What Is a Plastic Granulator?
A plastic granulator is one of the most important pieces of machinery in a factory that makes a wide variety of plastic products. This machine works much like a large shredder and turns full-sized bottles, jugs, and other plastic products into flakes, or granules. This material is later sold to molders and manufacturers of new plastic products as recycled raw material. This is one of the only ways that plastic can be reprocessed into items with similar properties to those made from brand-new material.
There are several different types of plastic granulators, each designed to perform specific tasks. The simplest of these is the roll-feed granulator, which takes flat plastic films and cuts them into small granules that can be used in injection molding or other plastic production processes. This type of granulator is usually used to recycle sprues and rejects from injection molding, blow molding, and extrusion lines.
In order to make the granulator more effective, it is often used in conjunction with a shredder. While granulators can do the bulk of the size reduction work, shredders are often better suited to handling heavy materials that may jam or damage a rotor. This is especially true if the granulator is operating under a press and needs to quickly reduce sprues and runners.
The main components of a plastic granulator are a large electric motor that drives a rotor, which has cutting blades encased within a chamber. This chamber is available in various sizes and shapes, with a screen located inside that serves as a sifter to ensure that the granulated material is fine enough. A rotary valve is also located in the chamber to control the flow of material and prevent the accidental escape of large granules.
These granulators are used in a variety of industrial applications, including the manufacture of plastic products, packaging, and building materials. They are typically powered by electricity, though some models can run on gas, steam, or other energy sources. Some even allow for the use of different kinds of abrasives, such as steel shot and aluminum oxide, to create more precise particle size distributions.
A simple open source waste plastic granulator has been built and tested to see if it can be easily fabricated for distributed recycling purposes. The results show that this granulator can be fabricated for less than $2000 USD in materials and uses only 380 to 404 W of power while running. This amount of power consumption represents only a minor contribution to the overall embodied energy of distributed recycling, as it is only used for the short time that it is needed to convert post-consumer waste, 3D printed waste, and sprues into polymer feedstock for a recyclebot or fused material extruder-based 3D printer.
The noise levels of the open source waste plastic granulator have been measured with an omnidirectional free field array microphone positioned at a distance of 0.3m from the machine, and the sound level measurements were recorded using a National Instruments Compact DAQ data acquisition system and custom LabVIEW software. The results have shown that the open source granulator can be retrofitted to reduce sound levels during operation by 4dB for the machine itself and 5dB for the shop vacuum.