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Processing, Dyeing & Finishing
  Fabric usage & various fabric losses in cutting room
The percentages of various costs which add up to give the garment cost are as follows: raw material cost 50 %, direct labour cost 20%, indirect labour charges and factory overheads 30%. The relative cost of raw material is the point of discussion here. The raw materials include fabrics, sewing thread, trims and accessories (button, zipper, fusible interlining, embroidery, bidding, labels, narrow fabrics, motifs, etc) used in the garment. The raw material cost ranges from 40% for hosiery to 60% for lingerie. The cost of fabrics is 80% of the cost of raw material. Though all materials are important for the garment, the fabric being the dominant among the cost factors should be managed properly. It can save many dollars if properly managed.

Mostly all the papers and research works are based on improving the marker efficiency. But very few work or research has been done to reduce the fabric losses outside the marker. For proper costing of a garment, and cost reduction, it is necessary to have good understanding of the fabric utilisation and various fabric losses that occur during garment production. In this article, the fabric utilisation and the various fabric losses that occur in garment production are being discussed.

Fabric utilisation

Before discussing about the fabric utilisation, one should have knowledge about various widths of fabric used in garment production. The fabrics can be broadly divided into the following three categories:

1.Tubular Knitted Fabric:

These fabrics are produced by circular knitting machines and may or may not be slit after production. If a slit is made, then it falls in the category of 2 or 3 discussed below, otherwise it is spread and cut in tubular form. Mainly the underwear and leisurewear falls under this category and the fabric width corresponds to the dimensions of the body panels as shown in Figure 1.

Figure 1. Tubular Knitted Fabric

2. Narrow Open-width Fabric:

The fabrics having a width of one metre fall under this category. The fabric width can accommodate two body pieces during marker planning as shown in Figure 2. In this type of fabric, during the pattern making process all the patterns for the medium size is done and it is then graded to sizes above and below it. Then in the marker the patterns are paired in such a way that the additional space occupied by the larger pieces is compensated by the corresponding lesser space occupied by smaller pieces. Maximum marker efficiency can be achieved if the numbers of smaller pattern pieces in the garment are relatively more (eg, menís shirt, ladies blouses etc.).

Figure 2. Narrow Open-width Fabric

3.Wide Open-width Fabric:

This type of fabric is having a width of 1.5 metre and three body pieces can be placed in the width of the fabric as shown in Figure 3. In this type of fabric there is very wide room to achieve maximum marker efficiency, as there is no constraint of fabric width. The highest marker efficiency can be achieved for the garments having large number of smaller parts as well as for the garments having relatively larger patterns.

 Figure 3. Wide Open-width Fabric

Requirement of fabric in relation to garment style

Among the various processes of garment production cutting is the major area where fabric waste is generated. In the cutting room much attention should be given to reduce the fabric wastage. One of the methods to minimise the fabric wastage is to prepare the most efficient marker by the CAD system. A marker is a diagram of a precise arrangement of pattern pieces for all the sizes of a specific style that are to be cut from a single spread. Marker planning or marker making is the process of judicious arrangement of pattern pieces according to the fabric width for various sizes so that there is maximum fabric utilisation. The process of getting the most efficient marker requires time, skill, mathematical ability and concentration. Nowadays, the CAD systems support in pattern digitizing, grading and marker making.

The number of markers required, the number of complete patterns of each size in a marker, and the number of ply that will be cut from each marker is decided according to cut order planning. The most efficient size ratio is 1:2:2:1 (ie, a marker may contain one small, two medium, two large and one extra large). Additional markers may include only small and medium depending on the number of pieces for which the order is received.

Markers are made according to the fabric width and the quantities of sizes. If the marker is wider than the fabric width the patterns at the edge of the fabric will be incomplete and if the marker is narrower than the fabric width, there is fabric wastage. When the fabric width is highly inconsistent, the fabrics in a lot may be grouped according to the width and different markers are made for each group.

Marker efficiency

The quantity of fabric usage depends upon the marker efficiency. Mathematically the marker efficiency is the percentage of the total fabrics that is actually used in garment parts, ie,

Marker efficiency = (Area of pattern pieces/Total fabric area)*100

Higher is the marker efficiency higher is the fabric usage. Expectations for marker efficiency differ from manufacturer to manufacturer. The area in between the pattern pieces, which is not used by garment parts, is waste. The area of each pattern piece may be determined by a planimeter or computer. A planimeter is a mechanical device that calculates the surface area as the outline of the pattern is traced. The marker making software calculates the combined area of all the pieces in the marker and the marker efficiency. Marker efficiency is commonly affected by fabric characteristics, shapes of pattern pieces, fabric utilisation standards and marker quality.

Fabric Losses:

The marker provides the dominant control of fabric usage minimizing the fabric loss. During the cutting process two types of fabric losses occur, namely marking loss and spreading loss. The marking loss arises due to the gap and the non-usable areas at places between the pattern pieces of a marker. Marker efficiency indicates the amount of marking loss. Spreading loss is the fabric loss outside the marker. The various fabric losses outside the marker can be broadly classified into different groups, namely ends of ply losses, ends of piece losses, edge losses, splicing losses, remnant losses, ticket length losses, etc, which are discussed below:

1.Ends of Ply Losses:

The flexibility, limpness and extensibility of fabrics along with the limitation of spreading machinery necessitate an allowance of some fabric at the end of each ply. These losses may be up to 2 cm at each end or 4 cm per ply. In case of some stable fabrics it may be less and for some unstable fabrics it may be more. The ends of ply loss (Figure 4) is 1-2% of the total fabric usage. Higher is the fabric length the lesser is the loss. If strong vigilance is not kept over the spreading machine setting and material handling, there is a tendency for the waste to become excessive. Standards should be established for this loss in the cutting room and it should be monitored properly by efficient supervisors.

2. Ends of Piece Losses:

In textile industry fabrics are produced and processed in different batches. During finishing these fabric ends are stitched together for continuous operation, which makes the fabric ends unsuitable for use due to marks or distortions created. The lengths affected should be as less as possible, ie, only a few centimetres. The most important loss comes because the fabric length is not exact multiple of the marker length. The spreader must either splice in the next piece, resulting in a loss of fabric from the end of the piece to the nearest splice point, or the part ply must be laid aside as a remnant and processed separately. The ends of piece loss varies from 0.5-1% of the total fabric usage.

This loss is minimised if the average length of the pieces that are purchased is increased. This strategy has a number of other advantages, including the reduction in documentation, reduced levels of shade variation, and higher productivity in spreading. However, the pieces are heavier and investment in material handling equipment is often necessary. The ends of piece losses cannot be eliminated completely, but it can be controlled by establishing clear procedures for splicing and processing of the remnants. This also requires good communication, training and systematic monitoring.

3.Edge Losses:

In normal practice during marker planning, the width of the marker is kept a few centimetres less than the edge-to-edge width of the fabric. The marker is made according to the usable width of the fabric. The usable fabric width depends upon the quality of the selvedge, the consistency of fabric width, and also on the precision of edge control during spreading. Let the fabric edge-to-edge width is 100 cm, and the marker width is 3 cm less than the fabric width. The edge loss is 3%. If the fabric edge-to-edge width is 150 cm, the loss is 2%. Thus wider width fabrics have other benefits besides improved marker efficiency.

If the fabric is exceptionally stable, it is possible for the marker width to be only 2 cm less than the edge-to-edge fabric width. In such case the edge loss with a 100 cm fabric is 2%. This simple calculation reveals that the fabric loss outside the marker is very sensitive to the edge waste allowances. Great care is needed to ensure that the allowance is not excessive. Width variation in fabrics must be controlled alongside the edge allowances. Most companies experience great difficulties because of inconsistency of edge-to-edge fabric width in case of narrow width fabrics.

4. Splicing Losses:

Splicing is the process of overlapping the cut ends (the end of one length of fabric and the beginning of another) of two separate pieces of fabrics so that spreading can be continuous. Splicing is necessary as one roll of fabric is finished and a new roll is taken into use. Also during spreading there may be some objectionable fabric faults, which make the product unsalable or substandard. These faults are removed by cutting the lay at the fault point and incorporating splicing position into marker plans. During splicing the splicing line should be so selected that none of the pattern pieces contains the fault or is incomplete. The distance between the splicing lines influences the amount of waste produced. The average waste per splice will be approximately half the average distance between splices lines. The distance between splice lines is dependent on the dimensions of the marked panels and on the way they have been positioned by the marker planner.

The position of the splice lines also dependent on the quality of the fabric being spread. If cutting out faulty material at the lay is a regular requirement, it is vital that markers are provided with clearly defined splice lines. A splicing allowance is made to ensure that only complete panels are cut. While certain development with automatic spreading can reduce this loss, splicing with manual spreading requires commitment and consistency on the part of spreader to minimise waste.

A clearly defined policy regarding splicing should be set by the management. Factors to be considered include: quality of incoming fabric, the dimensions of the patterns, the spreading technology in use and related procedure for processing remnant lengths. This policy may vary according to local needs and communication between the relevant parties is essential if integration is to be successfully achieved. The splicing losses may vary up to 5% of the total fabric usage.

5. Remnant Losses:

Remnant lengths are produced whenever companies separate different shades of fabric pieces and lay up only complete plies. Remnants may also be generated when short lengths of material are left over after the completion of a lay, and are returned to the stores. All remnants are put to one side and cut separately. Short markers are made to obtain further garments from these lengths. There may be single garment marked if the garment pieces are large, but more garments may be marked if the garment pieces are small. The remnants left over after cutting a remnant lay should be very short and if they are not unusable, should be suitable only for re-cutting individual panels.

The markers produced for remnant lays normally have a lower utilisation than the production marker, mainly because the reduced number of garments marked reduces the options open to the marker maker. Let the marker length is 10 m and the average fabric length is 100 m, the average remnant length is approximately 5 m. Thus 5 m out of every 100 m, or 5% of the total will be processed at a reduced level of efficiency. As this figure is quite significant, controls most be exercised over the sizes of the patterns that are cut from remnants. Two alternatives for remnant lays are possible:

Each lay is processed with a new marker after the main production lays. One remnant lay may be spread after every production lay, or the remnants may be accumulated over a period of time and a deeper lay spread to reduce cutting costs.

A step lay at one end of the production marker, which enables all remnants to be cleared with the main lay. This option is possible only if the marker maker prepares the way. The production marker must have all the pieces for a single garment at one end, so that after the main lay is complete, all the remnants can be spread as a step lay at that end. There is no additional cutting cost, but there may be difficulties with size ratios, as additional garments of one particular size are cut with each lay. Remnant losses can be reduced by utilising two or more production markers. For example if two markers are available, one of 10m and the other of 8m, it is possible to allocate individual pieces to specific markers so that the lengths of remnants is minimised. Thus a piece of 91m would be allocated to the 10m marker, whereas a piece of 97 m would be allocated to the 8 m marker. It is only feasible if both production markers have acceptably high utilisations.

6.Ticket Length Losses:

Woven fabrics and some knitted fabrics are sold by length. Each fabric piece is measured by the fabric supplier and a ticket is attached to each piece indicating the length for which the customer is invoiced. In many cases the gross length and the net length are marked in the ticket. The gross length is the distance between the ends of the fabric and the net length is the length for which the consumer is paying. When there are errors in the measurement of these lengths they are unlikely to be in favour of the purchaser. When the fabric is issued on the basis of the ticket length, there can be fabric shortage against the costed value. This loss can be reduced by inspecting the length of the incoming fabric and reporting the fabric supplier in case of yardage short.

Conclusion

As the fabric is the major raw material in a garment, the saving of very less amount of fabric per garment can save quite a large sum of rupees per annum, which can increase the profit of the organisation substantially. It is necessary for the management to have good understanding of the spreading performance and the distribution of various types of fabric losses in the cutting process for proper material management. Proper investigation of the fabric losses during the cutting process can help the management to minimize material wastage.

References

1. Chan S H, Ng S F, Lo T Y and Hui C L: Textile Asia, October 1998, 50-51.
2. Leary R H: Textile Asia, June 1983, 73-76.
3. Patrick C L H, Frency S F N and Klith C C C: Intl Jr of Clothing Sc & Tech, 2000, 12 (1), 50-62.
4. Ng S F, Hui C L and Leaf G: Intl Jr of Clothing Sc & Tech, 1999, 11 (2-3), 76-82.
5.Gupta B S, Leek F J, Barker R L, Ruchanan D R and Little T J: Intl Jr of Clothing Sc & Tech, 1992, 4. (2-3), 71, 78.
6. Jacobs B C and Riall W: Intl Jr of Clothing Sc & Tech, 1991, 3 (4), 13-24.
7. Tyler D J: Material Management in Clothing Production, Oxford BSP Books.
8. Glock R.E, Kunz G I: Apparel Manufacturing, Second Edition, Prentice-Hall Inc, New Jersey, pp 375-378.
9.Walfish J Bobbin: Vol 24, October 1982, 89-98.
10.Textile Horizons: Vol 4, February 1984, 13.

The authors are with the Technological Institute of Textile and Sciences, Bhiwani, Haryana.

published July , 2008
 
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