33 Role of Computers in the Garment Manufacture

R. Sheela John

MANUFACTURE 34.1 Introduction

India is the second largest manufacturer of garments in the world. Indian garment industry serves the local market and the export market. It contributes a major share of revenue to the Indian economy and also generates employment to many skilled and unskilled workers. It consists of textile mills, garment manufacturing industries, processing units, fashion designers, wholesalers and retailers.

34.2 Learning Outcome:

At the end of this lesson the student will

• Understand the significant role of computerised machines
• Computerised machines in the fabric inspection, spreading, cutting, sewing, computer colour matching system and embroidery machine Functions and significance of computerised machines
• Computers have become an inevitable part of this growing industry. Computer integrated manufacture has paved way for a smarter and faster manufacture of goods. This module concentrates on the computer integrated manufacture is discussed
• Fabric Inspection machine
• Computerised pattern making, grading and marker planning Spreading machine
• Cutting machine Sewing machine
• Computerised Labelling machine
• Computer colour matching machine Embroidery machine

Fabric Inspection Machine

The garment manufacturing process starts with the inspection of fabric. The fabric is the base of the garment and it may have defects. If this defect is not identified at this point, it will ultimately become a garment which will be defective. A defective garment will be rejected

This becomes a loss to the manufacturer. In this process the defects in the fabric is identified which inturn is corrected or eliminated. In computer controlled machines the fabric is unrolled and passed over the illuminated sensors and gets rolled onto another beam. During this process the sensors identifies the defect and stops the machine. The operator notes the defect and marks its position with ‘x’ mark. During the spreading process this portion is removed with a splice point. Certain models of spreading machines has inbuilt fabric inspection machines. The fabric defects are checked as they are being spread.

Computerised Pattern making, Grading and Marker Planning

Using the CAD software the patterns are prepared and the print out of the pattern is taken in a plotter. The plotter is large scale printer which prints out pattern in its full size. The patterns thus created are graded for different sizes using the same software.

Marker planning is a very important step which enables the economic layout. The economic layout helps in reduction of fabric thus bringing down the manufacturing cost. The marker plan is created for a combination of sizes and the same is loaded in the computerised cutting machine. The marker plan output in a print out form is not needed when the cutting is done through a computerised cutting machine. If the cutting is done manually the marker plan can be printed out in full size and placed over the top layer of fabric.

Spreading Machine

Spreading or laying is process where a piece of fabric is carried from one end of the spread table to a specified length. The end of the fabric is aligned and place at one end of the spread table and the remaining fabric is pushed to the other end. Thus the fabric is laid one over the other. The number of lays is determined by the number of cut pieces required, the thickness of the fabric and the blade height of the cutting machine

The computerised spreading machine can be preset to a number of plies. The machine will emit audible signal when it has reached the set number or when it has come to the end of the fabric. Turntable device functions when the spread is a face – to – face spread. When the fabric is finished, the auto lifter in the machine transfers the empty bar and lifts the next available roll of fabric. Some machines are inbuilt with sensors which detects flaws and damages marked during the inspection process. Once the defect is sensed the ply cutter cuts and makes a splice in that particular position

All the activities of the manual spreading machine are programmed in the microprocessor and therefore the machine works automatically. The spreading is usually a laborious process and thanks to the computerised cutting machines, the process is made simpler.

Cutting Machine

Computer controlled cutting machines are faster and more precise in cutting layers of fabric. The cutting surface of the table has nylon bristles, which are flexible. This supports the lay and keeps the lay in place. The flexibility in the nylon bristles permits the penetration and movement of cutting blade. The bristles allow the passage of air through the table to create a vacuum. The vacuum thus created reduces the height of the lay and holds the fabric in place

The cutting head in the carriage has two synchronised motors which drive the machines to and fro. The carriage moves on rail tracks laid parallel on the sides of the table. A third motor positions the cutting head on the table. These two movements are co-ordinated to give the knife a position on any point of the table.

The cutting head consists of knife, automatic sharpener and a motor. The motor rotates and positions the knife on the lay and makes the cut to the shape of the pattern as per the marker plan. The sharpener sharpens the cutting blade at regular intervals. This cutting machine does the function of a straight knife cutting machine, band knife cutting machine, notcher and drills which is greatest advantage of a computerised cutting machine.

Since the computer controlled knife cuts according to instructions from the computer rather than by following a pattern line drawn on the marker, it is possible to remove the printing of the marker plan.

Sewing Machine

The clothing industry is dominated by sewing machines and the automation of sewing machine is growing day by day. Automation is a process by which the processing of a product with little or no human intervention.

Automation in sewing machines is advantageous for the following reasons:-

• The monotony in the operation causes fatigue and this is reduced or sometimes eliminated by automation
• The cost of labour costs is reduced Efficient in production is increased
• The quality of the product is improved
• Automation in sewing machines includes automatic foot lifting, automatic back tacking and stitch counting.
• Disadvantages of sewing machine automation
• Variations in textile structure makes it difficult to handle
• The changes in the fashion leads to new styles and silhouettes makes the production sequence complicated
• Automation may lead to unemployment, particularly in developing countries

    Machines like button hole, bar tack, button sew and label machine are simple automatic machines which is controlled by CAM The shape of the sewing line is determined by the machine, hence achieving consistency, but the operator must still carry out all the handling activities both before and after sewing.

In a top stitching a shirt collar, it is possible to programme in a number of stitches to give the correct size. At the end of the collar band, the photoelectric or infra-red detection stops the machine at the right position with the needle down for long enough for the turn to be made. Such sensors can also detect different thicknesses of materials such as a thickness between  the patch pocket and the garment panel it is being attached to. Thus the machine can be set to stop automatically at the pocket corner for the operator to move the garment around.

Also the activities like raising the presser foot and bartacking at the end of the seam can be programmed with a microprocessor controlled machine along with needle positioning and the thread cutting. The operator has to perform the initial operations like positioning the fabric under the presser foot.

Fully automatic sewing equipment have been developed for assembling the types of garment which are made in very large quantities with minimum style change and which have within their design a number of parts which can be sewn with materials in a flat state.

These garments are primarily shirts and men’s jackets and trousers. On formal shirts, the top stitching a collar and cuff, label attachment to yoke, yoke attachment to body and patch pocket attachment. On men’s jackets and trousers the main opportunities for automation are in the construction of welt and flap pockets and the serging and joining of leg panels.

Computerised Labelling Machine

The labelling process is used as alternative to the elimination of printing marker plan on the top ply for the computerised cutting process. The labels have adhesives on the non printed side of the labels. This gives the necessary information that aids in bundling. The information includes the name of the pattern and the size codes. This helps in cost reduction as the marker printing is not done and also saves the printing time. The system is mounted over the lay of the fabric where a beam travels along the table. A label dispenser also travels with the beam which gives position to the label placement. Some label dispenser also print label during positioning. Otherwise the labels are printed separately and loaded into the dispenser. The process of positioning is faster if the dispenser is loaded with printed labels.

Computerised Colour Matching System

Computer colour matching system is a boon to the colourists and textile scientists with the fast growing technology. Colour matching requires two important steps; first, careful laboratory dyeing of each dyestuff are made in four concentrations on the substrate of interest such as nylon, tricot, polyester knits or wool carpets. Secondly the reflections of characteristics of these dyeing must be accurately measured by a spectrometer at different wavelengths in the visible spectrum. These reflection values can be measured by an elaborate recording spectrometer and the values are stored in the computer.

Computer programs are available for checking the calibration data which helps to pinpoint errors in measurements recording the reflectance values. This is done before the colour matching is started. The colour matching system permits the dyer to call for two, three, four or five dye combinations.

The result of a computer aided colour matching operation is always a theoretical recipe only. The calculations done by the system are based on the characteristics of single dyestuffs and on the assumption that the individual relations of absorption and concentration are also valid when the predicted dyestuffs are mixed together.

Functions of computer colour matching system can be listed as follows

1.      Colour match prediction.

2.      Colour difference calculation.

3.      Determine metamerism.

4.      Colour –fastness rating.

5.      Cost Comparison.

6.      Strength evaluation of dyes.

7.      Whiteness indices.

Advantages of Computer Colour Matching System (CCMS): Computer Colour Matching System (CCMS) has lots of great advantages in Textile Industry. They are as follows –

• Customers get the exact shade wanted with his knowledge of degree of metamerism.
• Customers often have a choice of 10-20 formulation that will match colour. By taking costing, availability of dyes, and auxiliaries into account, one can choose a best swatch.
• Three to three hundred times faster than manual colour matching. Maximising the first time dyeing to be perfectly right.
• Obtaining economic recipes
• Eliminating illuminant metamerism Minimising lead time
• Minimising dye inventory
• Minimising production loads and Maximising profit

Web based colour matching system is a modern concept that comes as a boon to the colourists whether in small or organised sector. Colour matching is done online where the image of the fabric swatch is submitted and the report is received in a short period of time. The primary function of this application is to provide recipes for shade matching and colour difference.

The following are some of the advantages:

• The speed of the application is much faster as the software works on the internet.
• The client need not worry about system breakdown, bug fixing, maintenance etc., All this will be taken care of centrally.
• The cost is greatly subsidised because the company pays only for one application.
• It is used for listing out various predicted recipes to match the target shade. The recipes are sorted by the order of increasing metamerism.

Embroidery Machines

Embroidery is a surface decoration applied in a fabric / garment to add value to the product. Traditionally embroidery is made in hand. It involves artisans with artistic skills and it takes a longer time to complete. Later the embroidery machines were developed which contains the set number of stitches which can be varied in length and width.This reduces the time of production, but it still calls for skill on the part of the embroiderer. With computerised embroidery machine the commercial production is made easier and cheaper. It can embroider upto 12 samples at a time and it takes only a few minutes for the design to be embroidered. The following are the steps involved in the computerised embroidery machines for creating embroidery design

1. Creation of embroidery design
2. Loading the embroidery design in the machine
3. Positioning the fabric in the machine
4. Embroidering the design

Creation of embroidery design – Designs for the embroidery can be created in any one of the following ways

1. Designs commercially available can be purchased to suit the machine.
2. Manual designs can be transferred into the system through the digitiser. In other words, the manual designs can be digitised with the help of a digitiser
3. Designs can be created in the system usingappropriate software.
4. CAD allows the designer to crop, scale, rotate, move, copy, paste, stretch or distort the designs

Texts can be added in the desired font and size. Many colour schemes can be created from which a final design can be selected. The designs thus created should be in the machine format, if not has to be converted into the machine formats.

    Loading the embroidery designs – Different machines require different formats. The most common home design format is PES. Other design file formats are ART, PES, VIP, JEF, SEW and HUS. Embroidery patterns can be transferred to the computerized embroidery machines through cables, CDs, floppy disks, USB interfaces, or special cards that resemble flash or compact cards.

Positioning the fabric – The embroidering a fabric is placed in a frame. This offers stability to the fabric. Certain types of fabrics require stabiliser to keep the fabric firm. These stabilisers are backup fabrics laid under the fabric or on top of the fabric. Stabilizer types include cut-away, tear-away, vinyl, nylon, water-soluble, heat-n-gone, peel and stick, and open mesh.

Embroidering the design –Embroidery is done with the embroidery head and thenumber of heads in a machine varies from one to fifty six. After the fabric is hooped it is fixed to the machine. The machine is threaded with embroidery threads of prescribed colour. Some machines may have single needed and some may have multi needles. Once the machine is switched on, all the machine heads starts to stitch the designs at the same time and the process needs only monitoring.

Advantages of computerised embroidery machines are

• Designs can be made faster and easier.
• It can be stored for a longer time and can be reused whenever needed. The space needed for physical storage can be eliminated.
• Thick and thin fabrics can be embroidered with ease. Stitch speed and capacity can be increased.
• Special applications like applique, quilting and sequence work are additional features. The quality of stitching is very high and is ideal for commercial use.

Conclusion

The garment industry and the technology is fast growing and the recent garments include seamless garments, where the garments are created in the knitting machine itself. It is widely acknowledged that the computers have an inevitable place in the industry. The computer controlled machines help in increased production and quality.

Bibliography

•  Catherine Fairhurst (2008), Advances in apparel production, Woodhead publishing limited, England.
•  Harold Carr and Barbara Latham (1994), The technology of clothing manufacture, second edition, Om book science, Delhi
• Mikell P Groover (1996), Automation production system and computer integrated manufacturing, Prentice hall of India private limited, New Delhi.
•  Capron, (1996), Computers: tools for an information age, 4th edition, The Benjamin/Cummings publishing company inc, California, P 2.
• Carr, H. and Pomeroy, J. (1992), Fabric design and product development, Blackwell science ltd, Australia, Pp 18, 29.
•  Chockalingam, P. (1999), Computer aided design and manufacturing-CAD/CAM, Paramount publications, Delhi, Pp 8-10, 91.
• Cooklin, G. (1991), Introduction to clothing manufacture, Blackwell science ltd, published by OM books service, New Delhi, P 33.