Choosing Types of Powder Coating for any Industry
By: B. Bondhus, Process & Estimating Engineer
Powder coating is a surface finishing option that applies a relatively thin film to provide excellent corrosion protection and chemical resistance in a highly cosmetic manner. While parts are often designed with specific colors, gloss, and textures – the types of powder coating are often overlooked, yet a critical component to every powder coating job.
Powder coatings are applied in a variety of types. Each resin system has specific attributes that are able to better suit needs of specific environments. Some of the most popular types of powder coating include: Epoxy Powder Coatings; Polyester Powder Coatings; Hybrid Powder Coatings.
Epoxy Types of Powder Coating
Epoxy powder coating is one of the first powder coating systems to become commercially available and still maintains its popularity today in various industries including Medical, Oil & Gas, Automotive and Defense. Epoxy based coatings display excellent performance in chemical resistance, wearability and also provide great corrosion protection. However, epoxy coatings can suffer from UV instability and therefore must be protected from sun-light and are not best suited for outdoor applications.
Polyester Types of Powder Coating
The two most widely used types of powder coating are TGIC Polyester and Urethane Polyester. Both types of powder coating provide excellent wear resistance and outdoor durability. Polyester Urethane powder systems provide excellent chemical resistance. This powder coating system is often seen in the automotive, plumbing and power transmission industries. Polyester urethane powder typically needs to undergo a higher temperature curing cycle, which limits its ability to be applied to low-cure candidates, such as aluminum extruded parts, cast parts and lead based parts. Another limitation of polyester urethanes is that they are limited to thin film applications of 1-3 mils (25-75µm). As a thickness increases, the film has the tendency pull back on itself which can produce an “orange-peel” effect.
Similar to Polyester Urethane Powders, TGIC Polyester powders are often used in power transmission and automotive industries. TGIC Polyester powder coating films on the other hand can be applied with greater ease as they can be sprayed at thickness greater than 3 mils (>75µm). TGIC Polyester powders can also be cured at lower temperatures making them ideal for cast parts and extruded parts. TGIC-Polyester is also very resistant to overbaking, which is associated with a lower gloss and a yellow appearance; however, the chemical resistance of this powder coating system is reduced.
Epoxy-Polyester Hybrid Types of Powder Coating
Hybrid powder coatings are very similar to Epoxy Powder coating systems as these types both offer good corrosion protection. Hybrid powder types typically have a greater ease of application due to their over-bake stability, similar to Polyester-TGIC films; although, the hybrid powders are not well suited for applications exposed to UV-ray’s similar to Epoxy powders and have a slightly reduced chemical resistance than epoxy powders. Hybrid powder coating systems are used across many industry subsectors, but often applied in the telecommunication, electronic and plumbing industries.
Powder coating is an excellent surface finish option that is used to protect many industries from a growing list of environmental hazards and regulations. It is important to factor in the types of powder coating when deciding what types of powder coating service may be best suited for specific applications.
Blog Written by B. Bondhus, Process & Estimating Engineer