I don't know if I am asking this question properly, but here goes, how do you define a preventive action item, especially in the manufacturing sector? Any examples would be appreciated.

Originally posted by dbulak:
I don't know if I am asking this question properly, but here goes, how do you define a preventive action item, especially in the manufacturing sector? Any examples would be appreciated.


Any action taken (and documented) to prevent a cause.

ASD...

A component in area "A' was contaminated. Cleaned it. (corrective action). Let's look at areas "B" and "C" for possible contributors to the contamination problem observed in area "A". (preventive action)
energy

A preventive action is an action put in place to prevent a non-compliance occurring in the first place.

FMEA is initiated to try to prevent a non-compliance, preventive action is taken to lessen the possibility of a nonconformance that has occurred, or not identified during FMEA.

Very general but there is a difference.

ASD...

We define the following four ares as our preventative action program:

1) Weekly sales call reports
2) Preventive maintenance on equipment
3) Enginnering change order system
4) Employee suggestion box

Carol X.

Preventive Action – action taken to eliminate, or reduce, the risk of a cause that if left untreated, may contribute to a nonconformance.

Cause and Effect Diagram – Man (Woman), Material, Machine (equipment), & Method

What is done in any (all) of these areas to prevent a negative effect?

Possible causes for nonconformance
Man – lack of training, insufficient education, poor physical & mental well-being, unmotivated or demotivated with the job
Material – Wrong material selection for application (design), environmental/thermal degradation, material obsolescence, damaged in handling or processing, not readily available
Machine – wrong machine (fixture/equipment) for the job, machine wear & tear, poor/long setups, cumbersome, at max capacity and can’t meet demand
Method – wrong method applied, no standardized method exists, wrong theory, too complex, not enough planning, physically difficult

FMEAs and Preventive Maintenance are classic examples of these as noted earlier. FMEAs are excellent in addressing all the traditional M’s.

Possible Preventive actions
Man – programs for physical and mental health. Eye programs for associates so those that need glasses to do their work get them! Environmental controls for comfortable working conditions, ergonomically design workstations, educational assistance and job training.

Material – Drawing specifications and design requirements with respect to material selection (how is the product used and what is the environment it subject to?). For example, virgin material versus regrind, plating and finishing, color.

Machine – proximity switches, photo or fluidic sensors and switches, safety guards & switches to protect people or will not cycle machine if not in place, fixtures to facilitate proper manufacturing or assembly, TPM

Method – Quality Culture and Program inclusive of, for example: Calibration, Document Control, Contract Review, Supplier Evaluation, Internal Auditing, Product Identification, Inspection & Test Status, Design Control (QFD, verification & validation, design review, DFM & DFA), Process Control (preventive maintenance, control planning, poka yoke, error proofing), Management Review, TPM.

Action taken to improve on trend indicators is generally considered preventive. Consider a pareto analysis that defines the leading cause of rejects; the action taken to address the leading cause would be considered preventive.

Dan,

Can you expand on your definition?

Regards,

Kevin

Kevin,

I'm thinking in terms of the rejects on a more global scale. My experience is with process based industries.

A large number of rejects from a particular customer for a particular part may define a "corrective" action ...there may have been an issue in translating a specific requirement to the specific process.

A large number of rejects for a number of customers for a variety of parts (but all the same process) could define a preventive action...there may be systemic issue with the process as it is defined internally.

Make a bit more sense?

Yes it does. Your response is leading to something I have been considering for a while now.

Trends of 4, 5, 6 or seven above the grand average but below the upper control limit or above the lower control limit suggest that the process has drifted (dependent on the organization’s protocol for adjustment), and is out of control. While the process may have not yield a defect, action is necessary to prevent the possibility of producing a defect.

My question for the group is this: are actions taken corrective or preventive? Remember, a defect (out of the specification limits) has not been produced.

Regards,

Kevin

Kevin,

I have to go with:

1: No nonconformance, no corrective action.

2: Process adjustment to prevent the possibility of a nonconformance equals a preventive action.

We have had heated discussions at work concerning trends and the 7 points above or below process average.

In this instance I argue that because perishable tooling is a major cost center we set-up the process to run up and down between 4 sigma. The Cp and Cpk's do not look great but we have the initial data to back up our decision and currently have 0 external PPM and an internal scrap rate of appx. 0.67% (over a 1 year period) in an industry that typically runs between 5% & 7%.

And tooling costs are optimized.

It is a fine line, and getting buy-in from quality, engineering, and manufacturing can be hard to overcome.

I guess it all comes down to having an effective APQP/Product Realization process.

A Long Winded ASD...

Al,

Great response! There is good value in the information you presented in your post for folks following this thread.

I also feel it is a Preventive Action. Same heated discussions here. Many argue that we are fixing an special cause such as tool wear, so it is corrective in nature. True enough I suppose and I'll concede that it is a corrective action to the process, but a preventive action to the production of a nonconforming product (out of tolerance).

Optimization is the key to your answer. You have nice balance between cost of tool replacement and cost of producing nonconforming product. Now if we can only optimize all the other processes........

Regards,

Kevin

Kevin,

Just my point of view, but I would not consider tool wear a special cause. (I don't believe you do either) I believe tool wear to be inherent to the process and controllable by many means. We use Mean Time Between Failure, or tool life studies.

ASD...

Al,

It is inherent, hence the 1.5 sigma shift for the Six Sigma folks. Still when viewing a SPC chart, the operator will detect a trend or shift based on the data. Something caused the shift or trend, perhaps a heavy hand, change of operator, or perhaps tool wear (dull turning tool). As you correctly point out, there are many means to prevent a worn tool, preventive and predictive maintenance being highly popular. While it is a common cause (it has not caused a 'flyer' outside of the limits), it is still assignable.

Common cause is attributable for the random up and down activity between the UCL and LCL. My question is this: if you have trends or shifts on the chart, displaying an out of control situation, do we attribute this to common or assignable (special) cause?

Regards,

Kevin

Kevin,

We are currently is a situation where we have integrated SPC in our process that makes the operator assign an inherent cause to that particular reason. If the inherent cause type is not available as a choice the operator can't continue processing until he/she or a group investigate the problem.

As I said before, we had a good APQP process and pretty well defined the inherent causes and removed the special causes. This is not to say that they don't occur, only that when they do, we have a robust response process available.

Now to answer your last question:

If I detected an uncommon pattern (i.e. other than the expected up & down between 4 sigma) on the chart I would suspect a special cause and investigate.

I wish I had a way to post a visualization, but we expect a basically straight line (45 degree) from the lower 2nd sigma to the top 2nd sigma. Any variation (such as a horizontal line over 4 or 5 readings) causes me concern and the notion that a special cause has been detected.

ASD...

Al,

Nice approach. I would be interested to hear how the operators like it.

I was thinking along these lines, in reference to Control Charts. Tell me what you think (and anyone else following this thread).

Corrective Action: action taken against the cause of a 'flyer', something outside of the control limits but perhaps within the Specification Limits (treatment of a Special Cause). The process is not in statistical control, unpredictable, and creating a nonconformance.

Preventive Action: action taken against the cause of a shift or trend within the control limits. The process is not in statistical control because of the shift or trend but no 'flyers' are present. The process has not produced a nonconformance. (How would we feel about flyers not beyond the specification limits? Still preventive?)

Continuous Improvement: the action taken against common causes of variation in the process, which is both stable and predictable (statistical control).

Regards,

Kevin

Kevin,

Our operators like it.

Some because it is an automated system and is less labor intensive.

Some because the good parts they make can be attributed to them. (i.e. review time)

I suspect some don't like it because their production, scrap, and performance is traceable. Time will tell.

As to your question:

Agree with all except corrective action (maybe semantics?). I would say we all need to define when a "formal" corrective action is required and when we just "tweak" the process. It is a fine line, but I would not issue a CA for a "flyer" that is in specification but out of "typical" control limits. I say this to you with the thought that there would be some type of action on any "flyer".

Also, I would not typically consider action on a "flyer" a continuous improvement.

100% agree with your definition of preventive action as it applies to control charts.

ASD...

[This message has been edited by Al Dyer (edited 23 May 2001).]

I am glad to hear that it is mostly positively received! I think the rest will come to appreciate it.

Good input. Anyone else out there willing to contribute to defining the three?

Regards,

Kevin

Thankyou for all your responses. It is a real thrill to have so many respond. But another question on the same subject. Would increasing the capacity of a machine be a preventive action? My thought is that the machine now has a larger capacity to produce product where new orders can be taken by sales. Sales will not be lost because of a limited capacity. Please, any ideas on this.

dbulak:

I would designate the action as a continuous improvement project.

ASD...

I agree with Al. Continuous Improvement. But I can see where you mind is taking you and have to agree that it can be twisted a bit to be preventive in nature. But my first impression is that it is a CI.

Keep in mind that the fact you are taking some kind of action is the most important factor and it is a step in the right direction.

Regards,

Kevin

"Preventive Actions are actually quite different from Corrective Actions. Every time you do a Corrective Action that responds to a specific incident then it is
and remains a Corrective Action, even if you decide to have a long term portion to the Corrective Action. Below are definitions of both Corrective and Preventive:

Corrective Action: Action taken to eliminate the cause of nonconformities
in order to prevent recurrence.

Preventive Action: Action taken to eliminate the causes of potential
nonconformities in order to prevent their occurrence.

Preventive Actions are typically generated through trend analysis of processes and product related issues. They can also come about from benchmarking and hypothetical situations that you have thought of but have
not yet happened.

Preventive Actions can also be demonstrated in applications like error proofing."

This quote has been brought to you by my registrar. We had a disagreement about this very thing so I asked for clarification.

I issue preventive actions when I see a trend in my NCR's or I see something that has the potential to be elevated to a more serious problem.

So that's my view.

Fire Girl,

Thanks for your contribution! Did your registrar mention anything about measuring effectiveness?

To the group: how do you measure something you prevent? How do you know the actions taken to prevent an occurrence are effective?

Regards,

Kevin

If the action is taken in response to a trend, then the measure would be a reduction in the trend. Outside of that, I must admit it becomes difficult.

Personally, I think the whole corrective/preventive argument has become rather muddied. To me, continuous improvement and preventive action are rather synonomous. As a company improves, trend indicators improve.

My gut feeling is that the next step in the quality arena will be to move PA from the CA clause and roll it into CI. Evolution is a wonderful thing!