Solid Powder Heating Process With Vaporization Modeling in the Warm-Up Stage of Process Chamber

Part accuracy and quality in rapid prototyping process using solid powder in the part cake are typically dependent upon thermal system and powder properties. The part cake is a rectangular mild steel cylinder with movable part plate piston. For maximum thermal stress reduction in the part-building process, about 1.27 cm or 2.54 cm initial solid powder was uniformly laid in the part cake. The powder was then warmed to a certain temperature before sintering. The amount of moisture present in the solid powder will have significant impact on the required warm-up time. In the moisture vaporization process, solid powder temperature in the computational cell will remain at 100°C until the moisture mass fraction reaches zero. The warm-up time of the cell will increase as the moisture content of the powder increases. Reference data has yet to be published on warm-up times, therefore machine operators will find variances in warm-up times. To better predict the warm-up time for the solid powder heating process with moisture vaporization in the warm-up stage of the part cake, a vaporization code model was developed that can also simulate the heating process with vaporization for any solid particle mixed with any liquid agent.Copyright © 2006 by ASME