Aluminum replaces stainless steel

Washdown gear units and special surfaces for
hygienic drive solutions

In the food and beverage industry and in pharmaceutical production, hygienic design is a must for machines and plants. Periodical cleaning and sterilization, usually carried out during the process, are a key hygiene requirement, which tightens the demands on the drive technology used in production facilities. Presenting new developments such as a special surface treatment and a new series of washdown helical bevel gearboxes, drive manufacturer NORD DRIVESYSTEMS provides technically and economically attractive solutions for machine builders and users.

A provider of oil-tight wet cell versions of geared motors, NORD DRIVESYSTEMS has been delivering hygienic drive solutions for the food and beverage industry for some time. Special feature modifications available for the complete product range include suitability for extended temperature range operation, protective finishes, and special lubricants. Introducing new washdown-optimized two-stage helical bevel gear units, NORD now also offers solutions that are designed to withstand frequent intense, aggressive cleaning processes. The systems are suitable for use with acids and alkaline solutions. Since all external surfaces have been designed with wide radii, cleaning liquids wash off easily in all installation positions. Furthermore, there are no indentations or dead spaces. The gear unit housings, which are manufactured from die-cast aluminum, resist corrosion considerably better than steel models. Through additional measures, such as the innovative NSD tupH surface treatment, they can be equipped with extra protection for specific applications. Designed according to the proven UNICASE principle, they provide excellent stability. The series covers five frame sizes with torques ranging from 90 to 660 Nm. All models are available in two versions: an open frame style – extremely lightweight yet with a very sturdy construction – and a closed type.

The washdown gear units are especially small and lightweight. Compared with its predecessor model, the power density has been improved by 60%. Therefore, they are suited not only for food industry applications, but also for other fields where standard helical bevel gearboxes are used, e.g. conveyor technology. Their reduced weight minimizes energy consumption especially in applications where geared motors have to be moved. The compact new gear units feature larger, highly resilient output shaft bearings and are therefore suited for high forces. If required, optional double seals ensure increased safety. The gear units are equipped with a short IEC adapter. They can be combined with NORD's complete state-of-the-art range of motors and with motors from other manufacturers, allowing customers to flexibly configure drive solutions. The washdown gear units are expected to be available from the second quarter of 2012.

Stainless steel alternative: NSD tupH

Optimized surfaces are another focus of development for NORD. Introducing the NSD tupH sealed surface conversion system, the company now provides a very versatile solution for excellent hygienic characteristics which usually require stainless steel units. In this case, the gear cases are not coated – instead, their surfaces undergo a special treatment. The ultra-robust finish requires no application of material. It is based on a catalytic process that makes aluminum gear cases 6-7 times harder. In order to create a smooth surface, a sealant is applied to the treated material. Geared motors with an NSD tupH surface withstand even very demanding environmental conditions, such as chemical cleaning treatments used in the food, beverage, and pharmaceutical industries. Extensive tests show that NSD tupH surfaces did not sustain any damages even after one year of salt water rinsing which included the use of aggressive cleaning chemicals and high-pressure cleaners. Salt spray tests showed no corrosion after 1,000 hours. The NSD tupH surfaces also proved superior compared with standard systems during chip resistance testing: with gear units featuring protective coatings or varnishes, users must always expect that such layers (whether they are varnish, nickel, or nickel/teflon combinations) can peel off, e.g. in case of damage. Thanks to their design, this is impossible for NSD tupH gear units: the treated surfaces are scratch-proof, very resistant, and do not corrode.

Wide product range instead of single special models

Unlike stainless steel models, which most manufacturers provide for only a few drive types, the NSD tupH treatment is available for a very wide range of products – users can choose from virtually all aluminum gear units. The weight factor is another advantage: since aluminum as a basic material is considerably lighter than steel, this solution has substantially less mass and thus provides better installation options for mechanical engineers. Moreover, NSD tupH units are also cheaper than stainless steel systems thanks to their choice of basic material.