Cleanliness is critical during the manufacture of integral parts, particularly for sensitive industries like pharmaceuticals and food. How can manufacturers preserve high standards when these components are in operation? Here, Chris Johnson, managing director of ceramic bearings supplier, SMB Bearings, gives his advice on maintaining high levels of cleanliness when installing, maintaining or replacing small bearings in a manufacturing plant.
Maintaining a high level of cleanliness inside precision bearings is vital. Contamination from even the smallest particles can affect the running quality and lifespan of the rotational elements. A contaminant particle of five microns or less is enough to cause a precision bearing to fail and the smaller the bearing, the greater the risk. To put this into context, human hair has 60 microns and fingerprint depth is just six microns. These particles may be minute, but their potential to cause damage is huge.
Contaminants that impede a bearing’s performance come from various sources. They can be airborne such as dust or small particles of material originating from work areas or storage areas of the plant. These may be kicked up due to the movement of vehicles and personnel or generated and passed into the air by factory processes. Contaminants may be transferred to the bearing during handling or as a result of contact with dirty surfaces in the machine itself. Wear particles generated by other components in the equipment may also find their way into the bearing. Finally , contaminants can be introduced to the bearing if dirt, dust or extraneous liquids are allowed to come into contact with greases or oils used for relubrication.
The obvious answer on how to minimise the chances of bearing failure through airborne contaminants is good housekeeping. For operators of warehouses of all shapes and sizes, maintaining a clean and organised facility is one of the biggest struggles of the job, but is resolved with thorough and consistent cleaning processes.
Transferred contaminants, such as dirt that has been picked up from one source and transferred to another, can also affect the life cycle of a bearing. This can be as simple as the smallest amount of sweat from your fingertips which can cause the surfaces of the bearing to corrode. Dirt from your hands can find its way into the raceways, ruining the bearing’s smooth-running qualities and drastically shortening bearing life.
When installing small bearings, there is a risk of contamination as soon as you pull them out of their packaging. Gloves are recommended for bearing handling to help avoid the transfer of contamination. Using surgical tweezers instead of gloves minimises the risk even further, especially for instrumentation-type bearings. Make sure that shafts and housings are clean before installing bearings as well as any workbenches, work-cloths or other surfaces that the bearings might touch. Extra care taken when handling bearings can go a long way towards extending bearing life.
Introduced dirt refers to impurities that enter the bearings through contaminated lubrication during maintenance. Any materials such as greases, oils or cleaning solvents should be kept in clean sealed containers when not in use and handled carefully to avoid introducing contaminants including moisture. Bearings operating with contaminated lubricant will have higher levels of vibration, wear faster and need to be replaced sooner than intended.
Contaminants can have a huge impact on machinery which can be detrimental to efficiency, maintenance costs and uptime. Proper attention paid to both the bearing and the environment will help to minimise risks and ensure longer-lasting performance of bearings.