Bearing replacements solve fish processing line failures

A bearing problem on a battered fish processing line centred on a conveyor which is used in the process of adding batter to fish products. The harsh nature of the process meant that the 25mm diameter bearings on the conveyor were lasting just four weeks on the line, due to the ingress of contaminates and frequent washdowns.

NSK's cost reduction programme has achieved a major success with a customer in the food processing industry, achieving annual cost savings of EUR437 839 per year on a battered fish processing line as a result of replacing bearing inserts with NSK's Molded Oil bearings.

Engineers from NSK's AIP cost reduction programme were called in to give advice. The AIP cost reduction programme is a value added service that actually helps bearing users to improve reliability, reduce operating costs, and improve efficiency and profitability. These objectives are achieved by delivering tangible savings to assets, such as equipment and machinery, and also by improving the working knowledge of maintenance and engineering personnel. The engineers visited the process, identified the problem and suggested a solution using NSK's Molded Oil Bearings.

Molded Oil bearings employ a special solid lubricant to positively transform the performance of machinery in environments exposed to high humidity, corrosion and contamination. The bearings achieve improvements in performance and reliability by offering more than twice the operating life of grease lubrication in water contaminated environments. The solid lubricant technology also means that operating environments are kept free of grease and there is no need for refilling of lubricant, as Molded Oil provides a continuous supply of lubricating oil. Sample Molded Oil bearing inserts were fitted to the conveyor and trialled over an extended period of six months. Impressed with the extended bearing life, the customer began replacement of the existing conveyor bearings with Molded Oil units. In addition to providing improved life, these bearings are also saving the customer the considerable cost of regreasing of bearings, estimated at EUR4680 per annum.

Meanwhile, substituting NSK's new HPS Series of spherical roller bearings (SRB) for conventional SRB on a baking dough mixing machine is providing cost savings of £93 512 per annum, plus extended product life, improved productivity and reduced maintenance for a major UK bakery chain. The failure problems were due to high loading on dough mixing spindles, causing premature wear due to deflecting shafts and 'swashing', or reciprocating motion within the SRB bearings, resulting in continuous failures. The cost was considerable: the yearly total for bearings, maintenance, engineering time and lost production, amounted to of £113 144.

NSK evaluated the problem and suggested a solution that would reduce the ongoing costs. The engineer's response was to suggest replacing the existing SRB units with a totally new design: the NSK HPS Series of high performance SRB. Crucially with its HPS design, NSK has clarified for the first time the mechanism that causes slippage and creates high friction on the bearing surfaces of SRB, leading eventually to damage due to surface fatigue. This was verified by extensive testing - that friction can be reduced by controlling the motion of rotating rollers - and that a special surface treatment of the outer ring is effective in achieving this. Based upon these findings, NSK developed HPS bearings, which can minimise/slippage, prolonging running life by more than twice that of conventional products.

The HPS series bearings were fitted to the dough mixing machine for trials. To date the trial has run for nine months with no failures - this compares with the regular 23 months lifespan of the original non-NSK units. Based upon this performance the customer has calculated savings of £93 512 per annum.

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