Ensuring the functional properties of responsible structural plastic elements by means of 3-D printing

This paper addresses the issues relating to the use of 3-D printing tools in order to manufacture the structural elements of machines and apparatuses. The features of printing with the application of PLA-Carbon and PEEK (PEEK-Carbon) plastics have been analyzed. It is shown that printing that employs PEEK-plastic is accompanied by a series of problems associated with the high residual thermal stresses at cooling the material, as well as with the issue of adhesion to the laying surface, which should maintain its properties to a temperature of 420 °C. The causes of defects in the printing of articles with a significant process duration (longer than 12 hours) have been analyzed. It is shown that the most acute problem has been the interlayer grip, which predetermines the anisotropy of the properties of the finished product. It has been proven that the use of PEEK plastic makes it possible to produce force elements by applying special print heads. Particular attention should be paid to the reliable connection between a printed element and the base (table) because the peeling and deformation of the base surface are one of the main causes of geometric defects, which subsequently predetermine the structural defects. Mechanical tests of finished products have been performed, including vacuum and degassing research. It is established that the destruction of samples, in general, corresponds to classical ideas about the destruction of a quasi-fragile body when it comes to the phenomena occurring in the plane of the material’s layers. Thus, any form printed by a printer is an orthotropic article whose behavior is satisfactorily described by Griffiths theory. At the same time, the strength characteristics, as well as elastic properties of a product demonstrate significant axial (orthotropic) differences. It is also shown that the functional properties of a product are ensured by the comprehensive dynamic-moving and thermobaric influence on the melt of the material in the space behind a nozzle owing to which the planes of adhesion and hollowness of the finished product are formed. The recommendations have been formulated for preventing defects and the elimination of delamination phenomena, errors in the geometric parameters of a product; it has been concluded that it is appropriate to implement these processes into production