TPT September 2015

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118 September 2015
Article VOSS Fluid GmbH
Regulation 1907/2006 for determination of the nickel release
of products coming into direct and prolonged contact with the
skin. When comparing the VOSS coat surface directly with
a €2 coin, this fell below the limit value by 2,230 times. The
surface is not only environmentally compatible due to the
hard nickel content, but also more wear resistant against the
mechanical loads to which hydraulic couplings are exposed
during transport and assembly through to practical application.
VOSS coat consists of a zinc-nickel base coat, which is then
passivated and finally sealed. These three layers prevent
corrosion of the base material and enhance the connecting
components in a sustainable way. According to VDMA
Standards Sheet 24576, the zinc-nickel surface attains the
highest corrosion resistance class K5. This denotes the
protective capacity of the surface, which exhibits resistance
a minimum of 720 hours against red rust and at least 360
hours against white rust. Under laboratory conditions with
non-assembled parts, corrosion resistance of more than
2,000 hours was attained in the salt spray test according to
DIN EN ISO 9227. In the practical test with random goods
from current production, they did not reveal any base metal
corrosion even after 1,000 hours of handling and assembly.
For optimum assembly torques, the friction coefficients are
continually improved in development and production for
cutting ring couplings. That means they are significantly
lower than for other zinc-nickel coatings. Depending on the
connecting component, a lubricant and partial inner coating
are used, for example union nuts. Experienced application
technicians support assembly-reliable production processes
at the customer facility. These technicians accompany fitters
and maintenance personnel, from selection of the system-
compatible hydraulic coupling and training covering all aspects
of leakage-free couplings through to regular assembly audits.
In-house electroplating
The company-internal electroplating forms the basis for
the high-quality coating of tube connections. This plant
corresponds to a high technological standard as well as
the current environmental provisions for mixed residential
areas. It is also one of the most modern plants in Europe
and is ideally designed for the internal process steps during
coating – this high degree of specialisation would not be
attainable via outsourcing. In contrast to normal coatings,
the process is optimised in respect to component damage
prevention, layer distribution, visual appearance and friction
coefficients – qualitative reproducibility of the 6,600 different
articles from which the larger product spectrum is derived is
always guaranteed. Weight, size, geometry – these are only
some of the on average twelve program parameters saved for
each article in the production system. They are an important
prerequisite for optimally coating the different connecting
parts on a recurrent basis.
Current strength during electroplating, retention time in
the basin, and handling are clearly defined specific to the
article. The frames and baskets used for transporting the
connecting parts in the plant are in-house developments.
Larger connecting parts with up to 2.5kg weight and sensitive
outer threads are placed manually on frames by personnel,
thereby preventing potential damage to the thread during the
coating process. During pretreatment, the articles are cleaned
via ultrasound in order to remove any dirt in the bores. Smaller
components are fed to the process via drums. The filling cycle
utilises a conveyor belt in order to minimise falling heights
and prevent process-related damage. A significantly reduced
coating time also conserves the material.
For resource-efficient production, the entire electroplating
process is controlled and monitored via online analysis and
sensor systems. Automatic dosing pumps ensure that the
correct amount of chemicals is always supplied specific to
the product. The baths thus remain stable within the specified
process limits. The chemicals are continuously kept in motion
to ensure they are distributed evenly. After the electroplating
process, the layer thickness and nickel content are monitored
for each production batch. This means the articles receive a
verifiable even coating with VOSS coat, which permanently
protects them against corrosion.
A pilot electroplating has been operated since 2013. This
enables the entire electroplating process to be mapped
in miniature form, while simulating production parameters
modified to save resources. Besides the refinement of VOSS
coat, optimisation of the internal processes in relation to
efficiency and sustainability are also integrated here. Users
therefore benefit from a future-orientated surface coating and
customised system solutions.
Smaller components with inner threads are fed to the process via
drums