Lubrication: Getting the perfect balance 

WHEN IT comes to lubrication, more is not necessarily better, however, it can be difficult to get the balance right to maximise bearing health and longevity. Working in the lubrication industry for over 20 years now and having been a chartered mechanical engineer in the oil and gas sector before moving over to the supplier side of things, I understand the day-to-day challenges and mistakes that encourage premature bearing failure.

Common bearing lubrication mistakes

Here are the most common bearing lubrication mistakes I see that can be remedied with careful grease or oil choice:

Over-lubrication - Over-lubrication must be the number one reason for premature bearing failure that I see in my daily work. Too much grease or oil increases the friction and heat for the bearing, leading to seal damage and eventual bearing failure. It is usually easy to spot over-lubrication when it gets to this stage, as there will be grease leakage, an increased temperature during operation or additional noise. 

Under-lubrication – Conversely, under-lubrication is almost as bad for bearing longevity, as insufficient amounts of grease or oil leads to metal-to-metal contact that inevitably leads to wear and overheating. The tell-tale signs of under-lubrication are a high operating temperature, unusual vibration and premature wear.

Wrong lubricant – Third on the list is using the wrong lubrication for the application or mixing incompatible thickeners or base oils. With different grease or oil viscosities and base types there is no guarantee that they will be able to handle the speeds, loads or temperatures thrown at them during normal operating conditions. The signs of the wrong lubricant use will usually be accompanied by excessive wear, noise, machine or grease breakdown and/or clogged lubrication paths.

Getting bearing lubrication right

A bearing can last up to six times longer if the right lubrication and amount are used on it. Therefore, it’s important to pay attention to OEM’s specifications for grease type, quantity and lubrication intervals, that are usually based on bearing size, speed, operating temperature, load and environmental conditions. If the manual advice isn’t specific enough, then calculations for grease volume from leading bearing companies are readily available.

Correct lubrication reapplication is equally as important. Manufacturer charts - based on operational conditions, online calculators and lubrication schedule spreadsheets - are good. Also, using ultrasound or vibration analysis, infrared thermography, or checking grease colour changes are useful indicators of lubrication needs. Another thing to take into consideration is lubrication application method. 

The importance of lubrication choice

Both the lubrication and bearings experts at Acorn were called in to help an offshore product engineering company solve a problem they were having with blackening grease on some large oscillating bearings. Two issues were highlighted. Due to the position of the bearings, the lubrication was being added from above, when they weren’t in full oscillation, which led to dissipation issues.

Also, the grease was getting hot and cooking. Acorn resolved the company’s issues by specifying a grease that had a higher operating temperature and to overcome the lubricant application problem recommended a switch to a more suitable bearing for the loading. The end result has been no more black grease and minimal changes to the machine to get it back in full working order and maximise its operational longevity and efficiency. 

When it comes to choice of lubrication, the most cost-effective solution is the one that is going to give the user the biggest return for total lifetime ownership cost. And to achieve this does not necessarily mean choosing the cheapest lubrication. This is because premium quality products are often better suited to the application, but due to their improved performance require less frequent reapplications.

Savings thanks to a lubrication survey

A case in point is Acorn’s work with a UK producer of bread and pies. They asked Acorn to carry out a lubrication survey of the site, as they wanted to maximise the lifespan of their ageing equipment. Following the analysis, the company took Acorn’s advice and switched to a better quality lubricant. Since that time, the maintenance team has noticed improvements in machine operation, without having to spend more than they were on lubrication. As a result of using ‘less not more’ of the premium product, the lifespan of their machines has been optimised.

Whether it is a high speed application that needs less grease more often, or a low speed or dirty production process that needs more grease less often, there is a lubricant to suit. Unnecessary wear, downtime and cost can be avoided if the right lubricant is chosen for the bearing and application, and relubrication is gotten right. So, if grease and oil keep things moving, shouldn’t you be paying more attention to what you are using and when?

Andrew Howard is lubricants and adhesives product manager at Acorn Industrial Services

For more information:

www.acorn-ind.co.uk

Tel: 0800 8766 441