Military Standard 105 E and 414 with solved numerical. SQC

1. 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 lots
rejected
5 consecutive
lots accepted
10 consecutive lots remain
on tightened inspection
Start
Discontinue
Inspection
AND conditions
OR conditions

5. 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

11. 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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12. 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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14. Procedure 1 (k-Method)
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15. Procedure 2 (M-Method)
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16. Double specification limit variability
unknown
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17. Example
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18. 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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19. Thank You
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