Quality Management Terminology for Injection Molding

Quality Management Terminology for Injection Molding

1. What is the specification limit?

In the specification, the management scope is set separately for each item.

example)

The length of the molded product is 1.0mm or more and 2.0mm or less

・The temperature of the molding chamber is measured twice a day, etc.

Specification limits define acceptable limits (upper and lower limits, frequency, etc.).

2. What is a feature element map?

Also known as a fishbone diagram, this is a method of identifying hidden problems by charting each feature separately by the spine, large bones, and small bones.

Each element is based on the 4M (man/machine/material/method) and the environment.

3. Frequency distribution

(1) What is the meaning of frequency and distribution?

Frequency: how many

· Distribution: spread

(2) What is a frequency distribution?

This is a table summarizing the frequency (quantity) and its distribution (spread) by level.

Example) Measurement result of outer diameter X dimension of molded product

4. What is a histogram?

A histogram is a graph of a frequency distribution table. The vertical axis is the frequency, and the horizontal axis is the grade.

5. What is a normal distribution?

Among distributions (spread), the most common is the normal distribution. Its distribution is in the shape of a bell or Mount Fuji, with a left-right symmetrical bottom around the mean.

6. What is a management chart?

A management chart is a chart used to determine if conditions are stable during a manufacturing process.

7. What is sampling inspection?

If the total number of products is too large to inspect (the cost is too high), or if some defects or defects are acceptable, a certain number is selected for sampling inspection. The standard of sampling inspection is determined according to customer requirements.