INVESTIGATION OF THE EFFECT OF VARIOUS BUILD METHODS ON THE PERFORMANCE OF RAPID PROTOTYPING (STEREOLITHOGRAPHY)

Stereolithography, which was the first commercially available Rapid Pr ototyping (RP) technique, currently represents a major portion of the worldwide RP market share. Parts manufactured with the stereolithograp hy apparatus (SLA) are presently used for design verification, medical modeling and rapid tooling applications. Dimensional accuracy of the prototype is very important for design and form/fit applications. Tool ing applications, such as patterns for investment casting, also requir e good surface finish. Stereolithography provides three different buil d styles and many part and recoat parameters which can be optimized fo r these various applications. This paper presents the results of an in vestigation into the effects of build styles (AGES, WEAVE and Quick CA ST) and build parameters (Z level wait, pre-dip delay, dip velocity an d acceleration, sweep period and workpiece geometry angle) on the perf ormance measures of dimensional accuracy, surface roughness and build time. All of the prototypes were built on an SLA-250 which used the SL -5170 photopolymer resin. Statistical analysis of the results of the f ractional factorial design showed that AGES produced the highest degre e of dimensional accuracy while QuickCast was the least accurate build style. On a horizontal surface, AGES produced the best surface roughn ess and WEAVE produced the least desirable surface roughness. However, on an inclined surface, QuickCast produced the best surface roughness and AGES produced the least desirable surface roughness. The QuickCas t workpieces were produced in the shortest time and AGES workpieces to ok the longest time. In addition to the statistical analysis, surface profiles of the prototypes were studied with Data Dependent Systems (D DS), a stochastic modeling and analysis methodology. DDS analysis of t he surface profiles found that layer thickness was the major component of the profile on inclined planes and hatch and fill spacing were the major components on horizontal planes.