Wednesday, May 25, 2011

CUTTING SYSTEMS IN GARMENTS FACTORY; AUTOMATED, NUMERICALLY CONTROLLED



Automated cutting is the best system for fabric lay cutting in garments. Automated cutting more faster than manual cutting system. Automated cutting system is operated by computerized numerically controlled cutting system. Required low labor cost and the lowest man power for automated cutting system.

Objectives of Automated cutting system:
 -Equipments and their operations
 -Recent development in equipments and techniques

 The four types of automated cutting systems are:
(I) blade cutting,
(II) Laser cutting,
(III) Water jet cutting, and
(IV) Plasma jet cutting.

Electronic microchips control the cutting device, travel pattern, and speed. Computer-generated markers are stored and used to guide the operation of the cutting head. Printed markers are not required for cutting but may be used to assist with bundling. The primary advantage of computerized cutting systems is the accuracy of the process.

Automatic Blade Cutting is the most highly developed and widely used computerized cutting system. Systems are specific to the standard volume to be cut. Numerically controlled knives cut multiple plies with great accuracy and speed. Information can be downloaded directly to the cutting system when needed. Easy data entry and instant communication with the main control unit allow technicians to preprogram multi-step commands, set parameters, and start the process with a single keystroke.

The central control unit operates the components of the system such as the cutting head, cutter carriage, knife sharpening, and conveyorized cutting table. A cutting head is a sophisticated mechanical component with the capacity to cut, mark, and drill as dictated by the computer. Automatic knife sharpening is done at preset intervals during the cutting operation. The cutter carriage moves the cutting head and provides lengthwise and crosswise motion during the cutting operation. The reciprocating blade can be adjusted to the height of the spread and density of the fabric. Knife speed automatically adjusts to the forward speed of the cutting head. As the cutting head slows for corners, curves, or notches, the reciprocating blade also slows to reduce heat and possible fusing. Most reciprocating knife systems use a vacuum to hold down the fabric. Placement of plastic film over a spread helps compress the fabric into a firm stationary lay-up when the vacuum is applies. The effect of the vacuum is to reduce the height of the spread and eliminate fabric movement during cutting. An intensified vacuum force is automatically applied to the area directly under the knife to further restrict material shifting

Laser Cutting focuses a powerful beam of light projected onto a minute area to cut fabric by vaporization. The fine, V-shaped beam is only 0.004 of an inch. The beam cuts without pressure on the fabric, which is a major advantage for some types of fabric. The fabric remains immobile during the cutting operation.

Lasers cut with incredible speed (twice that of automatic knife cutting), accuracy, and multidirectional ability, but with some heat emission. Laser-cut edges are sharp and clean. The heat produced tends to seal fabric edges, which can be an advantage for fabric that ravels and a disadvantage for cutting multiple plies as edges may fuse together. Laser-cut garment parts are easier to assemble, as they are consistent in size with smooth sharp edges to align.

Water Jet Cutting is another computer-operated, multidirectional method that has limited usage at this time. Water jet cutting is performed by propelling a tiny jet of water (0.0010-0.0015 inch) through fabric at very high pressure (70,000 pounds per square inch). The forward edge of the jet stream shears the fabric as it moves along the cutting line but does not wet the fabric, generate airborne contaminant, or exert an appreciable force on the ma-terial. The water jet will cut multiple plies without fusing, but it may fray and tangle the yarns of some fabrics, which makes it difficult to separate the plies. It is used when heat build up must be avoided and water absorption is not important. At the present time its use is limited to cutting leather and vinyl fabrics.

Plasma Jet Cutting is a computer-operated, high-speed, single-ply cutting device that offers many of the same features of a laser cutter but at a lower price. Along with the plasma jet cutting system, Investronica has developed a Matching System for automatic matching and cutting of striped, checked, or printed fabric. A TV camera reads the fabric on the conveyor, and a digital image processor decides the best way to match and layout the pattern pieces based on determined matching rules. Matches can be made among different prints, selvages, and fabric characteristics. This system eliminates recutting parts for more precise matching.

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Wish you good luck......................................................

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