FDA-approved alternative to stainless steel in geared motors

An anti-corrosion system for geared motors that goes far beyond the effectiveness of surface coatings to deliver a true alternative to stainless steel at a much lower cost has been released in Australia.

According to research by Curtin University of Technology, corrosion is costing the Australian economy around $30 billion each year.

Within industrial environments, exposure to things like water, acid or salt causes corrosion of geared motors. This, in turn, reduces the strength of the corroded parts and inevitably means they have to be replaced.

In corrosive environments the need for replacement is more than just occasional. Gearboxes need to be replaced as often as every six months. Apart from costs and downtime, such a maintenance regime presents businesses with all too frequent gearbox mounting challenges.

For obvious reasons, businesses in the food and beverage sector are required to maintain high hygiene standards. To do this, they need to follow strict washdown procedures, which have the unfortunate side effect of increasing the rate of corrosion.

Similarly, corrosion is a problem for operations dealing with chemicals, those located offshore or near the coast, and others (such as car washes) which just can’t avoid water.

Historically, businesses looking to deal with this problem have had two options: to use stainless products or products with a protective coating.

The attraction of stainless steel for this purpose is obvious. It eliminates the need for harsh cleaning chemicals and decreases the instances of leaks, rust and corrosion.

To date, stainless steel has rightly been regarded as a better anti-corrosion solution than the alternatives, namely paints and surface treatments.

The problem with such coatings is that when used on an original painted aluminium surface, they simply lie on top of the aluminium substrate and may even bridge across pores in the metal. In other words, they do not form a permanent bond to the substrate. They can easily be removed if bumped or scratched, and therefore offer only limited corrosion resistance.

A smart alternative to stainless steel

NORD, one of the world’s leading manufacturers of drive technology, recently released the nsd tupH Sealed Surface Conversion System in Australia. While the system has been available in Europe for some time, this was its local debut.

The system provides protection at a molecular level and has been hailed as a breakthrough in corrosion protection.

Unlike surface coatings, nsd tupH includes a base layer that is permanently bonded to the aluminium substrate and provides a powerful foundation for adhesion of the surface sealant. This foundation provides excellent roughness, is 6–7x harder than the aluminium substrate and up to 1000x harder than paint.

In other words, the product is superior to surface coatings and is a genuine alternative to stainless steel. Indeed, according to the company, it offers two advantages when compared to stainless steel. Firstly, it is significantly cheaper — nsd tupH delivers similar levels of corrosion protection at a fraction of the cost.

And secondly, products coated with the system are much lighter than stainless steel products. This makes mounting and maintenance easier.

The surface treatment creates an easy-to-clean surface that is resistant to acids and alkalis of wide pH range. Free from chromates, it prevents the spreading of corrosion, even in cases where machinery is physically scratched or damaged.

The nsd tupH drives can be used in demanding atmospheres much beyond the usual service life of paint-coated systems. Since no coating is applied and only the surface is hardened, contamination of products or process media is avoided, which is not possible with chipping paint.

The system conforms to FDA Title 21 CFR 175.300 and has successfully undergone ASTM D714 and proven its resistance to blister formation. Similarly, it has proven its effectiveness against corrosion through ASTM D610-08 and scribe per ASTM D1654-08 according to DIN EN ISO 2409.

Further tests performed on the system included ASTM B117-09 Salt spray test, ASTM D3170 Gravelometer test, DINEN ISO 9227 Salt spray mist test and DIN EN ISO2409 Cross-cut test.

It is approved for food applications according to FDA Title 21 CFR 175.300 with treated systems resisting cleaning agents in the pH2–12 range.

NORD uses nsd tupH on a range of products, including its helical gear units, bevel gear units, universal worm gear units, smooth motors and electronic SK 1xxE.

Businesses which incorporate these into their operations can look forward to high levels of process safety, prolonged service life and significantly reduced maintenance requirements.

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