Compressed air dryersare designed to be fitted directly to the throat of smaller throughput machines. These compressed air dryers are compact and light in weight, but still use desiccant bed technology, making them ideally suited for the technical moulding sector. The units use factory compressed air rather than using the electric blowers that are typically fitted to larger floor standing dehumidifying units.
Dehumidifying dryersare designed to remove any moisture present in polymer (i.e. held within the plastic granules due to absorption from the atmosphere) before being processed. Air is forced through a desiccant bed to make it extremely dry. This air is then heated to a specified temperature and fed into a drying hopper containing the material to be dried.This hot dry air draws the moisture out of the material. This removal of internal moisture prior to processing is critical for hydroscopic material grades such as Nylon and ABS.
Hot air dryersare designed to remove surface moisture from non-hydroscopic polymer, and also to pre-heat material prior to processing. They comprise an insulated stainless steel hopper with attached blower and heater. Hot air is blown through the polymer granules and the wet air is then expelled to atmosphere. These units are not suitable for use with materials that absorb moisture (hydroscopic).
Vacuum dryersdo not require the use of desiccants. After material is heated with hot air, a vacuum is applied to it, which reduces pressure to a level below the vapour pressure of water. This causes the water to boil off at a relatively low temperature. This reduces energy consumption and is less likely to cause material degradation.