B Buttress QMS

Control Plans Guide

Manufacturing process control documentation.

Control Plans
What is a Control Plan? Control Plan Phases Control Plan Structure Creating a Control Plan Special Characteristics Reaction Plans Approval Workflow Back to Help Center

What is a Control Plan?

A Control Plan is a documented description of the systems and processes used to control product and process quality during manufacturing.

Purpose of Control Plans
  • Document the methods for controlling product quality
  • Define inspection frequencies and sample sizes
  • Specify measurement techniques and equipment
  • Establish reaction plans for nonconformances
  • Ensure consistency across shifts and operators
  • Support process capability and continuous improvement
APQP Integration: Control Plans are part of Advanced Product Quality Planning (APQP) and are required elements of the PPAP submission (Element 7).

Control Plan Phases

Control Plans evolve through three phases as a product moves from development to full production.

Prototype

When: During prototype development

Purpose:

  • Verify design requirements
  • 100% inspection of key dimensions
  • Material and functional testing
  • Document lessons learned

Pre-Launch

When: During pilot/trial production

Purpose:

  • Validate production processes
  • Enhanced sampling rates
  • Process capability studies
  • Operator training validation

Production

When: Full production

Purpose:

  • Ongoing process control
  • Statistical process control (SPC)
  • Reduced sampling (if capable)
  • Continuous improvement
Progression: Control Plans should transition from Prototype to Pre-Launch to Production as the product and process mature.

Control Plan Structure

Each row in a Control Plan represents a process step with its associated characteristics and controls.

Column Description Example
Process Step Operation number and name from process flow OP10 - CNC Turning
Machine/Device Equipment used for the operation Mazak QT-250
Characteristic No. Unique identifier for the characteristic DIM-001
Characteristic Description What is being measured/controlled Outer Diameter
Special Char. Class SC, CC, KPC, or blank for standard SC (Safety Critical)
Specification/Tolerance Engineering requirement 25.00 +/- 0.05 mm
Evaluation Method Measurement technique/gage Digital Micrometer
Sample Size How many to measure 5 pcs
Sample Frequency How often to measure Every 2 hours
Control Method How results are documented X-bar R chart
Reaction Plan What to do if out of spec Stop, Contain, Notify QE

Creating a Control Plan in Buttress QMS

Step-by-Step Guide
Step 1: Start a New Control Plan

Navigate to PPAP > Select a PPAP > Control Plan tab, or create standalone from the Control Plans section.

Step 2: Enter Header Information
  • Control Plan Number: Unique identifier
  • Revision: Current revision level (A, B, C...)
  • Phase: Prototype, Pre-Launch, or Production
  • Part Number/Name: Associated part
  • Supplier: Manufacturing supplier
  • Core Team: Team members responsible
Step 3: Add Characteristics

For each process step, click + Add Characteristic and complete:

  • Process step number and name
  • Characteristic description and type
  • Specification and tolerance
  • Evaluation method and sample plan
  • Control method and reaction plan
Step 4: Mark Special Characteristics

Flag any safety-critical (SC), critical (CC), or key product characteristics (KPC) appropriately.

Step 5: Submit for Approval

When complete, submit the Control Plan for review and approval.

Special Characteristics

Special characteristics require enhanced controls and are typically identified in the design FMEA.

SC - Safety Critical

Characteristics that could affect:

  • Safety of vehicle/product
  • Compliance with regulations
  • Critical function

Symbol: (Shield or S)

CC - Critical Characteristic

Characteristics that could affect:

  • Product fit or function
  • Customer satisfaction
  • Downstream operations

Symbol: (Diamond or C)

KPC - Key Product Char.

Characteristics that:

  • Require process capability
  • Need SPC monitoring
  • Are customer-designated

Symbol: (Pentagon or K)

Enhanced Controls: Special characteristics typically require 100% inspection, SPC monitoring, error-proofing, or other enhanced controls.

Reaction Plans

A Reaction Plan defines the immediate response when a characteristic is found out of specification.

Typical Reaction Plan Steps
  1. Stop Production: Halt the operation to prevent further nonconformances
  2. Segregate/Contain: Isolate suspect material back to last known good
  3. Notify: Alert supervisor, quality engineer, or designated personnel
  4. Document: Record the nonconformance (NCR if required)
  5. Investigate: Determine root cause
  6. Correct: Implement corrective action
  7. Verify: Confirm process is back in control before resuming
Tip: Reaction plans should be specific enough that any trained operator can follow them without needing interpretation.

Approval Workflow

Control Plan Status Flow
Draft

Being created

Submitted

For review

Under Review

Being evaluated

Approved

Ready for use

Revision Management
  • Control Plans are revision-controlled documents
  • Changes require re-approval before implementation
  • Previous revisions are marked as Superseded
  • Revision history is maintained for audit trail

Related Topics

PPAP Guide Audits Help Center