The Process Flow Diagram—also referred to as a process flow chart—provides a structured visual representation of every step involved in manufacturing a part, from receipt of raw materials through to final shipment.
Its purpose is to clearly document how the part is made, ensuring that all production and support activities are understood, defined, and aligned across the organisation.
What the Process Flow Diagram shows
A compliant Process Flow Diagram must include all steps that affect the part, including:
- Incoming material receipt and verification
- Manufacturing and assembly operations
- Sub-assembly and rework loops
- Inspection, measurement, and testing activities
- Handling, storage, and transportation steps
- Packaging and shipment
In addition to standard production steps, the diagram must also clearly show the flow of:
- Non-conforming material (rejects)
- Rework or salvage operations
- Scrap or waste disposal
This visibility ensures that nonconforming product is properly controlled and prevented from reaching the customer.
Alignment with PFMEA and Control Plan
The Process Flow Diagram forms the foundation for both the PFMEA and the Control Plan. As such, it is essential that:
- Every step in the Process Flow Diagram appears in the PFMEA
- Every control identified in the PFMEA is reflected in the Control Plan
- All three documents are fully aligned and consistent
Any mismatch between these documents is a common cause of PPAP rejection.
Why it matters in PPAP
The Process Flow Diagram:
- Provides a shared understanding of the manufacturing process
- Supports effective risk identification in the PFMEA
- Ensures appropriate controls are defined and applied
- Helps auditors and customers quickly understand process logic and product flow
Key considerations
- The diagram should reflect the actual production process, not an idealised version
- It must be updated whenever the process changes
- All external or outsourced processes should be included
- Revision control must match related PPAP documents
A clear and accurate Process Flow Diagram is essential for building a robust PPAP submission and demonstrating effective process control.