QC Seven Tools

Machine:R12 Item Item 1 2 3 4 representative checker Note: Good Date A B C D 124 398 X:substitute 1 2 3 4
b. continuous check list:
Item antenna gap side gap top gap
The 1st: Check List
METHOD 1 Check list
Define: Check list is an excel or chart which use simple sign to collect and
statistic data .
The Type:
a. Check list for periodic check b. Check list for continuous check
《QC seven tools’ overview and application 》
What is ‘QC SEVEN TOOLS’
METHOD 1. METHOD
METHOD
METHOD METHOD
METHOD
METHOD
Check List 2. Pareto Chart 3. Fish Bone Chart 4. Histogram 5. Control Chart 6. Scatter Plot 7. Classification
Procedure:
a. Confine the classify item b. Confine deadline, collect data c. Collect data in each item d. X axle and Y axle e. Use the rate of the item form curve f. Write down the limit
Function:
Mostly used in the problem analyze stage
Example:
Machine Environment Man
Quality
Material
Method
Others
METHOD 4 Histogram(Ⅰ)
Define: A bar graph of a frequency distribution in which the widths of the bars
in or out of B area
Control Chart(Ⅲ)
Method IV : Eight continuous points in or out of C area
Method V : Several continuous points at one side
a. five continuous points up or down---Pay attention to following trend
Usually we can use below table as reference Quantity 50-100 100-250 250以上 Group 1-6 7-12 10-20
d. Confirm unit: H= R/K e. Confirm the upper and lower limit for each group
Control Chart(Ⅱ)
Judge of unsteady chart:
Method I: One point out of A area. Method II : Two points in three continuous points
in or out of A area
Method III : Four points in five continuous points
Function:
Pareto Chart is used to setup the aim to improve
Example:
Item A B C D Quantity 30 10 5 5 Effect(%) 60 20 10 10 Add quantiy 30 40 45 50 Add effect(%) 60 80 90 100
b. six continuous points up or down---need to investigate the root cause c. seven continuous points up or down---
need to analysis and take action immediately
50 40
100%
Quantity
30 20 10 0 A B C D
60%
Add effect (%)
METHOD 3 Fish Bone Chart
Define:
Use a systematic chart to display all the causes which will cause the defect. Simply say, it’s use a chart to show the relationship of the cause and the effect.
I. X-R Chart I. p-Chart II. X-δ Chart II. Pn-Chart III. X-Rm Chart III. C-Chart IV. u-Chart
b. Count Control Chart
BY usage
a. for control b. for analysis
the first radio thesecond radio the third radio
0.1 0.3 0.25
0.2 0.35 0.2
0.15 0.3 0.2
METHOD 2fy the collected data by its attribution like: the cause of the defect, the status of the defect, the position the defect happen, the defect customer complaint etc. Count each item’s rate, and array this item from high to low, and add up the rate then form diagram.
Establish procedure:
a. make sure goal b. Ensure the collection item c. sample frequency d. How to collection e. design the excel or chart f. write down the condition of the collection
f. Missing unit
remark: No data in the range of one or more group conclusion: error measurement.
g. Altiplano type
remark: like altiplano conclusion: mix different distributions.
are proportional to the classes into which the variable has been divided and the heights of the bars are proportional to the class frequencies.
Procedure: a. Collect data and write down on paper b. find out the Largest and the Smallest one and work out the Rebound=(L-S) c. Group: K=1+3.231ogN
d. Cliff type
remark: One side is the top. conclusion: Sample size in the process is 100%
e. Breast type
remark: Two top occur in each side conclusion: mix two different group series
Function: Usually, check list which show
the status of a thing is used to collect data and then the data will be used to do further analysis.
Example:
a. periodic check list:
Type of histogram:
a. Normal:
remark: middle is high and two sides are low. To be a focused trend. conclusion: Process is in control.
b. Alternately in middle part
remark: not smooth.
conclusion: too many groups or false data
C. One-way distribution
remark: The top point occurs close to one side and then become lower step by step. conclusion: should discuss the acceptance of criteria.
METHOD 5 Control Chart (I)
Define: It describes the trend of process capability as time goes by. Classification
BY static data a. Measurement Control Chart
The lower limit of the mini-group (XL)=minimum- accuracy/2 The upper limit of the mini-group (XU)=XL+ H, And so on
f. Count the middle point for each group (XM) XM=(XL+XU)/2 g. Statistic the quantity of each group h. Form Histogram i. Record data &condition in every step
Main function of QC Seven tools
(Collection Data) The 2nd: Pareto Chart (Make clear What’s important) The 3rd: Fish bone chart (to chase the reason) The 4th: Histogram Chart (show distribution) The 5th: Control Chart (discover the abnormal) The 6th: Scatter Plot (show relative between the cause) The 7th: Classification (for further analysis)
Procedure:
a. Make sure the effect b. Write down all the cause c. Show how does this cause happen d. More detail description e. Point out the most important cause f. Show the reason you choose that cause