Plastic size reduction


Injection Moulding

typical runners from injection moulding

Process Overview:

Injection moulding is used to create many things such as wire spools, bottle caps, automotive dashboards and so on. Injection molding is the most common method of part manufacturing. Some advantages of injection molding are high production rates, repeatable high tolerances, the ability to use a wide range of materials, low labor cost, minimal scrap losses, and little need to finish parts after molding. In the injection process melted plastic is forced into a mold creating the part. Most polymers can be used for injection molding, most common it is polyethylene (PE), polypropylene (PP) and Polyvinyl Chloride (PVC).

Typical challenges in recycling:

The main challenges in the injection moulding technology are recycling at the machine and central recycling of rejected parts and purges. Due to the big range of materials and additives used, recycling directly at the press is the most efficient solution. The most common is the recycling of runners, sprues and rejected products directly at the injection machine. Here the GSL slow speed granulators are an ideal solution. The low rotor speed results in a low noise operation and less fines in the regrind. The unique machine design combines a staggered rotor which is directly driven by a geared motor creates a high torque with low power consumption. The ground material is then directly reintroduced into the injection process via a blender or a proportional valve.
Another big challenge is the grinding of plastic lumps and head waste accumulated during start-up, color and material changes. The ZERMA ZBS single shaft shredders have been specifically developed for this scenario. These shredders are used to shred these pieces into smaller particles that can be processed further down in a smaller possibly already existing granulator.
The compact GSC and GSE granulators can be used as central granulators to process larger rejected parts. On top of that the Heavy Duty Granulators of the GSH range can be used to process start up lumps as well.

GSL slow speed granulator working inline next to injection machine
Reject part being fed into GSC granulator