Key technologies

Vacuum hardening

The process offers ideal conditions for highly sensitive components from tool and mould making, plant engineering, medical technology, food technology and aerospace. Components are hardened under controlled vacuum at up to 1,300 °C. Heating takes place under vacuum and subsequent quenching with up to 20 bar nitrogen overpressure. The aim is to produce surfaces free from decarburization and oxidation, eliminating the need for further mechanical processing.

Sustainability factor:
the process is particularly sustainable and environmentally friendly, as it does not generate any direct emissions and can be run on renewable energies.

Fewer dimensional and shape changes
Microstructure free from surface decarburization and oxidation
Bright metallic surfaces
High component cleanliness
Consistent quality

Nitriding and nitrocarburizing

Gas nitriding is a thermochemical surface hardening process without microstructure transformation at low temperatures of approx. 500 to 570 °C. Nitriding ensures hard surfaces and provides high resistance to wear, scratches and abrasion. In gas nitrocarburisation, the process is carried out in an additional carbon-producing atmosphere, whereby two layers ensure high wear resistance and corrosion protection. Our VT-N-OX® process provides additional corrosion protection through subsequent oxidation.

Sustainability factor:
Compared to other hardening processes, the process operates at significantly lower temperatures, with noticeably reduced energy requirements. The absence of quenching in oil also makes nitriding a more environmentally friendly process.

Very low distortion behaviour
Enables heat treatment of finished parts
Also suitable for unalloyed materials
Nitriding enables partial hardening

Low-pressure carburizing

In this process, the application is hardened under vacuum in combination with a fully integrated oil quenching system. The process is suitable for all classic case hardening steels (e.g. 16MnCr5 or 18CrNiMo7-6). The furnaces can achieve carburizing temperatures of up to 1,050 °C. Thanks to oil quenching, this technology can also harden all hardened and tempered steels, ball bearing steels and tool steels without oxidation.

Sustainability factor:
The process meets the most stringent requirements in terms of occupational and environmental protection. The process has no direct emissions and can be operated on renewable energies.

High, uniform component quality
Shiny and oxidation-free surfaces
High component cleanliness
Very low dimensional changes
Even carburizing of small holes, blind holes or narrow gaps

Case hardening / carbonitriding

Case hardening under protective gas takes place at VTN in multi-purpose chamber furnaces. In this process, the components are first carburized in a controlled protective gas atmosphere with the oxygen being displaced. These components are subsequently quenched in an integrated oil bath. Different quenching oils are used depending on the application. Carbonitriding is a variant of case hardening in which both carbon and nitrogen are deposited onto the surface of the workpiece.

Sustainability factor:
Thanks to state-of-the-art heating and burner technology, we ensure good energy efficiency throughout the entire process.

Very good serial reproducibility of results
Full automation enables 24/7 production
Partial hardening by insulation possible
Also suitable for unalloyed materials (carbonitriding)

Quenching and tempering

This process refers to hardening with quenching and subsequent tempering. In the first step, the workpieces are heated to the required hardening temperature. Quenching is then carried out in an oil or salt bath, where the maximum hardness of the selected material is reached. The final tempering process at lower temperatures sets the desired hardness or other mechanical properties of the workpiece.

Sustainability factor:
Thanks to state-of-the-art heating and burner technology, we ensure good energy efficiency throughout the entire process.

Very good serial reproducibility of results
Fully automated chamber furnace line enables 24/7 production
Very large dimensions can be treated in the pit furnace
Wide range of materials possible

Induction hardening

Induction hardening is one of the methods used for surface hardening: the component is heated locally up to austenitization temperature by means of electromagnetic induction and then quenched until the required hardness structure is formed. Even complex-shaped workpieces can be partially hardened without changing the rest of the component. In addition, we offer the expertise for the respective inductor and develop and build this tool for inductive heating in-house.

Sustainability factor:
In induction hardening, the required energy is used partially, i.e. it is only used at the points where the component is hardened. This saves energy. The process is also fully electric, which allows renewable energies to be utilised.

A number of frequency ranges (HF/ZF/MF) are available for a wide variety of applications
Ideal for complex-shaped workpieces
Targeted, partial hardening possible
Adapted tool development for inductive heating

Further processing


Even if unwanted dimensional changes are reduced to a minimum, distortion-free heat treatment is often not feasible for technical reasons. In many cases, distortions following heat treatment can be corrected with the straightening benches available to us and our qualified personnel.

Blast cleaning

Depending on the customer’s requirements, after many heat treatments, an improvement of the surface may be desired. For this purpose, we have a wide variety of blasting systems at our locations. This gives them a clean, uniform, matte, metallic surface.

Lapping with glass beads

Lapping is a cleaning blasting with a much milder blasting medium. The process is carried out by hand, with gentle cleaning of sharp edges and threads. This also gives them a clean, uniform, matte, metallic surface.


The cleaning of components before and after heat treatment is now an integral part of heat treatment processes.

VTN works exclusively with state-of-the-art cleaning systems. Both aqueous alkaline cleaners and isoparaffinic hydrocarbon mixtures are used

QualitY And Support

Quality assurance

Our well-equipped laboratories carry out the complete spectrum of materials testing at our sites. Hardness measurements, material analyses and grinding assessments ensure measurable quality.

Technical advice

Take advantage of our many years of experience and extensive knowledge in heat treatment and benefit from our expertise. Optimise your products by using suitable materials or by applying heat treatment tailored to your product.


Mechanical engineering is an extremely diverse sector. The range of parts is therefore very broad, using all the processes available at VTN: from the vacuum hardening of the smallest bearing components to the case hardening of complex gear components and the induction hardening of rollers or nitriding of shafts, to the processing of heavy industry products.
This includes the hardening of forming tools and (aluminium) die-cast moulds. VTN handles the hardening of these tools, which are often very geometrically complex and therefore very expensive. Thanks to VTN’s outstanding systems, large tools weighing up to five tonnes can be hardened. The toolmaking segment also includes all types of cutting and broaching tools.
VTN handles a very broad product portfolio for this sector, mainly consisting of sophisticated and safety-relevant parts. This is why VTN is certified in accordance with IATF 16949. Examples of products include drive components, brake components, steering gears, seat adjusters and stabilisers. Products for electric vehicles are also increasingly part of the product range.

In the aviation sector, landing gears are a focus of VTN. End customers include Airbus, Embraer, COMAC and other aircraft manufacturers. However, VTN also hardens many other components for civil or military aviation. In the space segment, for example, items for satellites are heat-treated.

VTN is certified according to the customer base according to NADCAP.

Medical devices, in accordance with their later use, tend to be small, but must be handled with the utmost care. Examples include vacuum hardening of stents, which are later used in the human body, and heat treatment of stainless steel or titanium components for medical instruments.
The constantly evolving recycling industry plays an important role here. VTN hardens the wide range of components needed to process and crush steel, plastic, paper and wood. In addition, VTN hardens drive parts required for the growing e-bike market, with more and more people leaving their cars at home.
The modern agricultural industry works with machines whose complexity and quality are no longer inferior to that of other industries or the automotive industry. VTN covers a variety of components for this segment. Examples include case-hardened gear parts for green chippers, vacuum-hardened rollers for combine harvesters and induction-hardened shafts for various machines.