A calender is a machine that processes polymer melts into sheets or films using heat and pressure between rollers. It works by softening the polymer and passing it through nips between two or more rollers to form a continuous sheet, with the thickness determined by the gap between the last rollers. Common uses of calendered sheets include flooring, rainwear, wall coverings, and signage. Thermoplastics are well-suited for calendering as they can soften without fully melting. Different roller configurations like I, L, and Z types address issues like separating forces between rollers. Calendering is advantageous for heat-sensitive materials but high capital costs and achieving precise thickness can be challenges

1. Calendering

2. Content
 Introduction
 How it works
 Uses
 Material Specification
 Types
 Advantage
 Disadvantage

3. Introduction
 A Calender is a device used to process a polymer melt
into a sheet or film.
 When first developed it was mainly used for processing
rubber , but nowadays it is commonly used for producing
thermoplastic sheets, coatings and films.

4. How It Works
 The basic idea of the machine is that squishes a heat
softened polymer between two or more rollers (this
area is called a nip) to form a continuous sheet.
 To begin this process the polymer must go through
blending and fluxing before it goes through the
calender.
 It make it a consistency easier for the calender to
handle.
 The thickness of the polymer sheet is dependent
mainly on the gap between the last two rollers.

5. Cont.
 The last set of rollers also dictate the surface finish,
glossiness and texture of the surface.
 Polymer is ready for going through the rollers tends
to follow the faster moving roller of the two that it’s
in contact with and it also sticks more to the hotter
rolls.
 That’s why calender typically end with a smaller
roller at a higher speed to peel the sheet off.
 It is also why the middle roller is kept cooler so that
the sheet won’t stick to the other rollers nor will it
split by sticking to both rollers which can happen.

6. Uses
 Floor Tile
 Continuous Flooring
 Rainwear
 Shower Curtains
 Pressure - Sensitive Tapes
 Automobile And Furniture Upholstery
 Wall Coverings
 Luminous Ceilings
 Signs And Displays etc.

7. Material Specification
 The best polymer for Calendering are thermoplastics.
 Because they soften at a temperature much lower than
their melting temperature.
 Thermoplastics melt have a fairly low viscosity, but they
are still strong enough to hold together and not run all
over the place.
 Heat sensitive materials also great for calender because
calender put immense pressure on the materials to work
them and therefore do not need as high temperature to
process them limiting the chance of thermal degradation.
 That is why Calendering is often the method of choice for
processing pvc.

8. Types
I Type
 It can built with one
more roller in the stack.
 This design was not ideal
though because at each
nip there is a an outward
force that pushes the
rollers away from the
nip.

9. Cont.
L Type
 L Type calender are often
used for processing rigid
vinyl's and inverted L type
calender are normally used
for flexible vinyls.
 These both setups have
become popular and
because some rollers are at
90 degree angle to other
their roll separating forces
have less effect on
subsequent rollers.

10. Cont.
Z TYPE
 The Z type calender
places each pair of rollers
at a right angles to the
next pair in the chain.
 This means that the roll
separating forces that are
on each roller
individually will not
effect any other rollers.

11. Advantages
 The calender is very good at handling polymer that are
heat sensitive as it causes very little thermal degradation.
 It is good at mixing polymers that contain high amount
of solid additives that don’t get blended or fluxed in very
well.
 Due to this calender is produce a large amount of melt
than extrusion.

12. Disadvantages
 It is a very expansive process to perform.
 If the thickness is below 0.006 inches then there is
tendency for pinholes and voids to appear in the sheets.
 If the thickness is greater than about 0.06 inches then
there is risk of air entrapment in the sheet.
 So to achieve the desired thickness is also a very difficult
process.

13. References.
 BRYDSON, J. A. (1999) Pl... Materials (7th ed.)
 Fred W. Billmeyer Jr. Textbook of Polymer Science
1984.
 The science and technology of rubber.

14. Thank You
Submitted by :Pankaj Kumar Das
roll no:1308023