Development of a plastic recycler applying TRIZ

This paper presents the development of a plastic recycler for rapid-prototyping (RP) machines with the support of TRIZ. A major cost factor of today’s RP machines is the filament, which is the base material for the production of the prototype models. Inside the RP machine the filament is fused and then printed in layers to produce 3D-models. Since the cost of purchase of RP machines is on the way to be dramatically reduced with the help of an open-source soft- and hardware program called RepRap, the filament is one of the remaining cost-pushers. The RepRap program provides all the important knowledge, e.g. software programs or design drawings, for building a RP machine. This allows reducing the cost of purchase of a RP machine to under € 1,000. One of the mayor advantages of RepRap RP machines is the self-reproducing aspect of the machines. Major parts of a typical RepRap RP machine can be printed with other RP machines, which makes it a popular RP machine for academic and do-it-yourself projects and even more important to have cheap base material available. The case study of the recycler builds on the RepRap idea. Therefore, one key requirement was the manufacturability of as many parts as possible with RP machines, on top of the functional requirement to produce a good quality filament out of misprinted models, outdated models, or plastic pellets. For the recycling two process actions are needed: disassembly of the models (1) and processing of the pellets or shred material to filament (2). A first-generation recycler which is compiled of a shredder and an extruder was developed with the help of product development methods. This recycler was able to produce filament in good quality, but had some major issues. Firstly, the shredder could only break small models. Bigger models or models with high material density could not be shred. Secondly, the feed rate of the filament is unsatisfactorily low. In the presented study the first-generation recycler was analyzed and improved applying TRIZ methodology. A specific set of established TRIZ methods was assembled. The scope of TRIZ methods reaches from innovation checklist, function analysis to technical contradiction. This paper especially focuses on the function analysis applied during the development. It presents the results of analysis of the first-generation extruder, which led to the identification of the development focus and technical possibilities and alternatives for the extruder. Furthermore the development of the function model is elaborated on. It depicts the changes of components and highlights function integration of components into a single component. The second part of the paper discusses the application of the chosen TRIZ methods during the project work. Advantages and application obstacles of TRIZ in academic projects are depicted. Additionally, an approach to increase the usability of the TRIZ function analysis is introduced. This approach combines a graphical representation of the observed object with the function model. The advantages of the presented approach and its application is discussed. Finally an outlook of further applications of the extruder is given.      «

This paper presents the development of a plastic recycler for rapid-prototyping (RP) machines with the support of TRIZ. A major cost factor of today’s RP machines is the filament, which is the base material for the production of the prototype models. Inside the RP machine the filament is fused and then printed in layers to produce 3D-models. Since the cost of purchase of RP machines is on the way to be dramatically reduced with the help of an open-source soft- and hardware program ca...     »