- Visual fabric inspection testSkew test
- Shrinkage test
- Shade matching test
- Ounce test
Visual Fabric Inspection Test
It is the first test performed in FID to check the fabric visually for weaving defects. Fabric is taken from the store room by the help of PCR activity report and rolls are brought for checking. An inspection machine is used for this purpose which has diagonal glass surface and lot of tube lights on its top, fabric roll is adjusted on one side of the machine and a specific length of fabric is unrolled from the roll to pass over the machine and to reach on other side where observer is standing. When machine runs, fabric also starts unrolled from roll and pass on a smooth speed so that observer easily mark fault if there is any under the light of several tube lights. Some of the defects, which are noted during this process are:
- Miss pick
- Double pick
- Wrong drawing
- Double ends
- Short ends
- Broken ends
- Startup mark
- Poly thread
- Loose ends
There are two systems to evaluate defects; one is a japan 10 point system and other is a Americans 4 point system. Japanese system is not used, now American system is mostly used in the industry. Actually it is the system to score a fault by seeing its length against 4 points as shown below.
Faults length (inches) Points 1-3 1 3.1-6 2 6.1-9 3 9.1-39.37(1 meter) 4
According to the table 1, score is allotted to any defect having any specific length to calculate DHU (defects per Hundred Units). At the end, average of all rolls is calculated according to the given below formula:
Point per 100 square meters = Total points * 100 / total fabric inspected*average width
It gives us average DHU per roll, we have DHU tolerance limit so if final score lie within the tolerance then fabric is passed and if it cross the tolerance limits then rejected. Different companies use different DHU tolerance limits, Â majority uses 15 points per roll in square meters length and 28 points per roll in linear meters length but normally calculations are based on square meters length. On the behalf of this evaluation, fabric is also categorized as A grade, B grade, C grade etc
Skew means twist, tilt, slanted or distorted, as it is showing its meanings this test is done to check the skew in the fabric which is produced when warp or weft changes its position due to very high twist in yarn. It is required in woven and especially in denim to accommodate the shape of body as body is not flat, it also has curvature, slanted and also flat portions but at the same time it is also a fault so a specific amount of skew is accepted. Silhouette of the garment will also be disturbed, if it crosses the tolerance limit. The method used to find it out in FID is that fabric of specific amount of length is taken from a roll normally 1 meter each side when folded, after folding both sides from opposite to each other (one sides right, others will be left), a cut from 3-4 inches of edge is marked and fabric is torn and same with the other side is done. After doing this, one side of folding is fixed in hands by equaling the edges of fold and a jerk is given to get a final shape after shredding process which results in difference of sides as one side is fixed in hands. That difference is noted and according to the given formula skew is calculated.
- Difference between sides = X so X / 2 = Y
- Percentage is taken by dividing Y with width of that roll Z
- Y / Z * 100 = Skew in %age
If the result is out of tolerance range then the fabric would be rejected.
It is a very important test performed in FID because your bulk totally depends on the shrinkage results. Customer provides us all required information about the product but his all measurements are the measurements which are finally required so in order to achieve that we have to be very careful during this test. On the behalf of FID test report, decisions are made and during Marker Making in GGT seam allowances plus shrinkage is added and then pattern is finalized to get final results after all processes like stitching and washing, now if this shrinkage test is not conducted rightly then definitely all further results based on this would suffer a lot.
Before wash, 4-5 swatches from different fabric rolls are cut and traced of 25 cm2 dimensions with the help of irremovable ink and that is then over locked by O/L machine to make legs. Then washing standard from PD is taken and according to that standard washing process is preceded. After washing process, shrinkage of those 4-5 legs is taken and that is reported sampling room that prepares 8 samples according to the shrinkage report. After that 100% taking swatches from all the rolls makes legs, and then these 100 % legs and 8 samples are taken together to washing. After washing, samples are sent back to sampling for their working and legs are given to FID. FID makes a shrinkage report by noting the difference as before wash is 25 cm, that difference is then multiplied with 4 to get results out of 1 square meter. Warp and weft shrinkage is determined separately according to the above-described method.
Shade Matching Test
It is also very important test to be performed in FID. It is a natural phenomenon that during dying process, there is a shade variance between lots and rolls even sometimes within a roll so it is very necessary to know about shades exist in roll because during spreading and cutting processes if garment pieces are from different shades then the final garment would be rejected by the customer as it will be having different parts from different shade families like front panels from one shade and back panels from another shade which will create a prominent difference and final look of the garment would be suffering, giving a bad impression to observer. This test is done under the light of tube lights or any other specific light source according to the demand. The method to perform this test is that swatches are compared with original sample and difference of color tone, hue is noted upon which families are created, means less the difference marked as 1 and greater the difference then number 2 would be marked and so on up to the highest difference between swatch and sample. As this is performed by simple naked eye so it is recommended that the observer must be having a good sense of colors and no color blindness problem as well.
Shrinkage and shading reports are used to compare with the fabric sourcing report because after this step fabric is allocated to cutting department and finally the quality manger and merchandiser sign shrinkage and shading reports. Shrinkage and shading reports are forwarded to cutting department from where these move to next departments
In knitwear, fabric is deal in Kgs while in woven it is deal in meters. In knitwear GSM (grams per square meter) is found while in woven and especially denim, ounces are used rather than GSM. Method of calculating ounces is that a disk of fabric is cut with the help of GSM disk cutter then that is weighed on electronic weighing balance. That weight is then divided with 0.339066 to get ounces. It is important during packing and shipping of an order.