Calendering is a finishing process used on cloth, paper or plastic film. A calendar is employed, usually to smooth, coat or thin a material.
- To upgrade the fabric hand and to impart a smooth silky touch to the fabric.
- To improve opacity of fabric.
- To compress the fabric and reduce its thickness.
- To impart the different degree of luster to the fabric.
- To reduce yarn slippage.
Preparation For Calendering
- The fabric is folded lengthwise with the front side or face inside and stitched together along the edges.
- The fabric is then run through rollers that polish the surface and make fabric smoother and lustrous.
- High temperature and high pressure required.
- Fabric that goes through calendering process feel than, glossy and papery.
Fabrics On Which Calendering Is Done
Polyester has the higher durability of the calendared finish.
Different Types Of Calenders And Finishes
- Beetling calenders.
- Watered calenders.
- Embossing calenders.
- Schreiner calenders.
- Swizzing calenders.
- Chasing calenders.
- Beetling is a finish given to cotton and linen cloth to make it look like satin.
- In this process, the fabric goes over wooden rollers and is beaten with wooden hammers.
- Also known as moire.
- Ribbed rollers used.
- Here rollers compress the cloth and ribs produce water mark effect by compressing the threads.
- Threads get compressed and flat.
- In embossing process, the rollers have engraved patterns on them and patterns become stamped onto fabric.
- End result: raised or sunk pattern depending on the roller.
- Best with soft fabrics.
- Rollers are ribbed, very fine with 600 ribs/ inch.
- High pressure.
- Threads become flat when pressed and little lines in them which cause fabric to reflect the light.
- Fabric has the high luster.
- Schreiner mercerized cotton fabrics give the nearest resemblance to silk.
- Has 7 to 10 bowls.
- Ambient temperature.
- Smoothness and lustrous appearance.
- In chasing calenders cloth makes several passes through the nips before it exits to a take-up roll.
- Thready-linen appearance and soft special feel.
Inlet unit: it contains tension device and break roll for even and proper feeding of fabric to the machine.
Metal detector: to detect metal particles in the fabric for avoiding damage to calenders rolls and fabric.
Cat walk: to avoid dust and dirt particle coming in contact with the fabric.
calendering unit: this contains one steel roll, plastic coated roll and one cotton roll. Steel roll is heated with thermic fluid. Hydraulic oil is supplied in the plastic roll to give enough pressure on the steel roll. Cotton roll is used to increase the weight of the fabric.
Cooling rollers: are used to cool fabric after passing from calendar unit.
Batching / Plaiting device: is used to wind fabric or plaiting of the fabric in the trolley.
- Improved appearance – Lustre, Whiteness etc.,
- Improved Feel which depends on the handle of the fabric and its Softness, Suppleness, Fullness etc.,
- It improves the wearing qualities – Nonsoiling, Anti-crease.
- It gives special properties required for particular uses – Water proofing, Flame proofing etc.,
- It covers the faults of the original cloth.
- It increases the weight of the fabric.
- It increases the sale value of the material.
- It improves the natural attractiveness of the fabric.
- It improves the serviceability of the fabric.
Calendering is used for manufacturing sheet rubber in various thicknesses, for plasticizing and heating rubber stock, and for rubberizing fabric.
In textile manufacturing, calendering is used for packing cotton, linen, and jute fabrics, adding luster to them, and applying embossed patterns.