The coating of products can be a complex manufacturing application, resulting in excessive waste and increased operating costs. Overspray, poor containment, and over- and under-applied material can all contribute to issues such as an unsafe work environment, contaminated equipment, and unacceptable end products. In addition, if the coating involves the application of viscous slurries and liquids, production problems can be compounded with the overall process being difficult to maintain consistency and repeatability.
Coating applications are varied and wide-ranging. Some examples include:
- Food processing involving the spraying of chocolate, oils, or flavoring slurries onto static of conveyorized targets
- Application of anti-microbial solutions onto packaging
- Enhancement of woven or non-woven textile products adding lotions or fragrance
- Lubrication of medical supplies, mechanical parts or systems
- Application of coating material to tablets in a rolling drum
The applications of coating processes are wide ranging and often include materials of various rheologies. For conveyorized coating applications, the most used facility in the Spray Analysis and Research Services laboratory is the mock-up conveyor system, which has the ability to change the line speed, spray height, number of nozzles, and overlap distance; spray angle and liquid distribution are critical in these applications. Transfer efficiency can be evaluated based on the nozzle flow rate and the weight of the deposited material onto a target. For tablet coating applications, volume flow rate combined with liquid distribution and droplet size across the spray plume are critical parameters.