Denim Quality Control Quality control is responsible for assessing the quality of the fab ric and determining whether the garments produced from the fabric will be able to meet customer requirements.
A system for verifying and maintaining a desired level of quality in the fabric by careful planning, use of proper prop er equipment, continued inspection, and corrective correct ive action as required. Usually quality check workings are based and according to the approved sample by the customer. Quality check is done in order to meet the requirements requ irements of the customer in the fabric. Quality control workings start as soon as the fabric is in-house and cutting department issues an t he quality control department. allocation (a form carrying order#, quantity, wash and etc) to the There are usually 4-5 quality checks done on the t he fabric. They are as follows: 1. 2. 3. 4. 5.
Inspection
Shading Shrinkage Width Weight
Inspection
of the fabric is done before wash, whereas the shading and shrinkage is done after
wash. Inspection: Inspection
is usually 100%. Meaning that all a ll the rolls of fabric required in making of the garment are checked. Inspection is done in other to see any visual defects on the fabric i.e. mispick, knots, lose ends/picks and etc. these t hese defects usually occur during the weaving process pro cess of the fabric. The fabric is graded according to the ³American fault 4 point system ´. In which a defect ranging from 1-3 inches is given 1 point, 3-6 inches is given 2 points, 6-9 inches is given 3 points and above 9 inches it is given 4 points. Then these linear points are converted into 100 square meters of the fabric.
It
should be noted that t hat these linear points are never added to grade the fabric; rather they are converted into 100sq. meter of o f the fabric. And according to the calculated ca lculated answer the fabric is graded. The value of 15 or anything less then 15; means the fabric is of good quality with minimum defects and cleared.
Shading: Shading is also done 100%. Shading depends on the original wash. Further after wash the rolls are classified according to the shade coming in them, because it is not necessary that after wash every roll will be of the same shade. s hade. So the rolls are classified according to the original shade required by the customer custo mer and the shade that is coming after-wash. Families are made and a packing pack ing list shade wise is made in which amount amou nt of rolls carrying particular shade is grouped.
o n 10-15 rolls. That usually comes out to be 15% of the Shrinkage: Shrinkage is usually done on required rolls. Shrinkage procedure is that swatches of fabric sizes 25 by 25 centimeters are cut
and sent to washing. After washing the swatches are again measured to see the length and width of them and the difference is noted. The difference is multiplied by 4 and recorded in wrap and weft direction. Width checking is also done 100%. All rolls are quality checked for width measurement. Usually width checking is done during the inspection of the fabric. Commercial standard for width is 63 inches. Width:
Weight :
Weight of the fabric is done by a standard GSM disc cutter.
Further a comprehensive report regarding quality check is sent to departments such as marketing and commercial for the approval of fabric for cutting.
Department of Cutting Once
the fabric sample is approved, the cutting department must ensure that proper cutting must be made according to the size requirements of the customer.
Cutting basically means the cutting of the fabric into required sizes so that it can be stitched into the required size and shape. The cutting department starts it working after it has been provided with the cutting standard by the PPC. As told before in report before bulk production starts, a sample has to be appro ved, and sample approval is done before cutting. First of all a Zero base pattern is made. Further ³Details of Cutting Standard and Order Closing ´ is sent to quality department, where the quality department gives it comprehensive fabric analysis report especially shrinkage values to the cutting department. Then marker making o f single size is done, fabric sample is cut out and stitched. There-after before wash measurements are done on the sample and sent to washing. After the fabric sample arrives from the washing department it is again measured for any changes. After that the fabric sample graded (given positive or negative values according to the amount of shrinkage) and that is done by tallying the made sample with the approved sample. Grading helps to cut the bulk fabric, as it minimizes errors. Because according to how much fabric is shrinking the fabric would be cut accordingly. When the fabric sample is approved the sample goes to the cutting master, who grades all the sizes according to the approved sample. He feeds all the sizes into the computer system and Gerber plotter makes a maker for all sizes required in the cutting standard. Further shade wise fabric layering starts to take place, the fabric is relaxed and the marker is placed on top of the pile of fabrics and the fabrics are cut according to the marker. After cutting, folding is done; folding is basically the marking of the fabric according to the size, lot, amount of pieces and etc. After that shade matching is done because w hen the fabric is stitched it should have one shade, not that front panel is of some other tone and the back panel of
other. After that the cut fabric is collected and fed to the stitching department by the feeding department. Note that there are two types of cutting; 1. Vertical Block Cutting 2. Normal Cutting Vertical block cutting is done when there is side to side or side to center variation in the fabric. Then one whole garment is cut from one side of the fabric and the other from center and like wise. This is done in other to stop shade variation in the garment. In this way a lot of fabric is wasted. Whereas normal cutting is one in which gar ment pieces can be cut from anywhere. In this way the fabric is utilized much more then vertical block cutting Spreading Methods: There are four basic spreading methods available to a cutting room. Each method can utilize equipment from the very basic to the very sophisticated, which depends upon the type of fabric being spread. First
a word or two on the terminology. A marker maker places the pattern pieces for one or more garments in to an area equal to the useable width of the fabric and to a length that has been predicted when the cost of the style was established. Spreading is the process of laying the fabric on a cutting table to the length of the marker with an allowance at each end for the m ovement or relaxation of the fabric once having been removed from the roll. Once the fabric is spread on the table, the fabric may be referred to a spread or lay depending upon where in the world you are. The diagram below shows a basic spreading machine.
A spreading machine is a device that holds the roll of fabric above the table from which the spreader (the person spreading the fabric) moves up and down the table. There are basically 3 types of spreading machines. The most basic, as shown above, allows the spreader to place a roll on a bar that is held parallel to the table. This type varies from a homemade ³A´ frame spreading only in two directions to a semi-automatic machine where the spreader rides on a platform attached to a power driven machine. The second type is similar to the above but has a turntable. This allows the roll to be rotated after each ply is laid on the table so that the face side of the fabric can spread alternatively up and down. This is face to face spreading. The third type of spreading machine is especially built to spread fabric face to f ace as shown above but with the use of end catchers. These machines are available as manual machines where the end catchers are positioned at the ends of the marker length and when the machine is driven in to the end catcher, a fold is made. This is most appropriate for fabrics such as fusible, linings and pocketing which are less expensive than shell fabrics. The use of end catchers causes slightly higher spread loss unless the equipment is maintained in perfect condition, which is usually not the case. More sophisticated machines provide options such as tension free feeding of the f abric to the table, automatic selvedge positioning and automatic defect tag detection. This last option is based on the mill tagging major defects with a metallic tag that a sensor on the spreading machine can detect and stop the machine from continuing. This is helpful where the speed of the machine is very high reducing the opportunity for the spreader to detect most of the defects. The only problem with this is that the mills in general are only capable of identifying major defects and some mills can only detect approximately 70% of the major defects. Because of this situation, the use of high speed spreading machines is more appropriate to fabrics that are known to have a v ery low incidence of defects. There are four basic methods of spreading fabric on a cutting table. Each method is appropriate for specific fabric types and m arker configurations. The four methods are: 1. 2 Way Face To Face. Also referred to as ³zigzag´ spreading, is used when spreading fabrics, which do not have a direction or nap. This includes denim, casual twills and some knit fabrics. This method is one of the fastest as the fabric folded at the end of the spread and continues back and forth. The markers made for this method of spreading allow for the pattern pieces to be placed in the marker in a random fashion as each ply of the pair that apply to the making of one garment are laid in different directions making the placing of pattern pieces in the marker in one direction redundant. This result in the most efficient markers with the least amount of waste. The folds at the ends of the spread fabric do however cause additional spread loss, as the folds are difficult to keep in line. 2. 1 Way Either Way. This method is used on fabric that has a direction or slight nap but also where the direction of the nap can fall in either direction. Included in the fabrics to which this may apply could
include some sportswear fabrics where if panels within one garment were cut in different directions, such as is the case with denim, a shade difference may be perceived but garment to garment the difference may not be detected. The advantage of this method is that half of the ply ends result in a fold, which is faster than turning the roll on the spreading machine and traveling back t o the beginning of the spread to start the next ply. Unfortunately, this method is rarely used, as it requires the person spreading the fabric keeps track of where they are to maintain the sequence, a process not required by the other methods. 3. Face-to-Face One Way. For fabrics where there is a direction or nap, this method allows for the fabric to be spread in pairs but each ply is spread in one direction. This may be used on plain fabric, plaids, and stripes. 4. Face-Up One Way. This one of the most widely used methods for fabrics which have a direction or nap and where there are asymmetric panels within the garment such as a front panel of a blouse where one front may have a grown-on (as part of the panel) facing where the other front panel does not causing the two pattern pieces to be different. Fabrics would include velvets, corduroy and other napped fabrics. This is the most expensive method as after each pl y is laid on the spread, the roll is transported back to the starting point where no work of direct value is being performed
Spreading Methods Spreading Matching Plaid Fabrics: The spreading and cutting of matching plaid fabric requires a special set of methods to ensure that the plaid lines match where required. Woven and printed plaid fabrics are inherently inconsistent. This is due normal variations in weaving and finishing, which are normally not detected, in plain fabrics. This means that the repeat of the plaid pattern varies to an extent that does not allow the spreading on multiple plies
of fabric where all of the plaid lines match. The repeat in plaid fabrics within a roll and from roll to roll can v ary several inches per yard so to control the position of the plaid lines, the fabric can either be spread a few plies at one time or special plaid matching pins can be used. Spreading a few plies at one time is very time consuming and therefore expensive although many companies use this method as was the case 100 years ago. The use of plaid matching pins involves the following procedure. First
the marker, which is usually shorter than would be used on a plain fabric, is l aid on the table parallel to the edge of the table. The pins are then driven in to the table at one end of the marker, usually 3 across the width of the fabric. Next another set of pins is positioned in a row across the width of the marker at a point usually at the end of the first pattern. This might be 30´ from the first row of pins. A third row of pins may be added at the end of the m arker to control the plaid lines in the warp direction as opposed to the first two rows of pins which will control the plaid patter in the fabric in both warp and fill directions. The diagram below shows the design of the plaid m atching pin and the ³chuck´ that is used to drive t he pin in to the table without damaging the point of the pin.
The diagram above shows the possible positioning of the pins when spreading an a symmetric plaid fabric.
Once the pins are positioned, the ends of the marker and splice points are marked on to the table, the marker is removed, underlay paper is laid down and the f irst roll is prepared for spreading. The fabric is spread from one end of the pins starting with the same plaid repeat each time. During the spreading of the first roll, the length between the repeats may change as shown below.
The fabric is allowed to stay reasonably flat and tension free throughout the process so that pattern pieces at the left end of the spread remain matched. The pattern pieces at the other end of the spread where the plaid lines have been allowed to mov e on the pins, may require re-laying again on a set of pins after the panels at the left end have been cut. This will be considered when the marker is made with pattern pieces that are laid side by side at the right end of the marker will remain constant within on ply or pair. Sleeves, pockets and facings may be laid in this area of the spread where each garment may be slightly different. Using this method allows for a reasonable number of ply to be spread at one time while ensuring that the panels that were placed at the left end of the marker remain identical. During cutting, the marker may be cut apart to allow exact placement of the pattern pieces in to the correct position. In Europe and South America, it is common to see in cutting a process which is quite different than what is considered in the US and Canada as normal. This involves the expectation that once fabric is spread, the cut parts must be removed from the table as quickly as possible. To do this, European manufacturers will use a manual cutting machine, called a straight knife, to cut the spread fabric in to large rough cut pieces. These pieces are then transported to a band knife, where more accurate cutting can be achieved than is t he case with a straight knife. In all methods of spreading, the objective must always be to conserve fabric. When spreading over several makers placed end to end, there is an opportunity to use or ³work-in´ the roll ends leaving very short pieces from each roll. This planning is normal in the minds of well-trained experienced spreaders but where inexperienced staff is used, there is a tendency t o create more roll ends and increase the fabric consumption. Good cutting room managers will emphasise this every day to their staff and not use more fabric than was planned. In good cutting rooms, the staff will go one step further. As the complete the spreading of an order they will stop and calculate the fabric that will be remaining at the end of the process. In some cases, this gives the customer the opportunity of cutting additional units from fabric saved in a specific ratio of sizes. This may cause the need f or a new marker to be made but the key point is the value of the fabric is far greater than the cost of the cutting room process and is therefore more important than the time required to complete the process. This causes a problem where the customer supplies the material and is paying a plant on a CM or CMT basis. The plant may place less emphasis on fabric consumption and greater emphasis on cutting output. This becomes evident when the plant has to report to the customer that they need more fabric than was planned for an order. Worse is a situation where the plant reports that they have cut 5 out six orders requiring the same fabric and then report they are short. Most plants do not understand that when a group of orders are planned against sales, the person planning the orders has created the best breakdown by size or i n a multi-style situation, the ideal breakdown across the styles to service their customer¶s needs. One simple way to identify if a plant has fabric consumption under c ontrol is to review the plants inventory control system. If there is a several day delay in the cutting room reporting the consumption of fabric for each order or the reporting does not clearly identify the specific rolls used and yardage returned to inventory, then the plant has no control. It is not unusual to find that the staff spreading the fabric is not
recording the rolls used and the length spread. If these kinds of problems are identified, then the plant is likely not a good choice and this attitude will be evident in other areas. In some plants that do not have good controls, the cutting room will spread more ply¶s than required in each order to cut up to 2% more units than planned. This will not be reported to a customer that only allows seconds and missing units to be no m ore than 1% to 2% and acts as insurance against havi ng problems when the orders are shipped. In this situation, the plant will over time accumulate units not shipped and occasionally sell the excess units. This is very dangerous as most customers who supply the fabric, will become very upset when they realize what has been happening to their fabric. Some customers may understand this process and unless they find t his abuse has been excessive will ignore the problem because they cannot assist or are not prepared to assist the plant in overcoming the reasons for the plant cutting more units than necessary. More on what a contractor m ay do to keep the customer happy later. Please feel free to comment through our blog.
Material utilization When we look at product costing in the apparel industry, we see that the largest amount of money is allocated to fabric, as much as 50% or more depending on the product. Each area of the production process from scheduling through sewing has to work in harmony to reduce the amount of money spent on piece goods. Material utilization is a continuous practice of using common sense, modern technology, analytical thought process and motivated people to best use material dollars to generate a bottom line profit. It
has been said that if we want to look for profits we need to look in the ³rag bag.´ In 1989 a South African study concentrated on these losses. This study conducted by the C lothing Industry Productivity Association (CLIPA) showed that there was an opportunity to save a minimum of 2.7% without touching the actual arrangement of parts in the marker. A 3% target is possible for any firm that doesn¶t currently have a material utilization program, but even if there is a program, there are areas that may have been overlooked. Shortage versus invoice - Discrepancies can occur when fabric is purchased by the pound then cut in yards per dozen, or the rolls just don¶t measure up. Length and width can vary from the invoiced total. Losses at roll start - Culprits in this area include: indelible marking to identify rolls, not squaring off the beginning of the roll, soil from being unwrapped and swatch cut outs. Something as simple as cutting the shortest length of the swatch acro ss the roll instead of the longest can make a difference in utilization. End losses can be at the end of a roll, when the fabric is not long enough for another marker repeat. Losses can be at the end of a marker section. Some cutting rooms allow additional space between marker sections so they can be separated and cut by two knife operators working on the same spread. The amount of fabric lost at the ends of a spread can vary with the lay up method. Face to face losses are greater than one way up due to the fold instead of cutting straight across, or extending beyond the marks on the table. The amount of end loss is also affected by the end cutting method; scissors can cause a loss of 1´ per ply over a cutter.
Width loss is mainly due to variations in width between rolls of fabric issued. The marker is based on the narrowest roll. For example, some the fabric may be 60´ wide but the marker is created for 58´. The question arises as to when was the measurement of that fabric known and how did the information get to the cutting room? In the past, when dozens of cut orders were issued for the same style, additional markers in incre ments of ½´ may have been created as time permitted. If we paid for 58´ and got 60´ fabric, it is a loss of material but also a lost opportunity. Discrepancies or unaccounted for from invoice ±Things that may be included in this category are: taking off more when sewing between rolls and setting aside leftover fabric that eventually gets lost. An example of this issue: there were inaccurate formulas for determining bias cut rib for cuffs which resulted in orders held for shortages of rib. Another example: an operator uses fabric to wipe up a coffee spill on the floor. The main causes are neglect, poor recording techniques of damages, splices and remnants and the current incentive system. Damages, re-cuts and remnants include things such as fabric overlaps and splice areas. Depending on a company¶s practices these losses may show up elsewhere. There are t hree choices in flagging defects: 1) don¶t worry at all ± spread, cut and sell all; 2) cut out defects; and 3) flag defects, then re-cut individual pieces. Options 1 or 2 are more typical when the fabric is less than $5 a yard. Marker fallout which was 15% on average in the African study is generally product specific but can be affected by the size mix. Marker efficiencies are ³value added´ and most companies have targeted percentages for their product. How can a company realize savings? One strategy might be if the plant could improve on yields, the company may feel they have ³free´ piece goods, and that this material could be used on new orders. If you get those new orders you win; if not, you lose. Fabric types can change and you may end up paying for storing and insurance just to sell it later for pennies on the dollar. The company could have used that money for a more profitable item without having it tied up. Also, because of yardage estimates they could charge the first customer too much to be competitive and lose the business. Another strategy could be to lower the ³buy´ figure, only buying what you need for the cuts you have. The result is less monies dedicated to material purchase up front, if the estimates are accurate and losses don¶t exceed expected. If not, you may have to buy more at a minimum order size when the extra is not needed. A lower buy figure results in lower inventories and inventory carrying costs are reduced. Assuming that we did a good job of estimating our fabric needs and markers, how can we save at Purchasing? Bargaining for the best po ssible prices? Keep in mind that with a lower cost point usually means lower quality piece goods, and more defects per yard. Do we have a ready market for irregulars? Do we have a quality name we don¶t want to injure? Partnerships with piece goods vendors are important to improve the bottom line. Textile and apparel partnerships provide an opportunity to control delivery and inventory, to have larger rolls with fewer seams, specific widths and lengths of fabric, more co nsistent shades and better quality. All of these things will have an impact on material utilization.
In
addition to planning, procedures in place can help improve material utilization. At Fabric inspection check the widths of rolls; if there is time, re-make the markers according to fabric widths. Measure the length of rolls, verifying that you received what was ordered and paid for. Inspection processes and frequency depend on the cost of material. A fabric inspection program gives a firm the ability to rate vendors for future partnerships. Design is another area that can affect material utilization. For example, in a rugby shirt with multi-color stripes, a designer may specify the green stripe has to be 1´ down from the top of the sleeve seam. This prevents laying the sleeve and body side by side and may increase yardage by 20-30%. The company needs to define who has control over the final product ± the designer, the merchandiser, or the engineer. Manufacturing needs input into the design process. Pattern engineering can evaluate: the width of seam allowances, the lengths of panels for hemming purposes, and the mitering of pattern corners. Can two pattern pieces be created from one piece? Generally smaller and more numerous pieces contribute to greater material utilization, but increased sewing costs. The origin of the ³riser/ back yoke´ on jeans led to better material utilization and better fit. Those savings will add up with every ply that is cut with the marker. In
this cost-conscious environment, companies have to look everywhere possible for savings. Don¶t forget to check out the rag bag.
