aql n quality

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



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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



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Defects of Quality in Apparels

Please take a Ten Minutes Break!


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aql n quality

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