One of the most important aspects of the recycling process is the process for breaking up plastic into smaller more manageable chunks. The machine used to perform this operation industrially is generally called a granulator, although other terminology such as shredder seems to be in popular use within the maker community.
There are various designs for granulators, most a scaled down versions of their larger industrial relatives. Pretty much any of these could be made to work for our process.
For our project we have decided to utilise the PreciousPlastic 'Shredder' which can be easily constructed from laser cut parts made from the plans available on the Precious Plastic website. The design is already in use by various recycling initiatives around the world and so has a proven track record, which is an important factor for this project.
Of course if you have access to other machines, or wish to build an alternative then you need to consider the granule size produced by the shredder / granulator. With the Precious Plastics shredder the granule size is determined by the holes in the screen mounted below the blades. In our case the screen has 5mm holes which means that it produces a pellet with a maximum of 5mm diameter. This size is important to consider when using the granules in other processes such as nurdle / pellet extruder.
Given the nature of this machine there are also some serious safety implications to consider as the blades could easily granulate fingers or pretty much anything else it gets the opportunity to grab hold of. This is a big factor when using or demonstrating these machines, especially within Educational and Public environments. To address this we've put together a Safety Forum to discuss what safety risks are present and how these risks can be mitigated.
The Nurdle community forums provide a place to discuss activities and equipment related to the Nurdle project as well as other related recycling and educational initiatives and opportunities.