GEOMETRY AND SURFACE ROUGHNESS OF POLYMERIC SAMPLES PRODUCED BY STEREOLITHOGRAPHY
The purpose of the present paper is to evaluate the geometric accuracy and surface roughness of polymeric samples manufactured by Digital Light Projection (DLP) Stereolithography. The standard cubic samples with dimensions 5 mm х 5 mm х 5 mm were printed of two polymers: NextDent C+B (white-yellowish color A3.5, VITA shade guide) and NextDent Cast (dark-red color), in two ways of placement to the base – horizontally and inclined at 45о. The samples were printed with two different layer’s thickness – 35 μm and 50μm. It was established that the samples of both polymers, manufactured in horizontal position with the lower layer’s thickness (35μm) possess highest dimensional accuracy and lowest interval of deviation. The most accurate are the dimesons parallel to the basis, while these, parallel or inclined to the print direction, have the highest deviations. The interval of the deviations of the dimensions of samples, manufactured inclined at 45o, is nearly 2-3 times higher, as the interval of the samples, made of NextDent Cast, is more than 50% higher than that of NextDent C+B. The horizontally printed samples have 1.5-2 times lower surface roughness compared to the samples, printed inclined at 45o. The surface roughness of the samples, made of NextDent Cast, is 30-50% higher than that of NextDent C+B independently of the layer’s thickness. The increase of the thickness from 35 μm to 50μm leads to 1.5-2 times higher surface roughness in the two samples’ positions. The optical properties of both polymers in the research strongly influence the geometric characteristics, dimensional accuracy and surface roughness of the objects, manufactured by DLP stereolithography.