When using 100% UV lacquers, there is absolutely no way to avoid the stage where crosslinking takes place under UV lamps. And that process depends on photoinitiators contained within the lacquer. These photoinitiators directly influence the cost of the lacquer and their cost and availability fluctuates heavily. They are also partly the cause for undesired yellowing effects and are harmful to the environment. One way of minimising these negative aspects would be to minimise a company’s need to use lacquers containing current quantities of photoinitiators. UV-I oven does exactly that.

An inert atmosphere reduces the need for photoinitiators

• reducing the cost of the lacquer
• reducing the harmful environmental aspects
• reducing the yellowing effect
• reducing a company’s dependence on external factors which influence costs

UV-I oven: better crosslinking, improved coating performance

Not only does the inert atmosphere reduce the negative aspects, it also increases the degree of crosslinking achieved which leads to better coating film performance and stain resistance. Fewer photoinitiators, a factor made possible by minimising the inhibitory effect of oxygen, makes it possible to crosslink even thinner layers than today. This allows companies to choose between using less lacquer or boosting production speeds by maintaining the same amount of photoinitiators inside an inert curing oven, even if the latter option will not benefit the environment.

Under normal circumstances, crosslinking is always superior where the lacquer is in contact with the panel surface. This is because the oxygen in a standard UV oven will counteract crosslinking on the outer layer.  The thinner the lacquer layer, the greater the risks are of poor crosslinking performance throughout the coating thickness.

UV-I oven favours excellent crosslinking on the outer layer, so even thinly coated panels will be perfectly cured.

Production costs also drop

Alongside the reduced lacquer costs, fewer UV lamps are needed for the curing process. This leads to lower energy requirements and costs. And as crosslinking takes less time in an inert atmosphere, production volumes can be increased and made more cost-efficient.

Discover our selection of ovens and drying solutions.

What is UV curing and what advantages does it provide in the delicate drying phases - essentially important to complete product finishing processes? The first consideration to make is that - regardless of the type of lacquer to be applied and the items to be processed (flat or raised panels, or panel edges) - new curing solutions keep appearing on the market, based on fast-evolving innovative technologies.

Understanding which winning combination could help you build the most efficient curing system to suit your needs - based on the substrates to be treated, your type of process and your production volumes - is essential in order to maximise the advantages offered by the new machines.

LED technologies

An analysis of the current curing scenario can only begin by mentioning LED technologies, which are playing an increasingly leading role in UV curing processes. After their introduction, LEDs have rapidly gained ground in several industrial applications, replacing traditional systems based on gallium or mercury lamps.

Some industry players are particularly interested in the opportunities offered by UV LED lamps. However, the general market has not yet fully grasped the potential benefits of LED technologies. These can offer significant advantages, particularly to companies active in specific areas:

1. Panel finishing companies willing to invest in a new integrated finishing line, or to replace old UV ovens equipped with mercury or gallium lamps.
2. Edge coating businesses interested in adopting LED UV technologies.
3. Companies that use industrial digital printers, a segment in which LED technologies are already widely used for the pinning and final drying phases.

LED UV Curing: main advantages

Obviously, each one of the three applications mentioned above has specific requirements, but it is still possible to identify a number of common benefits:

• improved sustainability
• operating costs reduced to a fraction
• safety and flexibility
• control over process stability
• long lamp life and minimal maintenance requirements

Differences between traditional UV and LED curing

Going into more detail, there are five factors underlying the clear superiority of LED curing compared to curing with traditional lamps. Let's review them:

1. Ultraviolet light source

In traditional UV curing, the lamps require a warm-up period and have a relatively short lifespan, requiring more frequent replacements.

LED UV curing uses light-emitting diodes specifically designed to emit UV light, typically in the UV-A range. LEDs turn on and off instantly, providing instant curing without needing any warm-up time. They also last longer and are much less energy-intensive.

2. Energy efficiency and environmental impact

Traditional UV curing is not only more energy-intensive but also requires the disposal of hazardous materials, resulting in environmental risks. Additionally, traditional lamps will expose the coated films (and consequently, the substrates) to considerable heating.

LED systems are more energy efficient, as they convert a greater amount of electrical energy into usable UV light and will produce less heat. This level of efficiency reduces energy costs and improves sustainability by minimising the carbon footprint associated with curing processes.

3. Material compatibility

In traditional UV curing, the broader light spectrum emitted by mercury vapour lamps can cure a wide variety of product formulations, including some that might not work well with narrower UV wavelengths. However, this versatility comes at the cost of increased heating, which can limit the types of substrates that can be used.

While if LED curing is compatible with a limited range of materials designed to respond to specific wavelengths, advances in product formulations are continually expanding the range of resins and coatings that can be cured.

4. Cost management

The initial investment needed for mercury vapour UV curing systems is lower. However, this cost tends to increase due to maintenance and lamp replacement requirements and increased energy consumption.

LED systems tend to have a higher initial cost, but long-term energy savings, low maintenance needs and longer life often make them a more economical option over time.

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Common issues in UV curing (and solutions provided by LED technology)

The differences listed here above lead to very different outcomes when it comes to the effectiveness and efficiency of production lines. First of all, it is impossible to achieve the required curing process stability with mercury lamps without having to frequently measure their intensity and constantly monitor their operation. This often leads to downtime and loss of production capacity. Additionally, a mercury lamp has a life span of 1500/2000 hours, while an LED lamp lasts approximately 30,000 hours without suffering any significant UV intensity losses.

Panel overheating caused by traditional UV lamps should also be considered. MDF panels and resinous woods are significantly affected, as they can exude resin at high temperatures. UV LED lamps, by contrast, are much cooler and have no adverse effects on these substrates.

And what about environmental sustainability? Disposing of mercury lamps requires a lot of red tape in addition to causing ecological concerns (the RoHS directive prohibits mercury lamps for home use, and this rule could easily be extended, in the future, to industrial applications), and UV LED lamps are so much easier to handle in terms of separate waste collection.

As mentioned, standard UV lamps are energy-intensive (which also increases production costs and makes setting up lines difficult wherever the energy supply is insufficient). UV LED lamps' consumption is between 50 and 60% lower than traditional systems based on mercury lamps.

As we mentioned before, cooling systems are required for mercury lamps and they release ozone, which is conveyed out of the facility via an air-cooling system. All this has economic and environmental costs, especially for large production sites, which could partially be avoided with UV LED technology.

UV LED Curing: a modern and sustainable technology

The aspect that ultimately tips the balance in favour of UV LED technology is technological innovation. A UV LED curing system is managed electronically, which means that only the actually required lamps are switched on, also setting the exact intensity needed. The UV LED lamps send information to the PLC, allowing system managers to achieve significant savings on energy costs. This makes the process truly sustainable from an ecological and economic point of view.

As mentioned above, a UV LED system requires virtually zero maintenance. The lamps last approximately 30,000 hours and without interruptions, production efficiency is boosted allowing for non-stop processing without any downtime and ensuring constant quality levels over time.

Why switch to UV LED lamps?

In a market scenario that is increasingly interested in UV LED curing techniques, the strategic elements in favour of this technology are mainly:

SUSTAINABILITY – operating and environmental safety is a key issue for future business success.

ADAPTABILITY – thanks to a wide and constantly evolving range of solutions, machinery manufacturers can now effectively customise their proposed solutions.

Cefla's expertise made available to companies looking for innovation

Cefla Finishing installed its first UV LED oven back in 2014, and has therefore been able to acquire and analyse technology-specific data for many years. With an installed base of around 200 units between wood panel coating lines and digital printers, the experience we have acquired to date is second to none in today's marketplace.

As a partner of Phoseon Technology, leading manufacturer based in Oregon, we can share our expertise based on 120,000 systems sold so far and 300 technology-specific patents. This makes our offer extremely flexible, but also allows us to provide consulting services based on our solid knowledge of different use cases and above all, on our systematic analysis of the data generated by countless implementations.

After all, this has always been Cefla Finishing's approach: listening to customers, understanding their business objectives and defining the most appropriate solution based on the key factors involved:

• environmental
• economic
• performance/production-related

The range developed over the years is so wide that it allows us to select the right UV LED lamps from a pool of different models, with different wavelengths and dimensions - catering for every need.

In particular, our UV-R LED ovens can be integrated into three types of lines:

• panel coating (new or retrofit solutions)
• panel coating incorporating excimer ovens
• industrial digital printing

Find out how we can help you make your business more efficient and innovative.

LOOKING FOR THE IDEAL COATING LINE SOLUTION?

Finding a way to match the finishing quality of your flat surface with the edge, especially when the market is looking for rounded edges and flat surfaces as part of the latest furniture trends, means you need to consider using the same paint and the same technique. Until today, this was just theoretical, but since we introduced Smartvacuum to combine with Smartedge, our vacuum coating solution for edges, it is now a reality.

Vacuum coating: sustainable and cost-efficient

Depending on the production volumes, with vacuum application technologies there are different solutions to coat the surface and edge of a panel. Outputs up to 1500 cabinet doors/shift can be handled with an island-type process dealing with:

• melamine sanding
• flat surface coating (Smartvacuum)
• edge coating (Smartedge)
• sanding prior to finishing

In-line processes are better for outputs exceeding 3000 cabinet doors/shift and can be either:

• melamine sanding
• panel surfaces coated in the Smartvacuum area
• panel edges coated in a 2-step process with Smartedge
• sanding prior to finishing

or for 6000 cabinet doors/shift as follows:

• melamine sanding
• in-line flat surface coating (Smartvacuum)
• all 4 panel edges coated using Smartedge
• sanding prior to finishing

Both Smartvacuum and Smartedge use 100% UV acrylic paints, avoiding release of solvents into the atmosphere. Processing times are reduced compared to alternative application technologies and less space is taken up by these machines.

Focusing on the edge coating process, we have developed patented solutions for Smartedge which are unrivalled on the market. EDGE&GO enables line operators to switch from one edge geometry/thickness to the next in no more than 15 seconds.

The dual function sanding unit for vertical corners with a radius and the flat section of a J-pull ensures compliance with the original radius and sanding of the excess product at the leading and trailing end of the handle.

The paint removal and panel cleaning unit seals the melamine between the flat part and the edge, recovers excess applied product and creates a perfectly flat panel surface. This prolongs the life of the abrasive paper in contact sanding machines, as wear is homogeneous over the whole surface.

The winning duo

The combination of Smartvacuum and Smartedge finally allows companies to streamline their coating process using the same technique and delivering the same top quality all round. It avoids pollution compared to spraying lacquers with solvents, it speeds up the process, reducing the handling necessities and, above all, cuts costs significantly.

Learn more about Smartvacuum in this webinar

Whereas elliptical spraying techniques ensured high speeds and large volumes in the past, more recent reciprocating solutions have outpaced machines based on a rotary distribution system, especially in face of smaller production batches required by today’s market. Reliability was also an issue which played against the choice of this technology, but today’s redesigned Elispray features new, patented solutions that enable extremely high speeds, excellent transfer efficiency, reliability and reduced lacquer consumption by up to 20%.

Elliptical spray coating: superior transfer efficiency

Several factors have increased the transfer efficiency of the new Elispray. Combining a high-performance spraying booth with high-speed distribution, we have achieved excellent results. Innovations include:

• double plenum directs overspray where it is needed, settling gradually on the workpieces instead of being forced down
• belt surface has been increased to maximise overspray recovery
• new layout of suction areas interferes less with overspray
• guns operate at lower speeds than a reciprocating machine, making it possible to use lower feed pressures and waste less lacquer

Reliability ensures minimal maintenance downtime

Elispray features a patented product distribution system on the guns, eliminating aspects that undermined reliability in the past. A rinsing circuit also runs right next to the seals of the lacquer delivery circuit. Conveying water or solvent, it rinses, helps detect leakage points and reduces the working temperature of the joints thereby extending seal life.

The following benefits are obtained:

• minimises defects and machine downtime caused by localised leakage
• critical machine components can be monitored while the machine is working to avoid unproductive stoppages
• allows companies to plan maintenance sessions without needing to react to problems which disrupt production

Discover more on Elispray in this webinar

How can vacuum coating technology improve primer application on panels?

Industry professionals know that primer application on wooden panels is typically carried out using one of three methods: roller coating, spray coating or curtain coating. Each approach has its own pros and cons, depending on various factors.

The introduction of vacuum technology helps overcome many of the limitations of traditional systems—without necessarily replacing them entirely—offering new opportunities and benefits, especially for manufacturers of cabinet doors, panels, and bathroom furniture.

How does vacuum coating technology work in primer application on wooden panels?

Vacuum coating technology creates a low-pressure environment to improve the primer application process, ensuring uniform and efficient coating.

During this process, panels are placed inside a vacuum chamber, where air is extracted to lower the pressure around the surfaces. The reduced pressure allows lacquers and primers to penetrate deeper into the wood grain, improving adhesion and minimising the risk of bubbles or imperfections.

Additionally, vacuum technology plays a crucial role in eliminating air bubbles that can cause uneven finishes. This results in a smoother, more uniform coating that enhances both the appearance and durability of the finished product.

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The advantages of vacuum primer application on panels

Any flat panel made of wood or wood-based materials, including those with rounded edges, can be coated using vacuum technology.

This makes it an ideal solution for manufacturers aiming for uniform finishes while minimising imperfections and achieving extremely smooth surfaces. The vacuum process takes place in a controlled environment, reducing the risk of dust contamination. This is the key to higher precision and longer-lasting products.

Compared to spray coating, vacuum coating also results in faster drying times, enabling quicker production cycles and reducing material waste. This innovation not only improves the aesthetic quality of panels, but also improves the operational efficiency of production processes.

The result? Perfectly finished surfaces with minimal material waste and much better final quality.

Smartvacuum: Cefla Finishing’s vacuum coating technology in detail

Given the advantages of vacuum technology, Cefla Finishing has developed a user-friendly solution for processing flat panels with rounded edges, J-Pull versions, and panels with ABS edges.

Smartvacuum is a machine capable of applying 100% UV acrylic lacquer in a single pass, without any physical contact between the application head and the substrate. Thanks to vacuum technology, it deposits between 90 and 140 g/m² of product with extreme precision and uniformity, avoiding build-ups on any part of the panel.

The flash-off phase takes place after primer application and before final drying in a UV-R oven.

The use of 100% solid UV products makes the process more sustainable, and the finish remains more stable over time compared to polyurethane or polyester-based products, also requiring shorter drying times.

A complementary solution to other application techniques

As mentioned, vacuum technology offers numerous advantages over other finishing methods, but this does not mean it should be seen as an exclusive alternative to existing solutions. To truly appreciate its benefits, companies should evaluate their traditional finishing lines and determine the best integration between existing machinery and vacuum technology.

Roller coating lines

Roller coating is one of the most widely used surface finishing techniques for flat panels. The process typically involves:

• Substrate sanding
• Primer application for adhesion
• Three layers of primer applied with single and double application rollers, with intermediate gelling
• Final drying
• Sanding of the primer coat, followed by finishing

Curtain coating lines

Curtain coating is performed using machines called curtain coaters. These systems utilise liquid coatings that form a curtain of lacquer that falls onto the moving panel in a uniform fashion, allowing even coating application. The steps typically include:

• Substrate sanding
• Primer application for adhesion
• UV gelling
• UV primer application using a curtain coater and flash-off tunnel
• Drying
• Sanding of the primer coat, followed by finishing
  
  

Spray coating lines

Spray coating lines use a closed-loop system for applying polyurethane or polyester-based primers in multiple layers on flat surfaces and edges. This set-up requires extended drying times, as panels must be stabilised at appropriate intervals before sanding and finishing.

Vacuum application technology: a comparative advantage

When correctly implemented alongside traditional techniques, vacuum technology enhances finishing processes, making them more efficient and sustainable.

The eco-friendly nature of 100% UV acrylic lacquers offers several advantages, reducing material consumption, costs, lead times, handling requirements and equipment footprint.

Additionally, when vacuum application is integrated with traditional methods:

•  Rounded corners are obtained directly using vacuum coating technology, meaning you only need to sand the flat surfaces after drying
•  Fewer machines required, meaning less cleaning and lower consumption
• Lower sanding costs and reduced material waste
•  Shorter lead times and greater production flexibility
• Reduced machine footprint
• Fewer process stages, minimising handling needs

By implementing Cefla Finishing’s Smartvacuum, the finishing line would consist of the following steps:

• Panel sanding
• Primer application and gelling
• Application of 90-140 g/m² of 100% UV product in a single pass
• 2-5 minutes of flash-off
• Drying in UV lamp ovens
• Sanding and matt/gloss finishing as needed, using other known coating techniques

Smartvacuum: the perfect partner for Smartedge

Smartvacuum works best when paired with another Cefla Finishing solution: Smartedge, a machine for edge coating, filling and sanding, configurable with modular options to meet different quality and productivity needs.

The coating application can be performed with a traditional vertical roller, a patented soft vertical roller that automatically adapts to edge shapes without the need for counter-shapes, or using vacuum technology.

Smartedge and Smartvacuum share both technique and lacquer. This ensures optimal continuity between the flat surface and the panel edge.

The result? A smoother finish compared to conventional application techniques, especially on panels with rounded edges. This reduces the number of steps required to process semi-finished products and, most importantly, helps achieve a high-quality final product.

LOOKING FOR THE PERFECT FINISHING LINE SOLUTION?

One of the key advantages involved in vacuum application technology is the degree of transfer efficiency achieved - almost 100% - meaning close control over lacquer consumption and very little waste – all adding up to significant savings while achieving superb coating quality.

Until recently, this technology was used for edges, in terms of coating, sealing or even waterproofing. Today, we have developed vacuum application solutions for flat panels as well as edges, which can be of all shapes and sizes.

Vacuum coating: flat panels

Manufacturers of cabinet doors, panels and bathroom furniture will welcome the recently released vacuum application machine, Smartvacuum. Any wood or wood-based flat panel can be coated using this technology, especially those with rounded edges.

Vacuum application avoids contact between the application head and the substrate. This enables clean, efficient processing using 100% UV acrylic paint in a single pass. Up to 140 g/sqm are deposited homogeneously, thereby avoiding product build-up on any sections of the panel. The process is simple, clean, eco-friendly and cost-efficient. Flash-off is performed after basecoat application and prior to the panel completing its drying in a UV-R oven. Using a 100% solid UV product, this makes it a relatively sustainable process and the coating is more stable over time compared to polyurethane or polyester-based products.

Vacuum application machines: edges

Vacuum application machines for edges have been around for longer, some of which combine sanding operations as a complete solution. We provide 3 different systems according to specific needs.

The perfect match for Smartvacuum is Smartedge, a machine which handles straight and shaped panel edges. The vacuum system will coat any type of edge as the application head adapts to each shape. When fitted with Edge & Go, consisting of an application head with interchangeable straight or shaped slats, changing from one edge shape to the next is accomplished without turning off the vacuum tower. In terms of speed, switching from a straight edge with a 3 mm radius to a J-Pull handle edge, for example, takes less than 15 seconds.

Smartvacuum and Smartedge use the same technique and the same lacquer. That makes it simple to achieve the best junction seam between the flat surface and the edge of the panel.

Sealing solutions

Sealing operations are performed to protect the integrity of a product by ensuring the edges are not vulnerable to humidity for example, something which compromises the durability of a panel or other item.

Vacuum systems for the sealing of edges include another machine in our range: Talent is a patented solution for the sealing of the shaped edges of laminated panels, coated with quick-drying water-based products for application on various types of material. Used as a sealing technique for items found in several sectors, including panels, mouldings, fibreglass ceiling panels, polycarbonate sheets, fibre cement tiles and many other materials used in the construction industry, Talent works with water-based coatings, also suitable for UV curing, 100% UV acrylic paints, sealants (wax, paraffin, glue).

Edge impregnation

A solution dedicated to sealing the edges of panels is required when the risk of water penetrating the panel is an issue. In certain instances, cabinet doors, but more frequently panels for flooring applications will need to have their edges well sealed so as to avoid quality decreasing over time. Hybrid implements a patented technique to impregnate the panel edge with a special UV polyurethane glue to protect against humidity and other harmful elements.

Contact us and discuss your needs with a finishing expert.