Cause And Effect Diagram

Cause and effect diagrams also known as, Fishbone Diagrams Ishikawa Diagrams, Herringbone Diagrams, and Fishikawa Diagrams is a visualization tool commonly used to identify root cause of potential defect. The concept of this diagram is invented by Dr. Kaoru Ishikawa Japanese quality control expert in 1943.

Ø  Cause and effect Diagrams tools are considered as one of the 7 QC tools in which defect is shown as the fish’s head and potential causes on bones in a Fishbone Diagrams.

Ø  Cause and effect Diagrams is used

·        When identifying possible causes for a problem
·        To reveal bottlenecks in any processes.
·        Identify the issues and corrective action to resolve

Ø  It is a visual representation of the factors that might contribute to an observed effect or phenomenon that is being examined.

Ø  The interrelationships among the possible causal factors are clearly shown. One causal factor may appear in several places in the diagram. For example, if temperature affects both moisture content and physical dimensions, then temperature would appear in both places.

Ø  The Problem statement is identified with the help of Brainstorming among the team members and written on flipchart or whiteboard with marking pen. Question “Why does this happen? Is asked about each cause.

Ø  The cause of a problem is categorize using the 5 Whys technique. The 5 Ms is one of the most common frameworks for root-cause analysis mainly used in lean manufacturing.

·         Man / mind power (physical or knowledge work)

·         Machine (technology equipment)

·         Material (consumables, includes raw material, and information)

·         Method (process)

·         Measurement / medium (environment, inspection)

Ø  Cause and Effect diagram is used in ANALYSE phase of DMAIC methodology .The cause and Effect diagram or Fish bone diagram shown below was drawn by a manufacturing team to try to understand the source Dry Solder in a printed circuit board . Layers of branches show thorough thinking about the causes of the problem. The possible causes for Dry solder are Stencil printer and Reflow process.

Cause and effect Diagrams or fishbone diagram are very effective tools and structured team process to use in process improvement.

Creating this Cause and effect Diagrams helps CFT (Cross-Functional) team to clear understanding the involved process, identifying potential factors causing an overall effect to defect prevention.