Alexander G. Cooper

Rapid prototyping and manufacturing by gelcasting of metallic and ceramic slurries

In this work an approach for rapid prototyping and manufacturing of metallic as well as ceramic parts is presented. By using Mold Shape Deposition Manufacturing (MoldSDM), a wax mold is fabricated which is filled with a slurry containing the final part material in powder form. The wax mold is manufactured by first decomposing the desired part geometry into machinable compacts. In a next step the mold is built up in a series of layers by machining either the wax or a sacrificial support material. The surface quality of the final mold is only limited by the abilities of the CNC machine. After casting a ceramic or metallic slurry, the wax mold is removed and the obtained green part debinded and sintered. In this work the mechanical and microstructural properties of the parts obtained by this method are presented. The materials which have been investigated are silicon nitride and stainless steels. Due to the high mold quality the process is suitable for a variety of applications in rapid prototyping and manufacturing where parts made of engineering materials are required.

Automated fabrication of complex molded parts using Mold Shape Deposition Manufacturing

Abstract Mold Shape Deposition Manufacturing (Mold SDM) is a solid freeform fabrication technique for producing complex shaped fugitive wax molds. A variety of castable polymer and ceramic materials have been used to make parts from these molds. This paper describes the Mold SDM method and an automated mold building machine based on a commercial CNC mill. Process steps, material selection and equipment issues are explained. Alumina, silicon nitride, polyurethane, epoxy and silicone parts with feature sizes ranging from 0.5 to 30 mm will be shown, as well as pre-assembled mechanisms and multi-material parts.

Rapid prototyping methods of silicon carbide micro heat exchangers

Abstract Conventional heat exchangers are mainly constructed of metal alloys. The manufacturing process of metal alloys usually requires assembling and joining techniques such as welding and diffusion bonding. In addition, the structures are limited to simple shapes due to the restrictions of the fabrication methods. This research focused on the manufacturing of compact heat exchangers made of high thermal-conductivity ceramic material, rather than on the performance of the devices. To achieve a high surface-volume ratio in heat exchangers, a strategy was adopted that fabricates miniaturized devices with a high shape complexity. This paper discusses an approach that uses a combination of mould shape deposition manufacturing (Mould SDM) and the gelcasting process to fabricate monolithic ceramic heat exchangers. This approach not only makes one-piece heat exchangers possible but introduces materials with superior thermal properties to the heat management applications. Silicon carbide is chosen for such applications because of its high thermal conductivity, thermal resistance, and corrosion resistance. The high chemical resistance of ceramic materials also extends the use of heat exchangers to chemical processing devices such as chemical reactors. The initial investigation of the process for micro reactors is also discussed.

An Interactive Drilling Simulator for Teaching and Research

An interactive program has been constructed that allows a student or engineer to simulate the drilling of an oil well, and to optimize the drilling process by comparing different drilling plans. The program operates in a very user-friendly way, with emphasis on menu and button-driven commands. The simulator may be run either as a training program, with exercises that illustrate various features of the drilling process, as a game, in which a student is set a challenge to drill a well with minimum cost or time under constraints set by an instructor, or as a simulator of a real situation to investigate the merit of different drilling strategies. It has three main parts, a Lithology Editor, a Settings Editor and the simulation program itself. The Lithology Editor allows the student, instructor or engineer to build a real or imaginary sequence of rock layers, each characterized by its mineralogy, drilling and log responses. The Settings Editor allows the definition of all the operational parameters, ranging from the drilling and wear rates of particular bits in specified rocks to the costs of different procedures. The simulator itself contains an algorithm that determines rate of penetration and rate of wear of the bit as drilling continues. It also determines whether the well kicks or fractures, and assigns various other accident conditions. During operation, a depth vs. time curve is displayed, together with a mud log showing the rock layers penetrated. If desired, the well may be logged, casings may be set and pore and fracture pressure gradients may be displayed. During drilling, the total time and cost are shown, together with cost per foot in total and for the current bit run. A demonstration version of the program is available on the World Wide Web at the Berkeley Petroleum Engineering Page. Its current address is : msel6.mse.berkeley.edu