Feasibility of design in stereolithography

Abstract

We study the feasibility of design for a layer-deposition manufacturing process called stereolithography which w orks by controlling a vertical laser beam which when targeted on a photocurable liquid causes the liquid to harden. In order to better understand the power as well as the limitations of this manufacturing process, we de ne a mathematical model of stereolithography referred to as vertical stereolithography and analyze the class of objects that can be constructed under the assumptions of the model. Given an object modelled as a polygon or a polyhedron, we give algorithms that decide in On time whether or not the object can be constructed by v ertical stereolithography. If the answer is in the a rmative, the algorithm reports a description of all the orientations in which the object can be made. We then de ne a more exible model that more accurately re ects the actual capabilities of stereolithography referred to as variable-angle stereolithography and again study the class of feasible objects for this model. We give a n On time algorithm for polygons and On logn a s w ell as On time algorithms for polyhedra. We show that objects formed with variable-angle stereolithography can also be constructed using another manufacturing process known as gravity casting. F urthermore, we show that the polyhedral objects formed by v ertical stereolithography are closely related to polyhedral terrains which are important structures in geographic information systems GIS and computational geometry. In fact, an object built with variable-angle stereolithography resembles a terrain with overhangs, thus initiating the study of more realistic terrains than the standard ones considered in geographic information systems. Finally, w e relate our results to the area of grasping in robotics by showing that the polygonal and polyhedral objects that can be built by v ertical stereolithography can be clamped by parallel jaw grippers with any positive sized gripper.

Conventional - and Cone Beam – CT - Derived Stereolithographic Surgical Guides in the Planning and Placement of Dental Implants

“…automotive, space craft jewellery) leaded emerging complex technologic advances. The term "streolithography" (abbreviated as SLA or SL) first introduced in 1986 by Charles W. Hull, defines the method and apparatus for making solid objects by successive printing of light-curable material one on top of the other (Asberg et al, 1997). The procedure is entirely computer-controlled and named by various tags such as "3D printing", "additive manufacturing", "rapid manufacturing/prototyping" etc.…”

Heuristics for estimating contact area of supports in layered manufacturing

“…Asberg et al [1997] (see also [Bose 1995]) describe efficient algorithms to decide if a given model can be built without supports using Stereolithography. Majhi et al [1999b] give algorithms to minimize the volume of supports and contact area for convex polyhedra.…”

Casting with Skewed Ejection Direction

“…The manufacturing industry has at its disposal a number of processes for constructing objects, including gravity casting, injection molding [7], [21], stereolithography [3], NC-machining [10], [11], and layered manufacturing [15], [12], [19]. In all of these manufacturing contexts, computer-aided design systems of growing sophistication are presently being introduced, and more and more real-world objects are modeled as geometric objects within a computer.…”