Quality and grade are different concepts

High-grade products may not necessarily be of high quality

Products with lower grades are not necessarily of lower quality

Low-grade products may not cause problems

Low quality is never a good thing

Accuracy

Accuracy

User finds bug

QC inspection and correction

QA process assurance

DfX design optimization

TAM total quality management

1. Craftsman self-inspection

2. Full-time quality inspection

3. QC quality control

4. QA Quality Assurance-Management Quality

5. DfX design optimization

6. TQM total quality management

development trend

preventive costs

In order to prevent substandard quality and inconsistency with our quality goals

prevention cost

Evaluate costs

corrective costs

In order to compensate for the losses caused by customers due to defects that have already occurred

internal failure costs

external failure costs

Analyze the relationship between production technology and quality

Analyze the relationship between indicators

L-shaped matrix: two dimensions

T-shaped matrix

X-shaped matrix

Y-shaped matrix

C-shaped matrix

Proposed by Deming

Follow two processes

from manufacturing industry

A new product is designed with full consideration

Ishikawa Kaoru

Fishbone diagram - Ishikawa diagram - cause and effect diagram

Target

1. Product quality data basically conforms to the normal distribution

2. Product quality data are all within the upper and lower specifications.

3. The mean is consistent with the center of the upper and lower specification lines

4. The upper and lower specification lines are located at 4 times the standard deviation.

Histogram analysis

bad histogram

Analyze whether there is a relationship between defects and certain variables, and what kind of relationship it is

Strong positive correlation, weak positive correlation

Strong negative correlation, weak negative correlation

irrelevant

nonlinear correlation

Check factors related to product quality one by one

Classify and count defects

One defect will be recorded once detected

italian economist

The 80/20 principle means that 80% of problems are caused by 20% of the causes

According to the statistical results of the checklist, different types of defects are sorted from left to right in descending order by the number of occurrences.

Find priorities for resolving defects

Help us solve most problems with limited energy

Histogram rotated 90 degrees to the right

The upper and lower control lines are located at 3 times the standard deviation of the mean

1. When the final quality data of the product appears on the side of the mean for 7 consecutive points

2. 7 consecutive points purely monotonic rise or monotonic decline

3. When data appears outside the control range

Non-random events, the cause needs to be found and eliminated

effect