military standard 105e and 414
TRANSCRIPT
MILITARY STANDARDS
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Military Standard 105E
Most widely used acceptance sampling system for attributes
MIL STD 105E is Acceptance Sampling System collection of sampling schemes
Can be used with single, double or multiple sampling plans We will consider single sampling plans for this course
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Inspection Types
Normal Inspection Used at start of inspection activity
Tightened Inspection Instituted when vendor’s recent quality history has deteriorated Acceptance requirements for lots are more stringent
Reduced Inspection Instituted when vendor’s recent quality history has been exceptionally
good Sample size is usually smaller than under normal inspection
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Switching Rules
- Production Steady- 10 consecutive lots accepted- Approved by responsible authority
NormalReduced Tightened
- Lot rejected- Irregular production- Lot meets neither accept nor reject criteria- Other conditions warrant return to normal inspection
2 out of 5 consecutive lotsrejected
5 consecutivelots accepted
10 consecutive lots remainon tightened inspection
Start
DiscontinueInspection
AND conditions
OR conditions
Procedure for MIL STD 105E
Choose AQL Choose the inspection level Determine the lot size Find the appropriate sample code size letter from table A-1. Determine the appropriate type of sampling plan to use. Enter appropriate table to find the type of plan to be used. Determine the corresponding normal and reduced inspection
plans to be used when required.
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Example
Suppose product comes from vendor in lots of size 2000 units. The acceptable quality level is 0.65%. Determine the MIL STD 105E acceptance-sampling system.
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Normal Insp. Level
Lot Size
= 2000
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AQL
Plan K
Sample 125 units.
Ac = 2, accept if defects ≤ 2.
Re = 3, reject entire lot if defects ≥ 3.
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AQL
Plan K
Sample 125 units
Ac = 1, accept if defects ≤ 1.
Re = 2, reject entire lot if defects ≥ 2.
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Sample 50 units
Ac = 1, accept if defects ≤ 1.
Re = 3, reject entire lot if defects ≥ 3.
AQL
Plan K
Military Standard 414
MIL STD 414 is a lot-by-lot acceptance-sampling plan for variables introduced in 1957.
Sample sizes are a function of the lot size and the inspection level.
All sampling plans assume the quality characteristic of interest is normally distributed.
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Military Standard 414
MIL STD 414 is divided into four sections: A: general description of the sampling plans including
definitions, sample size code letters, and OC curves for the plans.
B: variables sampling plans based on the sample standard deviation for the case in which the process or lot variability is unknown.
C: variables sampling plans based on the sample range method
D: variables sampling plans for the case where the process standard deviation is known.
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Procedure 1 (k-Method)
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Procedure 2 (M-Method)
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Double specification limit variability unknown
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Example
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Range method for variability unknown
If mentioned in the question then we will go for this method.
In this method all the steps are same as we have done before only difference is instead of calculating standard deviation we will calculate range.
The table used in this method is C1 or C2 and C3 or C4.
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Thank You
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