Powder for Heat-Sensitive MaterialsWe make vehicles that are used for building maintenance. A few of the parts are coated independently but many of our products are coated after assembly. The assembled parts have heat-sensitive components so we have not considered powder coating as a viable way to coat our parts. We are being pressured to replace our liquid coating process with powder by the local EPA. Are there any powders that can be used with rubber parts and other heat-sensitive materials or do we have to coat everything before assembly? How well does powder stand up to handling and tools during assembly operations? Our current liquid paint is not durable enough to withstand the physical abuse sustained during assembly. Also, can we expect better field performance with powder?
Powder coatings are widely used in the automotive industry on vehicle systems, which receive years of field service. I'm quite sure that if you would decide to replace your liquid coatings with powder, you would see some very positive results. Epoxy powders are used for under carriage drive train components as well as under the hood engine compartment accessories. They also are used as a primer for improved smoothness and durability on vehicle bodies. Polyesters and acrylics are used for exterior parts such as wheels and body trim. Acrylics are the system of choice for clear-coated wheels as well as some selected car bodies.
In your case, I would choose an epoxy for the under carriage, under-the-hood parts or anything that would not see direct sunlight. A good TGIC polyester would work on the exterior color of your heavy-duty commercial vehicles. Low cure powders are available but can be difficult with handling, storage and application for the newcomers entering the world of powder. If the powder system is selected properly and the product is fully cured, your parts should have few or no defects during preassembly. One last important thing, if the metal is not properly cleaned and treated, the best powder in the world will chip and peel right off.
Safety Inside the Spray BoothWe coat large agricultural assemblies that require our operators to work inside the powder booth so that they can reach all areas of the part. We are trying to find out what type of respiration equipment they should have when working inside a powder booth. We have been told everything from a dust mask to a fresh air supply system with a hood. Where can we go to find definitive information on what is required?
Occupational Safety & Health Administration (OSHA), Washington, details the requirements governing the use of personal protective equipment (PPE) as well as proper training requirements by the employer (OSHA 29 CFR 1910.132-138). All attempts also should be made to review the OSHA standards to determine what applies to the specifics of your booth size, number of guns, operators, etc. A careful review of OSHA's requirements will give you the specific details. Generally, operators inside a powder booth are exposed to unacceptable levels of airborne powder and should have complete breathing protection, including a fresh air supply. In most cases, it is not necessary for an operator to be inside a booth. Gun extensions are available that allow the operators a little extra reach for those far away or hard-to-reach areas. For operations that do require the operator to be inside the booth, proper PPE is very important.