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7/30/2019 Aql n Quality
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AQL & Defects in apparels
By:Ankur Makhija
NITRA,Ghaziabad
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Pre-production Check final check on the raw material used, style, cut
Initial Production Check First batch of garments is inspected, make
correction before bulk production
During Production Check
Final Random Inspection Checking the total production quality by
selecting the samples from the order. AQLsampling inspection may be applied
Stages of Garment Inspection
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No Inspection
100% inspection
Arbitrary Sampling Statistical Sampling
How much to inspect;
Some Options-
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No one knows if material is defective until
the material is in critical demand
This situation increases cost Defective products might reach the
customer
Cost is increased and a loss of goodwill
No Inspection
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This is the other extreme of no inspection.
100% inspection is the inspection of every
unit of a product It gives a better idea of product quality
than any other inspection alternative
However, 100% inspection does notguarantee detection of all defects
The direct cost of 100% inspection is high
100% Inspection
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Between no inspection at all and 100%
inspection
Consists of inspecting random shipments It is only partially effective since some
shipments are accepted without inspection
Spot Checking
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A certain percent of a shipment is inspected
Accept/reject decision regarding that shipmentis made, based on the inspection results of that
certain percent of the shipment. The most popular or widely used plan under
this alternative is called 10% sampling
For some shipments or lots, 10% is too small a
sample to be representative, whereas for othershipments or lots, it may be too large
Arbitrary Sampling
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Also referred to as random samplinginspection
Takes a sample of units from alot/shipment, inspects samples for defectsand makes a decision whether to accept orreject a lot.
It is applicable to inspections of rawmaterials, partially finished goods andoutgoing final product shipment.
Statistical Sampling
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AQL
The AQL is the maximum per cent defective that for the
purpose of sampling inspection can be considered
satisfactory as a process average."
In layman's language this means, when a buyer
specifies a particular AQL for sampling inspection, it is
an indication that as long as the percentage of defective
garments in the shipments (lots) supplied by a
manufacturer is lower than the AQL, most of theshipments will be accepted.
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The AQL inspection takes the samples from a goods,
inspect them and depends on the quality of samples
inspected and decide to accept or reject them.
The standard is based on Military Standard 105D (MIL-STD-105D)
It provides with the sampling plans, the number of
samples to be inspected and the acceptable quality level
(AQL) AQL 1.5 is applied to very severe inspection on high-
class expensive item.
AQL 2.5 is applied when textiles of normal/good quality
are involved.
AQL Random Sampling Inspection
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What type of risk in AQL?
Producer's risk: The chance of
rejecting a good lot that contains equal
or less percent defective than AQL. The Customer's risk: The chance of
accepting a bad lot that contains more
defective than the largest proportion ofdefects that a consumer is willing to
accept a very small percentage of the
time.
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Sample size Code Letter
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Single Sampling Plan for normal inspection
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Double Sampling Plans
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Assume AQL is 2.5% and lot size is 600
garments, find out the following :
The total number of samples need to inspect
The acceptable number of the samples
The rejection number of the samples
ExampleSingle Sampling Plan-Normal Inspection
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First, from Table 1 find out the code letter forlot size of 600 and inspection level II isJ
From Table 2 (single sampling plan), the letter J
corresponds to sample sizes of 80. So, 80 samples are needed to inspect out of 600
At AQL 2.5%, if defective garments are less thanor equal to 5, whole lots will be accepted, if it is
found to be 6 or more, whole lots will be rejected.
Answer
Single Sampling Plan
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If the garment lot is 300 dozens, and AQL
is 4.0%, find out
the number of samples to be inspected
the acceptable number and rejection
number
Try this one
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Assume AQL is 4% and lot size is 2000
garments, find out from double sampling
plan on the following: The total sample sizes need to inspect
What is the first acceptable number
What is the second acceptable number
Example II
Double Sampling Plan
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First, Table 1 of 2000 lots at inspection level II is
letter K
Table 3, double sampling plan shows thesample size of letter K is 80.
First inspection, at AQL 4%, the acceptable
number is 5, rejection number is 9
If any number between 5 to 9, second inspection
is needed
Answer
Double Sampling Plan
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For second inspection, the sample sizes again is
80
At AQL 4%, the cumulated acceptable number is12 and rejection number is 13.
Conclusion
If the number of defective garments found
in the first sample is 6, and in secondsample is 5, making a total of 11, then the
whole lot of 2,000 pieces will be accepted.
Answer
Double sampling Plan (II)
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A total of 3,000 dozens of sweaters were
produced. At AQL 2.5%, find out the
following at double sampling plan: The total sample sizes need to inspect
The acceptable number at first inspection
The acceptable number at secondinspection
Try this one
Double Sampling Plan
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Defects of Quality in Apparels
Please take a Ten Minutes Break!
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