Building a Better Powder Coating System: Application Equipment
Posted on Wednesday, February 6, 2019
As an equipment supplier to the finishing industry, it is very rewarding to travel the country and visit people who have realized “The American Dream” and own their own business.
When asked, most say they are “living the dream” with some level of sarcasm of course! All kidding aside, many of today’s custom powder coating facilities have evolved from humble beginnings. Many owners cite luck as a contributor, but most put in a lot of hard work, sacrifices and have made sound business decisions and investments along the way.
Batch booths can be scaled to accommodate very large parts and multiple sprayers. Typically, these booths will be fully enclosed and configured with multiple collectors. Attention to design is critical to ensure proper air flow and containment. Batch booths can be configured with removable filter modules which allow multiple colors to be sprayed and reclaimed. Modules can be dedicated for high volume colors and changed out as needed.
A process style powder booth used with a conveyorized system is typically fully enclosed and configured with one or more collector modules. The booth can be designed to accommodate both manual and automatic application equipment. To minimize the size of the booth and the overall airflow requirements, booths are designed based around a defined maximum part size or process window. Manual operators stand outside the booth and spray through an opening, while automatic applicators are inserted through a slot with machines located outside of the spray booth. A combination of manual and automatic equipment can be located on both sides of the booth based on coverage requirements of the product being coated.
To accommodate color change, process booths can be equipped with removable filter modules. A color change consists of the following process:
1. Purge the application equipment.
2. Clean the current color out of the booth enclosure by blowing into the filter module.
3. Remove the filter module.
4. Attach a new filter module.
Depending on the amount of application equipment and the size of the booth, this color change sequence may take anywhere from 30 – 60 minutes. It is common to have dedicated filter modules for high volume colors and one filter module used for “spray to waste” of lower volume colors. This type of system is most efficiently run by batching product according to color to minimize color changes and down time.
The above color change process can be reduced by having multiple booths that are configured to roll on/off line. With this scenario, downtime is reduced to the amount of time it takes to roll one booth off and the other on line (three - six minutes). The off-line booth is then cleaned while production continues.
Driven by current manufacturing trends, many end users are requesting more frequent and efficient color change booth technology. Current system designs utilize non-metallic booth wall technology with properties that repel the charged powder particles and move them into the containment air stream. Booth ducting is smooth, with minimal seams and balanced air velocity to minimize settling of the powder. This is coupled with a highly efficient cyclone technology to return the desired powder particles to a powder distribution center, where they are mixed with virgin powder and supplied to the application equipment. These systems operate at reclaim efficiencies in the high nineties and can accomplish color changes in 10 minutes or less.
All processes benefit when the number of variables that impact them are minimized or controlled. With powder, the temperature and humidity of the environment in which it is sprayed can have a significant impact on the result. Some powders and substrates are more forgiving than others. Optimally the temperature should be in the range of 60 – 80 degrees Farenheit, and the relative humidity 40 – 60 percent. If your facility is in an area where you have large swings in temperature and humidity, you will want to consider installing your powder coating operation in an environmental room. An environmental room is constructed with insulated walls and ceiling panels and has a dedicated HVAC unit. In addition to a more repeatable application, cleanliness can also be improved by isolating the coating process from the rest of the manufacturing facility.
There are many aspects to consider when designing a finishing system. Whether it is a small batch system or a highly complex conveyorized process system, I would encourage anyone who wants to build a system to reach out to the equipment suppliers that have demonstration lab facilities and utilize these resources to prove out your process. There are also systems integrators that can take you to see successful installations. Either way the old adage “you get what you pay for” holds especially true in our industry.
by John Owed, director sales & marketing at Col-Met Engineered Finishing Solutions