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What is a drying tunnel?
Very accurate, and intricate castings are made using investment casting processes. This is also called a lost wax, or lost foam casting process. The shape of the parts to be cast are created in a special wax form. This is then encased in a ceramic shell, by dipping the wax form into a slurry of the ceramic material. A problem arises that will demand close control of temperature and humidity conditions that will remove the water born in the slurry mixture. This is two fold since both time and quality are at stake in solving this problem. The wax form must not be heated after being encased, because this would place a damaging stress on the ceramic mold by expansion of the wax form. Many systems now carry the parts that have been coated in the slurry tank on a conveyor much like you might find in your local dry cleaner. The system is enclosed in a small room that must have the controls mentioned above.
Take a new approach
Fluidtherm’s approach saves space and creates an atmosphere that can be easier to control. A conveyor is enclosed in a fabricated tunnel. The tunnel has a circulating air supply that is conditioned to remove moisture, and to maintain a close temperature control . The water is removed with two systems.
A refrigerator chiller unit cools the air stream to close to freezing temperature, but avoiding the freezing point that would destroy the efficiency of the cooling coils. This will depress the temperature of the circulating air. The water evaporation also has a cooling affect.
A desiccant dryer is the second system that has a powerful drying affect on the air stream, it also adds heat to the system and this heating affect is governed with a pyrometer controller that will control the dryer. Controls are often specified by the user, and typically a Honeywell Universal controller does a fine job of monitoring, displaying and controlling the temperature in the system.
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