Aqua-Bearing for highly corrosive environments

Citation

(2002), "Aqua-Bearing for highly corrosive environments", Anti-Corrosion Methods and Materials, Vol. 49 No. 1. https://doi.org/10.1108/acmm.2002.12849aad.012

Aqua-Bearing for highly corrosive environments

Keywords: Corrosion, Food, Hygeine

The increasingly stringent demands made upon the food processing industry as a result of recent "food scares" mean that procedures for ensuring hygiene in the production of food are becoming ever more severe. This development, in turn, is impacting upon the equipment used in the production process, in terms of problems of corrosion, caused by specialised wash down operations utilising aggressive cleaning mediumsBecause of their universal application bearings are very much in the front line in this respect. Routinely they are exposed to water and chemicals (acids and alkalis) by either splash or direct application. To respond to these demanding conditions NSK reports that it has developed the Aqua- Bearing, described as a special highly corrosion resistant, low cost bearing for light load applications in the operating temperature range up to 150°C.

According to NSK the use of a special fluorine plastic for the inner and outer rings and a fluorine plastic cages, enables the Aqua- Bearingrm to achieve corrosion resistance equal to ceramic bearings and better than that of previous generations of plastic rolling bearings made of PE (Polyethylene) or PPS (Polyphenylene Suifide). The company believes that the effectiveness of its materials specification means that the Aqua- Bearing is even able to handle applications in strong acids or alkalis, ozonized water, various kinds of vapour and halogen gases (Figure 1).

Figure 1

The company also informs us that in addition to providing improved corrosion resistance, the fibre reinforced fluorine material gives the inner and outer bearing rings increased strength and rigidity. It also provides an endurance life of over 1,000 times that of A1S1440C stainless steel bearings and 5 times that of previous PE (Polyethylene) bearings under a light load in an acid solution (Figures 2 and 3).

Figure 2

Figure 3

NSK asserts that the all round excellent operating and life qualities of the Aqua- Bearings mean that they can be used widely, not only in Food Processing environments, but also in Semiconductor and LCD manufacturing, Pharmaceuticals, Chemical Production and in Surface Treatment processes. Also, in contrast to their normal operating environments where they are exposed to water and chemicals, the Aqua-Bearings are equally effective when operating under dry conditions.

The Aqua-Bearing is the latest in a range of specialised products, which NSK has developed for the Food Processing industry. Included in this range is the SPACEA Series a range of bearings and lubricants that reportedly provides high performance and reliability under all types of demanding operating conditions: super-clean, vacuum, non-magnetic, corrosive, high/low temperature, nuclear and high speed.

SPACEA bearings are said to meet the widest range of technical requirements with a programme of high performance materials, surface finishes and specially developed lubricants, including solid types. Depending upon the application, SPACEA bearings can be manufactured from Martensitic and Austenitic stainless steels for corrosive environments, ceramics, or a combination of both. Hybrid SPACEA types can have any combination of ceramic inner/outer rings or balls, however, the range also includes all ceramic bearings for use in highly corrosive and high temperature environments (Plate 1).

Plate 1 NSK introduces special Aqua-Bearing for highly corrosive environments in food processing, pharmaceuticals and electronics

Not all applications require the levels of protection provided by ceramics, so a range of surface coatings offering graduated protection has also been developed. In addition to hard chrome plating, the SPACEA bearings can be coated with Cold Flourine, in a low cost treatment that provides good resistance to most acids, and Nickel Alloy, which offers high resistance at moderate cost.

Another range of bearings introduced to cope with the rigours of Food Processing environments is the RHP Silver-Lube series. These are corrosion resistant, mounted bearing units, which are said to help users achieve hygiene improvements while reducing downtime and maintenance costs.

Silver-Lube series bearings are manufactured from stainless steel - a modified 440C type. They are said to be designed specially for use in industries where hygiene considerations and corrosion and chemical resistance are important. Typical industries include: food processing such as dairies, bottling and brewing, pharmaceuticals, fisheries and chemical processing.

Completing the list of recent food industry product introductions by. NSK is the newly developed Kl Lubricating Unit technology. This technology is thought to be improving the performance of machines, in terms of reliability, maintenance free intervals and operation in environments exposed to contamination such as water.

The Kl Lubricating Units have been developed for use on NSK's linear guides and ballscrews, which provide guiding, support and actuation functions on all types of food processing machines. Manufactured from a "porous synthetic resin" (known as Molded Oil), which is oil impregnated to eliminate the need for re-lubrication, the -Kl Lubricating Units are stated to be particularly effective in environments where oil related pollution must be prevented. The food industry with its strict hygiene regulations is a good example - as are semi-conductor and medical equipment manufacture. NSK asserts that in all these industry sectors pollution can be avoided, and sufficient lubrication provided, by using the Kl Lubricating Unit in conjunction with minimal grease.

Another problem which the Kl Lubricating Unit is said to address effectively is loss of lubricant due to washdowns. Machines used in food production and pharmaceuticals, which would normally suffer in this respect, can reportedly be assured of longer service life simply by specifying NSK Kl Lubricating Units in combination with a suitable pre- packed grease.

Details available from: NSK Europe Ltd. Tel: +44 (0)115 936 6470.