Standards for spreading ultimately affect the succeeding operations of cutting, assembly, finishing, and the final fit and quality of the finished products. Spreading operators have many -factors to monitor during the spreading process. A high- quality spread has the following characteristics:
1. Shade sorting of fabric
2. Fabric defect
3. Tension
4. Slack tension
5. Flatness
6. Ply alignment
7. Static electricity
8. Ply direction
9. Matching fabric design
1. Shade sorting of fabric
Fabric rolls that are nominally the same color have been dyed separately and are not exactly shade match. When deliveries of a number of rolls of fabric of the same color are received, they should be sorted into batches. This is normally done by a trained colorist but can be done more easily by spectrophotometer. Batching together rolls of the same shade gives a greater number of plies that in turn give larger bundle. For assorted color when multiple colors of fabric are to be spread, the spreader will alternate colors by roll. This permits easy shade separation after cutting. This will result in a ‘rainbow effect’ when looking at the cut edge of a bundle before sorting. In sorting, all the plies of one shade become a single bundle, which is marked, tied and sent to the sewing room. When only one-color rolls of fabric but different shades have to be spread adjacent to each other in the lay, they are separated by a layer of interleaving tissue or wax paper, which assists in easy separation of the plies for bundling.
i. Tissue paper
In order to create a noticeable separation between varying shades of the same color in the spread, Tissue Paper is used. The tissue separating paper on a roll that is the width of the fabric, is spread out over the last ply of one roll, before the first ply of the next roll of similar color (but different shade) is spread. After cutting, this tissue paper (often a pale pink in color) is visible in the cut bundle.
ii. Wax paper
Wax Paper would be utilized as a shade separator in the case where the lay is high, and friction from the cutting blade might burn or fuse the edges of the fabric near the bottom of the lay. The wax paper would be applied the same as the tissue paper described previously. As the cutting machine cuts through the lay, small amounts of the wax from the wax paper acts as a lubricant on the blade edge, reducing friction, therefore cooling the blade.
2. Correct ply direction and adequate lay stability
These two factors must be considered together. They depend on fabric type, pattern shape and the spreading equipment that is available. When the pattern pieces have been positioned in a particular direction in the marker plan, it is essential that the fabric is spread in away that maintains that direction. Effects of a surface design or fabric construction, problems of instability with special frictional characteristics such as those with a nap or a pile surface. This can required that some fabrics are spread with all the plies face up, some with all the plies face down and some face to face.
3. Elimination of Fabric defect
Fabric defects can have a major impact on the quality of a lay-up and the products to be cut. It is the responsibility of spreading operators to identify fabric defects and make a decision on how to handle them. When a flaw appears, the spreading operator determines its severity, where in the spread the flaw is located, and whether it must be removed. Flaws that are not removed in spreading may appear in the finished garment, which creates a second or a reject. There are three ways to responding to localized fabric faults:
Make through
Make-Through means leaving faults in garment and inspecting out at the end of production. This option is possible where there is a market for sub standard goods.
Cut out at the lay
Cutting out at the lay involves creating a splice. The spreader cuts across the ply at the position of the fault and pulls back the cut end to overlap sufficient fabric to allow complete garment parts by reference to the marker.
Sort and re-cut
Faults are normally marked but no action is taken during spread. After cutting is completed, the blocks are inspected for fault and any defective pieces are recut and replaced from remnant fabric. Re-cutting a flawed piece requires more time and labor cost, but it can be cost-effective when the fabric costs are high and the garment pieces are large in size, and fault rate is high.
4. Elimination of ply tension
Tension or tightness of a spread, is a major factor, that ultimately affects garment fit and quality because of the reaction of the fabric. Fabric should be as tension-free as possible when spread. A tight spread will contract in length, and the ends may tend to draw inward. This may occur while the fabric is waiting to be cut, which may result in a spread that is shorter than the marker. Tension can be a problem with any fabric, but it is a special concern for knits and fabrications containing spandex. To avoid excessive tension, fabrics may be spread having following measures:
Relaxing overnight
For most knit fabrics, the common practice is to let the entire lay “relax” on the cutting table overnight. If the lay is significantly long, it may be cut into long blocks in the length of the goods, allowing the shrinkage to occur more evenly.
Beating the Lay
Beating the Lay
To further ensure that the fabric is spread without tension, the practice of “beating the lay” is performed for most hand-spread modes. The spreader takes a wooden yardstick and hits the top layer of fabric repeatedly down the length of the table. This will cause the fabric to “jump” or purposefully shrink back prior to laying down the next ply.
Some spreading machines are equipped to vibrate or agitate the fabric as it leaves the roll and before it is placed on the table, which reduces the tension and elongation of stretch fabrics.
5. Ply alignment
Every ply should comprise at least the length and width of the marker plan, but should have possible extra outside those measurements. The nature of the fabric piece delivered from supplier vary in width, both roll to roll and to a lesser extend with in single roll. The marker plan is made to fit the narrowest width. Ply should be aligned during spreading as it affects fabric waste and accuracy in cutting garment parts. If there is no width variation in the piece goods, both edges will be aligned, but if variation occurs within a roll or between rolls, it is essential to keep one edge accurately aligned. Aligned edges of piece goods are matched with one edge of the marker for accurate cutting and effective fabric utilization.
6. Static electricity
In spreading plies of fabric containing man-made fibers, friction may increase the charge of static electricity in the fabric, which may cause fabric plies to cling to machinery or other fabric plies and creates problems with flatness and accuracy of alignment. Friction may be reduced by changing the method of threading the fabric through the guide bars of the spreading machine. Humidity in the atmosphere of the cutting room may also be increased, thus allowing the static electric to discharge continuously through the atmosphere. In some case it may be necessary to earth the lay.
7. Avoiding distortion
Distortion can be introduced to fabric lay during lay movement and cutting, which affect cutting quality and these need to be controlled carefully. A layer of glazed paper, laid glazed upside down, is normally placed at the bottom of the spread. This helps to avoid disturbing the lowest plies on the material in the spread when the base plate of a straight knife passes underneath. Also gives stability to the lay if it is to be moved on a table.
8. Avoidance of fusion during cutting
Fusion during cutting is not a spread problem, but there are things that can be done during spreading to help. Cut edge thermoplastic fabric may be fused together during cutting if the cutting knife becomes hot as a result of friction with the fabric. To help reduce the problem, anti-fusion paper can be inserted in to the lay. This contains a lubricant that lubricates the knife blade as it passes through the spread, thus reducing the generation of heat energy and the temperature of the knife. Fabric fusing may be reduce by using silicon lubricants on the knife blade directly or reducing ply height.
9. Fabric Control during spreading
Controlling the fabric during spreading is necessary for the cut parts to be of the highest quality. Ideally, each ply should be spread with the selvage (or fold) superimposed one atop another on the control edge, the fabric should be square, flat and without tension.
i. Smoothing fabric
Some fabric when delivered on the roll, may have pleats folded in the goods on the roll. The spreader must straighten out those pleats before cutting, or the cut parts will be misshapen. During spreading it is also necessary for the spreader to open out any unnecessary folds, or creases, and to eliminate ‘bubbles’ caused by uneven tension in softer fabrics.
ii. Skewing and Bowing control
Skewing may occur when the fabric comes off the roll angled across the weft (width). This condition known as skewing is when the weft at one selvage is further down the table than the other. This will cause the fabric to be off-grain in the (across) cross body direction. A spreader can pull the goods slightly to minimize this problem, but most often, management may decide not to spread skewed goods.
Bowing occurs when the cross-grain weft bends further down the table in the center of the goods only. This condition is difficult to minimize, so in extreme cases, the fabric will be rejected.
iii. Slack tension control
Slack tension is a lesser problem, but it still must be monitored. A slack spread contains excess fabric in each ply that may create billows and ridges in the spread. As other plies are positioned over loose folds, creases that may distort the cut garment parts. Operators are able to monitor slack tension better than high tension because slack tension is more visible.
iv. Tight salvage control
The flatness of a spread may also be affected by the finish and behavior of the selvage. Selvages may shrink excessively or be stretched during fabric finishing. If either edge of the fabric draws together, it causes the fabric fullness in the central area of the spread. In most instances the only solution is to remove the problem prior to spreading by relaxing the salvage. Spreader may take a short knife and slit the salvage (up to salvage depth) in every six or twelve inch.
Some spreading machines are equipped to vibrate or agitate the fabric as it leaves the roll and before it is placed on the table, which reduces the tension and elongation of stretch fabrics.
5. Ply alignment
Every ply should comprise at least the length and width of the marker plan, but should have possible extra outside those measurements. The nature of the fabric piece delivered from supplier vary in width, both roll to roll and to a lesser extend with in single roll. The marker plan is made to fit the narrowest width. Ply should be aligned during spreading as it affects fabric waste and accuracy in cutting garment parts. If there is no width variation in the piece goods, both edges will be aligned, but if variation occurs within a roll or between rolls, it is essential to keep one edge accurately aligned. Aligned edges of piece goods are matched with one edge of the marker for accurate cutting and effective fabric utilization.
6. Static electricity
In spreading plies of fabric containing man-made fibers, friction may increase the charge of static electricity in the fabric, which may cause fabric plies to cling to machinery or other fabric plies and creates problems with flatness and accuracy of alignment. Friction may be reduced by changing the method of threading the fabric through the guide bars of the spreading machine. Humidity in the atmosphere of the cutting room may also be increased, thus allowing the static electric to discharge continuously through the atmosphere. In some case it may be necessary to earth the lay.
7. Avoiding distortion
Distortion can be introduced to fabric lay during lay movement and cutting, which affect cutting quality and these need to be controlled carefully. A layer of glazed paper, laid glazed upside down, is normally placed at the bottom of the spread. This helps to avoid disturbing the lowest plies on the material in the spread when the base plate of a straight knife passes underneath. Also gives stability to the lay if it is to be moved on a table.
8. Avoidance of fusion during cutting
Fusion during cutting is not a spread problem, but there are things that can be done during spreading to help. Cut edge thermoplastic fabric may be fused together during cutting if the cutting knife becomes hot as a result of friction with the fabric. To help reduce the problem, anti-fusion paper can be inserted in to the lay. This contains a lubricant that lubricates the knife blade as it passes through the spread, thus reducing the generation of heat energy and the temperature of the knife. Fabric fusing may be reduce by using silicon lubricants on the knife blade directly or reducing ply height.
9. Fabric Control during spreading
Controlling the fabric during spreading is necessary for the cut parts to be of the highest quality. Ideally, each ply should be spread with the selvage (or fold) superimposed one atop another on the control edge, the fabric should be square, flat and without tension.
i. Smoothing fabric
Some fabric when delivered on the roll, may have pleats folded in the goods on the roll. The spreader must straighten out those pleats before cutting, or the cut parts will be misshapen. During spreading it is also necessary for the spreader to open out any unnecessary folds, or creases, and to eliminate ‘bubbles’ caused by uneven tension in softer fabrics.
ii. Skewing and Bowing control
Skewing may occur when the fabric comes off the roll angled across the weft (width). This condition known as skewing is when the weft at one selvage is further down the table than the other. This will cause the fabric to be off-grain in the (across) cross body direction. A spreader can pull the goods slightly to minimize this problem, but most often, management may decide not to spread skewed goods.
Bowing occurs when the cross-grain weft bends further down the table in the center of the goods only. This condition is difficult to minimize, so in extreme cases, the fabric will be rejected.
iii. Slack tension control
Slack tension is a lesser problem, but it still must be monitored. A slack spread contains excess fabric in each ply that may create billows and ridges in the spread. As other plies are positioned over loose folds, creases that may distort the cut garment parts. Operators are able to monitor slack tension better than high tension because slack tension is more visible.
iv. Tight salvage control
The flatness of a spread may also be affected by the finish and behavior of the selvage. Selvages may shrink excessively or be stretched during fabric finishing. If either edge of the fabric draws together, it causes the fabric fullness in the central area of the spread. In most instances the only solution is to remove the problem prior to spreading by relaxing the salvage. Spreader may take a short knife and slit the salvage (up to salvage depth) in every six or twelve inch.
No comments:
Post a Comment