Want to transform your old, dull metal parts to a shiny, bright appearance? Surface finishing service is a recommended choice. In this article, we’ll focus on the things to know about the powder coating, outlining the working and process of powder coating. In addition, understand the powder coating basics including its definition, advantages and disadvantages.
Powder coating is a finishing service that applying dry, free-flowing thermoplastic or thermosetting plastic powder material to the surface of an object, which can be made of metals, plastics, or glass, such as a CNC machining part, typically applied electrostatically and then cured under heat or with Ultraviolet light into an even coating. Thermosetting plastics get harder coatings than thermoplastic plastics, which enables them to withstand higher temperatures and show greater scratch resistance. However, harder coatings may also limit the impact resistance of coatings, and excessive hardening can cause brittle coatings. CNCLATHING.COM provides versatile powder coating services for your functional or decorative requirements in a wide selection of colors and textures on your CNC components.
Powder coating has its advantages over liquid coatings including higher durability, cost-effectiveness, and environmental friendliness, while also have some limitations in special applications.
What are the benefits of powder coating?
– Powder coat is a durable and long-lasting finish, which can be applied to various materials
– A wide range of color options are available, as well as different textures
– Powder coating does not contain any solvents, it’s a more environmentally friendly choice than liquid painting
– Powder coating is an economical finishing process, it does not need pollution control equipment
– The coated parts gained higher resistance to scratches, chipping, wear, and fading
– The color of powder coating can remain bright much longer than other finishes
What are the limitations of powder coating?
– The multi-color coating is challenging
– Difficult to get thin and even coating layers
– Easy to break down when exposed to UV rays
– Larger parts need longer time for drying and curing
– The substrate materials should be able to withstand the temperature requirements in the curing stage
– Higher start-up cost
For completing the powder coating, the essentials, powder gun, powder, compressor, regulator, oven, air filter and the part could all be required. Powder coating process has three stages, starting from preparation, go through the application, then to the curing stage. How does the powder coating process work?
1. Preparation of powder coating
There is a lot of preparation work to do before applying the coating. The purpose of preparation is to make the material be suitable to be coated. If there are oils, solvent and other residues adhere to the surface of the substrate, remove them with weak alkali and neutral detergents in dip tanks, or spraying the object with hot water, steam, detergent, and other solutions, to ensure the surface of the parts to be coated is completely clean. If the surface of the part with remaining debris like rust, scaling, and existing paint that difficult to clean, a blast room is required, it using pressurized fluid to propel abrasive material, such as sand, grit, or shot, against the surface, to achieve a smoother surface. Otherwise, the quality of the surface finish will be affected. In some cases, a certain area of the part needs to be exposed, masking products should be used to prevent the area from being coated.
How to apply the powder coating paint? Two methods using different coating materials are commonly employed by finishing services supplier.
– Electrostatic spray deposition (ESD): used on most metal parts, the electrostatic spray coating consisting of depositing electrically charged powder particles is applied on the metal surface through a powder spray booth, powder feeder, or electrostatic spray gun.
– Fluidized bed powder coating: in the process of fluidized bed application, preheated parts will be dipped into the powder material within a fluidized bed, another operation is applying the electrostatic fluidized bed powder coating, which generates a cloud of electrically charged powder particles above the fluidized bed through which the part is coated.
3. Curing stage
The characteristics of the curing stage are mainly affected by which powder coating method used. The machined parts coated with electrostatic spray deposition need to be cured in a powder curing oven, as the coated parts reach the optimal curing temperature in the oven, the powder particles melt and flow together, thus forming a continuous film on the surface of the parts. Parts in different sizes takes a different amount of time to complete the process. The parts coated with a fluidized bed can be heated and cured in a curing oven after it has been coated, like with coatings produced by the ESD method.