Types of Calenders in Textiles

With the simultaneous action of temperature, force and moisture, the surface of the textile substrate are modified. This simultaneous action is called calendering. Calendering in textile may simply be achieved while passing the textile substrate in between two heated drums or rollers. The rotation speed and pressure of the heated drum may be varied according to the need.

There are different types of textile finishes. Among them calendaring is a mechanical finishing process.We can definitely beautify our fabric by calendaring.

The effect of calendering is achieved by ironing. Ironing makes the fabric crease free. Not only calendaring process makes the fabric crease-free but also it does a lot.

 

Different types of Calenders

Swizzing calendar
Chasing calender
Compaction calender
Embossing calender
Friction calender
Schreiner calender

1 . Swizzing Calender
It is a British term
Denote that fabric runs through all the nips and then either plaiting or batching
Usually consists of 7-10 bowls
All bowls rotate at same speed
Softening and filling agents should be applied to produce lustre
It gives close inter stiches, smooth appearance and gloss without high glaze (which we get from friction calender)
Smoothness and lustre are increased with the increase of bowl temperature (150-180°C)

Advantages of Swizzing Calender
Uniform calendaring is obtained
Remove wrinkles and creases
Smooth fabric surface can be obtained
Very high glossy fabric is achieved
No risk of displacing of fabric

2 . Chasing Calender

It is similar with swizzing calender
5-7 rolls are needed & all of them rotate with same speed
The major difference is " the cloth makes several passage through the nips before it exits to a take-up roll
The cloth is compressed as 5-6 layers being superimposed and entering into the nip again
At this the weft of one layer will lie in between two adjacent wefts of the next layer and give additional pressure
Roller pressure and this additional pressure soften the fabric and gives a linen appearance (soft feel)

Advantages of Chasing Calender

Gives very smooth linen appearance
Produce soft handle
More the fabric is passed, more the glazy appearance is achieved
Removes wrinkles and creases

3 . Friction Calender

Friction calender apply friction force to the face of the fabric
Friction is done by driving the pattern roll faster (5-10%) than the support bowl
Here, strong fabric is needed to withstand the strain
Friction produces a high degree of lustre at one side and gets similar effect to ironing with hot air
It is generally 3 bowl m/c
Middle bowl is made with polished iron, heated and speed is more than its bottom roller
Pressure between bottom two bowls are more depending on the amount of starch and moisture in the fabric, the starch deposited on the fabric varies
If MC> 20%, starch sticks to bowl and if it is <15%, no lustre is produced
Generally a friction calender runs at 31.5 m/min
Highly lustrous, glossy surface, heavy closing up of threads, iron effect can be achieved
It is mainly used for share, lungi, bed sheet etc

Advantages of Friction Calender

Produce more smooth, glossy and higher lustrous appearance
Fabric thickness reduced
Heavy close up of threads
Remove crease and wrinkles
Suitable for finishing of highly glazed linings, prints etc

4 . Compaction Calender

A compaction calender has an adjustable gap between the pattern roll and bowl
Nip point between two rollers is controlled according to design to control thickness

Advantages of Compaction Calender

Produce filter media of certain thickness
5 . Embossing Calender

A special type of calendaring machine
Generally 2-3 bowls m/c
Middle one is engraved according to design feature
The other bowls are soft like cotton bowl so that it can accept the embossing pattern
Diameter of metallic bowl is more than half (20 cm diameter) than the compressed bowl (60 cm diameter)
Small roll provide sharper and a deep embossing effect
Fabric is deformed according to definite design by pattern roller and both the rolls may be heated
Used for thermoplastic fiber
This finish may be temporary or permanent
Raised design effect or pebble or crepe effect can be achieved

Advantages of Embossing Calender
Crepe or pebble effect is produced
Temporary or permanent effect may produce.
Mercerized cotton with starch (semi-permanent finish) or resin (melamine resin) for permanent embossing finish.
For thermoplastic fiber, this effect can only be achieved by 190-220°C temperature
For acetate, 190-210°C is required.
Due to smaller metallic bowl, it is cheap

6 . Schreiner Calender

Cotton fabric is given a silk like brilliance through this process. This is operated on sateen, cotton linings and printed fabric
A fine linen engraved pattern roller is used
A soft lustrous handle can be achieved by choosing correct cloth construction and the correct linen direction of the engraving
Approximately 250 to 350 lines per inch can be seen on schreiner steel bowl
The cut lines may be rounder or sharp
The cross-section of engraving is either a v-shape (high lustrous) or u-shape (low lustrous)
Angle of the line 200-300°C
15-19% moisture content, 120-160°C temperature, 3.5-5 bar pressure and 2-10 m/min will give silk finish to cotton goods

Advantages of Schreiner Calender

Gives silk like appearance to cotton

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