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Powder Coating

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What is Powder Coating?

Powder coating is a method of applying a protective and decorative layer to metal surfaces. Unlike liquid paints, it is applied in a dry powder form. This powder is also called powder coating paint.

It’s not possible to use this paint at home when you renovate your bedroom. But for manufacturing tasks, powder coating is the most modern and high-performance solution.

Powder Coating Overview

The powder consists of fine particles of pigment and resin. During application, it's electrostatically charged and sprayed onto conductive surfaces. The coated item is then heated in a curing oven, where the powder melts and forms a smooth, continuous film.

Powder coating technology utilizes both thermoplastic and thermoset polymers.

Technology Advantages

Powder coating is popular in markets where performance and environmental qualities are crucial.

The absence of solvents means no volatile organic compounds (VOCs) are released into the atmosphere, making powder coating an environmentally friendly option. Excess powder from the application process can be collected and reused, reducing waste and increasing production efficiency. The process allows for customization of texture, color, and coating characteristics to meet specific customer needs.

This method represents a significant advancement in the field of protective and decorative finishes due to their production efficiency, compliance with environmental regulations, and versatile aesthetic options.

Why Choose Powder Coating?

Powder coating offers significant advantages for various industries, thanks to its performance, environmental benefits, and economic efficiency.

Durability from 12 months to 30 years

Surface Protection: When melted, the powder forms a durable film that is more resistant to damage compared to liquid paints. The surface is highly resistant to chipping and scratching.
Long-Lasting Coating: The lifespan of the coating depends on the powder composition. High-durability polyester and polyurethane coatings last up to 5 years, while super-durable acrylic and fluoropolymer-based formulations can last over 30 years.
Corrosion Resistance: The polymer film creates a barrier against corrosion, protecting metal surfaces exposed to harsh environments.

Environmental Safety

No VOC Emissions: Powder coatings contain no solvents, so they do not emit volatile organic compounds (VOCs). VOCs can be harmful to human health, causing respiratory issues and potentially leading to cancer. Powder coatings help create safer environments for people and maintain environmental cleanliness.
Minimal Waste: During application, about 60% of the powder adheres to the surface, while the excess remains in the spray booth. This excess can be collected and reused in a process called reclamation. As a result, manufacturers can utilize over 90% of the powder, minimizing production waste.
Energy Efficiency: The curing process occurs at temperatures of 160-120°C for about 10 minutes, requiring minimal energy consumption from manufacturers.

Economic Efficiency

Reduced Operating Costs: The powder coating application process can be fully automated, reducing labor costs and production time.
Lower Waste Management Costs: By using powder reclamation systems, up to 95% of the excess powder can be reused, reducing waste volumes and disposal costs.
Long-Term Savings: The durability of powder coatings reduces the frequency of reapplications and maintenance. High-durability coatings can last up to 10 years without requiring repairs, which significantly lowers operational costs for industrial and infrastructure projects.

Aesthetic Flexibility

Wide Range of Options: Includes glossy, matte, and textured finishes to meet diverse design requirements. Over 5000 colors and textures are available on the market, including special effects like metallic, chameleon, and antique. Manufacturers can also develop custom colors and textures for specific projects.
Custom Color Matching: Powder coatings meet branding and design specifications. Color experts use spectrophotometers and computer color matching systems to create precise color formulations. The color matching accuracy can achieve Delta E<1, an imperceptible deviation from the standard to the human eye.
Versatile Applications: The technology is suitable for industrial equipment, automotive parts, household appliances, and architectural elements. The use of powder coatings is growing annually by 4.5-7% in the automotive industry for wheel coatings, in construction for protecting metal structures, and in appliance manufacturing for coating washing machine and refrigerator bodies.

Types of Powder Coatings

Powder coatings contain standard components, including pigments for color, additives for light stabilization, and protection against photodegradation. The base of the powder is a resin, and the type of resin used determines the application possibilities and durability of the coating. Based on the type of resin, the following types of powder coatings are distinguished:

Polyester

Polyester coatings are divided into standard and high-durability types. Standard polyester coatings maintain their color and gloss for 1-2 years in moderate climates when exposed to sunlight. They are used for items that are not permanently outdoors, such as bicycle frames or seasonal outdoor furniture. The advantage of standard polyester coatings is their unlimited color range. High-durability polyester coatings can last up to 5 years in harsh climates and are used for architectural elements and facades. However, their color options are less diverse due to the limited choice of durable pigments.

Applications

Epoxy-Polyester

Hybrid coatings combine the properties of epoxy and polyester resins. The epoxy component provides chemical resistance, strength, and high adhesion, while the polyester component improves flexibility, UV resistance, and aesthetic appeal. Epoxy-polyester coatings are not recommended for outdoor use because they degrade, chalk, and lose color under UV exposure.

Applications

Epoxy

Epoxy coatings offer high adhesion, strength, and chemical resistance. They form a hard surface that is resistant to abrasion and protects metal from corrosion. These coatings are effective in environments with intense chemical exposure or mechanical wear. However, they are not suitable for outdoor use due to their susceptibility to UV degradation, limiting their use to indoor and industrial settings.

Applications

Polyurethane

Polyurethane coatings are known for their high-gloss finish, chemical resistance, and excellent abrasion and impact resistance. They form a smooth surface that, when using high-durability resins, can maintain its appearance and integrity for over 5 years under harsh sunlight. These coatings are suitable for both interior and exterior applications. The wide range of color options allows for significant variation in aesthetic and functional adaptation.

Applications

Finish Options

Powder coatings offer a variety of finish options to meet different aesthetic and functional requirements. The texture of the coating is as crucial as its color and, in some cases, can be even more important.

Smooth Finishes

Smooth finishes are achieved through careful formulation of the powder and precise control of the curing process. These finishes typically utilize fine particle size distributions (typically 20-50 μm) and flow additives like acrylates or silicones to promote leveling during the melt and flow stages of curing.

This finish can highlight surface imperfections in the substrate and may be more prone to showing scratches.

Advantages:

Textured Finishes

Textured finishes are created by incorporating specific additives or by manipulating the powder formulation and curing process. Texturing agents such as silicon dioxide, polytetrafluoroethylene (PTFE), or specialized polymers are often used to create surface irregularities.

Textured powder coating can be more challenging to clean thoroughly and may trap contaminants in high-wear applications.

Advantages:

Glossy Finishes

Glossy finishes are achieved through the use of resins with high flow characteristics and careful control of the curing process. Epoxy and polyester resins are commonly used, often with flow modifiers to enhance surface leveling.

Textured powder coating can be more challenging to clean thoroughly and may trap contaminants in high-wear applications.

Glossy finish may create glare in certain lighting conditions.

Advantages:

Matte Finishes

Matte finishes are created by incorporating matting agents such as silica or by using resins with inherently lower gloss characteristics. The surface roughness is controlled at a microscopic level to diffuse light reflection.

Over time, it can appear burnishing or polishing in high-wear areas.

Advantages:

Color Variety

Powder coatings offer a wide range of color options to meet diverse aesthetic and functional needs. The two primary approaches to achieving the desired color in powder coatings are using standard color palettes and custom color matching.

Standard color palettes in the powder coating industry are pre-formulated sets of colors that manufacturers offer as readily available options. These palettes typically include a range of common colors and finishes that cater to a broad spectrum of applications and customer preferences.

Standard color palettes are particularly well-suited for:

Advantages for Customers

Textured powder coating can be more challenging to clean thoroughly and may trap contaminants in high-wear applications.

Glossy finish may create glare in certain lighting conditions.

Industry Use

In the powder coating sector, we rely on several standardized color systems to ensure consistency and ease of specification. The three primary systems are work here:

RAL System

The RAL system is the most widely used color standard in the powder coating industry, particularly in Europe. It comprises several collections:

In powder coating formulation, RAL standards are used as precise color targets, often measuring coatings’ color using spectrophotometers to ensure a Delta E value (color difference) of less than 1.0 from the RAL standard.

Pantone System

While primarily developed for the printing industry, the Pantone Matching System (PMS) has found significant use in powder coatings, especially for brand color matching. Key aspects include:

NCS System

The Natural Color System (NCS) is less commonly used in powder coatings but is gaining traction, especially in architectural applications. Its features include:

Custom Color Matching

In addition to these standardized systems, powder coating manufacturers develop proprietary color collections. These typically include:

When formulating powder coatings to match these color standards, the developer must account for various factors such as the resin system (e.g., polyester, epoxy, or hybrid), pigment stability, and curing conditions. The goal is to achieve not just a visual match, but also to ensure color stability under UV exposure and various environmental conditions.

Product Development

Qemtex offers customized powder coating development for your projects. Whether you want to make the coating corrosive-resistant, change its texture, or enhance its functionality, you can rely on us to provide solutions for any challenge.

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Applications of Powder Coating

Powder coating is versatile and can be applied across various industries due to its durability, efficiency, and environmental benefits.

Architecture & Construction

Types used: Primarily polyester and super-durable polyester powders.
Items: Aluminum window frames, metal facades, railings, light poles, fencing, garage doors, and HVAC equipment.
Functions: Weather resistance, UV protection, corrosion resistance, and aesthetic appeal.
Development opportunities: Improvements in heat-reflective coatings for energy efficiency, self-cleaning surfaces, and integration with smart building technologies.

Automotive & Transportation

Types used: Hybrid systems (epoxy-polyester), high-performance polyurethane powders.
Items: Wheels, bumpers, chassis components, engine parts, door handles, roof racks, and underbody components. In mass transit, entire bus and train exteriors.
Functions: Corrosion protection, chip resistance, and aesthetic finishing for both interior and exterior components.
Development opportunities: Ultra-low-cure formulations for heat-sensitive substrates, improved metallic finishes, and coatings compatible with lightweight materials like carbon fiber composites.

Furniture

Types used: Epoxy, polyester, and hybrid systems.
Items: Metal office chairs, filing cabinets, shelving units, table legs, bed frames, outdoor patio furniture, and metal school furniture.
Functions: Aesthetics, durability, and resistance to daily wear and tear.
Development opportunities: Antimicrobial coatings, improved texture options, and coatings with enhanced chemical resistance for commercial furniture.

Agricultural & Construction Equipment (ACE)

Types used: Super-durable polyester and epoxy-based systems.
Items: Tractor bodies and components, combine harvester parts, bulldozer frames, excavator arms, forklift bodies, and scaffolding equipment.
Functions: Corrosion and chemical resistance, UV stability, and high durability in harsh environments.
Development opportunities: Self-healing coatings, improved adhesion to complex substrates, and coatings with enhanced abrasion resistance.

Appliances

Types used: Epoxy and polyester-based powders.
Items: Refrigerator exteriors, washing machine drums, dryer bodies, microwave oven interiors, dishwasher racks, stove components, and water heater tanks.
Functions: Aesthetic finish, chemical resistance, and durability against frequent use.
Development opportunities: Energy-curable systems for heat-sensitive components, fingerprint-resistant finishes, and improved anti-microbial properties.

General Industrial

Types used: Varies widely, including epoxy, polyester, and hybrid systems.
Items: Pipe fittings, valves, pumps, compressors, electrical enclosures, machine tools, conveyor systems, and industrial fans.
Functions: Corrosion protection, chemical resistance, and specific performance attributes based on the application.
Development opportunities: Faster curing systems, improved edge coverage, and coatings with enhanced functional properties like electrical insulation or thermal management.

Functional

Types used: Specialized formulations including epoxy, polyester, and fluoropolymer-based systems.
Items: Electrical insulators, transformer components, heat sinks, friction-reducing coatings on industrial rollers, and chemical-resistant coatings on laboratory equipment.
Functions: Electrical insulation, thermal management, friction reduction, and chemical resistance.
Development opportunities: Nano-engineered coatings for enhanced properties, conductive coatings for EMI/RFI shielding, and coatings with improved tribological properties.

Electrification

Types used: High-performance insulating powders, often epoxy-based.
Items: Electric motor housings, battery casings, charging station components, electrical switchgear, and power distribution equipment.
Functions: Electrical insulation, thermal management, and protection against environmental factors.
Development opportunities: Coatings with improved dielectric strength, thermal conductivity for better heat dissipation, and formulations compatible with new battery technologies.

Home and Lifestyle, Consumer Goods

Types used: Primarily polyester-based powders with various finishes.
Items: Garden tools, bicycle frames, exercise equipment, lamp bases, picture frames, coat hangers, bathroom fixtures, and kitchen utensils.
Functions: Aesthetic appeal, durability, and resistance to household chemicals.
Development opportunities: Expanded color and texture options, coatings with improved tactile properties, and environmentally friendly formulations appealing to eco-conscious consumers.

How to Choose Powder Coating

To make the right choice, follow these tips.

For Manufacturing (Commercial Use)

Substrate Material. Consider the base material you're coating. Different substrates (e.g., steel, aluminum) require specific powder formulations for optimal adhesion and performance. For metals, ensure proper pre-treatment (e.g., phosphating, chromating) to enhance adhesion and corrosion resistance.
Environmental Exposure. Assess the environment where the coated product will be used. For outdoor applications, choose super-durable polyester systems with enhanced UV resistance.
Aesthetic Considerations. Factor in color, gloss level, and texture requirements. Remember that some effect finishes (e.g., metallic) may require special application techniques. For color-critical applications, always conduct physical sample approvals under intended lighting conditions.
Regulatory Compliance. Ensure the chosen powder meets relevant industry standards and regulations (e.g., AAMA, Qualicoat, GSB) for your specific application.
Application Method. Consider your application equipment and process. Some powders are optimized for specific application methods (e.g., tribo or corona charging). For complex geometries with Faraday cage areas, consider powders with enhanced penetration properties or specific application techniques.
Cure Schedule: Match the powder's cure requirements with your production line capabilities. Low-temperature cure systems can be beneficial for heat-sensitive substrates or energy savings. Always verify complete cure using solvent rub tests or differential scanning calorimetry (DSC) analysis.

For DIY Applications

Equipment Compatibility. Ensure the powder is compatible with your application equipment. Most DIY setups use corona charging guns. Look for powders with a wide application window to accommodate variations in application technique.
Cure Temperature. Verify that your curing setup (often a kitchen oven) can reach and maintain the required cure temperature. For DIY applications, consider powders with lower cure temperatures (around 180°C). For example, the glossy polyester powder coating paints cured at 160 °C. The cure temperature around 160-180 also suits epoxy-polyester and epoxy coatings.
Surface Preparation. Emphasize thorough cleaning and proper pre-treatment. For DIY, phosphate-free metal preparations are often more suitable. Always degrease surfaces and consider using a conversion coating spray for enhanced adhesion.
Powder Quantity. Purchase appropriate quantities. Unlike liquid paints, powder coatings can't be easily mixed for small batches. Look for suppliers offering small quantity packages suitable for DIY projects.
Ease of Application. For beginners, start with powders known for good flow and leveling properties to achieve a smooth finish more easily. It suits polyester and epoxy-polyester coatings with smooth texture. Practice on scrap pieces to get a feel for the powder's behavior before coating your final product.

In both commercial and DIY settings, it's crucial to thoroughly review the powder's technical data sheet and consult with the manufacturer or supplier for specific recommendations.

The Powder Coating Process - Step-By-Step Guide

1. Substrate Preparation:

2. Pre-treatment:

3. Drying:

4. Masking (if required):

5. Powder Application:

Ground the part properly to ensure electrostatic attraction.
For manual application, maintain a distance of 6-8 inches (15 - 20 sm) from the part.
For automatic systems, optimize gun settings (voltage, current, air pressure) based on powder type and part geometry.
Apply powder uniformly, targeting a film thickness of 60-80 microns for most applications.Use spray systems that have built-in thickness estimators based on powder flow rates and coverage area.

6. Curing:

7. Cooling:

8. Post-Cure Inspection:

9. Touch-up and Rework (if necessary):

10. Final Quality Control:

11. Packaging and Handling:

Key Considerations:

Qemtex manufactures and supplies powder coatings. We produce coatings in standard color palettes with different textures and effects for architecture, industrial applications and specialized coatings for corrosion protection. We also develop customized coatings to meet customers' production requirements. Leave a request to discuss your project.

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