Finishing options at Behlen Custom Fabrication include powder coat painting and hot-dip galvanizing. Our paintline accommodates items up to 4' x 6' x 25' at a rate of up to 20' per minute; meanwhile, our capacity for hot-dip galvanizing is 3' x 20' x 6'.
Need help determining which finishing option to choose? Below is a brief rundown of powder coat painting and hot-dip galvanizing processes and advantages.
Powder Coat Painting
Powder coat painting is a popular method for applying a durable and attractive finish to metal surfaces. It is widely used in various industries such as automotive, architecture, appliances, and furniture. The process involves several steps:
Surface Preparation
Before applying the powder coating, the surface of the metal must be properly prepared. This typically involves cleaning the surface to remove any dirt, grease, oil, or other contaminants that could interfere with adhesion. Surface preparation may also involve sanding or blasting to create a smooth, uniform surface and to remove any existing coatings or rust.
Application of Powder Coating
Once the surface is properly prepared, the powder coating is applied using a spray gun. The powder coating is typically made up of finely ground particles of pigment and resin. These particles are electrostatically charged as they are sprayed onto the metal surface. The electrostatic charge causes the powder particles to adhere to the grounded metal surface, creating a uniform coating.
Curing
After the powder coating is applied, the metal object is moved into an oven or curing chamber. The heat of the oven causes the powder particles to melt and flow together, forming a smooth and durable coating. The curing process typically takes place at temperatures ranging from 300 to 450 degrees Fahrenheit (150 to 230 degrees Celsius) for a specific period, usually around 10 to 30 minutes, depending on the powder coating material and thickness.
Cooling
After the curing process is complete, the coated metal object is allowed to cool to room temperature before handling or further processing.
Key Advantages of Powder Coating
- Durability: Powder coatings are highly resistant to chipping, scratching, fading, and other forms of wear and tear.
- Environmentally Friendly: Powder coatings contain no volatile organic compounds (VOCs), making them environmentally friendly and safer to use.
- Efficiency: Powder coating application is a relatively fast process, and there is minimal waste since unused powder can be reclaimed and reused.
- Versatility: Powder coatings come in a wide range of colors, finishes, and textures, allowing for customization to meet specific aesthetic and performance requirements.
Hot-Dip Galvanizing
Hot-dip galvanizing is a process used to protect steel from corrosion by coating it with a layer of zinc. It provides excellent corrosion protection for steel in a wide range of environments, making it a popular choice for applications such as structural steel, automotive parts, fencing, guardrails, and marine hardware. The thick, durable zinc coating formed by hot-dip galvanizing helps to protect the underlying steel from rust and corrosion for many years, even in harsh environments. Hot-dip galvinizing involves several steps:
Surface Preparation
The steel components to be galvanized are first cleaned to remove any rust, oil, grease, or other contaminants. This is typically done using a combination of chemical cleaning and mechanical processes such as abrasive blasting.
Pickling
After cleaning, the steel is immersed in a pickling solution, usually a dilute solution of hydrochloric acid or sulfuric acid, to remove any remaining rust and mill scale. Pickling also etches the surface of the steel, creating a rough surface that promotes adhesion of the zinc coating.
Fluxing
Once the steel has been pickled, it is immersed in a flux solution to prevent oxidation of the steel surface before it is galvanized. The flux solution typically consists of zinc ammonium chloride or zinc chloride.
Galvanizing
The prepared steel components are then immersed in a molten zinc bath at temperatures typically between 815°F to 850°F (435°C to 455°C). The steel and molten zinc are held in the bath for a predetermined period, allowing the zinc to alloy with the surface of the steel, forming a series of zinc-iron alloy layers. The thickness of the zinc coating can be controlled by the immersion time and the temperature of the molten zinc.
Quenching
After the steel has been galvanized, it is removed from the zinc bath and allowed to cool in the air or is quenched in a water bath to solidify the zinc coating.
Inspection
Once the galvanized steel has cooled, it undergoes inspection to ensure that the coating is uniform and free from defects such as bare spots, runs, or drips. Thickness measurements may also be taken to verify that the coating meets specified requirements.