
RCA: Check material resin batch (color lot certification document)
Corrective Action: If resin batch defective → switch to qualified supplier lot
If mixing process drift → adjust colorant pump setting, re-test on sample parts
Verify: Produce 5 sample parts, confirm color matches standard under standard lighting
Resume production with increased sampling (every 500 parts instead of every 1000)
Document reaction plans using the three-phase model: (1) Immediate containment (0-1 hour) to protect customer from nonconforming product, (2) Root cause analysis (1-24 hours) to understand what failed, (3) Corrective action (24-72 hours) to prevent recurrence. Avoid vague instructions like “investigate” or “adjust as needed” — specify exact measurements, thresholds, and approval gates so operators can execute without guessing.
Control Plan Field Interaction Matrix
This matrix shows how control plan custom fields interact and validate together:
| Field 1 | Field 2 | Interaction | Validation Rule |
|---|
| Characteristic (target, tolerance) | Measurement Technique | Must measure the defined target value | Technique must be capable of resolving tolerance band |
| Sample Size (parts per test) | Sample Frequency (how often) | Together define inspection volume/time | Total inspection cost = parts/test x frequency/shift |
| Measurement Technique (inspection) | Control Method (monitoring) | SPC charts need frequent, stable measurements; poka-yoke does not | If SPC method, sample size >= 5 (rational subgroup) |
| PFMEA Risk Level (severity, AP) | Sample Frequency (how often) | High severity/AP typically requires higher frequency | High severity -> higher frequency (e.g., every 2 hours vs daily) |
| Control Method (SPC, poka-yoke) | Reaction Plan (corrective actions) | Control method failure mode triggers specific reaction type | Reaction plan must include re-verification appropriate to control method |
PowerSheet Integration: Control Plan Risksheet
Control Plan Item custom fields display in the Control Plan Risksheet with the following column organization:
| Column Group | Columns | Purpose | Visibility |
|---|
| Control Identification | ID, Title, Characteristic, Failure Mode Link | Trace control to what is being controlled | Always visible |
| Measurement | Measurement Technique, Sample Size, Sample Frequency | Define inspection regime | Control plan phase |
| Control & Reaction | Control Method, Reaction Plan | Define prevention and corrective action | Control plan phase |
| Effectiveness | Detection Rating (from PFMEA), Verify Reaction (from task links) | Track control effectiveness | Execution phase |
- Measurement Technique: Text input; optional but recommended for MSA audit readiness
- Sample Size/Frequency: Dropdown with templates (100%, every shift, per lot, etc.) or free text
- Control Method: Text editor with callout library for common control types
- Reaction Plan: Large text editor (500+ character field for detailed procedure)
Control Plan Items link to multiple work item types in the RTM domain model:
| Linked Type | Relationship | Purpose |
|---|
| Characteristic | ”controls” | Specifies which design characteristic is controlled |
| Failure Mode (PFMEA) | “preventionFor” / “detectionFor” | Links to PFMEA failure modes that this control addresses |
| ProcessStep | ”appliedTo” | Specifies which manufacturing process step this control occurs in |
| Task | ”verifiedBy” | Links to verification tasks (SPC study, MSA, gage R&R, effectiveness audit) |
| Test Case | ”measuredBy” | Links to qualification test cases that verify control adequacy |
| SystemElement | ”appliesToComponent” | For component-level control plans, traces to affected system elements |
Standards References
- IATF 16949:2016 — Automotive Quality Management System Standard; Section 8.5.6 defines control plan requirements
- AIAG-VDA FMEA Handbook (5th Edition, 2019) — Risk mitigation and control selection guidance; distinguishes prevention vs. detection controls
- ANSI/ASQ Z1.4 — Sampling plans for inspection by attributes; referenced for AQL-based sample sizes
- ISO 7873 — Control charts for variables with warning limits; statistical process control methodology
- APQP (Advanced Product Quality Planning) — Chrysler/Ford/General Motors requirements; Appendix D covers control plan content
See Also
