Plastic Flat Film Extrusion Process

There are two major types of flat extrusion processes called film extrusion and sheet extrusion. Those processes used for production of film and sheets up to 4m width and thicknesses up to 0.25mm for films and 30mm  for sheets. In this post I will specially explained about flat film extrusion process. Polyolefin such as LDPE(low density poly ethylene), LLDPE(linear low density poly ethylene),HDPE(high density poly ethylene) ethylene and propylene co polymers, and poly propylene  are the most commonly used plastic for film extrusion. Generally three main equipments can be identified in film extrusion process. They are for cooling, taking off and winding up.

Flat film extrusion process can be divided in to two mainly according to the cooling method as follows.

Water quench process

 

This process required low operating cost compared to the chill rolled cooling process. In this method it is easy to maintain good optical properties.

Chill roll process

Now a day’s chill rolled cooling process is commonly using process. Matt finished rolls and high gloss finished rolls are used

There are three types of flat film dies containing manifold to spread the flowing polymer across the width of the die. 

• Manifold die V hanger type

Melt is distributed across V channel.

• Manifold die T type

This is used when processing low viscosity plastics that are not thermally sensitive.

• Manifold die Fish Tail type