Finishing
A fabric finishing process is a process for providing specific quality to the fabric that is required by the customer.
Finishing process in Stenter Machine:
Refinishing and topping:
Refinishing and topping is a repetitive finishing process to cotton fabric, TC fabric and yarn dyed fabric. To minimize the dyeing as per customer swatch and if necessary some pigment dyes are used for the purpose.
Equipment: MONFORTS STENTER MACHINE I & II
Key accessories: Two electronic measuring balance, two breakers, pH paper (3-12), sewing ma-chine, pinning brush.
Figure 9: Stenter machine
Materials and chemicals used:
The materials and chemicals used in the stenter machine for the TC fabric, 100% cotton, and twill fabric finishing as well as re-finishing process are described below. A sequence of chemical pouring is used in the wrinkle free finished fabric to avoid unwanted chemical reaction.
Safety:
During production never touch any rotating or movable part or machine.
Never mix two or more chemical in their concentration.
Follow all the safety instructions mentioned form in the machine.
Before entering into thermal area keep the blower and burner “off “.
Always use the fiber clips to avoid selvedge folding.
Do not touch pins bar/clip bar.
66 Operation procedure:
The pilot plant (fabric) provides customer approved swatch with recipe of the white fabric to the finishing department where as preparation department provides the bleached fabric. The finish-ing procedure begin with the calculation of solution a amount for a particular fabric the formula as below :
Solution amount = fabric weight (kg) X fabric length (m) X pick up % + through con-tent + 3% wastage
Pick up % = 60% - 70% (for white fabric)
= 50% - 55% (for colored fabric)
Through content is 80 L solution required in the through wastage is 3% of solution.
The trial process fast start with same fabric of 1 m and required chemical solution. Chemical are measured by using balance and takes in the bucket separately. Then tinting agent is measure and taken into a breaker to dilute with hot water. Other chemical are dilute with hot water on normal water based upon the reference of the chemical literature book of the chemical company.
Mixing tank is filled up with 50% of water to the required solution level (100L) and the chemical are poured separately into the tank through a piece of filter cloth. A sequence is maintained for chemical pouring into the mixing tank for the wrinkle free finished fabric so the fabric is not damaged by the chemical solution. Then the solution is measured to ensure the 100 L level by using a still rolled and water is added if necessary. Chemical are stirred for five minutes by the fan in the mixing tank and then sets to the upper tank.
The upper tank sets the solution to the trough machine which has a value at the level of 80 L the value close automatically. At that specific level and opens when the solution level goes lower than 80 L.
The operation fixes the one m of sample fabric on the pins on the endless chain at the feed side starts the machine to develop it. When the trial fabric is developed it is usually impacted with the approved sample for the parameters ( softness, hardness, stiffness, shade match etc ) ordered by customer. Then a piece of fabric ( Max “14 X 14” ) is cut from the trial fabric to scan the shade in the data color of pilot plant (Lab ). The shade scan is necessary to fixed out any deviation in the fabric and also to take corrective action to overcome these fault / deviation.
If the trial fabric matches with the customer approved sample then trial ends and production de-partment decide to go for bulk production. After every 1000 m. 1 m sample is sent to the QC for QC tests. If the trial does not match then the recipe, temperature or the machine speed is adjusted
from the reference of parameter register, and the shade scanning report and the same trial process repeat until it match with the customer approved sample. For the bulk production chemical solu-tion is prepared from the formula mensolu-tioned above and poured in the mixing tank of one bath at a time capacity of each bath is 400 L.
Production quality check:
In case of TC fabric, 100% cotton and twill fabric. The operator checks the shade in naked eyes in the stenter machine. If any deviation is found then he informs the responsible shift officer who take the necessary action to overcome the problem. If the officer then the departmental head pro-duction is informed and finally he give the decision. Shade checking is not applicable for the sanforizing process.
Fault check:
The operator check the weaving faults (.i.e. Double yarn, Warp and Weft missing, yarn contami-nation etc.) , spinning faults ( .i.e. Dye resist mark, Stop mark, Bend mark, Chemical spot, Drop-ping mark, Listing, Torn and Hole, Fabric structure etc.).
During process when minor fault occur within 30 m of fabric ( while running about 300-500 m of fabric) which is not resulted from previous process and also not recorded on the process route card, the necessary actions to be taken are as follows:
Check the feed side batcher to make sure that thus fault did not occur from previous process.
Stop the machine to identify whether thus faults are occurring due to machine faults or the faults are due to the chemical (checks cleanliness of machine parameters and chemical com-position).
If there is any spot on the fabric then it indicate that the sequence of the chemical pouring in the mixing tank for the wrinkle free finished fabrics not correct and hence the chemical reac-tion has damage the fabric.For this the chemicals have to be mixed up in the mixing tank following the proper sequence (reference are mentioned in the chemical composition for wrinkle free finished fabric).
Width check:
Measure fabric with by using a measuring tape. Compares with the required finished width that is mentioned in process route card, in case of wrinkle free yarn dyed width checking is 2cm less than the normal fabric finish fabric width.
Design the fabric bow check for yarn dyed fabric:
68 Pin setting check (for TC and yarn dyed fabric):
Check at the delivery side if the selvedge of fabric is set in pins correctly Clip checking (for 100% cotton and Twill fabric):
Check the feeding side (.i.e. the setting of fabric on the clips) QC sample test:
1m sample fabric is cut from each batch (which represent the bulk) and sent to the QC lab for test. The shade continuity card is checked with the sample for the QC sample test. QC depart-ment does the physical test , chemical test and analysis the test and notes the result in fabric test result for details of QC test. During scanning of twill fabric data color machine the sample must be set vertically warp wise. Refer to specification for details of the methods of sample scanning.
Heat setting and stretching:
Heat setting is a mechanical process before dying of TC+CVC fabric to give dimensional stabili-ty and shrinkage control. Whereas stretching is also a mechanical process before dying of all cot-ton fabric to remove crease marks and to get required width for next process
Key accessories:
The necessaries tools/accessories used for the stenter machine are as follows :
Sewing machine,
measuring tape,
White papers.
Material and chemical used:
Sometimes wetting agent (.e.g. mixture of surface active compound) are used as chemical for the heat setting and stretching process.
Calendaring process:
In fabric finishing process, calendar plays an important roll in achieving effect like smoothing, luster effects. In this process fabric is passed through a machine in which heavy roller (bowis) rotate in contact under mechanical or hydraulic pressure.
Four type of calendaring are done here
a) Chintz calendar (smoothing effect with paper roll and steel roll) b) Ironing (soft, smoothing and glazing effect with steel roll) c) Calendaring for smooth surface (mating effects with cotton)
d) Calendaring (soft and smoothing effect with cotton roll, paper roll and steel roll)
Process requirement:
Equipment: THE RAMISH CALENDERING MACHINE Material and chemical used:
Sometimes wetting agent (.e.g. mixture of surface active compound) are used as chemical for the heat setting and stretching process.
Safety measure:
During production never touch any rotating or movable part or machine.
Never mix two or more chemical in their concentration.
Follow all the safety instructions mentioned form in the machine.
Machine setup:
Described below is the machine set up for the stenter machine for Denim fabric finishing, re-finishing process.
Machine set up parameter Actual parameter range Steam pressure for steel bowl As required
Pressure for cotton bowl (50-100) K/N Pressure for paper bowl (50-200) K/N
Temperature (50-240) °C
Speed (30-70)_ m/min
Tension roller setting position 1,2,3 depends on the bowl used Seam distance setting 71-120
Table 5: M/c set up for stenter
Operation procedure:
The operator feed in fabric manually through guide, tension and bowl end roller.
The machine is started.
According to the degree of flattening the surface pressure of bowl and the speed are adjusted.
Due to the construction and nature of the steel bowl and resilient bowl, the fabric ic stretched and compressed which is passed through the nip. Thus smoothness of fabric configuration is achieved.
In case of steel roller the fabric passed through a pair of (air cooling) situated at the back of70
Then the fabric is send to the next stage of finishing or to the inspection department.QC sample test:
1m sample fabric is cut from each batch (which represent the bulk) and sent to the QC lab for test. The shade continuity card is checked with the sample for the QC sample test. QC depart-ment does the physical test, chemical test and analysis the test and notes the result in fabric test result for details of QC test. During scanning of twill fabric data color machine the sample must be set vertically warp wise. Refer to specification for details of the methods of sample scanning.
Machine faults:
Machine faults Response
Compensator problem Electrical/Mechanical engineer should called Air pressure valve problem Mechanical engineer should called
Rubber belt surface checking or rough sur-face problem
Mechanical engineer should called Batching roller , feed roller compensator ,
felt moving steam problem etc
Mechanical engineer should called
Table 6: M/c faults of stenter
The daily and weekly cleaning works for stenter machine are described below- Daily works:
Clean the reeves that can be reached from the outside of the machine. A minimum of once per shift.
Clean the entire upper filters every 4 hours.
Clean the heat exchanger a day of the heat recovery system.
Run the machine once a day to the maximum and minimum width.
Clean all the lower filters of the chambers check the right function of additional device such as Malho, Bianco, E and L etc.Weekly works:
Prior to lengthy machine downtime (week end), clean with a mixture of soap-flux and talcum powder.