6sigma Preparation Notes

Cpk • Cp • •

- see Natural Tolerance decreases with spec width - see Natural Tolerance decreases with spec width Cp = 1 for centered process - natural tolerance =spec width

Cause and Effect Diagram - Fishbone Diagrams - Ishikawa Diagrams • • • • • • • • used to identify and organize potential root causes problem solving analysis done by brainstorming common categories - Measurement, Materials, People, Process, Equipment, Environment ask “Why?” 3 times to get to root cause have detailed problem statement at head of fish - “effect” need corresponding process map should fit on one 8-½ x 11 page should have all 6 fishbones and at least 3 levels deep

C-bar • C-bar is the average of all the subgroup C-values in C-Chart - see Attribute Data Control Charts

C – Chart • • • •

Count chart a specialized version of U chart used to monitor the number of errors found - occurrences per unit - error count number of units or subgroup size MUST remain constant

Census • count or measurement of the entire population

Continuous Data • • measured – weigh, timed, can be measured and broken down into smaller parts and still have meaning. Money, temperature and time are continous.Volume (like volume of water or air) and size are continuous data.

Control Charts • indicate stability over time

Chart Rules – Control Charts • • P-chart or NP-chart - count number of items in error or defectives U-chart or C-chart - count number of errors or defects in items see variation

Common causes control limits

• Provide boundaries for a process running in control • based upon process data CTQ - Critical to Quality • • • • key measurable characteristics of a product or process whose performance standards or specification limits must be met in order to satisfy the customer CTQ’s represent the product or service characteristics that are defined by the customer (internal or external). They may include the upper and lower specification limits or any other factors related to the...