Problem Solving - Data Collection

 How to Collect Data

The purpose of collecting data

A great deal of data can be collected in factory situations. First consider the purpose of collecting these data.

When we introduce a particular method of doing a job, it is natural to consider whether the method is appropriate or not. The decision is usually based on past results and experience, or perhaps on conventional methods.

However in case of factory work, where data are collected through the actual manufacturing process, the procedural methods are introduced on the basis of the information obtained. The manufacturing procedure will be most effective if a proper evaluation is made, and on-the-job data are essential for making a proper evaluation.

Data and subsequent evaluation will form the basis for actions and decisions. As factory operations will vary with the manufacturing procedure involved, data should be classified in terms of the various purposes.

1.  Data to assist in understanding the actual situation

These data are collected to check the extent of dispersion in part sizes coming from a machining process, or to examine the percentage of defective parts contained in lots received.

As the number of data increase, they can be arranged statistically for easier understanding, as will be explained further on.

Estimates and comparisons can then be made concerning the conditions of lots received as well as the manufacturing process, utilizing specified figures, standard figures, target figures, etc.

2. Data for analysis

Analytical data may be used, for example, in examining the relations ship between a defect and its cause. Data are collected by examining past results and making new tests. In the case, various statistical methods are used to obtain correct information

3. Data for process control

After investigating product quality, this kind of data can be used to determine whether or not the manufacturing process is normal. Control chars are used in this evaluation and action is taken on the basis of these data.

 .  4. Regulating data

This is the type of data used, for example, as the basis for raising or lowering the temperature of an electric furnace so that a standardized temperature level may be maintained. Actions can be prescribed for each datum and measures taken accordingly.

    5.  Acceptance or Rejection Data

This form of data is used for approving or rejecting parts and products after inspection. There are two methods: Total inspections and sampling. On the basis of the information obtained, it can be decided what to do with the parts or products.

 

Book Ref:            Guide to Quality Control

Author:              Kaoru Ishikawa