Sunday, May 5, 2013

AQL | Acceptable Quality Limits or Level

Major concept of Acceptable Quality Limit or Level:

It is the allowable percent defective in a lot. This is introduced according to American military Standard of product inspection rules. There are generally 6 AQL used in textile which are as follows:- 1%,1.5%,2.5%,4%,6.5%,and 10%. Among them 2.5%,4%,6.5% and 10% are widely used and accepted according to price and type of garments.

Uses of AQL: In this system, sample is selected statistical method by using random sampling technique from a lot. After proper inspection along with the test results, the decision is taken, whether the lot will be accepted or rejected. Now a days this system is widely used in garments sector before the delivery. Although it is used from raw material to finished product also.

Acceptable sampling system consists of five parts:
1. Lot size
2. Sample size
3. AQL
4. Acceptable number
5. Reject number

Quality Inspection of factories:
According to JIS, Inspection is defined as “ to measure goods by some methods and by comparison with the results obtained against the criteria to judge whether the individual goods are defective or not

In textile factories the fabrics are inspected at the grey state, after pretreatment, coloration and finishing. After inspection the fabrics are classified according to their quality. Therefore fabrics are inspected to meet the requirements of the customers.

The fabrics are categorized in the following way depending upon the faults:

I. Fresh or First quality: Fabrics, hemming major, minor faults according to buyer specification and requirements.
II. Short length or two parts: It is a piece of cloth having a shorter length( More then 50 cm ). Jar parts become equal to fresh quality. Generally buyers gives (3-5)% discount value for the short length.
III. Seconds: Fabrics containing much objectionable minor defects and (8-15)% discount is allowed.
IV. Fents: Cut pieces of fabric measuring 90 cm or more but less than 150 cm lengths. For fents trade discount is (15-30) %.
V. Rags: Cut pieces of fabric measuring 25 c or more but less than 90 cm. This categories are sold by weight and realization is only about 50% of fresh fabric.
VI. Chilly: These are pieces of 25 cm length fabric less than this. These fabrics are bought & sold and trade discount generally given is ( 50-80).

Quality Parameters of Woven Fabrics to be inspected are as follows:

(1) Dimensional characteristics:
a) Length b) Width c) Thickness

(2) Weight of fabric:
a) Weight/unit area b) Weight/unit length

(3) Fabric strength & Elongation
a) Tensile strength b) Tearing c) Bursting

(4) Threads/inch:
a) Ends/inch
b) Picks/inch

(5) Yarn count
a) Warp count
b) Weft count

(6) Crimp
a) Warp count
b) Weft count

(7) Handle

a) Stiffness
b) Drape

(8) Crease resistance & crease recovery

(9) Air permeability

(10) Abrasion resistance and pilling.

(11) Shrinkages/Dimensional stability

(12) Different fastness properties:-
a) Washing fastness
b) Light fastness
c) Perspiration fastness
d) Rubbing

(13) Flameability

(14) Water resistance or absorption power

(15) Design of fabric

(16) Appearance of fabric

Quality parameters for knitted fabric to be inspected:

1. Strength & elongation
2. Course density
3. Wales density
4. Loop length
5. Deformation
6. GSM
7. Yarn count
8. Design

Wish You Good Luck..................................
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