POWDER COATING // 101
Powder Coating is the process of of applying a dry powdered paint compound that is made up of various resins, pigment, and fillers. These compounds are bonded to the metal with simple electromagnetic process during the spraying and are then fused together onto the metal during the curing process. This curing process easily exceeds 300 degrees and permanently affixes the compounds to the metal creating an tough durable finish.
The process of powder coating :
Step 1 : Prepare the surface. In the first step, the surface of the piece is cleaned either by media blasting or chemical treatment. Rust, oil, previous finishes (eg., paint, sharpie, etc.), machining coolant and loose metal fragments. When parts are welded the slag needs to be removed by media blasting. There are a number of processes ColorFast uses to ensure lint and debris are removed during this step.
Step 2 : Outgassing. Depending on the type of material being coated, steps are taken to outgas the material. Outgassing is the release or give off (a substance) as a gas or vapor. Gases trapped inside the metal will surface when the part is heated. This is especially problematic when the part has the coating applied and is being cured at a temperature of 400F. By heating the parts before the coating is applied the trapped gases can escape.
Step 3 : Coating Application. Powder Coating is applied through an electrostatic process where the part has a negative charge and the powder has a positive charge. As the powder exits the spray gun it seeks the negative charge of the part. This provides an even coating even in hard to reach places.
Step 4 : Curing the Powder. In order for the "powder" to cure into the hard protective coating, it must be heated to a temperature around 400F for 8 - 15 minutes depending on the specification. While the cure time is relatively short, the part's internal temperature must reach that temperature for the powder to cure properly. Material type and thickness play a significant roll in the time necessary for a part to reach the required temperature. It is not uncommon for parts to take 45 minutes to several hours to reach the desired temperature.
The measurable difference. // SureCure™
Our proprietary SureCure™ process monitors parts as they are heated providing real-time data which communicates with our ovens. As the part reaches the desired temperature, it starts a timer. When the cure time is completed, the oven automatically shuts off keeping the parts from over-curing.
The final step in our process is quality control and inspection. We measure parts for coating thickness and cure from each batch and each line run. Measurements are recorded and kept on file and can be passed along to our clients as part of our packing information. For companies with strict testing requirements or quality monitoring, ColorFast is well equipped to meet your needs.