Q. For several years we have operated our powder system without a room to enclose the booths and application process. It has worked out OK, but we need to make some adjustment for different humidity conditions. Is the cost of adding the room is justified? B.T.
A. Environmental rooms completely enclose the powder coating application area to isolate it from the surrounding plant environment. They can also be large enough to include space for powder storage. The construction is usually made of insulated panels with smooth surfaces that are easy to clean. The key features are: physical isolation from the plant environment, positive pressure, temperature and humidity control, and cleanable walls and ceiling.
The real value is based on the consistency that it provides for powder flow and application. Properly designed rooms can provide a consistent environmental control that will help the powder apply the same way, day in and day out, allowing application process development for defect-free parts.
The environmental room creates positive pressure inside to keep contaminates out of the room, whereas the spray booth works at negative pressure to contain the powder and eliminate drift from the booth. These two elements work together to keep powder and parts from being contaminated by plant debris. The environmental room will isolate the powder coating from the rest of the operations on the factory floor and limit contamination on the parts.
The financial justification for a clean room can be calculated by evaluating the process improvements. Rejects due to contamination of powder or parts will be substantially reduced, improving the output of the production line. Excessive film builds and gun spitting due to humid conditions will be eliminated. Employees will have time to work on process optimization for coverage and film build instead of constantly adjusting gun pressures and settings to accommodate ever-changing temperature and humidity conditions. If the environmental room is large enough, it can be a climate-controlled powder storage area, maximizing the shelf life of stored product.
Humidity control is particularly important. High humidity (above 60 percent RH) can cause clumping, poor flow and defects. Low humidity can cause poor charging and light coat in critical areas, and make it hard to build adequate film. The powder room reduces rejects, reduces powder use and reduces cost of the operation.
This alternative to TGIC-based polyester powder coatings offers similar performance and enhanced transfer efficiencies.
What is right for the customer?
Masking is employed in most any metal finishing operation where only a specifically defined area of the surface of a part must be exposed to a process. Conversely, masking may be employed on a surface where treatment is either not required or must be avoided. This article covers the many aspects of masking for metal finishing, including applications, methods and the various types of masking employed.