Anodising

Processes

Anodising

In contrast to the conventional galvanising process, no foreign metallic cover layer is applied during anodising. Instead, the surface of a light metal component is converted into an oxide layer by the galvanising/anodising process.

Since the oxide layer develops from the base material, the dimensional increase is only 50-55%. The remainder grows into the base material, which results in good adhesion to the base. Collini anodises aluminium (also known as Eloxal) and titanium. The anodising layers are hard, corrosion and wear resistant, and they have a good electrical and thermal insulating effect. Special anodising methods are offered for tribological systems.

Fields of application include all areas in which aluminium with increased technical specifications is required. For components made of titanium, there is an option for bio-compatible colour coding, which is particularly relevant for use in medical technology.

Inquiry Technical data

Advantage

Advantages at a glance

Corrosion - Surface protects.
The natural state of metals is an oxide. In the metalworks the oxide is extracted by using oxygen and energy and the pure metal is obtained. However, the metal is “predestined” to return to its original state at exposure to oxygen and water. And the less precious the metal is, the faster it happens. That is corrosion.

Surface technology slows down or prevents this corrosion process. Protection against corrosion through innovative surface technology increases service-life and thus raises the value of the product or structural component. Collini provides numerous possibilities to combat corrosion.

By means of electro-plating, structural components can be protected against corrosion with suitable metal coatings.

Powder coatings form impenetrable barriers against oxygen and water and thus protecting the underlying structure.

Hot-dip galvanising protects steel parts by specifically inducing the corrosion process on the zinc surface. And only there!
Design - Surface creates.
Collini surface technology makes it possible to create products in such a way that they appeal to the varying aesthetic requirements and wishes of consumers. Design is more than the form and functionality of an object. In many cases, it is the aesthetics that adds to the value. The look, colour or structure of identical materials can be changed through different surfaces.

Powder coatings with its almost infinite possibilities in terms of colouring, degrees of glossiness and structures give products their true character. It is irrelevant whether it concerns machine cladding, vehicle components or architectural design elements.

High quality metal surfaces can be created with electroplating, the properties of which distinguish it clearly from that of the base material. Hence, products are refined and the required effects in finish and structure of the respective product
are created.

Hot-dip galvanised structural components with its crystalsilver surfaces are, besides the corrosion protection, often specifically included as design elements.
Medical - Surface helps to heal.

Medicine is the science of prevention, recognition and treatment of diseases and injuries with only one goal: the preservation or recovery of the best possible health of man and animal. To make this possible, surface technology has become indispensable. In analytics, ultra pure, non-magnetic, metal surfaces provide the highest precision (e.g. magnetic resonance spectroscopy).
In the field of traumatology, Collini anodises titanium implants used in surgical treatment of fractures and deformations.
Antistatic powder coatings from Collini can easily generate purifying surfaces that comply with the hygienic requirements of many medical devices and facilities.
Tribology - Surface prevents wear.

Collini intensively deals with tribology: in other words, how friction and wear can be reduced or the lubrication between structural components can be improved. Because these factors are directly affected by the choice of the material, the surface coating and the surface topography.

Specially developed alloys and coating systems – Collini surfaces – reduce for example the energy input through the reduction in friction, increase the service life of bearing materials, plug contacts or improve the service performance of sliding contacts. Thereby the respective structural component can be manufactured from inexpensive basic materials. Then its required functionality – lower friction resistance or wear – is created with the coating system. By reducing friction and wear, energy and raw material resources are preserved and the service-life of products is increased. This is how Tribology contributes significantly to sustainability.

Technical data

	Anodising
Processes	Electrochemical process, also called Eloxal in aluminium (electrolytic oxidation of aluminium)
Coating colour	Depending on the material, silvery/grey/brown/anthracite, semi-glossy to glossy, dyeable
Base material	Aluminium and titanium alloys
Corrosion protection	up to 2000 h NSST
Hardness	up to 650 HV
Temperature resistance	up to 2000 °C, micro cracks starting at 250 °C
System technology	Rack
Conformity	EURAS/EWAA, RoHS, REACH – sometimes depending on alloy, 2000/53/EG (end of life vehicle)
Execution	Eloxal, hard eloxal, titanium anodising
From our R&D	Glatox®, Collossal®, Collini T-ELAD
Protective properties	Protection against corrosion and wear, resistant to heat and salt water
Functional properties	electrical (up to 50 V/μm) and heat insulating, adhesive, impregnable, dimensionally stable, lubricious
Decorative properties	glossy to semi-glossy, various colours possible, high colour stability
Special properties	suitable as a primer coat before painting for protection against filiform corrosion, easy to clean

Details

Typical components & applications

Typical components

Housings, fuel pumps, pistons, brakes, cooling systems, insulation components, couplings, valve controls, rail car doors, seat parts, suspensions, shock absorbers, ship parts, insulation and cooling units, façades, interior design, lights, window and frame profiles, guide rails, pistons, prostheses, kitchen appliances

Industrial applications

Automotive industry, electrical engineering, construction industry, mechanical engineering, aerospace, aircraft manufacturing, medical technology, household technology, measurement technology, precision engineering

Collini's product portfolio

Eloxal

During anodization, the base material aluminium is electrolytically oxidised to produce a 5 to 25 µm thin layer that protects against corrosion. The DC process (DC sulphuric acid) is most commonly used here. The thickness class must be defined for architectural applications. This depends on national standards and the respective aggressiveness of the atmosphere. Basically, there is a distinction made here between interior applications with a minimum layer thickness of 5 µm and exterior applications with at least 15 µm.

Collini has been awarded the QUALANOD quality label and is committed to working in compliance with the strict Qualanod regulations. Holders of this quality label are tested at least twice a year by a neutral entity.

Hard anodising

During hard anodising, the oxide layer develops from the base material and grows 45-50% into it, which ensures good adhesion to the substrate. The layer thickness can be determined by the current density and exposure time. Due to its micro-porous nature, the layer can be dyed by layering with dye material. With appropriate post-treatment, the micro pores can be closed. The anodising layers are hard, corrosion and wear resistant, and they have a good insulating effect. The layer properties can be further modified depending on the anodization method used and the composition of the material. Fields of application include all areas in which aluminium with increased technical specifications is required.

Collini offers Glatox® for special applications where abrasion wear and abrasion corrosion must be prevented. This hard anodised layer with a special structure to achieve an abrasion resistant, smooth surface features low abrasion coefficients, excellent corrosion resistance and a very compact, low-pore layer structure. The coating has been tested in tribological systems and is used in automotive manufacturing systems, amongst others. As an alternative to CrVI-free chromating, Collini has developed the Collossal anti-oxidation coating. This features good corrosion resistance and corresponding conductivity, and also serves as an excellent primer for subsequent coating systems, such as painting.

Titanium anodising

The importance of titanium and titanium alloys is based on two special features. This is a light metal (d=4.5 g/cm3) and, particularly in the alloyed state, a high strength to density ratio can be achieved. Titanium has excellent corrosion resistance. Titanium is used in areas such as aerospace, aircraft manufacturing and as a biometal for surgical fracture treatment. Titanium owes its excellent corrosion resistance to a thin oxide film. This TiO2 layer can be technically adjusted through targeted anodic treatment.

Colour coding: Collini offers titanium anodising in both acidic and alkaline solutions. This means that the thickness of the oxide film can be adjusted from a new nanometres to a few micrometres, which significantly improves the corrosion resistance and the tribological properties of the component. In addition, there is the option for colour coding of titanium components during anodisation in the acidic solution. The Collini Dübendorf location has audited its titanium anodising work area in accordance with ISO 13485.