Content area
Full Text
Behrokh Khoshnevis: Behrokh Khoshnevis, is at the Department of Industrial and Systems Engineering, University of Southern California, Los Angeles, CA 90089-0193, USA, E-mail: [email protected] [email protected] [email protected] [email protected]
Satish Bukkapatnam: Satish Bukkapatnam is at the Department of Industrial and Systems Engineering, University of Southern California, Los Angeles, CA 90089-0193, USA, E-mail: [email protected] [email protected] [email protected] [email protected]
Hongkyu Kwon: Hongkyu Kwon is at the Department of Industrial and Systems Engineering, University of Southern California, Los Angeles, CA 90089-0193, USA, E-mail: [email protected] [email protected] [email protected] [email protected]
Jason Saito: Jason Saito is at the Department of Industrial and Systems Engineering, University of Southern California, Los Angeles, CA 90089-0193, USA, E-mail: [email protected] [email protected] [email protected] [email protected]
1. Introduction
Contour Crafting (CC) is a new patented additive fabrication process developed at the University of Southern California (Khoshnevis, 1998). It uses computer control to exploit the superior surface-forming capability of a bladed trowel for creating smooth and accurate surfaces with intricate features. The overall process will combine an extrusion process for forming the object surfaces with a filling process (pouring or injection) to build the object core.
The current version of the CC fabrication machine, illustrated in Figure 1, consists of two trowels, whose function is to shape and smooth-out plastic material forming the outer surface of the object. As with any other rapid prototyping process, a part is fabricated layer-wise (Ashley, 1991; Sachs et al., 1992; Tech Update, 1994; Crockett et al., 1995).
The major application potential of CC includes fabrication of parts such as turbine blades which have complex surface profiles devoid of small and detailed features, large tooling for automotive and aerospace industries, and construction of civil structures such as houses and bridges (Khoshnevis, 1998; 2000). Figure 2 shows the schematic of automated construction of house walls. Note that, as shown in the figure, utility conduits may be built into the walls of a building structure in accordance with the CAD data.
The distinguishing feature of CC, as compared to similar types of layered-manufacturing processes (NASA, 1999) such as Stereolithography (SLA)[1] and Laminated Object manufacturing (LOM)[2], is the capability of the trowels to smooth out the striations between consecutive layers as can be seen in Figure 3. CC also provides for superior surface finishes with very little dependence on the choice of...