When manufacturing it’s important to put controls in place to drive success, reduce costs and errors that could disrupt production, and avoid poor quality products being manufactured. There are several process improvement tools that can be used for this purpose, one being the process control pan.
What is a Process Control Plan?
It is an overview of all the controls in place along with the manufacturing process steps, usually in a manufacturing facility.
It takes the form of a document that outlines the activities to be taken throughout the production process (for example, performing inspections or checking that the process in question is performing within its required parameters). The ultimate goal is to provide a clear plan for production operators and quality inspectors to implement in order to manufacture the best possible quality products, including guidance on what to do if defects are found. Over time, if processes are improved, the control plan will be updated accordingly.
What’s a control?
A “control” can take several forms. Here are a few examples:
- 100% of plush toys go through a metal detection machine
- An automated visual inspection device checks if all components are placed correctly
- An operator uses a go/no go gauge to confirm a dimension
- An inspector at the end of the line scans a barcode to ensure it is correct
The format of that plan is relatively standard. I show ours in the video below. The AIAG suggests a slightly different template. But the key idea is to make the whole system visible and to remind people to focus on the more critical steps.
What are the steps to set up a Process Control Plan?
I asked one of our engineers who is particularly experienced in this regard, and he gave me a list of 11 steps. If you want to do this exercise ‘by the book’, this is a great guide.
1. Set up a multi-functional group
If someone from the quality department works on this alone, there are two issues:
- She might miss some important points, fail to assess criticality properly, etc.
- Sending a finished plan ‘over the wall’ is usually ineffective if the people who will need to apply it were not involved in designing that plan.
At the very least, involve manufacturing, a process engineer, and someone in close contact with the customer(s). If this product was developed in-house, bring in R&D. Purchasing should also be involved, at least when the discussion covers incoming QC on components.
2. Review and confirm the flow chart
Having a good idea of the process steps is a must. This information goes into the left columns of the document.
3. Review and confirm special characteristics
With a view of the whole and a good understanding of what the customer considers very important, the team can decide what steps are critical vs. very important vs. less important.
At this stage, a process FMEA can help a lot in pointing to high risks that need to be addressed. It is always a great input.
4. Review and confirm the control method
Based on the criticality of the steps, and on the risks perceived, the team decides what controls make sense.
The factory should spend resources where they are most needed. Show them how to control risks in an efficient manner, or they will be much less likely to sustain this approach over time.
5. Review the sampling method
This is tightly related to point 4. Checking a point on 100% of pieces might take much more effort than “1 in 10 parts”, for example.
6. Verify the effectiveness of the measurement system
Checking for the sake of checking is worthless. Are nonconforming parts really detected? Are some conforming parts put aside? This is an entire topic on its own, and it deserves some attention.
7. Confirm the person in charge
Who will be primarily responsible for the application of the process control plan, and its adaptation over time as new risks, new problems, and new customer requirements appear?
8. Confirm the escalation process
When a decision needs to be made by a higher level of management, who does the team go to?
9. Write control plan draft
Fill out the remaining columns. Train the people. Adapt the operators’ and inspectors’ work instructions. Observe, at least during a pilot run or a mass production batch.
10. Review and modification
It is a draft and needs to evolve! Certain controls might be overly burdensome, poorly specified, lacking clear criteria, and so on. Similarly, new issues might appear, calling for extra controls.
Every time, the process engineer needs to revise the corresponding work instructions and explain the changes to the operators.
11. Control the implementation in the mid-to long-run
Now, the plan needs to stick. No regression to the old way of doing things!
If there is sufficient buy-in in the team, if it has been translated into clear work instructions, if there are periodic audits, and if top management (and maybe a big customer) applies pressure to keep this in place, there are good chances the plan will be effective.
Are process control plans a part of your strategy? Do you use a similar list as I’m illustrating here, or do you have anything to add that isn’t included here?
Leave any points and questions you may have as a comment below, please.
Editor’s note: This post first appeared on QualityInspection.org here in 2019 and has been republished here with minor changes for Sofeast readers.
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