Case Study: NORD develops seawater-resistant drive systems for seafood factory conveyors

NORD Drivesystems has introduced an innovative surface treatment to toughen
drive systems to be resilient and seawater-resistant in seafood factory
conveyor applications.

To maintain their freshness, mussels, clams, oysters
and other shellfish must remain alive until the very moment they are cooked. Factories
specialising in these delicacies tend to keep fresh catches submerged in salt
water before they are processed. Machines used in such facilities for cleaning,
sorting, and packaging shellfish products are inevitably exposed to the
seawater-infused environment, taking a heavy toll on their components such as regular
conveyor drives.

The solution introduced by NORD Drivesystems has been
specifically designed for these applications.

Yerseke is a Dutch seaside village south of Rotterdam.
Shellfish has been the principal industry for almost a century and a half.
Krijn Verwijs Yerseke B.V., a family business established here in 1880 as a
breeding company for oysters, has developed into one of the largest players in
the European crustacean and shellfish market. Blue mussels are harvested in
breeding grounds in the Netherlands, Ireland, the UK, and Germany and brought
to the factory directly by ship or in cooled trucks, where they are put into
large basins supplied with a constant flow of cooled, clean North Sea salt

The containers are kept right next to the processing
facilities inside the factory. The mussels then make their way through various processing
stages in the factory where further cleaning will remove damaged and dead
specimens, and de-beard the mussels. The quality-controlled processed products are
then packaged and taken away to the designated customer.

of salty air on machinery components

A humid, salty atmosphere is pervasive in the factory
from the presence of large containers full of salt water and the fact that live
mussels are conveyed wet. Continuous exposure to this saline environment leads
to swift corrosion of all metal parts across the process automation equipment.
In the case of the many 1.5 kW class geared motors driving various conveyors,
rusty spots first appear on brand-new systems in a matter of weeks.

Corrosion requires early replacement of the drive unit
after a year or two with a new geared motor. It’s impossible to keep a drive in
service much longer; with cast iron systems, even a protective coating or
varnish is often eventually compromised, and will therefore only moderately
delay the onset of corrosion.

In such installations, stainless steel drives are the
most obvious alternative, but are unfortunately not suited to this application,
and not just due to the extra cost. Practical cleaning routines can also be
compromised; stainless steel units would require a significant cool-off period
before every hose-down to protect them from excessive stress to the material, resulting
in too much disruption to the factory operation.

Dutch drive supplier Drive & Flow introduced Krijn
Verwijs to a new approach recently pioneered by global drive technology
specialist NORD Drivesystems to toughen drives for use in aggressive

ingrained protection

NORD’s portfolio includes a broad range of drive
systems with a specially treated aluminium surface that offers proven
durability under adverse conditions similar to the salty atmosphere experienced
at the Krijn Verwijs processing facility. Though more expensive than regular
cast iron units, these geared motors will deliver greater value as they will typically
outlast the lifetime of a conveyor line as a whole, and therefore eliminate
follow-up expenses for several replacement drives.

NORD’s drives with the nsd tupH surfaces are already proven
to resist corrosion even after 1,000 hours of immediate exposure to salt spray.
Notwithstanding NORD’s test results, Krijn Verwijs opted to conduct their own
hands-on testing to ensure the real-life viability of this innovation. In
spring 2013, the first nsd tupH geared motor was installed at the shellfish
production facility. The motor’s scratch-proof surface proved to be
spectacularly resilient, showing hardly any sign of wear after several months
of operation.

According to Bram de Visser, Technical Service
specialist at Krijn Verwijs, their use of standard cast iron geared motors
forced them to replace the units repeatedly, sometimes up to ten times during
the usual service life of a conveyor line. Given that the factory employed
several drives, the replacements were never-ending. However, following the
installation of the new NORD solution, there is no need to worry about drives. Krijn
Verwijs expects the nsd tupH systems to last at least five times longer than the
old geared motors, if not longer.


The nsd tupH treatment is not a coating but a surface
conversion that produces a base layer permanently bonded to the substrate.
Based on an electrolytic process, this treatment renders aluminium cases
similarly unsusceptible to corrosion as stainless steel. The treated surface
also becomes more than six times harder than untreated aluminium alloy, and a
thousand times harder than paint.

Key advantages of nsd tupH surface drive systems include
lightweight, compact and self-draining design without indentations or dead
spaces, allowing easy washdowns; impervious to common chemical cleaning agents such
as acids or alkaline solutions; no damage from high-pressure cleaning routines;
and no risk of chipping as the nsd tupH treatment does not require any
machining as a final step, leaving the aluminium surfaces unexposed. The nsd
tupH treatment is universally available for all NORD aluminium products.

According to Bram de Visser, a full transition is now
underway with every drive that needs to be replaced at Krijn Verwijs in the
months and years to come to be eventually swapped for an nsd tupH unit made by
NORD. With hundreds of drives being replaced at the seafood production factory,
the process is expected to take some time.

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