Causa y Efecto

C&E (Cause and Effect) Matrix and
Diagram

Objectives

• Link the Cause and Effect (C&E) Matrix to the Process Map
• Review steps to create the C&E Matrix
• Link the C&E Matrix to further steps in the Process Improvement Plan
• Perform an exercise to actually create a C&E Matrix
• Define the C&E Diagram as a separate tool used to capture key causes
via brainstorming.
• Perform anexercise to actually create a C&E Diagram
C&E a Powerful And Easy Tool.

What is a C&E Matrix?

• Key Principles:
– This is a simple matrix to emphasize the importance of understanding
customer requirements.
– Relates the Key Inputs to the Key Outputs (Customer Requirements)
using a process map as the primary source.
– Key Outputs are scored as to importance to the Customer
– Key Inputs arescored as to relationship to Key Outputs with the
following results

• Pareto of Key Inputs to evaluate in the FMEA and Control Plans
• Input into the Capability Study step in the Measurement Phase
• Input into the initial evaluation of the Process Control Plan.

A C&E matrix drives ranking through customer weights on Key Process
Parameters. This is different from a C&E diagramwhere we focuson finding the true sources of defects & or variation.

C&E Matrix Steps

• Identify key customer requirements (outputs) from Process Map
• Rank order and assign priority factor to each output (Usually on a 1 to
10 scale)
• Identify all process steps and materials (inputs) from the process map
• Evaluate correlation of each input to each output
– low score: changes in theinput variable (amount, quality, etc.) have
small effect on output variable
– high score: changes in the input variable can greatly affect the output
variable
• Cross multiply correlation values with priority factors and add across
for each input
Ranking the inputs sets the input priority.

Process Map To Be Used In Example

Inputs Type
Raw material* SOP
Die sets N
Press set-up SOPRaw material feed SOP
Press cycle time C
Tool wear/condition N

Stamping

Outputs

Lever part #49901
Rate
Critical dimensions
Ship to heat treater

Two Approaches to the C&E Matrix

• The Focused Approach
– Phase I

• Place the Outputs across the top of the matrix and rank

• Place the Process Steps down the side of the matrix

• Correlate Process Steps to Outputs• Pareto the Process Steps

– Phase II

• Start a new C&E Matrix with the inputs from the top three or four
Process Steps

• General Approach
– Place the Outputs across the top of the matrix and rank
– Place Inputs down the side of the matrix starting with the first process
step and moving to the last
This approach is OK for small processes with relatively few steps and
inputs.Exercise

• Split into teams
•Build a C&E Matrix using the Focused Approach
• Follow the steps of C/E Matrix as explained on the previous pages
• List no more than 6 Output Variables (for the sake of time)
• Rank importance according to known Customer concerns with the
variables
• List top process input variables (no more than 10 for the sake of time)
• Return and report results tothe group

Relating Inputs to Customer Requirements

• You are ready to relate the customer requirements to the process input
variables
• Correlational scores:
No more than 3 levels
–1, 3, and 5
–1, 3, and 9
• Assignment of the scoring takes the most time
• To avoid this, spell out the criteria for each score
– 0 = No Correlation
– 1 = The process input only remotely affects thecustomer requirement
– 3 = The Process input has a moderate effect on the customer
requirement
– 9 = The Process input has a direct and strong effect on the customer
requirement
• All correlations are positive. NO NEGATIVE NUMBERS!

Initial Evaluation Questions

• Are the Standard Operating Procedures…
– … available or do they exist?
– … understood and being followed?
– … current?
– …...