The impact of 3D printing assumptions and CNC machining conditions on the mechanical parameters of the selected PET material

This article focuses on a comparative analysis of the technology of additive shaping and multi-axis CNC machining. The authors examine the impact of 3D printing assumptions and CNC machining conditions on the strength of the selected PET material used to produce machine elements on the example of a shaft-type element. The purpose of the study is to identify a better production method.The analysis was carried out by producing six samples of different diameters and lengths from the same thermoplastic material (ethylene terephthalate) by both 3D printing (FDM) and CNC machining. The resulting samples were subjected to a static compression test, for which a universal testing machine by Zwick & Roell 100 kN was used. The following factors during the production of elements were compared: the difficulty of preparing the project, the time of execution, the cost of execution, the accuracy of the execution and the properties of the elements made.Elements made by CNC machining have higher compressive strength and yield strength, as well as lower relative expansion and relative shortening. Those produced by CNC machining are created as a monolith (semi-finished product), and the printed elements are incrementally shaped layer by layer. During the strength test, the spaces between the layers decrease, which in turn causes an increase in relative shortening and a decrease in strength properties.Further research is planned on the analysis of manufacturing technology using incremental shaping technology (e.g. change of filling density, change of filling type, change of material) compared to CNC machining.In the conducted tests, a universal method was used, which can be translated into a comparative study of elements made of other materials.The research carried out allowed for the initial assessment of the use of PET material for the production of machine elements through 3D printing and CNC machining.