Assembly Line Balancing (ALB)
Assembly line balancing problems that occur in real world situations are dynamic and are fraught with various sources of uncertainties such as the performance of workers and the breakdown of machinery. This is especially true in the clothing industryFlow chart of ABL gives in bellow: For Denim Pant:
Front parts:
Operation MachineCoin pocket rolling plain
Coin pocket joint Plain
Coin pocket saw stitch Plain
Front raise stitch over lock
Single ply joint Plain
Jipper joint Plain
Saw stitch Plain
Jipper topsin attach with double ply joint Plain
Front rise topsin Plain
High ¼ topsin ¼ Plain
Facing joint Plain
Facing joint 2 Plain
Front pocket Plain
Front pocket joit 2 Plain
Pocket over lock 1 Over lock
Pocket over lock ¼ 2 Over lock
Base pocket ¼ 1 Plain
Base pocket ¼ 2 Plain
Back Parts
Back yoake stitch overlockBack yoake topsin Chain stitch
Back rise Over lock
Back raise topsin Over lock
Marking
Pocket ironing iron machine
Pocket joint 1 Plain machine
Pocket joint 2 Plain
(Both sides joint)
Inseam Over lock
Feed off the arm topsin feed off the arm
Side joint over lock
Side topsin Plain
(Belt)
Belt joint verticalBelt topsin Plain
Belt topsin joint with belt Plain
Loop making Flat lock
Loop joint Plain
Level attach Plain
Belt top Loop Plain
Bottom loop joint Plain
Bottom hemming 1 over luck
Bottom hemming 2 over luck
Button hole button holing
utton attach button attaching
Bar tacking bar tack
Eyelate hole Eyelate holing Snap button attach Snap button attach
Machine wise sewing thread consumption (for 1"stitch)
Machine wise sewing thread consumption per inch are gives in bellow:
| Machine | No. of needle | Thread consumption per inch |
| Plain | 1 | 2.5” |
| Plain | 2 | 5” |
| Over lock | 3 | 16” |
| Over lock | 4 | 18” |
| Over lock | 5 | 21” |
| Flat lock | 3 | 19” |
| Flat lock | 5 | 32” |
| Bar tack | ----------- | 7”---8” normally per operation |
| Button hole stitching | ----------- | 6”—7” normally per hole |
| Button attaching 2 hole | ---------- | 4” per button |
| Feed off the arm | ---------- | 4 “per one needle |
| Kanshai Stitching | ---------- | 4” per one needle |
| Back tape stitching | | 7 “per one needle |
Finishing Section
Materials used in garment Finishing
Iron
Neck board
Back board
Full board
Hand tag
Tag pin
Tissue paper
Al pin
Ball pin
Elastic clip
Hanger
Poly bag
Size sticker
Jucker
Gun tap
Inner box
Muster cartoon box
Pp belt
Blister
Inspected for fused area or fused stain if any.
Inspected for water spot if any.
Inspected for shade variation area if any.
Inspected for broken chain or button if any.
Inspected for correct folding of garments.
Inspected for crinkle area and rough surface if any.
Inspected for stretched garments area during pressing if any.
Inspected for proper drying of garments after pressing.
Inspected for crinkle area and rough surface of pocket if any.
Inspected for unexpected crease in lining.
Inspected for proper shape.
This is also informed that, the temperature, pressure of pressing head and time during pressing must be inspected.
Flow chart of working processes in Finishing Section of ABM Fashion Ltd. is gives in bellow:
Inside quality control
(To checked inside of a garments)
Get up quality control
(To checked all processes of garments making)
Ironing
(To iron the garments)
| | |
| | |
Measurement checking
(To measure all parts of the garments for accuracy)
Waistic
(To attach Waistic)
Button attach
(To attach button)
Re-ironing
(To iron again)
Again checking
(To check again)
Hand tagging
(To attach hand tag)
Folding / hungering
(To folding/hungering according to buyer requirement)
Shading
(To separate various shade of garments)
Packing
(To pack in the poly bag)
Cartooning
(To keep on carton on buyer requirements)
Final Inspection
Garments are inspected by AQL. In this system samples are collected inspected by statistically from the lot size and will decide the lot of garments to be granted or rejected. AQL is mainly used in final inspection after garment making.
Acceptable quality level (AQL) sample inspection methods have been proven to be accurate over a long run. However, the quality level of merchandise at destination is sometimes lower than the per-shipment inspection results. This may be due to transport, handling, change in environment and/or reliability problems. Buyers are therefore advised to take this into consideration when deciding the AQL levels.
Defect Classification:The client defines the AQL and the maximum number of defective goods allowed in the sample size.
Defects detected during visual inspection are usually classified within 3 categories: "Critical", "Major" and "Minor"
1. Critical: likely to result in unsafe condition or contravene mandatory regulation or reject by import customs.
2. Major: reduces the usability/function and/or sale of the product or is an obvious appearance defect
3. Minor: doesn't reduce the usability/function of the product, but is a defect beyond the defined quality standard more or less reduces the sale of the products.
An Individual with defect(s) is called defective sample. In the inspection process, one defective sample is counted one for the most serious defect only no matter how many defects found in the said sample. Clients can specify what points are minor, major or critical in a defect classification checking-list together with the inspection criteria and product specification.
EXAMPLES OF INSPECTION:
The below example illustrates the procedures for utilizing the single sampling plan.
A. Given: FM/AM auto scan radio
B. Batch size = 8,000 pcs.
C. Method: level II major 2.5 & minor 4.0
D. Sample size = 200 pieces
E. Acceptance number = 10 pcs of major &
14 pcs of minor.That means either the major defects exceed 10 pcs or minor defects exceed 14 pcs or both are considered to be “Fail”.
Definition of AQL:
The acceptable quality level or AQL of a sampling plan is a measure of the level of quality routinely accepted by that sampling plan. It is defined as the percent defective (defectives per hundred units X 100%) that the sampling plan will accept 95% of the time. This means lots at or better than the AQL are accepted at least 95% of the time and rejected at most 5% of the time.
The AQL can be determined using the operating characteristic (OC) curve by finding that quality level on the bottom axis that corresponds to a probability of acceptance of 0.95 (95%) on the left axis.Associated with the AQL is a confidence statement one can make. If the lot passes the sampling plan, one can state with 95% confidence that the quality level of the lot is equal to or better than the AQL (i.e., the defective rate of the lot < AQL). On the other hand, if the lot fails the sampling plan, one can state with 95% confidence that the quality level of the lot is worse than the AQL.
The AQL describes what the sampling plan will accept, but it is also important to know what the sampling plan will reject. Information on what the sampling plan will reject is provided by the LTPD of the sampling plan.
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