A plastic granulator is an important piece of equipment used to turn full-sized bottles, jugs and other plastic products into flakes that can be reused. These granules are then sold to molders and manufacturers to use in the production of new plastic items. This process is known as plastic recycling and it has both environmental and economic benefits.
A granulator uses blades to cut and crush plastic materials into small flakes or pieces. The size of these granules is determined by the type and structure of the plastic being shredded. Plastic granulators are available in many different models that have varying blade sizes, types and designs. A plastic granulator can be either a beside-the-press model that is designed to grind large volumes of sprues, runners and off-spec parts or it may be a central granulator for high-volume work in a manufacturing environment.
The main components of a plastic granulator include the blades, screen and housing. The blades are typically made of stainless steel and they can be designed to cut a variety of different plastic materials. The granulator’s housing is constructed of a sturdy plastic and it provides a sealed environment for the machine’s operation.
In order for a plastic granulator to operate effectively, it needs to be kept clean. The rotor and screen should be oiled periodically and the inside of the chamber should be wiped down after each large job the machine completes. This will prevent the granulator from jamming and it will ensure that all of the material is sheared into smaller sized particles.
Plastic granulators can create quite a bit of noise when in operation. This is because of the cutting and power transmission systems. The sound level of a granulator can be reduced by simple retrofits that decrease the size of the panel gaps and seal these appropriately. The vacuum pump is also an important source of noise and this can be reduced by sealing the pump in its own bespoke housing.
This study demonstrates the design, build and testing of an open source waste plastic granulator that can be built for less than $2000 USD in materials. It is capable of converting post-consumer waste plastic and 3D printed waste into polymer feedstock for recyclebots and direct material extruder-based 3D printers. Its experimentally measured embodied energy is only a small fraction of the total embodied energy required for distributed recycling and manufacturing using open source 3D printers.
The results of this research suggest that the open source waste plastic granulator can be used in community, library, maker space or fab lab environments to facilitate distributed recycling and manufacturing using open source recyclebots and 3D printers. Its relatively low embodied energy and particle size distribution make it an attractive technology for localized waste plastic processing and reuse. Further optimization of the granulator’s design is possible and could result in further reductions in energy usage. This would be particularly beneficial for communities where the cost of electric power is prohibitive.