Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.
-
Upload
violet-clarke -
Category
Documents
-
view
224 -
download
6
Transcript of Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.
![Page 1: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/1.jpg)
Statistical Process Control
(SPC)
![Page 2: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/2.jpg)
What is Quality?
Fitness for use Conformance to the standard
![Page 3: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/3.jpg)
Quality ImprovementQuality improvement processes that involve statistical method;
1. Incoming Quality Control
2. Statistical Process Control
3. Outgoing Quality Control
![Page 4: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/4.jpg)
Incoming & Outgoing QCAcceptance Sampling
Lot by lot sampling plan for attributes Acceptance sampling by variables
![Page 5: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/5.jpg)
Lot by Lot Sampling Plan For Attributes
Types Of Sampling Plan Single Sampling Plan Double Sampling Plan Multiple Sampling Plan Sequential Sampling Plan
MIL STD 105E (ISO 2859)
![Page 6: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/6.jpg)
Acceptance Sampling By VariablesTypes Of Sampling Plan Plan that control the lot/process fraction
defective/nonconforming. Plan that control the lot/process parameter
MIL STD 414 Tables
![Page 7: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/7.jpg)
Statistical Pocess ControlChance and Assingable Cause Of Quality
Statistical basis for control chart Basic Principles Choice Of Control Limit Sample Size & Sampling Frequency Subgroups Analysis Of Patterns On Control Charts
![Page 8: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/8.jpg)
Control Charts For Variables (Univariate)
chartsRandx
xxx
chartssandx
![Page 9: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/9.jpg)
Statistical basis of the charts Development and use of the charts Interpretation of the charts The operating characteristics function Average Run Length (ARL) for the mean chart
chartsRandx
![Page 10: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/10.jpg)
Constuction & Operation of the charts
Control charts with variable sample size
chartssandx
![Page 11: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/11.jpg)
Control Charts For The AttributesControl Charts for the fraction non-conforming Development & Operation Variable sample size OC and ARLControl Charts for non-conformities Procedure with constant sample size Procedure with variable sample size OC and ARL
![Page 12: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/12.jpg)
Process Capability Analysis
Using histogram Using probality plots Process Capability Ratio (PCR)
Cp
PCR for an of center process Normality and PCR Confidence Interval & Test on PCR PCR using control charts
![Page 13: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/13.jpg)
Chance and Assingable Cause Of Quality 2 types of variation
1. Natural variability (chance)
2. Assignable causes
Process with assignable causes is said to be out of control.
![Page 14: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/14.jpg)
Basic Principles Control charts consist of
Center line Upper control limit Lower control limit
These limits is chosen so that when the process is in control, almost all the sample points will fall within the control limits.
![Page 15: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/15.jpg)
Choice Of Control Limit2 types of control limits Three-sigma limits.
The distance between CL and the UCL/LCL is 3 sigma.
The 0.001 probability limits chart (use 3.09 sigma). The distance between CL and the UCL/LCL is 3.09 sigma.
Note:-
3-sigma limits popular in US.
0.001 prob. limits popular in UK & Western Europe.
![Page 16: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/16.jpg)
Sample Size & Sampling Frequency Larger samples easier to detect.
Use large sample if the shift of interest is small and small sample if the shift of interest is large.
Frequent sampling is better.
Current practice favour small but more frequent samples.
![Page 17: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/17.jpg)
Analysis Of Patterns On Control Charts
Process out of control if
1. One or more points fall outside the control limits.
2. Points exhibit some non-random pattern.
3. Exhibit a cyclic behaviour.
![Page 18: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/18.jpg)
Pattern recognitionProcess is out of control if One point plots outside the control limit. Two out of three consecutive points plot beyond the
two sigma warning limits. Four out of five consecutive points plot at a distance
of the one sigma or beyond from the center line. Eight consecutive points plot on one side of the
center line.
![Page 19: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/19.jpg)
Control Charts For Variables (Univariate)
chartsRandx
xxx
chartssandx
![Page 20: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/20.jpg)
Control Charts For Attributes
•Control Chart For Fraction Nonconforming
•Control Chart For Nonconformities
![Page 21: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/21.jpg)
chartsx
RAxLCL
xCL
RAxUCL
2
2
![Page 22: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/22.jpg)
chartsR
RDLCL
RCL
RDUCL
3
4
![Page 23: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/23.jpg)
chartsS
24
4
24
4
c1c
S3SLCL
SCL
c1c
S3SUCL
![Page 24: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/24.jpg)
givenstd)chartsp(
ChartgminNonconforFraction
n
)p1(p3pLCL
pCLn
)p1(p3pUCL
![Page 25: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/25.jpg)
)givenstdno()chartsp(
ChartgminNonconforFraction
n
)p1(p3pLCL
pCLn
)p1(p3pUCL
![Page 26: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/26.jpg)
)givenstd()chartsc(
ChartControlitiesNonconform
c3cLCL
cCL
c3cUCL
![Page 27: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/27.jpg)
)givenstdno()chartsc(
ChartControlitiesNonconform
c3cLCL
cCL
c3cUCL
![Page 28: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/28.jpg)
Process CapabilityCalculated using
1. Process capability ratio (PCR), Cp.
2. Probability ;
*need to know process std deviation
)ˆ
xUSLz(P)
ˆxLSL
z(P
)USLx(P)LSLx(P
![Page 29: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/29.jpg)
Process standard deviation
Process standard deviation is calculated by
*use to estimate process capability
2d
Rˆ
![Page 30: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/30.jpg)
Process Capability Ratio (PCR), Cp
6
LSLUSLCp
And is estimated by
ˆ6
LSLUSLCp
![Page 31: Statistical Process Control (SPC). What is Quality? Fitness for use Conformance to the standard.](https://reader036.fdocuments.net/reader036/viewer/2022062803/56649f345503460f94c5185b/html5/thumbnails/31.jpg)
Interpretation
What does it mean if Cp < 1 Cp = 1 Cp > 1