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Statistical Process Control Library

Steve Prevette

Deming Disciple
Staff member
Super Moderator
#1
I originally wrote these materials while assigned at the US Department of Energy Hanford (WA) site. These were all reviewed by the appropriate government representatives for unlimited public distribution.

After Fluor (my employer) transferred me from the Hanford Site to the Savannah River Site, Hanford took down the materials. I then was able to get the "Energy Facility Contractors Group" to host the materials, but a few years ago they revamped their website and removed them.

So, here they are. I've renamed the pdf files to indicate their subject matter. Much of this work was "borrowed" by the Institute for Nuclear Power Operations for a Good Practice on Performance Analysis (INPO 07-007). Several locations have used this work for their company trending procedure. You may also find hints on the internet if you google HNF-4931 which was the Hanford trending procedure number.

I currently work for Fluor Government Group Headquarters, developing an overall SPC based dashboard for FGG, and also have SPC based dashboards at Chalk River Site, Savannah River Site, Paducah KY, and Portsmouth OH. To my knowledge, no examples of these methods remain at Hanford.
 

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#6
Re: Statisical Process Control Library

Hi Mr. Steve

I had some doubts with regards to a SPC format and look forward for your suggestion and guidance on the same

The questions are as follows

A. SPC I have attached a SPC format with the records filled and have doubts
on why is the following terms required and how do they effect the process control(Please refer the spc chart attachment)
1) process width, 2)design center, 3)starting point ,4) Interval , 5)Index(K) , 6) Selecting no. of classes , 7) Shift of X'bar from D and 8) the Frequency and Cumulative Frequency required.

B. How do we choose the right sample and subgroup base for the SPC process on what factors
 

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Steve Prevette

Deming Disciple
Staff member
Super Moderator
#7
Re: Statisical Process Control Library

A. Looks like the file you attached came from some SPC package running in Excel, but I could not tell you what the terminology it uses means. It is not only doing SPC, but also throwing in a distribution histogram, so some of the terms (like selecting no. of classes) refers to the histogram and has nothing directly to do with SPC itself.

B. Generally I just use X individual Moving Range charts and avoid the subgroup issues altogether. Knowledge of the process and production batch sizes may point you in the direction of xbar-R. As far as how often to measure the process, that is balancing the cost of collection of the data with the costs of if you have a shift in the process after you collected the last data set, and how long you wait until collecting and analyzing the next batch.
 
#8
Re: Statisical Process Control Library

Hi Mr. Steve ,

Thanks for your suggestions i also want to know does time of delivery also matter, as the produced batch is dispatched every 2 days to the customer and even if we collect 5 pieces per hour for a 12 hours shift we dispatch almost production worth 2.5 shifts. The issue is when we collect the material every hour the results of SPC is available only at the end of the shift as the line going outside the control limit is detected after all the data is collected
 
#9
Re: Statisical Process Control Library

Steve,

In a previous thread (ca. 2008) you mentioned PowerPoint training files, later you also mentioned updating these. Is this something you have and could share? I am putting together some basic training sessions for SPC and am trying to gather as much information possible to help me. I am a horrible teacher!!! Thanks for the input.

Kerry D. Green
 
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