“A control plan is a critical document used in manufacturing to ensure product quality and consistency.” …according to Automotive Industry Action Group (AIAG). As stated in Control Charts article, “To measure is to know, and if we don’t measure our current performance… how can we improve it?” In this article, we will look at Control Plan – why they are so critical – and how they are applied in manufacturing processes.
What is Control Plan?
Control Plan is used to document the systems or inspections that are used to minimize variation. It reffers to Product and Process control.
They consist of a table-like format with the following sections: Process Number, Process Name, Machine/Tooling/Device, Characteristics (Number, Product, Process), Classification, Methods (Tolerance, Evaluation, Sample [Size, Frequency], Control Method) and Reaction Plan (Action, Responsible).
We will discuss each section later in the article!
When is Control Plan used?
Control Plan is used throughout the product lifecycle and can be categorized in the following phases:
- Prototype – specific checks required for developmental products.
- Pre-Launch – specific checks required for Off-Tool products.
- Production – specific checks required for Off-Process products.
What are the inputs to a Control Plans?
Let’s assum your business is not a start-up and manufacturing a product for the first time. Then the following inputs are critical when creating, developing and maintaining a Control Plan:
A common misconception with manufacturers who work with PPAP is that they see Control Plan as only applicable in Serial Production. They do not see “control” is required through the development phase. Control Plan is “Living Document” which is continuously reviewed and updated throughout the product life cycle.
When should I review and update a Control Plans?
We’ve covered the Control Plans Purpose and Scope. We now need to review when a Control Plans need to be reviewed and updated. The following list is by no means exhaustive. However, it gives a real-world assessment to when a Control Plan should be reviewed:
- Change in design – does the design change cause more or fewer checks?
- Change in process – does the process change improve or weaken the product quality?
- Internal product non-conformance found.
- External product non-conformance found (a customer complaint was received and a corrective action was implemented that was useful for application).
- The organization identified that a nonconforming product was shipped to the customer;
- Change to: measurement, logistics, supply source, production volume changes, or significant risk (FMEA)
- during compliance checks at a frequency determined by the risk analysis.
Generic vs Specific Control Plan?
In Automotive Manufacturing, it’s common for Tier N suppliers to use a “Generic” Control Plan over a Specific Control Plan. What does this mean?
- Generic Control Plans show the combined Process Controls based on the manufacturing processes at the supplier.
- Specific Control Plans detail by Product Part Number, the specific controls in place to ensure that the product meets the specifications and quality requirements.
Which control plan will be used depends on different factors. In example such as the arrangements with the customer and the complexity of the product families.
Control Plan Elements
Process Number/Name
The process number/name is used in correspondence to the Process Flow Diagram. For example:
10. Goods In.
15. QC Inspection.
20. Stores.
30. Smelting.
40. Casting.
Machine, Device, Jig, Tools for Manufacturing
This section shows what machines, i.e. cutting, pressing, folding etc. are used to manufacture the product.
Characteristics
The Characteristics section is split into 3 columns:
- Product or Process Characteristic number.
- Product Characteristic – measurable features against the specification.
- Process Characteristic – key characteristic process settings to control product quality.
Classification
This column is used to identify Special or Key Characteristics. They are categorized as:
- Safety.
- Regulatory.
- Pass-Through Characteristics.
- Other – specific to the manufacturer.
Methods
The Methods section used to identify:
- Specifications and Tolerances for the Product or Process.
- Methods of Evaluation (Measurement).
- Sample Size and Frequency i.e. 100%, 1:5, 1:10, First-Middle-Last.
- Control Methods used such as error or mistake proofing.
Reaction Plan
For each process number (stage), there must be a reaction plan when the product or process is found to be out of control and who has the action to resolve.
Note: Control Plans have their own manual and were separated from the APQP 2nd edition manual. We offer training in both APQP 3rd edition and the Control Plan 1st edition!
Tips for Control Plans
- “Walk” the process!
- Many Quality Engineers make the mistake of creating a Control Plan from their desk. They don’t check how the product is made.
- Review the PFMEA & Process Flow Diagram.
- Both documents are important when creating or updating a Control Plan.
- Review internal and external concerns or complaints.
- Using the Voice of the Customer and Operator can help prevent recurrence.
- Review Process and Design Changes with the Control Plans in mind.
- Never underestimate the size of a Design or Process change and its impact on the current controls to ensure quality.
Control Plans in IATF 16949:2016
In accordance with clause 8.5.1.1. the organization shall prepare control plans at the system, subsystem, component and/or material level for the relevant manufacturing locations and for all delivered products, as well as for processes that produce both bulk materials and parts (components).
Control Plans are created at the individual part number level, but may be created at the family level for common processes.
The organization shall have a control plan for the pre-series and serial production phases that indicates the connection and includes information from: the product risk analysis (if provided by the customer), the process flow diagram and the output from the manufacturing process risk analysis (such as FMEA).
If required by the customer, the organization shall provide measurement and conformance data obtained during the performance of the controls resulting from the pre-series and serial production control plan.
The control plan must include:
- control activities including verification of setting data
- approval of first and last item, if applicable
- methods for monitoring/supervision of special characteristics
- information required by the customer, if applicable, e.g. product audit
- a specific response plan in the event of detection of non-conforming product, statistically unstable process or failure to achieve statistical capability.
Listen to our podcast
Let’s sum up!
The Control Plan, according to AIAG (Automotive Industry Action Group) guidelines, is a key document in the quality management system in the automotive industry. Its purpose is to ensure that production processes are conducted in a controlled and repeatable manner, which translates into compliance of products with customer requirements and quality standards such as IATF 16949.
An effective Control Plans should be a living document, updated in response to changes in the production process, quality problems and improvement activities. A well-developed Control Plan not only minimizes the risk of defects, but also supports process stability and compliance with customer requirements, which is key to ensuring competitiveness and reliability of supplies.
Hope you found the article interesting.
Thank you for your presence.
For people who want to know more:
Control Plan, 1st edition, 2024
IATF 16949: 2016 Requirements for quality management systems in serial production and the production of spare parts in the automotive industry, 1st edition, 2016
All content on the qualitywise.pl website is a private interpretation of publicly available information. Any convergence of the described situations with people, organizations, companies is accidental. The content presented on the website qualitywise.pl does not represent the views of any companies or institutions.