Surface treatment

Nickel-free design components

Innovative technologies, state-of-the-art plants and over fifty years of experience allow Anodica Trevigiana to anodize aluminium parts without using nickel, granting high aesthetic value, resistance to wear and safety.

Elena Corti

Non conventional treatment phases: this is the choice made by Anodica Trevigiana Spa to anodize the aluminium. That process, which can be implemented with several techniques and allows conferring gloss and colour to the metal, consists in progressively transforming the aluminium surface into aluminium oxide through an electrochemical reaction that sees the metal itself acting as anode (hence the treatment name). After the anodizing, the component surface shows regular micro-porosities and substantial transparency, for a depth of around a 10-20 microns, and it is ready to eventually receive the addition of very small quantities of dyes. We afterwards pass to the colour fixing phase, in which the micro-porosities are sealed by water molecules, opportunely bound to the oxide through chemical-physical process. We so obtain a very hard, resistant and homogeneous surface, which stands out for luster and features various colour shades, according to a range of finishes that can be widened upon demand.
Specific characteristic of the Nickel-Free anodizing by Anodica Trevigiana is that aluminium not only is without coatings, being the oxide layer integral part of the base metal, but the eventual minimal additions of colouring substances are neither dangerous nor noxious for man and environment. This is a very important aspect, because the components treated by the company are then touched or handled by final consumers or they are integrated into appliances and objects that can come into contact with foods or human skin. The main application of such products is represented by the household appliance industry and by the furniture sector in general (for instance handles, frames, knobs or dashboards), the field of the professional preparation of foods (parts of appliances intended for catering or communities) or the medical ambit, “where – explains Mr Giorgio Zanchetta, managing director of Anodica Trevigiana – besides Nickel-Free anodizing, we offer the special HygenOx treatment, based on silver nanoparticles, which we have specifically developed and patented to confer anti-bacterial properties to the anodized surfaces”. Finally, components are used also in the luxury sector (for instance for the production of perfumery products) and in the segment of sporting goods.

The Nickel-Free anodizing process by Anodica Trevigiana grants components with high aesthetic value, resistant to wear and safe for the health and the environment.

The Nickel-Free anodizing process by Anodica Trevigiana grants components with high aesthetic value, resistant to wear and safe for the health and the environment.

If we examine in detail the different phases of the Nickel-Free anodizing process by Anodica Trevigiana, it is worth highlighting that the company has decided to carry out the colouring by absorption rather than using the electrocolouring, in which the dyes are salts of metals like tin, copper, cobalt and nickel, which through the application of an electrical potential are pushed to the bottom of the anodic oxide pores.
With the technology chosen by Anodica, less conventional, the dye is instead generally organic and soluble in water, and it is captured by the more external surface of the anodic oxide, remaining partially bound in it and filling its micro-porosities. We so avoid the use of nickel (allergenic and carcinogen) and we can anyway obtain a wider chromatic range than what achievable by electro-colouring. Besides, the latter technology, due to the electrochemical process used, requires the use of aluminium fastenings systems (unlike titanium frames adopted in the absorption process), subjected to a progressive wear in the course of their short service life. Fastenings must in fact be regenerated at each anodizing cycle, to remove the undesired oxide layer that is gradually formed, hindering a safe contact in the successive cycle. “In addition to what above described – states Mr Giorgio Zanchetta – the electrocolouring involves also bigger electrical consumptions, higher plant engineering complexity and the management of the dangerousness of the used substances, therefore determining a higher treatment cost than that involved by the colouring by absorption”.

One of the main applications of Nickel-Free products is the sector of household appliances and furnishing in general.

One of the main applications of Nickel-Free products is the sector of household appliances and furnishing in general.

Among the finishes attainable through the technology used by the Venetian company there are steel, gold, brass, copper and bronze ones, and in general a broad array of colours characterized by the typical metallic shade of aluminium. “On the Nickel-Free anodized components – adds Giorgio Zanchetta – it is possible to apply easily also logos and marks with traditional techniques, like silk-screening of the glueing of labels of various materials. Besides, Anodica has developed a very suitable application for the Nickel-Free finish, called LaserOx. It is a parameterized laser engraving, followed by protective anodizing, which allows obtaining the wished touch sensitivity in bas-relief, coupled with a chromatic effect resistant in time, without the introduction of any additional chemical substance”.

Colouring phase with the absorption technology.

Colouring phase with the absorption technology.

Concerning then the fixing phase, Anodica Trevigiana adopts the hot technology instead of the cheaper low-temperature technique. The materials to be treated are immersed into demineralised water close to boiling, thus obtaining the sealing of pores and the hardening of the aluminium oxide, due to chemical hydration reactions thanks to which water molecules simply bind with the oxide layer. After the treatment, the material is very hard and it therefore better withstands scratches and small collisions better that the base material. Besides, it does not retain any trace of fingerprints even after a manual contact. The cold fixing, on the contrary, allows obtaining the sealing of pores and the aluminium oxide hardening through the use of substances composed by nickel salts and fluorides, they too toxic. The fixing occurs at lower bath temperatures than in the hot technology and therefore grants lower energy consumptions. “The way chosen by Anodica Trevigiana – comments Mr Giorgio Zanchetta – is in countertendency, but it permits to obtain a better quality of the coloured anodic layers, especially if mild, as well as a safer and more immediate resistance to corrosion and to wear. Moreover, we avoid the use of nickel-based additives, used in the majority of anodizing plants”.

Hot fixing. It is more expensive than the cold one but it allows achieving a better quality of coloured anodic layers and higher resistance to wear, besides avoiding the use of nickel-based additives.

Hot fixing. It is more expensive than the cold one but it allows achieving a better quality of coloured anodic layers and higher resistance to wear, besides avoiding the use of nickel-based additives.

In terms of quality control and safety, “Nickel-Free components – explains Zanchetta – are subjected to the standard and frequent tests to verify the oxide thickness, according to Uni Iso 2360 regulations, and the fixing efficacy in compliance with the directives 12373-4. Besides, they undergo the periodical control of nickel yielding according to the EN12472 and EN 1811 regulations, and the tests of saline mist resistance in conformity with Uni Iso 9227. Finally, the Nickel-Free characteristics of the surfaces that we treat are certified by a TÜV laboratory”.
Anodica Trevigiana carries out the anodizing process in a modern structure, purposely built in 2000. “We avail ourselves of a computerized and innovative plant – declares Mr Giorgio Zanchetta – studied to be able to assure the best qualitative reliability and repeatability of the treatment, at the same time maintaining great flexibility both in finishes and in the treated quantities. Moreover, the plant has been conceived in integrated manner, with its own system of fume purification and of water management, to grant the minimum environmental impact and utmost attention to operators’ safety. All this consistently with the sustainable vision of a company that for several years has been investing in a certified organizational system, not only according to the qualitative ISO9001 directives but also in compliance with the environmental ISO14001 regulations, the safety OHSAS 18001 and ethical SA8000 norms”. “The structure, then, – adds Zanchetta – is characterized by an innovative geometry and sequence of baths, and by an accurate arrangement of plant engineering devices, which allow a high control level of the main operational parameters. A further innovative element is represented by the hooking system of the components, characterized by high positioning flexibility, which grants a handling reduction to full advantage of quality and of costs”.
For the management of the various phases of the anodizing process, the company can rely on skilled personnel with broad expertise in chemical ambit and able to maintain baths always in the expected conditions. Besides, the sophisticated plant engineering always requires technical knowledge, both for the hydraulic and the electrical aspects.

In 2000 Anodica Trevigiana decided to invest in a new anodizing plant.

In 2000 Anodica Trevigiana decided to invest in a new anodizing plant.

The high professionalism of human resources is a key aspect for a company that intends to represent for its customers not only a supplier but also an integrated design partner, able to offer the best solutions in a very competitive market. “The technical-commercial staff of Anodica Trevigiana – ends Mr Giorgio Zanchetta – knows that to provide its customers with true value it is first of all necessary to put themselves in their shoes, thus trying to understand any aspect, even if not completely expressed, of their requirements, to take then care of developing with them the most suitable solutions for each single situation. We therefore put at customers’ service all of our competences in terms of materials and related finishing technologies, but also of transformation and assembling, gained in over fifty years of activity, enriched and extended with the creation of strong partnership relationships with some key suppliers and the establishment of a real Business Network, the NAT Network (Network Automotive Triveneto, of which we have been member since 2011), able to support the development of complex design and multi-technological products, from metals to plastics and composites”.

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