UV-Cured Powder Process
UV Powder Coating Overview
UV-cured powder coatings have distinct finishing advantages by reducing cycle times, increasing finishing capacity, reducing defects, and providing a safe and easy way to apply the coating. A summary is illustrated below.
Pre-Conditioning/Heating: In the case of non-conductive substrates, the substrate requires conditioning to provide a uniform conductive substrate for powder deposition. The use of a conductive primer and pre-heating is required for electrostatic powder deposition.
Powder Application: An electrostatic charge is generated on the powder coating material typically through corona or tribo spray process. The grounded substrate attracts the charged powder to the substrate to deposit a uniform layer of powder coating on the piece.
Melt and Flow: Applied heat melts the powder which coalescences and flows to form the coating. Finally, exposure to high intensity UV lamps cure the coating in seconds.
Powder Recovery and Utilization: A powder coating recovery system enables re-captured powder coating to be re-sprayed to provide up to a 98% material utilization. Non-reclaim systems have the capability to provide substantial material utilization as well.
Finishing Process Comparison
UV cure powder coating systems have a distinct process advantage over liquid and thermal cure coatings. A brief summary of process steps for liquid and thermoset powder coatings is illustrated below.
- Liquid Coatings: Once applied, liquid coatings require a flash off oven for solvent or water removal to allow for firm formation, meaning further exposure time in an oven to cross link the coating. The 20+ minutes of exposure the heat increases the surface temperature of the part; requiring an additional process step to cool parts prior to handling.
- Thermoset Powder Coatings: Once applied, thermoset powder does not require the removal of solvents, however substantially higher temperatures (400°F) and exposure times (10-20 minutes) are required to melt and flow powders and cure the coating. Lower cure temperature powder coatings are available, however equal or longer cure times are required. This requires a longer cooling period to handle the part.
- UV-cure powder coatings: Once the coating is applied, the short oven time (1 minute) allows the melt and flow process to occur, and is followed with UV exposure to cure the coating. The UV cure powder coating system significantly reduces the thermal exposure.
Process summary of liquid and thermoset powder coating technologies compared to UV are shown here.
To check out our process in action, watch our production video.
Opportunity for New Applications
UV-cured powder coatings have distinct advantages over thermal cure systems; shorter process time reduces thermal exposure. The lower internal temperatures reduces the degradation of the substrate. This allows for:
- New application areas for powder coating heat sensitive substrates
- Minimization of outgassing of porous substrates
- Parts can be immediately handled after finishing