Control Plan first edition: changes and practical implementation

What is a Control Plan?

A Control Plan describes:

• How the manufacturing process is controlled.
• Which characteristics require control.
• Which control methods are used.
• How often checks are performed.
• What action is needed when a problem is found.

The objectives of a Control Plan are to:

• Prevent defects.
• Reduce process variation.
• Maintain conformity with customer requirements.
• Support stable series production.

Why did AIAG publish a standalone Control Plan manual?

AIAG published the standalone Control Plan manual alongside APQP third edition in 2024. Separating the documents clarifies how to develop, use and update control plans while maintaining their connection with APQP.

Main changes in Control Plan first edition

AIAG's official introduction highlights:

• Clearer requirements and links between Control Plan and APQP.
• Additional guidance, forms, tables, checklists and examples.
• Safe Launch as a phase of the Control Plan.
• Examples for highly automated manufacturing processes.

Source: AIAG: APQP third edition and Control Plan first edition.

Implementation principles and factory examples

The following sections give practical guidance. Many of these principles existed before the first standalone edition. Example parameters must be validated for the actual process and customer requirements.

1. Combine product and process controls

A common situation Companies focus on measuring products, final inspection and sorting defective items.

Examples include dimensional measurement, visual inspection and end-of-line checks.

Practical approach Control the conditions that create the product.

For example, alongside checking a length of 100 ± 0.2 mm, determine appropriate controls for machine temperature, moulding pressure, holding time, mould speed and material moisture.

Why this matters Effective process control supports consistent product conformity.

2. Maintain a clear link with AIAG & VDA FMEA

A common situation Some businesses develop PFMEA and Control Plans separately, without a clear connection.

Practical approach The Control Plan should be developed with the relevant PFMEA findings.

Failure modes, causes, prevention controls and detection controls should be reflected in the applicable Control Plan controls.

Illustrative example

PFMEA: A potential failure cause is an injection-moulding temperature that is too low.

Example process characteristic: barrel temperature of 200 ± 5°C, monitored through the PLC. The reaction plan must define action for any result outside the validated range, including a temperature below 195°C. These values are illustrative, not a universal machine setting.

Why this matters The Control Plan becomes an operational expression of the controls identified in PFMEA.

3. Make the reaction plan actionable

This is an important implementation principle.

A common situation Vague instructions such as “notify supervisor”, “adjust machine” or “recheck” may be insufficient.

Practical approach The reaction plan should be specific, practical and immediately usable at the production line.

Example

Insufficient detail: “Adjust process if NG”.

A more specific response Stop the machine; contain output since the last confirmed acceptable check; inform engineering; investigate heater zone 1; produce five first-off parts; and obtain QC approval before restart. The exact actions and sample size must be validated for the process.

Why this matters The reaction plan acts as a practical instruction for responding to an abnormal condition.

4. Control product and process characteristics

A common situation Businesses sometimes focus only on product characteristics.

Examples include length, thickness and colour.

Process characteristics also need appropriate control.

Example

Why this matters Consistent quality depends on control of the conditions that produce it.

5. Control special characteristics

Identify special characteristics clearly, define suitable controls and establish appropriate reaction plans.

Examples may include: Safety-related torque, assembly-fit dimensions, airtightness, coating thickness and heat-treatment hardness.

6. Make the plan usable on the shop floor

A Control Plan should support actual production rather than exist only as an audit document.

In practice: Operators should be able to understand and use the relevant controls.

Example The plan should be readable, have clear reaction instructions and link to visual controls, work instructions and procedures where appropriate.

7. Support layered process audits

Control Plan implementation can be checked through layered process audits, process audits and VDA 6.3 audits, as applicable.

The defined controls should have evidence of implementation at the workplace.

Auditors may examine machine settings, SPC charts, first-off records, check sheets and reaction logs.

8. Manage changes systematically

Changes to machines, materials, parameters, tooling, suppliers, layout or software should trigger review of the relevant PFMEA, Control Plan, work instructions and standardised work.

9. Treat it as a living document

The Control Plan is maintained and updated throughout the process lifecycle.

Review it after customer complaints, internal defects, increased scrap, technical changes, lessons learned and audit nonconformities.

Benefits of effective Control Plans

Effective implementation can reduce defects, complaints and scrap; improve process stability; support IATF 16949 and VDA 6.3 audits; and strengthen the effectiveness of PFMEA.

Common implementation mistakes