The technological secrets of relubrication facilities
If you are changing the bearings on a skateboard, you can do it in your garage with a pair of tweezers. For many applications though, the process of relubrication requires precision, expertise and sophisticated technology. Here, Chris Johnson, director of bearing relubrication specialist SMB Bearings, examines some of the specialist equipment you might find in a bearing relubrication facility.
As a specialist bearing supplier we used to receive requests for bearings with non-standard lubricants, or for help with relubrication. For smaller or mid-volume orders, larger manufacturers were often unwilling to offer this service. We wanted to help and so, around thirty years ago, we established our own inhouse bearing relubrication facility.
Over the years, our expertise in this area has grown exponentially and we have acquired a range of sophisticated equipment. If you want to know more about the kind of technology and equipment you can typically find in a bearing relubrication facility, here are five key elements, plus one that is so secret I can’t really tell you too much about it!
For precision applications, it is imperative that the process of relubrication takes place in an environment free from potential sources of contamination. Particles far smaller than the naked eye can see could easily compromise the working of a bearing if they are allowed to enter and contaminate the lubricant.
A good relubrication facility requires filtered air. Although in most cases it is not necessary to have a certified cleanroom, many customers, particularly those involved in the manufacture of electronic, pharmaceutical or medical products to name a few, should expect a facility that can offer a highly controlled environment, free from sources of contamination and akin to a cleanroom environment.
In some applications, the quantity of grease is just as important as the type of grease in ensuring the performance of the bearing. For example, while a standard fill might be 30 percent, for certain low torque applications this would be too stiff and a customer might need a ten percent fill instead. When dealing with miniature bearings and quantities on this scale, you have to be very precise. A job like this requires high-tech specialised scales, that are ultrasensitive and capable of providing the necessary level of precision.
Ultrasonic cleaning equipment
Degreasing or cleaning out the bearings is just as important as adding in the fresh lubricant. If the process of degreasing is not carried out in the right way, traces of the old grease can remain and cause problems. In addition to special solvents and chemicals, relubrication specialists might use ultrasonic cleaning technology. Ultrasonic waves cause cavitation and the tiny bubbles released in this process provide a gentle scrubbing effect on the surfaces.
Standard greases can become combustible in high oxygen environments. This reiterates the importance of degreasing properly, with the right chemicals and equipment, to avoid potentially explosive consequences. Bearings used in oxygen systems, such as those found in medical applications for example, should not have any hydrocarbon-based oil in the lubricant, due to the risk of spontaneous combustion. Making sure the bearing is properly cleaned out is therefore essential. Having cleaned a bearing, a specialist can use ultraviolet light to ensure no traces of potentially combustible material remains, as hydrocarbons will fluoresce under this light.
Relubrication specialists are often called for because of the need for a specialist lubricant. Often, a problem with a bearing could be easily resolved with the correct lubrication. One interesting area here is dry lubricants. The inner surfaces of a bearing can be coated in dry coatings, such as molybdenum disulphide, which will help prevent micro-welding between steel surfaces in vacuum environments. If you need dry lubricants to be burnished or sputtered on to the balls or raceways of a bearing, this is something that requires specialist expertise, particularly in precision applications such as those being specified for vacuum environments.
Some of the technology that might be deployed in a relubrication facility is so sophisticated that full details of its operation cannot be disclosed. For example, at SMB Bearings, we have proprietary technology that allows us to relubricate bearings without removing the shields. Customers who need a specialist service like this can inspect the facility to see the equipment in action and assure themselves of its efficacy. However, they must sign non-disclosure agreements to make sure the secrets stay with the experts.
From ultrasonic cleaning devices to secretive technology that can degrease a bearing without removing the shields, a modern relubrication facility has an impressive array of equipment. If you don’t have the expertise or access to the right equipment, stay clear of botched DIY jobs and rely on the experts.