The Powder Coating Process
Before you begin the powder coating process, you must first determine your desired color as well as what type of material you will want to use. You will have to choose from either thermoplastic or thermoset polymer powders. Consider what you are coating and what function it will serve when deciding between these two.
As the name would imply, thermoplastic coatings are more reversible and are good for items that may be changed or remolded in the future. Thermoplastic coatings combine a mixture of strength and flexibility, and also has increased impact resistance. The downside of thermoplastic coatings are that it could melt under high enough heats, and thermoplastic coatings tend to be more expensive than thermoset coatings.
Unlike thermoplastic coatings, thermoset coatings are best on items that will remain the same. Thermoset coatings use an irreversible chemical bonding process and cannot re-melt. While this coating cannot be changed, the coating does reinforce the structural integrity of the coated item, can withstand extreme temperatures and has higher durability. This makes thermoset coatings ideal for auto parts, electronics and appliances.
After you’ve decided what type of coating you want, you will need to consider the different powder formulations. IronShield offers 2 different varieties and each has its own benefits.
Polyester powders have a low cure temperature and are often great for using on smaller components. It also provides impact, mechanical and chemical resistance to these powder coated items. Polyester powders are commonly used for applications such as agricultural, construction, recreational, lawn & garden equipment, electrical enclosures, appliances, lawn furniture, wheels and rims.
Epoxies were the original “powder coating” powder, and are still very popular. Epoxies keep a durable and long-lasting coating while also being environmentally friendly. It also boasts the best corrosion and chemical resistance when compared to other powder types. The downside of epoxies is that when used for applications that are outdoors, they weather more easily. Epoxies are best for use on items that will generally stay inside and be protected from the elements.
The first step of powder coating is preparation. Before you start anything, you should disassemble the item and remove anything you don’t want coated and/or anything that doesn’t hold a charge or could melt during the curing process. Then the item must be cleaned. In order for the item to be cleaned and prepared before powder coating, you must first rinse off the item. Then, depending on what materials or residue may be on your item, it will need to be blasted with an abrasive material like sand or a chemical solvent. Abrasive blasting materials are ideal for removing dirt, rust and mill while chemical solvents are best to get rid of oil, grease or paint.
After the item has gone through the blasting process, it should be rinsed and dried again before it is then dipped in a chemical solution that neutralizes the surface to create a film that will allow the powder to adhere to the surface.
Powder coating is more complex than some other coating options, such as liquid coating, because it involves using electrical charges in order to get the powder to stick to the metal or other conductive material. A gun that electrostatically charges the powder is used to spray the material, which is grounded to provide an opposite charge to attract the particles. You may take multiple passes to cover a part for your desirable coat thickness. After powder coating is applied, be careful not to brush or blow on the surface at all as it could cause the powder to fall off.
After the powder is applied, the item is then put inside an oven to cure. These ovens are normally heated between 350 to 400 degrees Fahrenheit for 15 to 30 minutes. After this point, the item is then removed from the oven and allowed to cool at room temperature. During the curing process, the powder melts at the target temperature and flows together, forming long chemical chains that give it durability and rigidity. It then becomes gel-like as it cools.
IronShield has one of the largest ovens in all of the Midwest, at a whopping 10’ x 10’ x 35′. We can take on any project that can fit in our oven, including car bodies, trailer frames and farm implements