aoq(average outgoing quality
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The Average Outgoing Quality (AOQ)Industrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
The Average Outgoing Quality (AOQ)The average of rejected lots (100% inspection) and accepted lots ( a sample of items inspected)
To calculate the AOQ for a specific fraction nonconforming and a samplingplan, the first step is to calculate the probability of accepting the lot at that level of fraction nonconforming. Then, multiply the probability of acceptance by the fraction nonconforming for the AOQ.
AOQ = Pac
*p(N-n)/N
w hereP
ac= Probability of accepting a lot
p = Fraction defectiven = sample sizeN = Lot size
The average outgoing quality limit (AOQL) is the maximum AOQ for all possible levels of incoming quality
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The Average Outgoing Quality (AOQ)Industrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
Average total inspection (ATI))
The average total inspection represents the average number of units that will be inspected for a particular incoming quality level and probability of acceptance
ATI = n + (1- Pa) (N-n)
w here:P
a= Probability of accepting a lot
n = sample sizeN = Lot size
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The Average Outgoing Quality (AOQ)Industrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
Consider the comparison between sampling inspection and 100 inspection
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The Average Outgoing Quality (AOQ)Industrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
Break- even point
If the sample size is assumed to be small compared to the lot size , the break – even point p
b, is
Pb = I/A
Where I is the inspection cost and A is the damage cost
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Sampling StandardsIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
ANSI/ASQ Z1.4 and Z1.9 standards
ANSI/ASQ Z1.4-2003 is probably the most commonly used standard for attribute sampling plans
Levels of Inspection
There are seven levels of inspection used in ANSI/ASQ Z1.4-2003: Reduced InspectionNormal inspectionTightened InspectionFour levels of special inspection ; The special inspection levels should be used only when small sample sizes are necessary and large risks can be tolerated.
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Sampling StandardsIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
A general procedure for selecting plans from ANSI/ASQ Z1.4-2003 is as follows:
1. Decide on an AQL.2. Decide on the inspection level.3. Determine the lot size.4. Find the appropriate sample size code letter. See Table 1 from
ANSI/ASQ Z1.4-2003.5. Determine the type of sampling plan to be used: single, double, or
multiple.6. Using the selected AQL and sample size code letter, enter the
appropriate table to find the desired plan to be used.7. Determine the normal, tightened, and reduced plans as required from the
corresponding tables
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
A manufacturer receives cable wires from its supplier in batch of 1000every week. To properly inspect the wires, an engineer of themanufacturer decides to establish a sampling plan.
After talking to the supplier, both sides agree to use the following criteriato create the plan:
Acceptable quality level (AQL) = 2%, with α = 0.05Lot Tolerance Percent Defective (LTPD) = 8%, with β = 0.10
User Minitab to design the acceptance sample plan
Then Compare the following plans:Sample size = 100, Acceptance Number = 0Sample Size = 100, Acceptance Number = 20Sample Size = 100, Acceptance Number = 6Using the same AQL, LTPD
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples
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ExampleIndustrial Engineering
The Average Outgoing Quality (AOQ)
Sampling Standards
Examples