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AHC Oberflächentechnik GmbH - Surface Treatment

AHC Oberflächentechnik GmbH in Germany consists of 18 locations with headquarters in Kerpen, near Cologne, and specialises in functional coatings for technical surfaces. AHC strives to meet the needs of its extensive client base, which typically involves the supply of high quality components to organisations working within the automotive and machinery sectors. It also has a series of esteemed customers in defence technology, aerospace, electronics and the medical instrument fraction. With about 900 employees AHC treats one billion industrial parts per year. The company licenses their patented coating processes world-wide. Furthermore it delivers process chemicals for the metal finishing industry.

Corrosion and wear protection of aluminium base material

In order to protect aluminium base materials AHC offers hard anodising as a service. This process is called HART-COAT®. The layer is built by anodic oxidation in a cooled acid electrolyte, transforming the aluminium base material into aluminium oxide at its surface. The oxide film grows inwards and outwards in equal portions, thus creating a defined size alteration of the component. Especially worth mentioning is the excellent - based on atomic bonding strengths - composite with the base material from which the layer has been built. The hardness of the aluminium oxide provides a high wear resistance of the layer.

angle rotor

Angle rotor for micro-litre centrifuges. The aluminium body is protected from corrosion by a 40 µm HART-COAT® layer.

Other applications of anodic coatings for aluminium parts in the medical technology include the following: holders for dental drilling turbines, form applications for manufacturing dentures, anaesthesia tanks and vessels for small autoclaves for sterilising medical instruments. Hard-anodic oxidation is also applied to hydraulic cylinders used on hospital beds for setting the incline or to moving compressors for compressed air in dental offices.

Alkali and acidic resistance

Electrophoretic dip painting, according to the SILA-COAT® 5000 process presents a kind of sealing. The regularly developed network structure of the dipping paint seals and levels the surface. Very regular layers are formed, even for complex components with inner surfaces, for example drilled holes and cavities. With regards to the safety of foodstuffs for human consumption, the coating fulfils the marketability requirements demanded by the Food and Drug Administration (FDA) regulations and by the German Directive on Materials and Articles. Furthermore, SILA-COAT® 5000 is bio-compatible, which means it does not damage tissue cells. As a result of its properties, combination coatings of anodic coating (e.g. HART-COAT®) and dip coating have applications where aluminium components come in contact with alkaline or acidic media.

container for medical technology

Container for medical technology: the black parts are provided with a combination layer. The yellow plastic inserts hold the implants and instruments.

Contour true coating with wear and corrosion resistance

Electroless nickel coating is applied to metallic material. The process name is DURNI-COAT®. This is a nickel-phosphor alloy coating, deposited from an aqueous nickel salt solution by reduction with hypophosphite. The process, which requires no external current, permits a contour true reproduction of the surface, as well as good wear resistance and high resistance to corrosion. Sharp edges and impressions, accessible cavities and bores are coated uniformly. The AHC Group is the right market partner for you in electroless nickel plating with high precision and production reliability for virtually all metals.

automatic gas cylinder

Automatic gas cylinder switching valve with electroless nickel plating: high protection against corrosion and decorative appearance

Tricky colour coating

Another interesting coating process is colour anodising of titanium materials. Components made of these materials are electrically contacted to a rack. The rack is then dipped in an aqueous acid electrolyte in which it serves as anode. On the component's layer a thin and very adhesive layer of titanium oxide will be formed. The layer thickness can range within a fraction of the wavelength of visible light. The light that strikes the surface is reflected by the colourless layer and the layer base. The colour impression is caused by interference between the overlapping light rays.

coloured anodised pedicle screws

Coloured anodised pedicle screws and lamina hooks made of the alloy TiAl6V4 for an instrumentation system used for the fixing of vertebrae. The anodisation is bio-compatible and helps with faster recognition of the parts by the operator.

Black coating to minimise scattered light

KEPLA-COAT® is a plasma-chemical anodising process producing greyish-white oxide layers in an aqueous electrolyte solution under spark discharge. KEPLA-COAT® layers on aluminium substrates withstand aggressive gases such as chlorine and boron trichloride. The protective layer, being free of pores and cracks, cannot be infiltrated by reaction gases.
As well as a good corrosion protection, KEPLA-COAT® layers show a high wear resistance and an excellent fatigue strength. Due to an increase in volume, 50% of the produced oxide layer grows outwards. There is no material deformation. With KEPLA-COAT® even components with complex geometries are uniformly coated without layer build-up at edges and corners, which is typical of the conventional electrolytic processes.

The KEPLA-COAT® technique is well suited for the treatment of aluminium and titanium substrates. It is also possible to produce deep black, light-resistant oxide ceramic layers (KEPLA-COAT® black).

Endoscope housing

Endoscope housing with KEPLA-COAT® black to minimise scattered light.

The potential of the surface treatment presented here is far from being exhausted in the area of medical device technology.

Outline of the company history

The AHC group was initially established back in 1960 and has since progressed to become one of the leading specialists in the field of surface treatment in Europe. It is particularly known for its outstanding services in the hard anodising of aluminium alloys and electroless nickel plating of metals, but it also has the competency to provide functional coating of technical surfaces. The first subsidiary was founded in 1970 near Stuttgart. Now AHC has 18 sites, 17 production sites and one chemical supplier called RIAG Oberflächentechnik AG. RIAG joined the AHC group in 2000. Latest development of AHC is the oxidation process for aluminium alloys LASOX-COAT®. The wear resistant oxide layer is applied via laser without the use of chemicals. AHC Group is owned by Aalberts Industries N.V., a famous Dutch company which has more than 200 group companies in over 30 countries.


AHC Oberflächentechnik GmbH
Boelckestraße 25 - 57
50171 Kerpen
Tel: +49 2237 502-0
Email: info@ahc-surface.com
URL: www.ahc-surface.com