Rework

When making plastic products plastic remains (the “scrap”) are in many cases are inevitable. When producing plastic film, trims are left over as scrap. When producing hard parts in moulding, moulding residue as flow channels is left over. By in-company recycling of the plastic scrap, directs savings on feedstock are the result.

Plastic scrap can be fed back into the extruder, after grinding, cutting and/or repelletization. There are different systems of machinery to reclaim plastic scrap. For larger flows these machines are more automatized, for smaller flows these machines have a simpler yet economical set-up.

Simple systems for small flows

A simple system to reclaim plastic scrap is in many cases modular in design. The plastic scrap is fed in grinder or granulator where the plastic scrap is sized to a particle size suitable for the extruder. The sized plastic is fed, in many cases via a screw conveyor back to a batch mixer-dispenser or a container mixer. These mixers feed the sized plastic with plastic granulates directly tot the extruder. Some granulators are equipped with a simple air conveyor system, that feed directly into a mixer or straight into extruder. Most of these systems have throughputs of typically 50 kg/h up to hundreds of kg/h. There are systems as small as a throughput of 1 kg/h, for very small flows

Film scrap recycling systems

Film scrap systems have basically the same system lay-out as the simple system, but is in most cases completely automatized. When making film, in many cases trims are inevitable and the amount is usually precisely known. The trims are picked up in manifold of air conveyor systems. The trims are shredded in sizes suitable for the extruder and transported via air conveyors to a refeed machine. Air and shreds are separated by a cyclone. The shreds of trim are mixed with virgin pellets to be fed to the extruder. Most systems have throughputs of hundreds kg/h.

Repelletizing systems

These systems are used in many cases for plastic film scrap, and post consumer plastic film waste. The plastic scrap is fed into a cutter to size the scrap small enough to be fed into an extruder, followed by a pelletizing system. The plastic pellets can be stored and used for other products. These systems are larger and more expensive than film scrap recycling systems, due to an investment in an extruder en pelleting line. Most systems have throughputs of hundreds to a few thousand kg/h, starting from as low as 80 kg/h.

 

Overview of granulators for small flows

Granulator

Minimal throughput
(kg/h)

Hellweg

3

Rapid Granulator

5

Getecha

6

Wittmann

7

Dreher Granulators

50

Inan Plastik

150

HMG

200

Wanner

-

Sikoplast

-

Nuga Systems

-

(is your system not mentioned? Please send us an e-mail)

 

Overview of mixer-dispenser and container mixers

Mixer

Throughput
(kg/h)

Labotek

10 - 750

Maguire

< 63

TSM Control System

50-150

Wittmann

> 80

Conair

< 175

ProTec Polymer Processing

180-600

Prominent

-

Heger

-

(is your system not mentioned? Please send us an e-mail)