The Wurster process is an effective means to coat powders, spheres, granules and tablets. A variety of coating formulations can be used, including aqueous and organic solvents, hot saturated solutions, and hot melts.

In the Fluid Air Wurster coating process, the airflow through the system is controlled by an air-handling package which consists of a fan, fan damper, inlet air conditioning system and chamber filter system (see below).


Process Multiple Products with a Single Plate System

Traditional Wurster plates utilize round holes drilled in a distributor plate to create an airflow pattern for a specific application or product. This is problematic when processing a multitude of products, as a number of plates would be required to cover the range of products being processed. Different plates may also be required just to change the amount of material in a given batch. However, the new Fluid Air MAGNACOATER^® distributor plate system is designed to eliminate the need for multiple plates.

The MAGNACOATER plate system consists of two parts. The outer part of the plate is a standard perforated/drilled plate or a Turboflo screen. The inner portion of the plate is a drop-in assembly comprised of two plates riding on top of each other that function as an adjustable shutter. The shutter is designed to be adjusted to predefined open area percentages, and permits adjustments to be made without the need to remove product from the product container. This allows the user to adjust the ratio of airflow in the inner bed to airflow in the outer bed, permitting the processing of multiple products with a single plate system.

In multi-partition Wurster coating, balancing the airflow to all of the coating zones is critical to maintaining a functioning system and assuring uniform production. In addition to the primary distributor plate described above, multi-partition Fluid Air MAGNACOATER systems are equipped with an airflow balancing system that provides a means to balance the pressure drop between the zones, resulting in identical airflow in each of the coating zones. It also prevents the "loss" of a coating zone due to an upset in the system.


Increase Throughput and Spray Rates with Flared Partitions and Conical Nozzles

To effectively increase batch throughput and coating spray rates, the product must not be allowed to travel too close to the nozzle tip area and become oversaturated. Mechanical installations, such as collars, can be used to achieve this. However, mechanically stopping the product can cause particle abrasion during the process.

The MAGNACOATER design uses the fluidizing air to prevent the product from coming into contact with the nozzle tip, avoiding this problem. This is done by means of a flared partition which is configured with a standard upper diameter and larger bottom diameter. The larger bottom diameter means the product, once inside the partition, has a longer distance to travel before it reaches the spray nozzle. The distributor plate is designed to enure the product is adequately fluidized before it reaches the spray nozzle.

In addition to the flared partition, the MAGNACOATER design utilizes a conical spray nozzle. The top of the nozzle is smaller in diameter than the bottom, which helps ensure product does not travel too close to the tip area.


Choose from Standard, Self-Clearing, or In-Process Removable Spray Nozzles to Fit Your Application

There are three different nozzle types available for use with the MAGNACOATER system: standard, self-clearing and in-process removable. The standard nozzle is used for applications where the coating solution does not tend to build up in the tip or on the cap of the nozzle.

The self-clearing nozzle is designed for solutions that have suspended solids which tend to build up in the tip. When the system senses high liquid pressure (indicative of build-up in the nozzle tip), the nozzle fires a pin which clears the nozzle tip and then retracts to permit normal spraying.

The in-process removable nozzle is ideal for spraying solutions that build up on the nozzle cap, and allows the flow to the nozzle to be stopped (if clogged) while the other nozzles in the system continue to run. The build-up on the cap can then be removed by hand and the nozzle reinstalled.


Precisely Control Complex Coating Processes with Batch Architect™ Process Control Software

Total airflow through the system needs to be accurately controlled and adjusted as particle size and mass change during the process. The Batch Architect process control system allows the programming of a progression of stages of coating to match the most complex layering formulations. Various solvent recovery or solvent destruction options are also available to match the particular process, EPA, and economic requirements.