In the metal fabrication industry, metal finishing has been a very crucial process in order to:-
Pro-long the metal lifespan via a protective layer coating
Prevent rust formation
Provide a professional, quality look of finished goods
For the finished product to last over time, metal-fabricated components’ durability is highly dependent on the type and method of coating applied onto it.
There are two methods we are able to implement for coating metal surfaces: spray painting or powder coating.
While spray painting is the conventional method, powder coating has grown in popularity due to the raise in market demand.
So, which metal finishing techniques shall we apply to best fit into our application? Let’s understand both the methods together in this article.
Introduction to Powder Coating – How Does Powder Coating Work?
The process of powder coating involved spraying dry powder paint onto the exterior of the coated component using compressed air and electrostatic gun.
The powder receives a negative charge from the electrostatic gun output and the negatively charged powder is drawn to the grounded metal pieces.
The powder’s attraction to the constituents and the dry application technique enable a thick paint layer, ranging from 0.002 to 0.006 inches on either side.
There is no requirement for a solvent to carry the resins and pigments to the surface due to powder coating systems being applied in dry conditions. The metal piece then brings along the powder charged on it into the baking process for curing.
Standard cure cycles range from 300 – 400F, last from 10 – 30 minutes. A surface tension is then created when the solid powder particles melt during the curing process.
As various resin systems are available in the market, they hold different properties in terms of UV stability, hardness, flexibility, corrosion protection and chemical stability.
From the resin summary tabulated above, it is commended that the best all around resin system is a polyester as they provide both stability and corrosion resistance, meanwhile sustaining the hardness but not losing its flexibility.
Pros of Powder Coating
As far as our concern, powder coating finishes are more aesthetically pleasing and versatile, allowing them to be rapidly known and demanded by the market in protective coating to the surface of metal pieces. The benefits of powder coating are as follows:-
1. Durability
Powder coating is typically 3-6 times thicker than wet spray paint. It provides a thick attractive finish which indirectly improves the corrosion resistance such as rust, dirt and preserve overall durability.
The thermal bonding process of powder paint provides a stronger bond and structure of paint, making it less prone to chipping off.
2. Efficiency
Powder Coating technique requires a single thick coat to achieve an efficient finish, whereas spray paint involves several steps and works best with thin coats.
3. Cost-Effectiveness
The enhanced durability and corrosion protection of powder coat paint frequently lead to a longer product life, which can help reduce the overall coating cost per year of product service in terms of life cycle cost. Besides, its efficiency and ease of use results in a material that is also extremely cost-effective.
4. Eco-friendliness
Powder coating method and process defines no VOCs, toxic ingredients, and generates minor waste which are environmentally friendly. On the other hand, the solvent carriers used in spray paints are a health risk as well as highly flammable, in comparison to powder coating.
Cons of Powder Coatings
The downsides of the powder coating can be further breakdown into:-
1. Thick Coats
Powder coating application on metal surfaces could be tricky if coated too thick, the appearance of the metals could be in orange peel defects. To rework, it would cost a hassle.
2. Equipment Requirements
In order to perform powder coating, its basic requirement requires high-cost equipment such as an industrial oven and electrostatic booth. For small orders on powder coating work, it may not be cost-effective due to the number of procedures involved, especially on colour changing can be challenging.
Introduction to Spray Coating – How Does Spray Coating Work?
Utilization of electricity and dry powder to paint a metal surface in powder coating, spray coating only required a pneumatic source to spray.
In the spray coating context, the paint’s resin is suspended in a solvent or carrier when applying liquid paint in a fine spray. If applied too thickly, the paint will drip and sag due to surface tension holding the paint on the part’s surface.
The solvent will then evaporate from the part’s surface, resulting in a painted surface which has cured. Baking the components can speed up this process, and apply several coats of paint to increase overall thickness is common.
TCW Group, a one stop HVAC manufacturer based in Malaysia offers our valuable clients the option of Heresite coatings, which is the one and only certified Heresite service provider in Asia.
This Heresite coatings provide a protective layer on the HVAC components against corrosion and are able to prolong the lifespan of the HVAC systems. Learn more about the benefits of Heresite’s HVAC coatings.
Pros of Spray Coatings
There are several factors that you might consider choosing spray coating over powder coating or vice versa as below:-
1. Thin Finishing
Wet spray coating can be applied to a surface with minimal thickness and still achieve a smooth coat. Even though thinner coatings are less durable, in certain aspects of applications where part tolerances, fitment or a smooth, mirror-like finish are crucial, wet spray coating has been the best fit.
For example, Heresite protective coatings which applied a thin layer of spray coating onto the HVAC components allowing corrosion-resistance on the coils, meanwhile preserving the maximum and efficient air flow in heat transfer.
2. Self-curing
Spray coating, generally known as wet liquid paint, possesses properties of curing independently, with no oven nor heaters. It will be a strong point especially in applying fine spray coating onto materials or substrates that do not work with heat such as rubber and fabric.
3. Variety Color Options
Paint in liquid is unlike powders, they are available in a wide range of options for the consumers in the market. Application of several colors simultaneously can create a perfect match in color, to catch attention especially signages and product assortments.
4. Smooth texture
Spray coating provides thin coats, where thin coats of paint are able to generate smooth, efficient finishing with good texture. It will definitely be the best option for projects which require delicate touches.
Cons of Spray Coatings
Looking into the drawbacks of spray coating, they are defined as below:-
1. Less Durable & Uneven Finishing
The thin layer of coating sprayed will show less durable and more susceptible to outdoor elements. Besides that, the thin finish will likely cause an uneven finish during the first time around, resulting in the reworking of re-paint one more layer of liquid paint.
2. Safety Concerns
Paint has VOCs, and it is harmful chemical compounds that can impact our environment and health.
Summary
In a nutshell, both spray coatings and powder coatings possess its pros and cons, and it is dependent on the application of finishing being performed.
Having explored the strengths and weaknesses of these two paint application techniques, the summary features and performance on various factors are tabulated shown below:-
TCW Group, as a one-stop HVAC manufacturer based in Malaysia, provides all our valuable customers with both spray (Heresite Protective Coatings) and powder coating options to suit all types of applications in order to meet the market demands.
For any inquiries on the spray coating and powder coating, feel free to contact us via email at support.hvac@tcw-my.com .
Comentarios