# Re:Factors for Control Chart.

Six Sigma – iSixSigma Forums Old Forums General Re:Factors for Control Chart.

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• #48103

depp
Participant

Dear Dr. Scot and all. Thank you for your attention.
I post new message with details.
I’m working in glove factory. For 3 days, we run new line. Every single day, we use different parameters. For example, 1st day, the latex tank temperature is 160oC and the second day is 200oC. We doing that to get the optimum output. We assume, if the defect of the output is less, means the parameters for that day is appropiate for running line.
Our machine is running 24 hours. For each day, we take 125 samples from every 35,000 for 44 time.
I want to plot control chart for variables with data of defected glove. So, what i have understtod, the subgroup is 44 right because one day I take samples for 44 times.
My problem is, I cannot plot the chart because I cannot find the factors for control limits for x-chart, s-chart and r-chart for n=44. I mean the value of A2,A3,B3,B4,D3 and D4.All my reference book only stated n=1 until n=25. So how can I plot the control chart?
So am I wrong at any stage? please advice.
TQ so much. I’m not English. Sorry for not so good in writting.

0
#161076

drquality
Participant

Depp,
Can you post the data for each INDIVIDUAL value measured here? For the moment, forget about subgroup size, that is yet to be determined.
Also, why are you looking at temperature only? There are likely other factors that influence the quality of the gloves.
But for now, try and post the temperatures, and the quality measure you are using to “judge” the quality of the gloves. Preferably, the measure would be a variable measure (e.g., weight, thickness, strength, etc.) rather than an attribute measure (e.g., “good or bad” which sounds like what you have now). But either way, we can learn something from what you have.
I am happy to help if you wish.
Dr. Scott

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#161077

depp
Participant

Dear Dr. Scott.
For your info, we already fix the temperature for latex tank for each day. Means it is constant. Day 1,T=32oC, Day 2,T=42oC and Day 3, T=52oC.
T=Temperature.
The quality of measure I’m using to “judge” the quality of the gloves is counting the defect of the glove for every 125 sample from every 35,000 for 44 x.
I will post the data on next message.

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#161092

walden
Participant

deep,
If I understand your message correctly, 44 is the number of subgroups not the number of samples in each subgroup. So you would not look up n=44 to find the constants. It also appears that you’re charting the number of defects in your samples. If this is correct, you would not use a variables control charts (Xbar & R or s) so the values of A2, A3, B3, etc. don’t apply.
You should be using a c-chart to chart the number of defects. Good luck.
Chris

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#161108

depp
Participant

Dear Dr. Scott,
What I understood, to study capability process, I have to know the control chart for variable.That why I want to plot Xbar and R chart.
Below, I give result for Day 1 only.For Day 2 and Day 3, the result are similar but have bigger defect.
Day 1
QA lot                    Sample                  Defect
1                                125                       3
2                                125                       3
3                                125                       3
4                                125                       3
5                                125                       3
6                                125                       3
7                                125                       3
8                                125                      3
9                                125                       4
10                              125                       3
11                              125                       3
12                              125                       4
13                              125                        3
14                              125                       4
15                              125                       4
16                              125                      3
17                              125                      3
18                              125                      3
19                              125                     4
20                              125                     3
21                              125                      3
22                              125                     5
23                              125                      3
24                              125                     4
25                              125                     3
26                              125                     3
27                              125                     4
28                              125                     3
29                              125                    4
30                              125                    4
31                              125                   3
32                              125                   5
33                              125                   3
34                              125                    3
35                              125                    4
36                              125                    3
37                              125                    3
38                              125                    3
39                              125                    4
40                              125                    3
41                               125                   4
42                               125                    3
43                               125                     5
44                                125                    4
Do you have any idea how to process the day for study the process of capability ?
Tq for your attention.

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#161109

depp
Participant

Dear Chris,
Can I study the process of capability through C-chart?
TQ for your attention.

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#161113

Ahsan
Participant

yes c’ chart may tell us about your process direction over time and will also your process movement on UBL and LBL

thanks
Ahsan

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#161137

Erik L
Participant