CASE STUDY
Industrial Painting Maintenance
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Indigo recently performed a cleaning of a Northwest Ohio industrial paint line system, cleaning out the overspray inside the exhaust system stacks, the exhaust fan blades and motor and the roof stack vents.
The build up was extensive, creating a potential combustion source, and seriously affecting the efficiency of the system. Cleaning the system increased the efficiency of the system dramatically, and the company experienced fewer quality defects from paint fallout on just painted parts on the conveyor, and the gondolas and conveyor had all the build up removed which also prevented the overspray and dirt falling onto parts throughout the system.
The Issue
Industrial painting systems operate in many different configurations, there are small batch paint booth systems, long elaborate conveyors into automated painting robot chambers, and lots of configurations in between. Within this variety, almost every system has one or more of the following components, paint booths, the conveyance system (if any), the spray equipment, the paint handling and mixing equipment, lighting, exhaust fans, stacks, and drying system (if any). These components may have many different options and configurations, such as robotic painters, or conveyors that are floor trolleys, hand rolled parts carts or overhead rails. What everything has in common is the need to be serviced and maintained for optimal quality and performance.
In our case, cleaning and maintaining the exhaust system, we are concerned with three general areas of paint systems the exhaust system, the conveyance system, and the paint booths. These systems are generally covered in overspray, dust in the industrial atmosphere, sometimes oil or grease that is airborne from other plant operations, grease from the conveyor system itself among others. We see three major types of problems that customers experience with systems in need of cleaning.
The major issue is the exhaust fans and paint stacks having excessive paint overspray buildup, reducing the efficiency of the air movement through the paint booth. The secondary issue is overspray, dirt, dust, oil and/or grease causing these contaminants to fall on the parts before, during and after the painting process. The last issue is the condition of the paint booth itself, where overspray can accumulate, with dirt and dust, to build up on the walls, ceiling and floor and create problems with safety and blocked lights. Many companies use booth coatings, booth grease or lining materials that they can change as needed, but if these are not used the buildup presents enough of a concern about fire ignition and fueling a fire that regular cleaning is required.
The hazards of paint systems not being routinely cleaned and maintained include:
- Fire hazards. Excessive paint buildup and overspray accumulation can in some situations ignite spontaneously, may becoming an explosion hazard, and safe practice requires keeping the overspray off the system components and avoiding excess buildup.
- Quality Issues. Inefficient air handling produces fallout, fallout is when overspray fails to be captured or exhausted, and lands on parts, resulting in quality defects, rework or rejection of the parts. Fallout exists because the exhaust system is not working properly. Causes of improper operation are in order of likelihood dirty exhaust filters, dirty intake filters, improperly sealed booth systems and using excessive paint.
- Downtime. Equipment that has overspray, dirt, dust and grease and oil on it does not operate as efficiently as it is designed to function. Overspray weighs down conveyor systems, makes the motor run hard and shortens their life. Fan blades coated with overspray are harder to turn and strain their motors, shortening their life. Equipment that fails results in unplanned maintenance downtime, which is expensive and reactive which does not help production efficiency.
Overspray is the primary culprit for most industrial paint systems cleaning requirements. Overspray refers to the application of any form of paint, varnish, onto an unintended location, in our case it primarily occurs on the walls, floor and ceilings of paint booths, the conveyor rails in the paint area, the conveyor trolleys, chains and hooks/hangers cycling through the system, and what gets past the exhaust filters and into the exhaust system to coat the fan blades, drive system, housing and motors plus the exhaust stack interior walls and any rooftop caps or vent structures.
3 Key ways to reduce overspay
A three-legged stool process
The first stool leg, and the number one priority for maintenance of industrial paint systems iso keep your intake and exhaust filters operating at the highest level of efficiency. Changing filters regularly for the intake system is essential, in high volume systems probably monthly, and twice per year in lower volume systems. For the exhaust filters these should be changed based upon usage, the more you spray the more often you should change. Exhaust filters should be inspected daily in high operation booth systems, and changed as soon as they show any sign of being coated with overspray.
The second leg of the stool is making sure you use the correct paint spraying system, guns, gun tips, and air pressure, plus keeping the system clean and in optimum operating condition. Failure to maintain this system results in excessive wasted paint and high rates of overspray. Remember, the easiest way to get rid of overspray is to not create much of it in the first place.
The third leg of the stool is training your operators (or programming your robotic system) to paint in a process that directs the vast majority of the paint onto the object being coated. Often operators spray into the air to verify the gun operation, or on the booth walls before painting. Use of tear away spray sheets for this purpose will eliminate a ton of overspray in your filters and exhaust system.
Cleaning Industrial Paint Systems
Dry-Ice Blasting
First, by using dry ice blasting, a high-power blasting method that introduces no outside dust from media into the facility, the blasting process allows for the efficient removal of overspray, dirt and lubricants from exhaust fans, stacks, conveyor and to a lesser extent the paint booths.
SCRAPING
Second, either before, during or after blasting, we use scraping, in conjunction with the dry ice blasting, which often improves the speed and effectiveness of cleaning flat surfaces, areas of high thickness contaminants or overspray. In our experience, a flat walled paint booth is often best scraped first and then blasted to remove remnants, as the adhesion of the overspray directly from the painting adheres to the surfaces and can be difficult for blasting alone to efficiently remove.