Is SPC (Statistical Process Control) useful?

It's absolutely useful,nevertheless as I know most companies don't implement spc really,they use spc in order to handle customer's audits or requirements.

Steve Prevette said:

Generally I have found SPC, and the way of thinking that goes with it, to be useful to most anything. The idea is we are trying to separate the random noise that occurs on a day to day basis (common cause variation) from a signal that something is changing (special cause variation). SPC (in my opinion) is the easiest statistical tool that allows that separation to be made reliably. You may wish to see some of the materials on the Hanford website about SPC at https://www.hanford.gov/rl/?page=1144&parent=169

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Good answer, and a helpful link. It might help for the OP to recast the question from "Is SPC useful?" to "Is understanding the variation in my processes useful?" The answer becomes a bit more obvious, I think.

fireonce said:

It's absolutely useful,nevertheless as I know most companies don't implement spc really,they use spc in order to handle customer's audits or requirements.

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This is true. We have been doing SPC for years and are just now starting to use it to improve processes. In order to do this the operators must understand thew concept. Most think it is just to collect data, which has been the case in the past, so they don't even use the real-time charting in our software. One customer we have is pushing for improvement using SPC which has given us the drive we need to possibly implement Real SPC! Only time will tell if it works out.

When properly applied, SPC provides you a gage by which you can tell if your process is yielding the results you expect - or needs an adjustment. You can live without it - just like you can live without a gas gage or speedometer in your car. But, why would you want to? What harm is there in knowing what is going on with your process??

If we remove ineffective application issues, SPC is without question useful.

In my opinion, the greatest benefit from SPC is to predict future behavior of a process, not to look at where the process was. SPC should be first and foremost used as a prediction tool. This is where the savings and benefits really are with SPC.

My opinion.

Regards,

Dirk

SPC is great for quantitative data (when operators measure and say good or bad), but in case of alternative data with small ppm and 100% control, SPC waste time (when even 2 defects cause point out of limits). Am I right?

russiankate said:

SPC is great for quantitative data (when operators measure and say good or bad), but in case of alternative data with small ppm and 100% control, SPC waste time (when even 2 defects cause point out of limits). Am I right?

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Yes, in cases where a process is highly capable and has a very good history, a small number of defects close together will cause a signal. That in itself is not necessarily a waste of time. The waste of time comes in as to how the workers and managers respond to the signal.

I also need to point out that with a highly capable process, the emergence of a small number of defects could be very important, and heading off an emerging problem early has many benefits. If you catch the problem at its onset, it is much easier to correct than if you let it run long enough to have a significant impact on your production. And if it runs long enough, it becomes ingrained in the process and is much harder to fix.

Steve Prevette said:

Generally I have found SPC, and the way of thinking that goes with it, to be useful to most anything. The idea is we are trying to separate the random noise that occurs on a day to day basis (common cause variation) from a signal that something is changing (special cause variation). SPC (in my opinion) is the easiest statistical tool that allows that separation to be made reliably. You may wish to see some of the materials on the Hanford website about SPC at https://www.hanford.gov/rl/?page=1144&parent=169

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Steve, You provided excellent reference information about SPC and other similar/companion areas. I have enjoyed your contributions on various ASQ forums as well. Have a great day. Feel free to contact me with a PM or e-mail!

My company builds high mix low volume products. We used to collect data but it was not used and was a wasts of time. We started to collect "incidents" as they happen daily but we are not sure this will help either. Does anyone have any thoughts on using a simple SPC for high mix low volume manufacturing?

Steve Prevette said:

Yes, in cases where a process is highly capable and has a very good history, a small number of defects close together will cause a signal. That in itself is not necessarily a waste of time. The waste of time comes in as to how the workers and managers respond to the signal.

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Steve:

I am a bit confused on your answer. Do you mean to say that a small number of out-of-control product close together will cause a signal rather than "defects".