Find and analyze possible causes
Collect and analyze information to determine possible causes in order to select the real cause of the problem.
- Most used tools:
-Ishikawa diagram (including NGT).
- Definition: Diagram that shows the possible sorted causes of a problem.
- Process elements:
- - Methods
- - Men
- - Raw materials
- - Measurement
- - Environment
- - Machinery and equipments
Steps: Based on a process of “brainstorming”:
1.- Each member generates a single idea (cause) each round. All of the ideas are numbered and registered.
2.- Discard repeated ideas.
3.- Verify that the remaining ideas are related to the problem (discuss).
4.- Place the resulting ideas into the appropriate
category in the Ishikawa (cause-and-effect) diagram.
Example 1) Hypothetical example involving scrap in a certain area:
- Definition: Technique used to analyze information based on the classification of its origins.
Some examples of strata are machinery by model or type, workers (training, shift,gender), raw material (supplier, lot), and the operating conditions (temperature,humidity...).
Example 1) Suppose a certain factory produces the same product in three different areas. Each area has three identical machines. The following table shows information on the number of defects in the three areas:
After analyzing the data a new table is obtained based on the information by area.
They now decide to stratify the above information for area 3:
- Definition: A simple graph of two variables. You can visualize the type and the degree of relationshiop (correlation) between these two variables.
Type of relationship
Degree of relationship
- How to do it? We will use the Microsoft Excel to help in the process.
Example 1) The table below shows information about the hardness of a group of manifolds vs. their solidification time. Draw and interpret a scatter plot.
- Definition: Forms to collect, analyze and report information. Standardize and facilitate the collection, analysis and reporting of information.
1.- To visualize distributions
2.- To score the total number of defects by type
3.- To locate defects
4.- To stratify the number of defective units
5.- Check list