Reduction in replacement bearing costs

24 April 2009

A manufacturer of domestic appliances is benefiting from savings of £12,000 per annum on replacement bearing costs, together with extended product life and reduced maintenance, following a solution provided by NSK’s Cost Saving Programme. The manufacturer was experiencing problems with housed bearing units on a fan application.

Reduction in replacement bearing costs

The bearings were running hot due to their location above an oven, and this was causing failures resulting in bearing replacements once a month, at a combined cost of £12,000 per year.

The nature of the bearing problem was compounded by the fact that the temperature at which the failures were occurring was well within the operating range (-40C to +180°C) of the fan bearings. This fact was revealed when an NSK engineer visited the manufacturer’s site in an attempt to reduce the high costs resulting from the failures.

This discovery moved the focus of the inspection procedure from the bearings themselves onto the maintenance procedures adopted by the fan users, and in particular, the type of lubricant used. Self-Lube bearings with high temperature HLT inserts are initially filled with the Kluber Asonic HQ72-102 grease during manufacture. This is a high performance grease developed to ensure long term, reliable operation in high temperature applications. However, NSK’s investigation revealed that the failed bearings were filled with another type of grease which had inferior operating performance to the Asonic HQ72-102; this was the cause of the failures.

The role of grease selection in ensuring reliable bearing life is much misunderstood, and is one reason why NSK runs regular Maintenance Seminars as part of its Cost Saving Programme. The seminars also address another major issue with grease: that of incompatibility. Some greases cannot be mixed with others, even when both types meet specifications. Unless this incompatibility is understood and accounted for, switching to different grease can have serious consequences for bearing life.

Having identified the nature of the problem on the oven fan bearings, NSK recommended a maintenance programme to overcome it, and prevent it happening again. This involved, among other activities, regular regreasing of the HLT inserts on a weekly basis. The programme has proved a complete success; the bearings have now been operating satisfactorily for 12 months without problems, saving the manufacturer £12,000 in replacement, lost production and maintenance costs.

This level of cost saving is not exceptional; NSK is producing even higher levels of savings across a wide range of industry sectors. The company’s Cost Saving Programme looks at all aspects of bearing systems: design, specific problem applications, lubrication, and even training issues.

The process often starts with a site survey, which is very detailed. NSK engineers visit a customer’s premises, talk to them and get to understand what the difficulty is.

Data acquired from the visit is subsequently analysed, leading to recommendations for improvements. These improvements are then quantified in cost terms, demonstrating the level of savings that can be expected by the customer as a result of adopting the solution proposed by NSK.