M
minudil2000
as quality engineere, could you please tell me whether statistical process control is useful or not?
Re: New Folks - Please Take a Minute and Introduce Yourself / Say Hello!
I have moved this post to this forum since it is a question regarding SPC.
I have moved this post to this forum since it is a question regarding SPC.
Usually it is. What is the specific situation you want to use it on?
F
fabricator
Re: Question regarding SPC-Is it useful?
I have found that as a tool to monitor high volume processes, yes, it is useful. The problem I have with SPC is that companies use it only for data collection and do nothing with the data itself. Often, SPC is a requirement from the customer (H-D is notorious for such requests) to meet Tier 1 responsibilities. I've also seen where the people doing the exercise have no understanding whatsoever of what they are doing. They do it because they were told to. IMHO, I think this is the norm and often a result of some overzealous manager who really knows nothing of the tool.
I have found that as a tool to monitor high volume processes, yes, it is useful. The problem I have with SPC is that companies use it only for data collection and do nothing with the data itself. Often, SPC is a requirement from the customer (H-D is notorious for such requests) to meet Tier 1 responsibilities. I've also seen where the people doing the exercise have no understanding whatsoever of what they are doing. They do it because they were told to. IMHO, I think this is the norm and often a result of some overzealous manager who really knows nothing of the tool.
M
martin elliott
There is no straight answer to this question without knowing what you are trying to achieve and under what circumstances where the question has arrisen.
Statistical Process Control is generally used "live" to control a process where a fit, form, function and loss function satisfactory distribution is needed or so that there is no need to subsequently inspect 100%.
It can also be used retrospectivley (as Ppk) to study final inspection batch release or even good inwards release with the usual reservations if mixed process batches are assessed.
There are a few circumstances where it might not be appropriate but if it is specified as a customer requirement, you are going to have to really understand and explain your objections.
In my opinion, you have to know what your aims are, and if SPC is the way you must fully commit to do it right and understand the theory.
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 http://www.hanford.gov/rl/?page=1144&parent=169
SPC is a great tool. Great tools imply two things: applicability and knowledge of use. There are great applications for SPC, and some that are not.
Too, there have to be people knowledgeable/trained in applying and interpreting SPC. Otherwise, one may create a worse situation than not having it in the first place.
Too, there have to be people knowledgeable/trained in applying and interpreting SPC. Otherwise, one may create a worse situation than not having it in the first place.
C
Coleman
We are a manufacturer of automated assembly and welding equipment and we find SPC a requirement to sell our equipment. Most of the companies we supply to set the CPK limits to runoff to. A very useful and convinsing tool.
J
John Nabors - 2009
I'm with Martin. I have seen SPC used diligently to drive process improvement with excellent results and I have also seen an SPC program result in nothing but an utter, tragic waste of time, effort, and perfectly innocent trees.
Regards -John
L
lee.moffatt
In order to fully understand your process, SPC is the way to go. It provides so much information provided you use the data to your benefit. There is no point collecting data because your customer says they want it, use the data (you have it anyway) and see how you can improve the process.
I find a lot of people fire fight, that is they address non conforming products one at a time, yet they could have hundreds of different parts coming through the manufacturing facility and would never find the time to understand and improve the performance of each part. However, looking at the processes used to manufacture each part, and grouping all the hundreds of parts into smaller processes, would enable the user, using SPC data, to address many parts within a process thus reducing the amount of time fire fighting.
Combating the worst performing processes will enable you to hit the majority of parts. But in order to do this, SPC is required to isolated the actual performance of each process.
Well that’s my first ‘post’ finished with, longer then I had envisaged but there you go!
Regards
I find a lot of people fire fight, that is they address non conforming products one at a time, yet they could have hundreds of different parts coming through the manufacturing facility and would never find the time to understand and improve the performance of each part. However, looking at the processes used to manufacture each part, and grouping all the hundreds of parts into smaller processes, would enable the user, using SPC data, to address many parts within a process thus reducing the amount of time fire fighting.
Combating the worst performing processes will enable you to hit the majority of parts. But in order to do this, SPC is required to isolated the actual performance of each process.
Well that’s my first ‘post’ finished with, longer then I had envisaged but there you go!
Regards
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