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10-1 Quality Control CHAPTER 10 (Quality Control) McGraw-Hill/Irwin Operations Management, Eighth Edition, by William J. Stevenson
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chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

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Page 1: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-1 Quality Control

CHAPTER

10

ก������������(Quality Control)

McGraw-Hill/Irwin

Operations Management, Eighth Edition, by William J. Stevenson

Page 2: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-2 Quality Control

���������� �ก��!�"ก#$�������������� �ก��!�"ก#$����

������������ ก ������ก�����ก �

ก ���������� ���������

�������ก���������ก ����������������ก����� ������ �ก �����

�!" #$%ก�����&������'�����ก�����ก �

�() ��� ����*+��, �() ��� � ก*+��,

�%!&'( 10.1

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10-3 Quality Control

ก�����,- �ก�����,- � ( (InspectionInspection))

• ���,- � "3��4�� / �� 67��38$• &'(38$ / 9�:( 3� • ���,- �,�ก-��$ก;�� (Centralized) vs. ���,- �&'(

8$4���$ (On-site)

Inputsก�����ก �����%� (Transformation)

Outputs

������������ ก ������ก�����ก � ������������

�%!&'( 10.2

Page 4: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-4 Quality Control

�4$&�$ก�����,- ��4$&�$ก�����,- � ( (Inspection CostsInspection Costs))�)

����

���

�) ���ก ��������*+����*+��,

���*�ก �����������*�� กก �������������+�� �

���*����*�(���,

�%!&'( 10.3

Page 5: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-5 Quality Control

,�C38$D$ก�"��$ก��&'(���,"���,- �,�C38$D$ก�"��$ก��&'(���,"���,- �

• �#�E�CF�7;"�FG$-��$&'(H:G ��9�:( $I�3!D�4D$ก��J;F�

• J;F�#KL&'(-I�9�M,7;4�

• ก� $ก�"��$ก��DC�&'(�'�4$&�$-%�

• ก� $ก�"��$ก��DC�&'(3��-����E64 $ก;#�3C4

• ก� $ก�"��$ก��8�4�DC� (Covering process)

Page 6: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-6 Quality Control

����� �����,*+�����+ก ������������� �����,*+�����+ก ��������

Type ofbusiness

Inspectionpoints

Characteristics

Fast Food CashierCounter areaEating areaBuildingKitchen

AccuracyAppearance, productivityCleanlinessAppearanceHealth regulations

Hotel/motel Parking lotAccountingBuildingMain desk

Safe, well lightedAccuracy, timelinessAppearance, safetyWaiting times

Supermarket CashiersDeliveries

Accuracy, courtesyQuality, quantity

�����&'( 10.1

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10-7 Quality Control

• ก��������ก���ก����� ������������� (Statistical Process Control): ก��!�"9�F$J;J;J;F�,�กก�"��$ก��8$P(��C4�69&�$F�&��-EF�F

• ��%������&��'�&� (Quality of Conformance):J;F�#KL8�: ก����Fก��&'(- C�;4 �ก#��4 �%;,I�9��"(Specifications) &'(กI�8$C3�4

Page 8: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-8 Quality Control

J#�������J#������� ( (Control ChartControl Chart))

• J#������� (Control Chart)

• .����/�0�� : 9�:( &'(,"9TU�C%J;J;F�,�กก�"��$ก�����9!V$ก��ก�",�6�#�7��-���8�: 3�� (Random process)

• 9!V$J#�&'(7-C����-EF�F�����&'(�#C3C4,�กก�"��$ก��J;F� HP(����-EF�F98;��$'G,"9�'6�ก#$���9�;�&'(9กFC (Time-series)

• �"C#��������$7;";��� (Upper and lower control limits) ���� กEP�����&'(6 ��#�3C4� ����-EF�F&'(\Pก]�

Page 9: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-9 Quality Control

J#�������J#������� ( (Control ChartControl Chart))

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

UCL

LCL

����� ���

� �:�+��

��ก������ ก ��*+������

��*+���%��ก�����ก �;��� ��

����,�ก��

����,�ก��

�%!&'( 10.4

Page 10: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-10 Quality Control

ก ������ก�����ก �,����*����* ��$��� (Statistical Process Control)

• ,�C-I��#_� �8;#กก��������ก�"��$ก��C4�69&�$F�&��-EF�F (SPC) กM�: -����E&'(,"7$�D,��� ก��ก�",�6�#�� ����-EF�F&'(�#C,�กJ;J;F�� �ก�"��$ก��9!V$3!���a������F 8�: &'(9�'6ก��� ก��ก�",�6�#�7��-��� (Random process) 9�:( &'(,"7$�D,��� J;J;F�D$ $���กM3C4,�กก�"��$ก��7��-���98�:( $ก#$

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10-11 Quality Control

ก ������ก�����ก �,����*����* ��$��� (Statistical Process Control)

• �#G$� $D$ก��&I�ก��������ก�"��$ก��• กI�8$C���&'(,"������• �#C���&'(,"������• &I�ก��9!�'6�9&'6����&'(�#C3C4ก#��"C#������������• !�"9�F$-E�$ก��L• 7ก43��4 JFC�;�C • �FC���J;8;#�,�ก3C4&I�ก��7ก43�7;4�

Page 12: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-12 Quality Control

• ����7!�!��$ (Variations)

• ����12�2��1����/� (Random variation): ����7!�!��$���a������F&'(9กFC,�กก�"��$ก��J;F�HP(��'-�98����,�ก!c,,#69;Mก���ก��6

• ����12�2���67���.8�9�� (Assignable variation): !c,,#6&'(&I�D849กFC����7!�!��$98;��$'G-����E&'(,"���,��3C4

ก ������ก�����ก �,����*����* ��$��� (Statistical Process Control)

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10-13 Quality Control

ก��ก�",�6�#�� �ก;����#� 6���ก��ก�",�6�#�� �ก;����#� 6��� ( (Sampling DistributionSampling Distribution))

ก �ก��� �������ก������� � (Sampling Distribution)

ก �ก��� ����*+��*��������ก�����ก � (Process Distribution)

� �:�+�� (Mean)

�%!&'( 10.5

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10-14 Quality Control

ก��ก�",�6�#�7��!ก�Fก��ก�",�6�#�7��!ก�F ( (Normal DistributionNormal Distribution))

� �:�+��−3σ−3σ−3σ−3σ −2σ−2σ−2σ−2σ +2σ+2σ+2σ+2σ +3σ+3σ+3σ+3σ

95.44%

99.74%

σ = σ = σ = σ = �����+������� ��H �

�%!&'( 10.6

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10-15 Quality Control

�"C#��������"C#������� ( (Control LimitsControl Limits))

Mean

��,���������(Lowercontrollimit)

��,�������� �(Uppercontrollimit)

ก �ก��� �������ก������� � (Sampling Distribution)

ก �ก��� ����*+��*��������ก�����ก � (Process Distribution)

�%!&'( 10.7

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10-16 Quality Control

����JFC�;�C� �9&�$F�����JFC�;�C� �9&�$F� SPCSPC

• Type I error• ก��-��!���ก�"��$ก��&'(�#C 6%�$#G$3��3C4 6%�D$ก��

������&#G��&'(����,�F�7;4� ก�"��$ก��$#G$6#� 6%�D$ก��������

• Type II error• ก��-��!���ก�"��$ก��&'(�#C 6%�$#G$3C4 6%�D$ก��

������&#G��&'(����,�F�7;4� ก�"��$ก��$#G$3��3C4 6%�D$ก��������

Page 17: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-17 Quality Control

Type I ErrorType I Error

Mean

LCL UCL

αααα/2 αααα/2

α = α = α = α = Probability of Type I error

�%!&'( 10.8

Page 18: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-18 Quality Control

���&'(�#C3C4,�กก;����#� 6������&'(�#C3C4,�กก;����#� 6���

����� ���

UCL

LCL

1 2 3 4

�%!&'( 10.9

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10-19 Quality Control

J#�������-I�8�#��#�7!������J#�������-I�8�#��#�7!������

• J#����������9n;'(6 (Mean control charts)• D�4-I�8�#�9TU�C%ก��ก�",�6�#�� �ก�"��$ก����� 6%�� ��

���ก;��8�: 3�� • 9��9�'6กJ#�������$'G��� X bar charts

• J#������������ �ก��ก�",�6�#� (Range control charts)• D�4-I�8�#�9TU�C%ก��ก�",�6�#�� �ก�"��$ก����� 6%�D$

���6&'(กI�8$C8�: 3��• 9��9�'6กJ#�������$'G��� R charts

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10-20 Quality Control

J#����������9n;'(67;"����ก��ก�",�6�#�J#����������9n;'(67;"����ก��ก�",�6�#�

UCL

LCL

UCL

LCL

R-chart

x-Chart #�ก ����+�������

(� �:�+�����ก�����ก ���(��+ก ����+��������#����'(�)ก �ก��� �������

ก������� �

�%!&'( 10.10A

��#�ก ����+�������

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10-21 Quality Control

x-Chart

UCL

UCL

LCL

LCL

R-chart

Figure 10.10B

(�� �����������ก�����ก ���(��+ก ����+��������#����'(�)

ก �ก��� �������ก������� �

��#�ก ����+��������#����'(�

#�ก ����+��������#����'(�

J#����������9n;'(67;"����ก��ก�",�6�#�J#����������9n;'(67;"����ก��ก�",�6�#�

See Page 457

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10-22 Quality Control

J#������� :($�J#������� :($�

• p-Chart r J#�������&'(D�4-I�8�#�9TU�C%-#C-��$� �� �9-'6 (Defect) D$ก�"��$ก��

• c-Chart - J#�������&'(D�4-I�8�#�9TU�C%,I�$�$� ��4 �ก��� � (Defect) D$J;F�#KL8$P(��

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10-23 Quality Control

ก��D�4ก��D�4 p p--ChartsCharts

• 98��"-�D$ก�'&'(-����E76กก;����#� 6��� ก9!V$ 2 !�"9& 9��$• C'8�: 9-'6 (Good or bad)• J��$8�: 3��J��$ (Pass or fail)• D�4ก��3C48�: D�4ก��3��3C4 (Operate or dontt operate)

• 98��"-�D$ก�'&'(�4 �%;&'(-#�9ก�!�"ก �3!C4�6�4 �%;HGI��8;�6��4 �%;

����� 10.3

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10-24 Quality Control

ก��D�4ก��D�4 c c--ChartsCharts

• 98��"-�&'(D�4D$ก�'&'(�4 �ก��� � (Defect) D$J;F�#KL�FG$8$P(�� -����E$#�3C4 9��$• � 6�%C�'C � 6E; ก � 6��� • � 67�ก&'(�#C3C49!V$�"6"&��• � 6�4��8�: � 6n'ก��CD$�:G$&'(8$P(�� • ,I�$�$7��&'9�'68�: -F(�9,: !$�� !�F����• ,I�$�$ก��u&� ก���4 �9�'6$ 8�: ����;4�98;��� 8$P(�

����9�;�

����� 10.3

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10-25 Quality Control

ก��D�4J#�������ก��D�4J#�������

• ,�C38$D$ก�"��$ก�����,"D�4J#�������

• �$�C� �ก;����#� 6���&'(-������,"9!V$9&��3�

• J#�������!�"9&38$&'(98��"-�&'(,"D�4

• J#�������9n;'(6, J#������������ �ก��ก�",�6�#�

• p-chart, c-chart

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10-26 Quality Control

Run TestsRun Tests

• Run test r �: ก��&C- �����4 �%;&'(3C4��,�กก�"��$ก��7��-���8�: 3��

• ก��&'(9�����,���%!7�� (Pattern) � ���C�4 �%; 8��6������� �4 �%;98;��$#G$3��3C49กFC,�กก�"��$ก��7��-���

• EP�7�4����4 �%;&�ก,�C," 6%�D$�"C#������� (Control limits) กM3��3C48��6������� ก�"��$ก��$#G$�,"9!V$ก�"��$ก��7��-���

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10-27 Quality Control

�%!7��&'(3��9!V$7��-���&'(�#ก��D$J#��������%!7��&'(3��9!V$7��-���&'(�#ก��D$J#�������

• 7$�u$4� (Trend)• �#w,#ก� (Cycles)• ����9 $9 '6� (Bias)• 9กFCก��9!;'(6$7!;�� ����9n;'(6 (Mean shift)• ก��ก�",�6�#�&'(��ก9กF$3! (Too much dispersion)

�%!&'( 10.11

See Page 466

Page 28: chap010 Quality Control Control.pdf · 2018-05-11 · 10-6 Quality Control ˚ ,*+ ก Type of business Inspection points Characteristics Fast Food Cashier Counter area Eating area

10-28 Quality Control

����) ��� Runs *+�� กก� ���*+�����ก� � ก� � (7 runs)

����) ��� Runs *+��'(����*+��� (8 runs)

U U D U D U D U U D

B A A B A B B B A A B

�%!&'( 10.12

�%!&'( 10.13

ก��$I�,I�$�$ก��$I�,I�$�$ Runs Runs

A – �4���$

B – �4��;���

U – �PG$

D – ;�

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10-29 Quality Control

• Tolerances or specifications

• ����� �����J#$J�$&'(�#�3C4 HP(�,"E%กกI�8$C�PG$uC6�F\�ก�J%4 ก7��8�: 3C4,�ก�����4 �ก��� �;%ก�4�

• ����J#$J�$� �ก�"��$ก�� (Process variability)

• ����J#$J�$&'(9!V$3!���a������F

• ����-����E� �ก�"��$ก�� (Process capability)

• ����J#$J�$� �ก�"��$ก��9�:( 9&'6�ก#��4 �%;,I�9��" (Specifications)

����-����E� �ก�"��$ก������-����E� �ก�"��$ก�� ( (Process CapabilityProcess Capability))

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10-30 Quality Control

����-����E� �ก�"��$ก������-����E� �ก�"��$ก�� ( (Process CapabilityProcess Capability))

LowerSpecification

UpperSpecification

A. �� �� � �$���ก�����ก �#�,+ก���� �����ก �

LowerSpecification

UpperSpecification

B. �� �� � �$���ก�����ก �,+� กก� �� �����ก �

LowerSpecification

UpperSpecification

C. �� �� � �$���ก�����ก �,+� กก� �� �����ก �

�%!&'( 10.15

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10-31 Quality Control

-#C-��$����-����E� �ก�"��$ก��-#C-��$����-����E� �ก�"��$ก�� ( (Process CapabilityProcess Capability RatioRatio))

-#C-��$����-����E� �ก�"��$ก��-#C-��$����-����E� �ก�"��$ก��, Cp = �� �ก�� ���� specification�� �ก�� ����ก�����ก �

Upper specification – lower specification6σ

Cp =

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10-32 Quality Control

� �:�+�����ก�����ก �

Lowerspecification

Upperspecification

1350 ppm 1350 ppm

1.7 ppm 1.7 ppm

+/- 3 Sigma

+/- 6 Sigma

����7������7�� 3 Sigma 3 Sigma 7;"7;" 6 6 SigmaSigma

ppm – parts per million (,I�$�$�� ;4�$8$��6)

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10-33 Quality Control

ก��!�#�!�������-����E� �ก�"��$ก��ก��!�#�!�������-����E� �ก�"��$ก�� ((Improving Process CapabilityImproving Process Capability))

• &I�D84ก�"��$ก�����6�PG$ (Simplify)• D�4ก�"��$ก��&'(9!V$7������z�$ (Standardize)• D�4�"��&'(�'ก��!U �ก#$����JFC�;�CD$�#� (Mistake-

proof)• D�4 �!ก�L&'(C'�PG$ (Upgrade equipment)• D�4ก�"��$ก��&'(9!V$ #�u$�#�F��ก�PG$ (Automate)

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10-34 Quality Control

Taguchi Loss FunctionTaguchi Loss Function

���*�(Cost)

��L �� �Lowerspec

Upperspec

Cost function *�����

Cost function��� Taguchi

�%!&'( 10.17

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10-35 Quality Control

�4 ,I�ก#C� ��#��#C����-����E� �ก�"��$ก���4 ,I�ก#C� ��#��#C����-����E� �ก�"��$ก��

1. ก�"��$ก�� �,,"3���'����9-E'6� $#($�: �#$ �,,"9!;'(6$7!;�3!,�ก� $&'(9���#C

2. J;J;F�&'(3C4,�กก�"��$ก�� �,,"3��3C4�'ก��ก�",�6�#�9!V$7��!ก�F (Normal Distribution) กM3C4 7��-%��&'(9��D�4�'-���Fz�$&'(��� ก�"��$ก��,"�'ก�",�6�#�7��!ก�F

3. ���9n;'(6ก�"��$ก�� �,,"3��3C4 6%�&'(,�CกP(�ก;��� C' &I�D84ก��D�4�#��#C Cp $#G$3��98��"-�