On Geometry Deviations of the Small Vessel Components Obtained Using Additive Technologies
Currently, there is not enough data on the cumulative error in the geometric characteristics of large-sized objects assembled using the technology of gluing in parts. The hull of the small vessel "Nerl" was chosen as a large-sized object created by the FDM method. The deviations of the diameter along mutually perpendicular planes and the heights of the glued products were measured on the example of test specimens of a cylindrical shape and gluings from them. The field of tolerance for glued products made of polylactide was determined. Recommendations for designing large-sized products when printing in parts by the FDM method were issued. The causes for the appearance of geometric deviations of single parts and gluings are described. The main disadvantages of the FDM method related to manufacturing accuracy are considered. Causes of geometric deviations are divided into three groups. The first is related to the parameters of the product material (thermal expansion coefficient, uniformity of the rod and hygroscopicity), the second is related to its design (multiplicity of linear dimensions, layer height and motor pitch, filling parameters, the presence and size of overhanging elements), the third is related to the features of the additive installation ( calibration along the X, Y, and Z axis, extrusion drive calibration, extrusion unit design, acceleration and travel speed, and nozzle diameter). It was found that preparing the production of 3D printing of a large-sized object using the technology of gluing in parts, for example, the hull of a small vessel, it is necessary to additionally take into account the numerical parameters of the layers of adhesive joints.