Control charts for fraction defective

GB/T 4091.6-1983 Non-conforming Product Rate Control Chart (p Chart) GB/T4091.6-1983 Standard Download Decompression Password: www.bzxz.net

1 Introduction
National Standard of the People's Republic of China
Control chart for defective rate
(p chart)
Control chart for fractilon defective519,241: 658
502(08.5)
GB4091.6-83
The control chart for defective rate is used to determine whether the defective rate of the production process is at or maintained at the required level. The control chart for defective rate is recorded as a force chart.
2 Preparation
2.1 According to the provisions of GB4091.183 "General Principles for Conventional Control Charts" 6, determine the quality characteristics, grouping principles, sample size, number of samples, sampling interval and sampling location.
When determining the sample size, make sure that each sample has at least one defective product on average. 2.2 Extract preliminary data according to the provisions of 2.1 of this standard. 2.3 Record the number of defective products in each sample in the data table. 2.4 Calculate the defective rate and its mean value P of each sample; =
Where (p) is the number of defective products in the first sample, which can also be recorded as d, k is the number of samples, and n is the size of the i-th sample.
2.5 Calculation of center line and control limit
General calculation formula
National Bureau of Standards 1983-12-21
UCL = p+3
i=1,2,,k
(1 - )
=p+A,F(Ip)i-1,2,\-,k
LCL-P-3
p(1-p)
=FA,vp(1-p)i=1,2,*,k
1984-10-01 implementation
GB4091.6—B3
When the sample sizes are not equal, the control limits should be calculated for each sample separately. The values ​​of Al
can be found in Table 1 and Table 2 respectively. wwW.bzxz.Net
2.5.2 Approximate calculation formula
When max2, nmin
where: A=
, it can be calculated according to the following formulas:
UCL=P+3
LCL= B-3
Values ​​can be found in Table 1
p(1-p)
For points that fall near the above approximate control limits, the control limits should be recalculated according to formulas (4) and (5) of this standard to determine whether the point is within or outside the limit. 3 Make a control chart for analysis
3.1 Make a p chart on grid paper
The ordinate is P, the abscissa is the sampling time or sample number, CL is represented by a solid line, and UCL and LCL are represented by dotted lines. 3.2 Plot points
Plot the values ​​of each sample on the graph.
8.3 Determine whether the production process is in statistical control according to GB4091.1-83Φ17.1. 3.4 Analyze the causes and take measures
According to GB4091.1-8318.3.
Determine whether the production process meets the quality requirements according to GB4091.1-83 8.4.
5 Control chart for control
According to GB4091.1-83418.5.
Modification of center line and control limit
According to GB4091.1-83 8.6.
GB 4091.643
Table 1A=
Numerical table
GB 4091.6-83
Table (1-) Numerical table
GB 4041.8--80
Continued Table 2
Vp(1-p)%
Product name
Quality characteristics
Observation method
Specification limit
Specification number
Sample serial number
GB 4091.6-88
Appendix A
P chart data sheet
(reference)
Work order number
Specified daily output
Observation instrument number
Quality requirements for production process
Data collection period
Equipment number
Operator
Inspector
Product name
Test method
Regulation
Specification number
Inspection procedure 2-
7—112
Quality requirements for production process
9 : 00
9 : 2(1
9 : 4]
10 : 20
10 : 4h]
11 : 00
12 : 40
13 : 20
14 : on
14 : 10
Sample number
GB 4091.6-83
Appendix B
Application example
(reference)
1Order number
Specified product
Observation instrument number
Average defective rate 5 %
7—1056
Workshop 4
20—275 pieces
20 minutes
Collecting data period
Design director
Operator
Inspector
A/P(Ip)
July 15, 2019
Li Yulan
The production process is in a state of statistical control. But
the quality
requirements are not met.
GB 4091.6-83
6:0= 131
(d- 2 -1
/ (d-ngn
GB 4091.68a
B.1 The analysis control chart indicates that the production process is in a state of statistical control B, 2 Calculate the estimated value of the defective rate
B. The actual defective rate does not meet the quality requirements, and the production process needs to be improved to reduce the defective rate until the analysis control chart is converted into a control control chart until the requirements are met. Additional notes:
This standard was proposed by the National Technical Committee for the Application of Statistical Methods. This standard was drafted by the Working Group of the Statistical Methods Sub-Technical Committee in Quality Management of the National Technical Committee for the Application of Statistical Methods. The main drafter of this standard is Meng Yi.
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