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Improving your process equipment step by step

MRC Ultra corrosion-resistant deep groove ball bearing
MRC Ultra corrosion-resistant deep groove ball bearing

2017 January 31, 09:00 GMT

A survey of food manufacturers and processors* revealed that almost three quarters of respondents were hard put to meet the costs of improving their production systems due to pricing pressures imposed by the major retailers. David Oliver, Food and Beverage Segment Manager at SKF believes one solution is to make incremental improvements, such as enhancing the efficiency and reliability of individual components in process systems at low initial costs, which subsequently reap significant savings over time.

The value chain in the food sector is dominated by the major retailers, who seek lower prices from their suppliers without compromising food quality and safety. These demands place considerable pressures on food producers to find greater efficiencies in their manufacturing processes, reducing waste and energy consumption, and improving machine availability. So, at the machine component level, where can these efficiencies be made?

Bearings are to be found in almost every machine used in food and drinks production and, occasionally, they fail prematurely. The reasons for this are manifold, but where food and beverage plants are concerned, the operating environment is likely to be the prime cause of premature bearings failure. The costs associated with a sudden bearing failure and consequent machine downtime can be prohibitive, so it is prudent to assess the likely failure modes and select bearings and their associated lubrication systems that are designed to function reliably in these difficult duties.

Food and beverage processing plants are wet, chemically aggressive environments that create a host of problems for bearings and lubricants. The hot conditions in and around ovens, grills, dryers and fryers, for example, can reduce lubricant viscosity, allowing grease to escape from the bearing, hastening failure and providing a source of potential product contamination.

Meanwhile, processes that regularly cycle between sub-zero and ambient temperature can lead to condensation inside the bearing, increasing the risk of corrosion and the potential for lubricant to be displaced into the production environment. Lubricants can stiffen or even freeze at low temperatures, increasing friction, driving up energy costs and potentially causing bearing components to crack and fail.

With these extremes in mind, let’s now take a closer look at the impact of cold environments on bearings and how the latest bearings designs and their materials of construction can mitigate these problems.

Of particular relevance here is the use of bearings and lubrication systems in ice cream and cold food hardening tunnels, where incremental improvements in component performances can be shown to deliver long term cost benefits. For example, if the total cost of ownership of a hardening tunnel is reduced by a mere quarter of one per cent during its lifetime as a result of appropriate bearings selection, significant savings will be made - particularly in unplanned maintenance and the costs associated with waste product resulting from grease contamination.

SKF has addressed the freezing, abrasive, wet and corrosive environments of cold food hardening tunnels with its re-lubrication-free MRC Ultra corrosion-resistant, sealed deep groove ball bearings, which are supplied with food grade Solid Oil lubricant (US National Sanitary Foundation category H1*) and FDA approved blue coloured, synthetic rubber machined seals. High nitrogen corrosion resistant stainless steel technology is used for the bearing inner and outer rings and this, combined with ceramic balls, ensures that the corrosion resistance and fatigue life of these bearings is far superior to bearings made from 52100 and 440C stainless steels.

One ice cream manufacturer that had been experiencing problems with standard steel bearings on its hardening tunnel upgraded to MRC Ultra corrosion-resistant sealed deep groove ball bearings and achieved a five-fold increase in bearing life. The original bearings fitted to the hubs of the hardening tunnel were lasting about a year, and suffered gradual deterioration due to ingress of water and ‘breathing’ during cleaning cycles, which was causing corrosion.

Since the retrofit, the lifecycle of the bearings has potentially increased to six years, a prediction based on analysis after one year of operation. In addition, the new bearings have provided the ice cream manufacturer with re-lubrication-free operation, which has reduced maintenance, the risk of product contamination from lubricant, as well as lubricant waste, grease clean-up and its eventual disposal.

The above technical article was originally published in the January 2017 edition of Food Processing magazine.

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