Open Cut » Maintenance & Equipment
New lubrication specifications are needed to improve the quality of lubricants used in the mining industry. The mining industry spends more than $20 million a year on lubricants, however, lubrication specifications for machinery are inadequate. Two sets of specifications are used - the machine manufacturer's and lubricant supplier's. The manufacturer's specification states the minimum standard that the lubricant used on the machines must meet. The lubricant supplier's data sheets provide the actual performance details of the lubricant. Quality is lacking in many of these specifications. Poor specifications mean that comparison and evaluation of lubricants for their intended purposes is either not possible or very difficult. Manufacturers normally quote test results that are low-cost and easy to obtain, but may not be relevant. The procedures for the preparation of automotive lubricant specifications are much more comprehensive than for mining machines, despite the price disparity of the machines.
To improve the quality of lubrication used on draglines and other mining equipment, specifically in open and enclosed gears, bushes, wire ropes and hydraulics. Biodegradable lubricants are also assessed.
- Improvement in operational reliability, reduction in maintenance activity and the reduction of wear of lubricated components.
The criteria used to assess the quality of lubrication include:
- The reduction of friction, the promotion of efficiency and reduction in operating costs.
- The control and reduction of temperatures.
A standard specification needs to be adopted with suppliers required to provide data sheets to this standard.
To assist in producing new specification parameters, several test rigs and test methods have been developed, including:
- Residual film thickness method (two systems of measurement have been developed) · Volatility
- Film durability
- High load shear stress
- Two disk rig
- High pressure chamber
- Impacting ball apparatus
- Gear lubricant film durability
- Bush lubricant film durability
- Wire rope penetration
- Oxidation protection
These tests produce results that allow lubricants to be compared effectively.
The researchers also recommend that:
- The new dragline lubricant test methods developed as part of the research are used by maintenance practitioners.
- Shear stress proportionality coefficient (as measured by impacting ball or high-pressure chamber) is limited. This will improve the efficiency of energy utilisation and improve the life of gears and lubricants.
- The film durability of open gear lubricants is determined to identify those lubricants which will be the most cost-effective.
- Other special tests are conducted to progressively lift the performance of lubricants.
- Conventional hydraulic fluids are used in preference to biodegradable fluids for normal operations.
- Environmentally-friendly lubricants and hydraulic fluids are used only when performance standards are not compromised and it is cost-effective.
Where To From Here
The researchers have recommended that a lubrication network is developed and lubrication workshops are conducted to provide a forum where common interests could be discussed and industry standards developed.