LATEST TECHNOLOGY IN MECHANICAL FINISHING
Finishing is the last manufacturing step in the production of textile fabric.
Finish can be either chemical that change the fabrics aesthetic and /or physical properties or change in texture or surface characteristics brought about by physically manipulating the fabric with mechanical devices. It can also be a combination of the two.
FinishingMechanical (Dry) Chemical ( Wet)
In chemical finishing, water is used as a medium for applying the chemicals. Heat is used to drive off the water and to activate the chemicals.
Mechanical finishing is considered a dry operation even through moisture and chemicals are often needed to successfully process the fabric. Mechanical devices are used in both categories-the major distinction between the two is what caused the desired fabric change, the chemical or the machine.
Mechanical finishing uses mainly physical (mechanical) means to change fabric properties and usually alters the fabric appearance as well. It also encompasses thermal processes such as heat setting (thermal finishing). Typical mechanical finishes include calendering, emerising, compressive shrinkage, raising, brushing and shearing or cropping, and especially for wool fabrics milling, pressing and setting with crabbing and decating.
DIFFERENT MECHANICAL PROCESS
Calendering Raising Compressive shrinkage Cropping Emerising
Calendaring:Compression of the fabric between two heavy rolls to give a flattened, smooth appearance tot eh surface of the fabric.
Raising:Plucking the fibres from a woven or knitted fabric to give a nap effect on the surface.
Cropping:Cutting the surface hairs from the fabric to give a smooth appearance, often used on woolen goods where the removal of surface hair by a singeing process is not possible.\
EEmerising:Rubbing the fabric surface through emery roll, producing peach skin finish.
Compressive shrinkage:The mechanical shrinkage of the warp fibres in woven fabrics so that shrinkage on washing is reduced o the desired level.
CUSTOMER REQUIREMENTSAestheticSmooth Luster Raising
FeelSoft handle Drape
FunctionalShrinkage Air permeability.
CALENDERINGObjectivesSmoothing the surface of the fabric Increasing the fabric luster. Closing the threads of a woven fabric. Decreasing the air permeability. Increasing the fabric opacity. Improving the handle of a fabric. example : softening. Obtaining gloss. Surface patterning by embossing. Consolidation of nonwoven.
Normal glossA cold calendar A smooth flat fabric A lustrous surface
Chintz or glazingHighly polished surface (chintz glazed) Bowl speed greater than the speed of fabric For very high gloss, the fabric is often pre impregnated with a wax emulsion Often called friction calendaring.
The heated top bowl of a two bowl calendar is engraved with an appropriate pattern which is then transferred to the fabric passing through the bowl.
Schreiner or silk finishSilk like finish on one side of the fabric. Bowl contains series of fine embossed lines at an angle of 30 O warp wise. Popular on curtains and drapes.
This is commonly achieved by passing the fabric through the bottom of two bowls of a three bowl calendar, where these are elastic. However the steel bowls with a special matt finish have been manufactured that are very effective for this purpose.
The fabric is threaded through the calender in such a way as to press the fabric against itself several time. It is common to use a five or seven bowl calender, the fabric passing through each nip of the calender in two or three layers.
Control shrinkage along the warp. Mechanical type finish. Based on compressive shrinkage principle.
ObjectivesMinimize residual shrinkage Stabilize fabric structure. Complete the surface treatment Improve the hand of the fabric.
FunctionsMoisturizing/Steaming with steaming rollersSteam applies moisture to the fabric Moisture provides lubrication for compacting process
Conditioning of the fabric
Selvedge spreading, weft straitening
Compacting in rubber belt machine
Continuous shrinkage process
Dry/heat settingRemoval of excess moisture through drying Stabilizing on the shrunken fabric structure
DECATINGThe process is also known as decating and is mainly carried out on wool by exploiting its elastic properties in hot and we conditions by the direct action of the steam on the fabric. This treatment gives the processes fabric the following characteristics:
Dimensional stability Setting of pile raising Reduction of possible glazing effect after calendaring Modification of the hand, which is much more consistent after treatment Pre-stabilization to autoclave dyeing Increase fabric drape
Hydro settingHydro setting is so rarely used particularly to get fuller and softer handle on polyamides at 125-135c in autoclaves for 20-30 minutes. It can be combined with dyeing or optical brightening.
Steam settingSteam setting can be done by saturated or super heated steam.
ensured by initial sequence of alternate short steaming and vacuum application for 20-30 min at 130C under pressure. Super heated steam can be used in stenters and setting time is 25% shorter than for hot air on account of quicker heating up rate. Acrylic fibers have to be protested as some may under go excessive shrinkage or loss of handle. Before the material is heat set, it should be thoroughly washed to remove spin preparations, lubricants, sizing agents and impurities as these are likely to be burned in drying heat setting
MR. AHMER ADNAN BALOCH
General Trends in Mechanical Finishing
Many general trends in the mechanical finishing area follow those in other areas of the textile world. Many of the companies are consolidating and combining representatives in the market place. Examples of this include the alliance of Gematex and Vollenweider to form Xetma and the merger of Sistig, Menschner, Hemmer, and Kettling+Braun to form m-tec.
Other trends include incremental machinery and monitoring techniques.
There is a noted increase in the degree of technology used to monitor machines both visually and otherwise. Several vendors are featuring integrated visual digital cameras in which other areas fabric formation or coloration typically provide for greater flexibility and can be done with limited investment. Many vendors stressed flexibility and variation in the enhancements that could be obtained from fewer pieces of equipment. Finally, many vendors highlighted changes modifications to equipment designed to reduce costs. and
Energy savings, consumption data, and reducing required operator intervention were highlights in many vendors presentations. Following are some specific vendor highlights to elaborate on theses trends. Other vendors may offer similar features. This is not intended to be exhaustive, but representative of general trends.
Calendering Machine (KLEINEWEFERS)Calendaring is an operation carried out on a fabric to improve its aesthetics.
Purpose of calendaring is:
To upgrade the fabric hand and to impart a smooth silky touch to the fabric. To improve the opacity of the fabric To compress the fabric and reduce its thickness. To impart different degree of luster to the fabric. To reduce yarn slippage. The mechanical finish is done for softness and shining of the fabric or stiffness according to the nature of the chemical, this process is done after the chemical finishing as per buyer requirement. Speed of the machine is 10-100 m/min.
Components of machine:
Winder Metal detector Seam detector Rollers (cotton, ryclon and steel) Anti static rod Oscillating roll Batcher sensor cooling drum
Seam detector: Function of seam detector is to bypass the seam. the latest calender machines provided with seam detector to avoide the damage of the bowl and cloth due to bad sewing of the two layers of fabric.
Metal detector: the fabric may contain any metal particle after going through different mechanical processes the machine equipped with a metal detector the function of metal detector to detect metal particles as to avoid the damage of the bowl.
Anti static rod: some fabric may produce static charges and may stick to the machine parts due to static electricity. Anti static rod is used to remove static charges and production increases. Small winder: When we have to calendar short width fabric and we can also run short width fabric with long width fabric. Oscillating roll: To avoid selvedge overlapping on batcher.
For soft finish the fabric is passed through cotton bowl. This roller is made up of cotton. Steel roll: To give smoothness and luster. The temperature is provided to steel roller about32-200C with help of electric heater as we increase the temperature shining will increases only used for cotton CVC and percale and PC.
Ryclon roll: When fabric passes through Reclon roll and steel roll giving smooth and luster effect is generated. When it runs with steel roll and reclon roll and cotton roll dull effect is generated. When it runs b/w steel and reclon gloss effect is generated. Cooling drum: Cool down the fabric water circulates inside the cooling drum.
NIPCO L calendar
The star among calenders
A textile finishing calender with two nips with independant pressure settings, a revolution in calender technology.
The system allows, high glazing, softness, density control and other sales requirements in one calender combined.
The hydrostatic support elements of o