Reducing the surface deviation of stereolithography using in‐process techniques

Abstract

Builds on previous research by the authors to establish a mathematical representation of the surface roughness of stereolithography (SL) parts. It is the intention of the research to use this modelling technique as a design tool for defining optimum build orientation and planning post‐process finishing operations. During the development of this model, a number of in‐process attributes inherent in SL were seen to affect surface deviation. Most notably the phenomenon known as “print‐through” on down‐facing planes produces a build orientation envelope of very smooth surfaces. Although capable of providing low roughness over some 50°, print‐through smoothing cannot easily be extended to other angles, hence complementary processes for surface smoothing must be developed. Discusses a number of possible solutions, showing how the generation of a meniscus between layers can prove beneficial in reducing SL surface roughness, hence reducing the need for lengthy manual finishing operations.

Additive manufacturing methods and modelling approaches: a critical review

“…D p depth of penetration P L laser power W 0 laser beam spot diameter V S laser scanning speed E C critical exposure time OC overcure Reeves and Cobb in [26] and [49] presented an analytical model for SLA surface roughness that took into consideration the layer profile as well whether the plane was up-facing or down-facing, which was verified with experimental data. Podshivalovab et al [35] has used a 3D model to verify the dimensional accuracy of scaffold-like structures used in bone replacement via CAD and FEA.…”

Materials analysis of stereolithography resins for use in Rapid Manufacturing

“…The build orientation and its affect on the isotropy of the material is one of the aspects considered in this paper and is covered in Section 3.1. However, it should also be noted that the build orientation also has a profound affect on the surface finish of the completed part due to the layer-wise manufacturing process employed [15], though this aspect is not considered in this paper as it has no bearing on the tests undertaken.…”

RP part surface quality versus build orientation: when the layers are getting thinner

“…For example, stereolithography apparatus (SLA) has a notable phenomenon called print-through on down-facing planes. This effect may cause the need for complimentary surface smoothing processes [4]. In general, the determination of build orientation needs to consider many factors such as part cost, build time, surface quality, overhang area, and support volume or area [5,6].…”