1. Six Sigma Quality Engineering
Week 6
Chapter 6 (Analyze Phase)

2. Chapter 6 Outline Process Map Inputs characteristics Cause & Effect
Fishbone Diagram (Minitab)
C&E Matrix (Excel)
FMEA
Process Capablity
Cpk Cp
Normality Analysis

3. Detailed Process Map Example

4. Characterising Inputs
Inputs can be classified as one of three types
Controllable (C)
Things you can adjust or control during the process
Speeds, feeds, temperatures, pressures….
Standard Operating Procedures (S)
Things you always do (in procedures or common sense things)
Cleaning, safety….
Noise (N)
Things you cannot control or don not want to control (too expensive or difficult)
Ambient temperature, humidity, operator...

5. Example Machining a shaft on a lathe Outputs (Y’s) Diameter Taper
Surface finish
Machining a shaft
on a lathe C S N
Inputs (x’s)
Rotation speed
Traverse speed
Tool type
Tool sharpness
Shaft material
Shaft length
Material removal per cut
Part cleanliness
Coolant flow
Operator
Material variation
Ambient temperature
Coolant age

6. The Eight Steps in Cause and Effect Analysis
Define the Effect
Identify the Major Categories
Generate Ideas
Evaluate Ideas
Vote for the Most Likely Causes
Rank the Causes
Verify the Results
Recommend Solutions

7. Cause & Effect (Fishbone Diagram)
Objectives
To understand the benefits of Cause & Effect Analysis
To understand how to construct a C & E Diagram
Analysis
A method a work group can use to identify the possible causes of a problem
A tool to identify the factors that contribute to a quality characteristic

8. Uses of C & E (Fishbone Diagram)
Visual means for tracing a problem to its causes
Identifies all the possible causes of a problem and how they relate before deciding which ones to investigate
C & E analysis is used as a starting point for investigating a problem

9. C&E (Fishbone Diagram)
Effect
The problem or quality characteristic
The effect is the outcome of the factors that affect it
Effect

10. Causes (Fishbone Diagram)
All the factors that could affect the problem or the quality characteristic
Five Major Categories
Materials
Methods
People
Machines
Environment

11. Machine
Environment
Effect
Material
Methods
People

12. Cause and Effect (Matrix)
Benefit
Gain new knowledge and perspectives by sharing ideas with others
Helps us understand our processes
Provides a basis for action
Whenever a problem is discovered, using C&E analysis forces us to take a proactive stance by seeking out causes

13. 2 1
5&6 3 4

14. C&E Matrix Instructions
This table provides the initial input to the FMEA and experimentation. When each of the output variables (requirements) are not correct, that represents potential "EFFECTS". When each input variable is not correct, that represents "Failure Modes".
1. List the process output variables
2. Rate each output on a 1-to-10 scale to importance to the customer
3. List process input variables (from the process map)
4. Rate each input's relationship to each output variable using a 0, 1, 3, 9 scale
5. Select the high ranking input variables to start the FMEA process; Determine how each selected input variable can "go wrong" and place that in the Failure Mode column of the FMEA.

15. FMEA It is an approach to:
Identify potential failure for a product or a process
Estimate risks that are associated with causes
Determine actions to reduce risks
Evaluate product design validation plan
Evaluate process current control plan

16. FMEA types There are two types: Process: Will focus on Process Inputs
Design: Will used to analyze product designs before they are released to production

17. The use of the FMEA
Improve processes before failure occur (Proactive approach)
Prioritize resources to ensure process improvement efforts are beneficial to customers
Track and document completion of projects
It is a living document. It will be updated and reviewed all the time

18. Inputs & Outputs to FMEA
Process Map
C&E Matrix
Process History
Process technical procedures
Outputs
Actions list to prevent causes
Actions list to detect failure modes
Document history of actions taken

19. FMEA step-by-step
For each process input, determine the ways in which the input can go wrong- the failure modes.
What can go wrong
with input

20. FMEA step-by-step
For each failure mode associated with the inputs, determine the effects of the failures on the customer.
What the effect
on outputs?

21. FMEA step-by-step Identify potential causes of each failure mode.
What are
The causes?

22. FMEA step-by-step
List the current controls for each cause or failure mode (Prevent/Detect).
How are these
Found or prevented?

23. FMEA step-by-step
Create Severity, Occurrence, and Detection rating scales.
Severity of effect- importance of effect on customer requirements. It is a safety and other risks if failure occurs.
1= Not Severe, 10= Very Severe
Occurrence of cause- frequency in which a give Cause occurs and creates Failure Mode. Can sometimes refer to the frequency of a failure mode.
1= Not Likely, 10= Very Likely

24. FMEA step-by-step
Create severity, Occurrence, and Detection rating scales.
Detection- ability to:
Prevent the causes or failure mode from occurring or reduce their rate of occurrence
Detect the cause and lead to corrective action
Detect the failure mode
1= Likely to Detect, 10= Not Likely at all to Detect

25. FMEA step-by-step Risk Priority Number:
After rating we get the output on an FMEA Risk Priority Number. It is calculated as the product of Effects, Causes, and Controls
RPN= Severity X Occurrence X Detection
Effects
Causes
Controls

26. FMEA step-by-step Dynamics of the Risk Priority Number:
The team defines the rating scales 1-10 for the severity, Occurrence, and Detection ratings. The team choose the levels and numbers:
How severe is it: Not Severe = 1
Somewhat = 3
Moderately = 5
Very Severe = 10

27. FMEA step-by-step Dynamics of the Risk Priority Number:
The team defines the rating scales 1-10 for the severity, Occurrence, and Detection ratings. The team choose the levels and numbers:
How often does it Occur?
Never/rarely = 1
Sometimes = 3
Half the time = 5
Always = 10

28. FMEA step-by-step Dynamics of the Risk Priority Number:
The team defines the rating scales 1-10 for the severity, Occurrence, and Detection ratings. The team choose the levels and numbers:
How well can you detect it?
Always = 1
Sometimes = 3
Half the time = 5
Never = 10

29. FMEA step-by-step Determine recommended actions to reduce high RPN’s:
What can be done?

30. FMEA step-by-step Take appropriate actions and recalculate RPN’s
Assign responsible
Parties

31. Process Capability Study

32. Cpk & Cp
Cpk incorporates information about both the process spread and the process mean, so it is a measure of how the process is actually performing.
Cp relates how the process is performing to how it should be performing. Cp does not consider the location of the process mean, so it tells you what capability your process could achieve if centered.

33. Process Capability Study

34. Non-normal distributions
Use Capability Analysis (Nonnormal) to assess the capability of an in-control process when the data are from the nonnormal distribution. A capable process is able to produce products or services that meet specifications.
The process must be in control and follows a nonnormal distribution before you assess capability. If the process is not in control, then the capability estimates will be incorrect.
Nonnormal capability analysis consists of a capability histogram and a table of process capability statistics

35. Questions? Comments?