All About Powder Coating
Powder Coating: Everything you need to know
A blank bare sheet of metal often lacks visual appeal and is prone to be damaged by external factors such as corrosion and abrasions. Powder coating emerges as a transformative process that not only enhances the mechanical properties but also elevates the visual aesthetics of surfaces by applying and curing a powdered coating material. This versatile technique has found applications in numerous everyday objects, ranging from windows, doors, and furniture to industrial machinery and specific automotive components. Furthermore, recent advancements have expanded its scope to non-metallic surfaces like plastic, wood, and glass.
Various Advantages of Powder Coating
- Solvents Free
- Protection and Decoration
- Resistant and resilient surface
- Close to 100% material utilization
- Outstanding results in one coat (single coat excellence)
- High mechanical resistance
- Easy, clean and effortless application
- Applicable on various substrates
Looking for a particular product?
Contact our experts for more info
What are Powder Coatings made of?
Powder coating is a versatile and sustainable method for enhancing surfaces, offering a range of benefits, and is composed of carefully balanced elements to achieve the desired finish and functionality.
Powder coatings are dry mixtures and usually consist of four main components:
Binder
The binder serves as the foundation of every powder coating and determines essential properties of the resulting desired surface such as hardness:
- Epoxy Resins
- Polyester Resins
- Polyurethan Resins
- Acrylate Resins
- Hybrid Systems
Pigments and Dyes
These colorants, whether organic or inorganic, are insoluble in the medium they are meant to dye. They are uniformly dispersed within the binder and ground with it, influencing factors like color, opacity, color strength, and light fastness. Dyes, in contrast, fully dissolve in the medium to provide color.
Additives
Additives are introduced to impart specific properties to powder coatings, including flow, gloss, texture, and surface hardness. They also contribute to functional characteristics, such as improved abrasion resistance and optimized outgassing behavior.
Fillers
These substances contribute volume to the powder and ensure optimal packing density due to their particle size (ratio between pigments, fillers and binders). Common fillers include natural minerals like calcium carbonate.
Formulation
Each powder coating is inherently unique, mirroring the distinct requisites it must cater to. Thus, prior to commencing production, a tailored formulation is indispensable. This formulation can be meticulously customized to align with the specific demands of our clients and their intended applications.
Formulation
Each powder coating is inherently unique, mirroring the distinct requisites it must cater to. Thus, prior to commencing production, a tailored formulation is indispensable. This formulation can be meticulously customized to align with the specific demands of our clients and their intended applications.
Precision Weighing
In the subsequent phase, the constituent ingredients are accurately measured and allocated into a receptacle. At this juncture, disparities in density and granular dimensions are not yet significant factors in the process.
Thorough Mixing
The weighed raw materials are subjected to a meticulous blending process, which involves both horizontal and vertical movements, facilitated by specialized equipment. The velocity of the mixing apparatus and the duration of the blending operation are meticulously stipulated to ensure consistency.
Extrusion
The composite material is then subjected to extrusion, a transformative step where it is melted. The primary objective of this extrusion process is to attain a uniform and homogenous mass, accomplished through the application of heat and the resultant shearing forces generated within the machinery.
Cooling
As the amalgam emerges from the extruder, it is promptly subjected to a cooling procedure, employing a cooling belt and subsequent rolling. The solidified mass is subsequently fragmented into small chips through a shredding mechanism.
Grinding
The next phase entails the gradual transformation of the now solidified and cooled extrudate, initially broken down into coarse chips ranging between 10 to 20 millimeters in size. Subsequently, a fine grinding operation is undertaken to yield the desired powder coating texture.
Filling
The refined powder coating product is then precisely measured, meticulously packaged, and sealed in hermetically sealed containers, ready for distribution and application.
How does Powder Coating work?
The powder coating process comprises three distinct phases:
Pre-treatment
The initial phase involves the meticulous preparation of the substrate. This entails the removal of dust, scale, rust, grease, dirt, and any oxide layers (for instance, on aluminum). Both chemical and mechanical pre-treatment techniques are employed to achieve this. Additionally, a conversion layer is applied to the workpiece during this stage, enhancing corrosion resistance and optimizing adhesion for the subsequent powder coating. Thorough drying of the treated surface is imperative.
Powder Coating Application
In this step, the powder coating is expertly applied to the grounded surface through the utilization of a powder spray gun. A critical aspect at this juncture is the prevention of dust and dirt from contaminating the surface. The powder spray gun generates a charged cloud of powder particles, which electrostatically adhere to the workpiece, forming a cohesive layer.
Curing
The final phase involves curing the powder coating. This is achieved by subjecting the coated workpiece to controlled temperatures within an oven, typically ranging from 110 to 250°C. The curing process duration is influenced by several variables, including heating time and the thickness of the substrate, culminating in a fully cured and durable finish.
Pre-treatment
The initial phase involves the meticulous preparation of the substrate. This entails the removal of dust, scale, rust, grease, dirt, and any oxide layers (for instance, on aluminum). Both chemical and mechanical pre-treatment techniques are employed to achieve this. Additionally, a conversion layer is applied to the workpiece during this stage, enhancing corrosion resistance and optimizing adhesion for the subsequent powder coating. Thorough drying of the treated surface is imperative.
Powder Coating Application
In this step, the powder coating is expertly applied to the grounded surface through the utilization of a powder spray gun. A critical aspect at this juncture is the prevention of dust and dirt from contaminating the surface. The powder spray gun generates a charged cloud of powder particles, which electrostatically adhere to the workpiece, forming a cohesive layer.
An overlook of the most common powder coating errors:
During application
- Poor fluidization
- Powder drizzles off the work piece
- Fluctuations in layer thickness
Surface defects
- Powder puffs on the work piece
- Craters
- Pin holes
- Picture framing effect
- Dripping
- Orange peel effect
Optical & Technical defects
- Color deviations
- Gloss level deviations
- Poor mechanical properties
- Loss of chemical resistance