Coal is one of the most important and abundant fossil fuels in India. Accounting for 55% of the country’s energy needs, the commercial coal mining in modern times has been dictated by the needs of the domestic consumption. The growing needs of the steel industry are the propellants to the systematic exploration of coal reserves in the country.
Coal India Limited
Coal India Limited (CIL) as an organized state owned coal mining corporate came into being in November 1975 with the government taking over private coal mines. Headquartered in Kolkata, with a modest production of 79 Million Tonnes (Mt) at the year of its inception, CIL is one of the largest coal producer in the world.
Situation in hand
Aneesh khan and Company (AKC), CIL’s contractor had been using a Lithium-Complex grease for lubricating the bush pins of their Heavy Earth Moving Machinery (HEMM) which includes large excavators made by Volvo, Tata Hitachi & Komatsu. They had been facing issues pertaining to loss in productivity due to higher downtime caused by re-greasing once in eight hours.
The bush pins produced noise after almost 6-7 hours of operation, due to the deterioration of the existing grease. Deterioration of the grease, resulted in metal to metal contact during continuous operation, causing premature pin failures. Regreasing at regular intervals was the only solution then in hand, for which the entire equipment had to be shutdown in every eight hours. Thus, causing unwarranted downtime and loss in productivity.
CIL’s contractor AKC, reached out to ExxonMobil’s Field Engineering Services (FES) experts to understand the major cause behind higher loss in productivity, downtime, and premature pin failures.
The FES experts carried out an on-site inspection of the failed & operational bush-pins of the equipment along with the competition grease used, functioning under the existing working conditions of re-greasing practices.
Post the inspection the FES experts sent the used grease to ExxonMobil’s Lubricant Technical Services (LTS) laboratory in Canada to analyse the work penetration and metal content (Chromium, Copper, Iron, Silicon, Lead, and Titanium) of the used competition grease.
After the analysis, it was realised that the used grease had significant amount of Iron wear (8.16%) after 6-8 hours of re-greasing showing inadequate lubrication/film to protect the pins against wear. Presence of wear elements like Chromium, Lead & Titanium were also observed
The FES experts recommended the use of Mobilgrease XHP™ 322 Mine, an advanced Lithium-Complex soap based grease with ISO VG 320 base oil, fortified with high quality MoS2 solid additive for adequate lubrication of the bush-pins for the existing operational conditions
Followed by the recommendation of Mobilgrease XHP 322 Mine, the FES experts conducted an on-site inspection of the bush pins and the used grease, Mobilgrease XHP 322 Mine.
Similar to the previous drill, they sent the used grease to the ExxonMobil’s Lubricant Technical Services (LTS) laboratory in Canada to analyse its condition.
Even after 48 hours of continued machine functioning, the used grease, ‘Mobilgrease XHP 322 Mine’ had not deteriorated at all in terms of consistency. It exhibited, superior protection of ISO VG 320 base oil & solid additives resulting in much lower Iron wear, hence offering superior mechanical stability.
The re-greasing intervals extended from eight hours to once in 48 hours; a six fold increase. It was also observed that the pins did not produce any noise even after 48 hours of continued usage This led to reduced excavator downtime, thus increasing the functioning by more than two hours per day. It ensured superior protection to the bush-pins, leading to increased safety, lower grease consumption & a potential annual savings of US$ 1,141,038.