Lubricating Grease Making: An Art/Science! By Dr. Anoop Kumar
Director R&D and Business Development Royal Mfg Co. LP, 516 s, 25th W Ave., Tulsa, 74127, Oklahoma, USA
The art of reducing friction and wear by use of lubricants was known to mankind since ancient times. Semi-solid fluids/lubricating greases used in those days were mainly oil thickened with animal / vegetable fat, wood ash, tar / resins etc. In the past two centuries, there have been remarkable scientific and technological advancements in the industry, however the developments in the field of lubricating greases have been much slower and less scientific. Till 20th century, the processes of making lubricating greases perhaps closely resembled washing soap making techniques and were broadly similar to typical cookery-book techniques. The post-oil discovery era revolutionised the entire industry, including the lubricating grease industry; a field in which many new processes and techniques have emerged.
Lubricating greases primarily consist of base oil, thickener and additives, with thickeners acting as a sponge and may be considered as the backbone of the lubricating greases. Thickeners can be classified into two main categories, soap/ complex soap based and non-soap based.
Challenges in Manufacturing of Lubricating Greases: Unlike lubricating oil blending, lubricating grease manufacturing is much more complex and sensitive to processing parameters like time, temperature, agitation / mixing, and pressures/vacuum. Therefore scaling up the process from lab to manufacturing plant might sometimes be a challenge.
Lubricating greases could ether be made by continuous or batch process, however the more popular process of making grease is batch process. Conventionally, these soap-based greases (suchas as sodium, calcium, aluminium, lithium greases) were made in open kettles. These kettles were hooked up with different types of agitation systems and were initially heated with either an open fire or electric heated followed by thermic fluid heated kettles, which are the most popular ones these days. The most popular lithium/lithium complex greases could either be made by any of these types of kettles, however the most revolutionary process is the Stratco Contactor process which, conceptually, works in a similar way to pressure cooker. Contactor process is not only a faster way to make grease, but also the product quality and yield is better than with any other processes.
Figure 1.
Lithium base greases are the most popular greases and constitute about 75% of the total worldwide grease market. Calcium greases are perhaps the oldest known greases.
Figure 2. Continued on page 10
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LUBE MAGAZINE NO.138 APRIL 2017
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