Integrating Flowchart, PFMEA, Control Plan and Work Instructions

What do we mean by integrating documentation for a correct Quality Management?

When we talk about integrating documentation for proper quality management we mean that all key documents (flowchart, PFMEA, Control Plan and Work Instructions) are aligned and complement each other. This implies:

• Consistency, coherence and traceability: in each document the same information must be shown consistently, i.e. for example in the flowchart the same process steps must be shown as are shown in the PFMEA and Control Plan. For example, if step two of the flowchart is “Quality inspection of raw material”, this should be shown in the PFMEA, Control Plan and Work Instruction as Step 2: “Quality inspection of raw material”.
• Identify and mitigate risks: Following the steps shown in the flow chart, the PFMEA detects the possible failure modes that can appear at each point of the process. Through the control plan, the measures to be taken to mitigate the detected risks are detailed and this is put into practice with the Work Instructions.
• Operational efficiency: By integrating all these documents, duplication of efforts is avoided and it is ensured that all employees are working with the same information, improving the efficiency and effectiveness of operations.
• Regulatory Compliance: To ensure that all process areas comply with relevant regulations and quality standards.

Importance of the Process Flow Diagram (Flowchart)

The process flow diagram is a fundamental tool for proper quality management for the following reasons:

• It allows a clear visualization of the process: A flowchart provides a visual representation of the process, facilitating the understanding of each stage and its sequence. This tool ensures that all team members understand how the process unfolds and where the critical points are where failures or errors may occur, allowing quality teams to focus on the areas that need more attention and control.
• Reflects continuous improvement: The flowchart is ultimately a living document that must be continually updated to reflect improvements and changes in the process. By documenting the process in this way, organizations can monitor and evaluate the effectiveness of implemented improvements, promoting a culture of continuous improvement.
• Facilitates communication: Flowcharts are the standard way of conveying information about a process within an organization, and allow both training new employees in the processes, and communicating and making the steps of the process understandable to anyone such as a customer.
• It is the basis of the PFMEA, as it allows to identify and evaluate the different failure modes that can occur in each step of the process.
• Regulatory compliance: In many industries, maintaining an accurate and up-to-date flowchart is essential for the quality of the process.
• It allows to identify areas of process optimization: By visually analyzing the process through a flowchart, it is possible to identify waste (see How to identify the 7 Wastes of Lean Manufacturing), bottlenecks (see Theory of Constraints - TOC - Introduction), inefficiencies, etc. This allows organizations to optimize their processes, reducing costs and improving operational efficiency.

What is PFMEA and Why is it Crucial?

PFMEA (Process Failure Mode and Effects Analysis) is a risk analysis through a structured proactive methodology that allows us to identify potential failure modes of a production process before they reach the final customer. After identifying them, we have information that allows us to make decisions when it comes to allocating resources to prevent problems or mitigate their effects.

The PFMEA plays a crucial role in preventing failures in the production process by proactively identifying them and implementing corrective and preventive actions to improve the quality and reliability of the process.

The Control Plan

The control plan is a document that details the methods and procedures to monitor and control manufacturing processes, ensuring product quality. It helps prevent defects, ensure regulatory compliance and optimize process efficiency.

The control plan uses the flow chart to structure the process steps and the PFMEA to identify and prioritize risks, ensuring that effective controls are implemented at identified critical points.

Work Instructions

Work Instructions are detailed documents that describe step-by-step how to perform a specific task within a process. They are important because they ensure consistency and quality of the work performed, minimizing errors and variability.

Work Instructions incorporate the controls and preventive measures of the control plan, detailing how these controls should be executed at each stage of the process.

Integration Structure: Step by Step

For a better understanding of how the integration of all documents should be done correctly, let's do it through an example.

In the factory Manufacturas Marmetic a product is manufactured through the following process:

1. Reception of raw material for plastic injection.
2. Plastic injection process
3. Final assembly with screwing of two components (previously purchased and received) to the injected part in step 2.
4. Final product storage
5. Final product shipment

Creation of the Process Flow Diagram

Below we could see the flow chart of this process, from the reception of the raw material and its components, to the expedition of the final product to the customer.

Development of the PFMEA

Based on the Flow Diagram we would take the steps that are related to the production process, these would be:

1. Reception of raw material, component 1 and component 2.

3. Preparation and drying of raw material

4. Injection

6. Assembly of injected part + component 1 + component 2.

7. Final packaging of finished product

A logistics FMEA should also be done which we will not go into in this post but should cover:

1. Receipt of raw material, component 1 and component 2: all failure modes related to transportation of components, raw material.

2. Warehouse

5. WIP warehouse

8. Final Product Warehouse

9. Shipment to final customer

As mentioned, we will focus on the PFMEA. After assembling a multidisciplinary work team, from each of the steps described above, the potential failure modes should be identified.

Let's take as an example step 6, assembly of injected part + component 1 + component 2. In order to elaborate a PFMEA as accurate as possible, this process should be broken down into its operations and then categorize the failure modes of each one. This process consists of placing components 1 and 2 on the injected part, one on the right side and the other on the left side (Component assembly) to later join component 1 with 3 screws and component 2 with another 3 screws to the injected part (Component bolting).

Then for step 6.1 - Assembly of Component 1 we would have the following failure modes:

• Incorrect placement of component 1: this may cause noises or the part to be non-functional.
• Absence of component 1: this will cause the part to lose its functionality.
• Hits and scratches: the component may rub affecting the aesthetic appearance of the final assembly.

In the FMEA document it would be shown as follows:

For step 6.2 - Assembly of Component 2 we would have the following failure modes:

• Incorrect placement of component 2: this may cause noises or the part to be non-functional.
• Absence of component 2: this will cause the part to lose its functionality.
• Hits and scratches: the component may rub affecting the aesthetic appearance of the final assembly.

In the FMEA document it would be shown as follows:

For step 6.3 - Component 1 screwing we would have these failure modes:

• Use of incorrect screws: this can result in not being able to screw or in the case that it can, having an incorrect diameter or length can cause damage to the material on which the joint is made or the final fastening to be inadequate.
• Insufficient torque: This can cause the bolt to loosen over time and compromise the stability of the assembly.
• Excessive tightening torque: Applying too much torque can cause damage to the material on which the assembly is made and even to the bolt (if it is more fragile) and may cause it to break.
• Absence of screw: a missing bolt in the assembly will most likely compromise the stability of the assembly.
• Fallen screw inside the assembly: If a screw falls inside the assembly it will probably cause noises in the final assembled product.
• Screw misaligned: If the screw is not properly aligned with the hole it can result in uneven tightening and potential damage to the threads.
• Incorrectly positioned screw: If the bolt is placed in the wrong hole it could compromise the overall assembly and cause structural problems. For example, imagine putting a screw where there should be a rivet.
• Screw with defects
• Scratches and impactacts during screwing operation

In the FMEA document it would be shown as follows:

For step 6.4 - Component 2 screwing we would have these failure modes:

• Use of incorrect screws: this can result in not being able to screw or in the case that it can, having an incorrect diameter or length can cause damage to the material on which the joint is made or the final fastening to be inadequate.
• Insufficient torque: This can cause the bolt to loosen over time and compromise the stability of the assembly.
• Excessive tightening torque: Applying too much torque can cause damage to the material on which the assembly is made and even to the bolt (if it is more fragile) and may cause it to break.
• Absence of screw: a missing bolt in the assembly will most likely compromise the stability of the assembly.
• Fallen screw inside the assembly: If a screw falls inside the assembly it will probably cause noises in the final assembled product.
• Screw misaligned: If the screw is not properly aligned with the hole it can result in uneven tightening and potential damage to the threads.
• Incorrectly positioned screw: If the bolt is placed in the wrong hole it could compromise the overall assembly and cause structural problems. For example, imagine putting a screw where there should be a rivet.
• Screw with defects
• Scratches and impactacts during screwing operation

In the FMEA document it would be shown as follows:

Establishment of the Control Plan

The Control Plan is an extension of the PFMEA that details the critical characteristics of the process and the control measures necessary to guarantee the quality of the product. Based on the PFMEA related for example to the bolting process of component 1, we would have the following Control Plan:

Writing Work Instructions

When writing the standard work instructions, for example if we look at point 7 of the control plan, the standard work of the operator must take into account the specification of placing the screw in the correct hole. For this purpose, it should be specified in these instructions with the help of descriptive images where the screw should be placed and also where it should NOT be placed to serve as a guide for the operator.

This same exercise should be done for all the points of the control plan so that everything is covered in the actual operation of the process.

Continuous Review and Update

Continuous updating of documents such as the Flowchart, PFMEA, Control Plan and Work Instructions is necessary as processes evolve, whether due to continuous improvements, design changes or production adjustments. An effective update could be done in the following way:

1. Establish a periodic review process: It is important to set a periodic document review schedule, involving a multidisciplinary team (quality, engineering, production, logistics, prevention).
2. Implement a document management system that records all changes and revisions to documents, providing a clear history of the modifications made.
3. Real-time integration of changes: changes in the process, such as adjustments to the PFMEA or Control Plan, should be reflected as soon as possible in the related documents. Real-time integration can be achieved by digitizing processes and using software tools that automatically synchronize updates across documents. This ensures that there are no discrepancies between what happens on the production line and what is documented.