Incredibly matt surfaces, pleasing to the eye, pleasant to the touch and resistant to scratches and light: this is what excimer technology and UV finishing make possible. After looking in depth at the benefits of UV LED curing, in this article we explore the new frontiers for the treatment and finishing of flat and raised panels.

These are extremely innovative solutions, and it is no surprise that many, even within the industry, are not familiar with the meaning of the very term excimer.
The first goal of this article is therefore to explain what excimer finishing means. It will then be easier to describe its characteristics and benefits, before reviewing the machines that enable this process.

What excimers are and what “excimers” mean in UV finishing

Etymology first: the term excimer derives from “excited dimer”, that is, an excited dimer, a molecule composed of two sub-units (atoms or simpler molecules) that exists only in an excited electronic state and not in the ground state.

In the context of finishing and, in particular, in curing processes, these molecules are used to create high-quality coated products. How? By means of short-wave ultraviolet (UV) light sources inside a specially designed environment, typically an oven.

Unlike conventional UV lamps, which emit a broad spectrum of UV radiation, excimer lamps produce highly focused monochromatic UV light at specific wavelengths, generally between 172 and 222 nanometres.

When the UV light of an excimer lamp irradiates a liquid lacquer layer, it triggers rapid surface photopolymerisation of the resin, creating a resistant and durable surface. The specific wavelength of excimer UV radiation produces controlled energy transfer, enabling modifications at a superficial level without affecting the underlying substrate.

It is precisely this capability that makes excimers particularly suited to curing processes. With excimer finishing, it is possible to create matt finishes, textured effects, or surface ripples with minimal heat generation.

The machines that exploit this curing technique, in particular UV ovens, are also suitable for evenly matting three-dimensional products, typically doors and panels.

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Excimer technology: benefits and applications in UV finishing

Excimer technology offers several benefits: first of all, it meets the need to reduce energy costs and the environmental impact of processing. This is thanks to the efficiency ensured by short-wave UV curing, which requires limited electricity and does not involve the use of traditional matting agents. In addition, UV lamps generate fewer volatile organic compounds and reduce ozone formation to a minimum. Moreover, the rapid surface curing reduces production times, resulting in lower process and labour costs. 

The high-energy monochromatic UV light of excimer lamps ensures complete curing of the lacquer layer, producing uniform surfaces that are entirely free of gloss or shine.

Then there is the matter of resistance: excimer curing transforms the resins used for coating into fine networks that increase product longevity, protecting them against scratches and chemical aggression. A key advantage for manufacturers of furniture and interior design elements that must combine aesthetics with durability.

More generally, excimer UV techniques are ideal for creating high-end furniture, interior panels, and customised decorative surfaces: the precision of the technology makes it suitable for processing objects with complex designs and structured textures, products where uniform finishing and tactile qualities are a key selling point for end customers.

Excimer finishing process: how it works

So how does the excimer matting process actually work, and what stages make it possible to obtain attractive, durable, abrasion-resistant surfaces without the need for additional chemical agents?

The excimer finishing process consists of several stages, each designed to achieve, as an overall result, a perfectly matt finish with distinctive sensory properties.

Excimer liquid lacquer is usually applied using roller techniques: after being coated, the products are transported into specially designed ovens and subjected to a short-wave UV curing procedure in an oxygen-free environment. This condition is essential, as oxygen would inhibit the curing process.

At this stage, UV photons penetrate the surface of the lacquer: this is the step that triggers the surface curing process of the excimer liquid, which, as it dries, reduces its volume. The rapid exposure minimises heat build-up. The effect is usually the creation of micro-folds of varying thickness, which in turn deform the surface.

The final appearance of the surface depends on the paint formulation and process parameters: this transformation is invisible to the naked eye, but sufficient to deflect light instead of diffusing it, generating a matt visual effect and a very pleasant tactile sensation.

The process ends with the hardening phase of the lacquer layer, usually achieved again by irradiation with a UV dryer.

Excimer oven technology for high-quality matt surfaces

We know that the market increasingly values the sensory aspects of home décor items. The tactile component, in particular, is becoming crucial in choosing furnishings. Soft-touch finishes are therefore gaining prominence: not only do they make contact with the object more pleasant, but they also increase surface resistance to scratches and wear.

To achieve this type of finish, manufacturers need a solution that effectively treats all sides and edges of their products, maximising quality and reducing costs wherever possible. Excimer ovens, capable of processing more complex objects than simple flat panels, are therefore ideal for producing high-quality matt surfaces.

What results do excimer ovens achieve?

Let us be more specific and analyse the results that can be achieved with conventional excimer ovens: the machines, as mentioned, work on flat panels through a short-wave UV curing process in an oxygen-free environment.

To produce high-performance soft-touch surfaces, the lacquer must be treated in such a way as to reach a very high level of mattness, no more than 5 gloss (on a scale ranging from 0 to 100 gloss). This step is essential to achieve another increasingly popular effect, the so-called  "fingerprint-proof" effect: thanks to the light rippling of the surfaces, excimer technology effectively prevents fingerprint marks from forming.

This is exactly what Cefla Finishing’s line allows, dedicated to companies wishing to harness all the advantages of excimer technology.

UV-R: the integrated solution ensuring maximum versatility

UV-R for instance, is a UV curing oven that integrates into a single body all the machine’s elements: conveyor, UV body, and electrical panel. It represents the ideal solution for those seeking versatility and ease of use, without compromising on guaranteed quality of the final result.

Exydry: the future of excimer ovens

For those aiming even higher, there is Exydry, perfect for working on 3D products, which typically must feature matt, resistant edges as well as surfaces. The result of an in-house R&D project, Cefla Finishing’s Exydry is an innovative solution that achieves the matt effect thanks to treatment before full cross-linking, easily reaching values below 5 gloss.

Despite these characteristics, the surface resistance of panels treated and cured in Exydry is extremely high. Furthermore, the nitrogen used to remove oxygen from the X, Y, and Z axes of a shaped panel is significantly less than that required by conventional excimer ovens.

Exydry: How does it work?

With several patented technologies, this innovative system can process, for example, doors coated by oscillating sprayers or robots. The design enables a continuous flow of shaped panels through the oven, removing all oxygen without ever stopping production.
The key benefits, as mentioned, go beyond better finishing quality and the ability to achieve it on three-dimensional objects: they also include reduced production costs, especially thanks to optimised nitrogen consumption.

UV-I: sustainable UV curing with fewer photoinitiators

On the path towards increasingly sustainable finishing, UV-I represents a technological breakthrough. A solution that combines high performance with environmental awareness: UV-I merges UV curing and sustainability.

This innovative oven uses UV curing in an inert environment, significantly reducing oxygen during the curing phase. The result is more efficient cross-linking even with fewer photoinitiators, improving operator safety and reducing the environmental impact of the chemicals used.

UV-I also minimises the use of mercury-containing UV lamps, while maintaining high curing performance. Thanks to controlled use of nitrogen, the process becomes more energy-efficient, bringing tangible benefits in terms of consumption and sustainability.

This technology perfectly matches today’s market needs, offering a compact, safe, and eco-friendly solution, in line with the latest European regulations and the expectations of environmentally responsible companies.

UV iCure: the first mercury-free technology

Finally, still in the field of sustainable innovation, Cefla Finishing’s latest development is UV iCure, the first completely mercury-free UV curing technology, capable of maintaining the same performance as traditional solutions.

The system is designed to comply with European directives on hazardous substances and to effectively replace lamps containing heavy metals, without requiring manufacturers to change the types of lacquers currently in use.

UV-iCure combines excimer and UV LED lamps with optimised wavelengths, in an inert environment, ensuring excellent curing performance without the use of mercury. The absence of fans and the use of water cooling prevent heat transfer to coating and substrate, while the immediate on/off effect reduces start-up times and simplifies system management, eliminating the need for mechanical shutters.

The result is a more compact, safe, and accessible solution compared to electron beam technologies, ensuring top quality and maximum sustainability, making UV-iCure a strategic choice for those wishing to innovate while respecting the environment and regulations.

Learn more on our page dedicated to replacing mercury lamps and in the white paper "From UV-R to UVl LED."

WHITE PAPER: FROM UV-R TO UV LED
A practical guide to replacing traditional mercury vapor UV-R ovens with high-efficiency, sustainable UV LED solutions.

Excimer matting technology: why choose Cefla Finishing

With 60 years of experience in the design and manufacture of finishing systems, Cefla Finishing is the partner of hundreds of companies worldwide. We provide tailor-made solutions, designed to integrate seamlessly into existing production processes, with a particular focus on the most innovative technologies such as excimer finishing.

We offer customers the expertise of a team of specialists able to identify the most suitable technologies to meet each need, working above all to integrate new machines into existing processes. After analysing the product, requirements, and business goals, we collaborate with our clients to define a customised roadmap for system development, which can also be tested beforehand at one of Cefla Finishing’s finishing laboratories.

LOOKING FOR THE IDEAL COATING LINE SOLUTION?

The world of manufacturing is constantly seeking solutions that enable the production of increasingly high-performance products while maximising the efficiency of the value chain. In this context, the thermoforming process is emerging as a key technique for applying plastic films to various substrates.

Among coating technologies, thermoforming represents an innovative method in which a plastic sheet is heated until flexible, allowing it to be shaped into precise forms that adhere closely to the underlying materials, such as MDF panels.

Naturally, not all solutions are equal, and increasing efficiency and quality in production lines first means understanding the complexities of the thermoforming process, then choosing the machines that best meet the specific needs of the company and its customers.

This guide aims to provide a comprehensive overview of the process, its variations, and the benefits it can offer today to companies operating in various manufacturing sectors. 

Overview of the thermoforming process 

The thermoforming process plays a crucial role in modern industry, especially in sectors where aesthetics and durability are key success factors for business development.

By using heat to soften plastic sheets, manufacturers can create complex and customised designs that enhance the visual appeal and functionality of products. The process begins with selecting the appropriate plastic material, followed by heating the semi-finished product – typically a sheet – to specific temperature thresholds. Once heated, the sheet is deformed and adheres to the substrate.

This is an efficient and versatile technique suitable for a wide range of applications, from furniture component wrapping to parts used in the automotive industry.

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Process steps: from glue application to cutting 

More specifically, the thermoforming process can be broken down into several stages. Each is essential to ensure the final product meets quality standards.

It begins with the glue application phase, where a uniform layer of adhesive is spread onto the substrate. Ensuring maximum homogeneity in this step is fundamental, as any inconsistency may result in a weak bond between adhesive and semi-finished sheet, or visual defects in the final product. Once the adhesive is applied, the next stage involves various drying techniques that evaporate all water content, ensuring optimal adhesion.

After preparing the substrate, the heated PVC sheet is applied to the surface using a thermoforming press. The press applies both heat and pressure, enabling the film to conform exactly to the contours of the substrate. Final steps include trimming excess material to achieve clean edges and brushing to remove adhesive residue or debris.

Thermoforming process: how does it work in detail?

As previously mentioned, achieving uniformity across the panel is key; otherwise, the risk of defects after film application increases exponentially.

That’s why some recommendations must be kept in mind throughout the thermoforming process, especially during the critical initial phase: edges in particular require five to eight times more glue than flat surfaces.

Once the water in the glue has evaporated through oven drying and the PVC sheet has been applied with a press, it is essential to be precise when removing excess material.

Regardless of whether this is done manually by two operators or handled by an automatic trimming unit (which removes, collects, grinds, and disposes of sheet scraps), the rear of the panels should always be carefully inspected for any glue residue.

Variations and types of thermoforming processes

What has been described so far is a general outline: the thermoforming process is not a fixed, one-size-fits-all formula, but rather an industrial approach that includes different configurations and variants. Each has its own specific characteristics, involving the use of particular techniques to create tailored lines that meet customer demands and production requirements.

Depending on production volume and panel properties, manufacturers can choose from different types of thermoforming processes, such as vacuum forming, pressure forming, and twin-sheet forming.

Vacuum forming is the most common technique, using a vacuum to pull the heated plastic sheet onto the mould, while pressure forming employs air pressure to create more complex shapes and finer details. Twin-sheet forming, finally, makes it possible to produce hollow parts by forming and sealing two sheets together simultaneously.

Each variation offers unique benefits, so manufacturers must choose the solution that best suits their operational needs and order specifications.

The importance of adhesive application in thermoforming

Regardless of the technique used, achieving a high-quality result requires that adhesive is applied correctly – both on the surface and edges of each part – particularly when working in furniture production and wood processing.

In this scenario, one of the processes that demands the most attention and care is the application of PVC sheets to wardrobe doors, drawer fronts and panels, typically made of composite materials such as MDF.

Benefits of the thermoforming process
As outlined, thermoforming processes offer numerous benefits. One key feature making them an increasingly popular choice among manufacturers is their ability to significantly boost production efficiency: the speed at which thermoforming can be performed supports higher output rates and shorter delivery times. The process also improves finish quality, as the ability to minimise tolerances and produce detailed designs results in more visually appealing end products.

Thermoforming also reduces the need for manual labour, as many of the steps mentioned above can be automated, cutting human error and streamlining labour costs.

From an environmental perspective, the process supports companies aiming to lower their carbon footprint by reducing waste through efficient use of raw materials and facilitating the recycling of scrap materials.

In short, thermoforming not only improves production efficiency and product quality, but also aligns with modern environmental standards – making it a smart choice for the finishing industry.

Cefla and thermoforming: an integrated and customised approach

In the field of thermoforming, Cefla Finishing offers complete, integrated solutions that also cover the preliminary processing stages, such as loading the semi-finished panels and brushing/cleaning them. This is followed by all process phases previously described, including final removal of glue residue.

The real added value of Cefla’s offering lies in the customisation of production lines: depending on the customer’s needs, available space and expected production volumes, our engineers will define the best configuration to guarantee maximum productivity.

It’s not just about maximising efficiency in terms of the number of presses to feed: Cefla Finishing’s technological know-how and process expertise are placed at the customer’s disposal to develop synergistic solutions, ensuring precision and consistent application in automating a process that, if properly implemented, can free up operators for higher value-added tasks.

Thermoforming solutions

Spraying machines:

• iBotic - glue application

A high-performance five-axis application robot (configurable with one or two arms) to suit different productivity levels. iBotic solves issues related to application consistency, repeatability and operator safety. Most importantly, it ensures precise glue application, considering the difference between panel surfaces and edges. It also avoids glue contamination on the back of the panel.

• Mito - glue application only for flat surfaces

This machine ensures uniform application across the entire surface of the panel and all pieces, making it a first step toward automation for small businesses still applying glue manually. Before feeding the press (third-party equipment), we recommend maintaining a clean, dust-free environment to optimise process and application quality.

Before the press is involved (third party equipment) we recommend maintaining a clean, dust-free environment to optimise the process and application quality.

Drying Technologies

• Pieffe - hot air drying for edges and flat surfaces

A flexible hot-air oven for glue drying on flat surfaces and edges, ensuring excellent productivity.

• Aquadry - drying system for water-based glue

Water must evaporate from the glue before the PVC sheet is applied. This solution handles panels where glue has not been applied to the edges.

Trimming and scrap foil solutions

• Twister – scrap foil removal

With a compact footprint, this machine grinds and removes scrap film for recycling, helping preserve the environment while optimising the process.

• Tarcut – trimming solution

Although film trimming is often performed manually, an automatic solution provides higher efficiency and precision (guaranteed by a 3D camera that monitors each operation). Processing speed is also much higher than manual cutting.

Why thermoforming is a smart choice

By now, the value of the thermoforming process should be clear. Compared to other finishing techniques, it stands out as a versatile and efficient method for applying plastic films to substrates, offering significant advantages that improve both productivity and environmental responsibility.

As the manufacturing sector continues to evolve, mastering this process will be crucial for producers who want to stay competitive. And Cefla Finishing will always be there to provide integrated, tailored solutions

LOOKING FOR THE BEST SOLUTION FOR YOUR COATING LINE?

If digital printing is on your wish list, we’ll help you put it on your shopping list.

Industrial digital printing solutions are increasingly popular in response to rapidly evolving market demands, especially for flooring specialists. Suited to all floor surfaces, furniture and skirting to glass, laminates or plastics, digital printing techniques enable exciting alternatives and we will be showcasing our latest digital printer at our LAB.