1. Optimizing and controlling process through statistical process control
page 442

2. Chapter Outline Rationale for SPC Control chart development
Major topics:
Statistical Process Control Defined
Rationale for SPC
Control chart development
Management’s role in SPC
Role of the total quality tools
Implementation and deployment of SPC
Inhibitors of SPC

3. STATISTICAL PROCESS CONTROL DEFINED
All process are affected by multiple factors such as:
The environment the machines employed
The materials used
The methods(work instruction) provides
The measurement taken
The manpower(people) who operate the process
These factors are called the 5 M’s

4. STASTISTICAL PROCESS CONTROL DEFINED
Statistical process control (SPC) is a statistical method of separating variation resulting from special causes from variation resulting from natural causes in order to eliminate the special causes and to establish and maintain consistency in the process, enabling process improvement.

5. Rationale for SPC Control of variation Continual improvement
Predictability of processes
Elimination of waste
Product inspection
See page no. 444

6. Control chart development
Data category
Chart type
Statistical quality
application
Variables(measured values)
x bar-R(
See figure page 453
Mean value and range
Charts dimensions and their precision, weight, time, strength, and other measurable quantities.
example: anything physically measurable
x tilde-R(
Median and range
Charts measurable quantities, similar to x bar-R, but requires fewer calculation to plot. Example as above

7. Control chart development(continue)
Data category
Chart type
Statistical quality
application
Variables(measured values)
x-Rs(also called x-chart
See figure page 453
Individual measured values
Used with long sample intervals; when subgrouping not possible. Example: products made in batches such as solution, coaching, etc. or grouping too expensive.
Histogram must be normal

8. Control chart development(continue)
Data category
Chart type
Statistical quality
application
Attributes(counted values)
p-chart
See figures page 454, 455
Percentage defective (also fraction defective)
Charts the number of defects in samples of varying size as a percentage or fraction. Example: anywhere defects can be counted
np-chart(also pn)
Number of defective pieces
Charts the number of defective pieces in sample of fixed size. Example: as above, but in fixed-size samples

9. Control chart development(continue)
Data category
Chart type
Statistical quality
application
Attributes(counted values)
c-chart
See figure page 457
Number of defects
Charts the number of defects in a product( single piece) of fixed size. Example: specific assemblies or products( e.g., pc boards, tires)
u-chart
Number of defects per unit area, time, length, etc.
Charts the number of defects in a product of varying size (i.e., unlike products). Example: Carpet( area), extrusions length)

10. Management’s role in SPC
Commitment
Training
Involvement
See page 462

11. Role of the total quality tools
There are several tools:
Pareto charts
Cause and effect diagrams
Stratification
Check sheets
Histograms
Scatter diagrams
Run charts and control charts
Flow charts
Design of experiments
Five-s
Failure mode and effects analysis(FMEA)

12. Role of the total quality tools(continue)
With SPC, the total quality tools have a dual role:
First: they help eliminate special causes from the process so that the process can be brought under control.
Second: their second role comes into play when, from time to time, the control chart reveals cause or when the operators wants to improve a process that is in control.
See page 463

13. Implementation and deployment of SPC
The implementation steps are divided into three phases:
Preparation
Planning
Execution
See page 465 for detailed study

14. Implementation and deployment of SPC (continue)
phase
responsibility
action
preparation
Top management
Consultant or in-house expert
Step 1:Commit to SPC
Step 2:Organize SPC committee
Step 3:Train SPC committee
planning
SPC committee assisted by consultant or experts QA
Management
Step 4: Set SPC objectives
Step 5:Identify target processes
Step 6: train appropriate operators and support personnel
Step 7: ensure repeatability of instruments and methods
Step 8: delegate responsibility for operators to play key role

15. Implementation and deployment of SPC (continue)
phase
responsibility
action
execution
SPC committee, operators, suppliers, customers
Operator w/ expert assistance
Consultant or in-house expert
Operator
SPC committee and management
Operator w/ assistance as required
All
Step 9: flowchart the process
Step 10: eliminate the special causes of variation
Step 11: develop control charts
Step 12: collect and plot SPC data; monitor
Step 13: determine process capability
Step 14: Respond to trends and out-of-limits data
Step 15: track SPC data
Step 16: eliminate root causes of any new special causes of variation
Step 17: continually improve the process (narrow the limits)

16. Inhibitors of SPC Capability in statistics
Misdirected responsibility for SPC
Failure to understand the target process
Failure to have processes under control
Inadequate training and discipline
Measurement repeatability and reproducibility
low production rates
See page
Discussion Assignment 18-2 on page no. 479 “ The start of the Japanese Quality Movement”

17. External Links
Watch the Youtube link and go through the research to understand the topic better.