Thermal manufacturing processes are typically those in which a material is subjected to a temporal thermal cycle like casting, extrusion and heat treatment of metals and plastics. The complexity of the design process for all these systems stems from the need to simulate complicated heat transfer, fluid flow and phase change phenomena and couple the results with the design rules and knowledge available on the manufacturing processes to obtain satisfactory designs. In this regard, the ability of expert systems to use heuristic reasoning has proved to be a powerful tool in the computer-aided-design of thermal manufacturing systems.
In this paper, the salient features of a knowledge-based system developed for the design of ingot casting process has been outlined. A Prolog based decision making front-end is interfaced with a Fortran based computational engine for rapid design. The results from the heat transfer analysis obtained from the computational module, are coupled to the evaluation module, which checks for satisfaction of the design criteria and violation of the design constraints. The decision making module uses a set of design rules to manipulate the variables until the design specifications are satisfied. Modularity and flexibility are maintained using an object-oriented format. Several interesting design acceleration features like learning from simple mathematical models and design extraction from previous designs are illustrated. The main features of this knowledge-based tool and the savings in time resulting from using these special features are discussed in detail.