Phil Burge explores the ways in which plant and maintenance engineers can reduce operating costs, while improving machine reliability and plant productivity, through the use of a new generation of dedicated component technologies.
The surging population, rapidly growing economies and burgeoning global development, particularly in non-OECD areas such as in the Asia-Pacific region, are the main drivers behind an ever increasing consumption of mineral commodities and ore bodies. In order to meet the rampant demand, mining companies the world over are now under heightened pressure to ensure that sufficient supply is in place to satisfy the need.
As if that was not tough enough, mining plants and organisations are faced with a number of other challenges, including some of the world’s harshest operating conditions. Indeed, from abrasive dust and dirt, to extremes in temperature, this difficult environment makes it hard, and sometimes even dangerous to maintain equipment, with unplanned downtime and worker injuries posing a constant risk.
As a result, many mines often operate below optimum capacity or efficiency, despite the best efforts of plant and production engineers. For example, mine operators will typically run larger vehicle fleets than necessary in the expectation that at least one vehicle will always be out of service for repair or maintenance. The maintenance itself also represents a significant proportion of total costs in the mining sector, with recent market research indicating that this figure could be anywhere in the region from 20 per cent to a massive 50 per cent - the highest ratio of all manufacturing and heavy industries.
On the other hand, there are the stringent new regulatory requirements and rising energy, raw material and waste disposal costs that only serve to compound the issue. Consequently, these challenges see many mining plants being forced to drive down energy consumption and emissions in order to remain environmentally responsible and commercially competitive, presenting yet another issue.
Ultimately, the industry is plagued with a variety of challenges that create a difficult market in which to operate and thrive in. In essence, increasing productivity and reducing costs are the keys to success in surviving the sector and, as a result, mining organisations are now increasingly looking to contain and reduce costs to sustain profitability, primarily through improvements in machine performance, reliability and efficiency.
In many cases, the key to achieving these goals lies not just in the performance of larger systems, such as engines and gearboxes, but also in the smaller components, including bearings and seals; for if these essential but frequently overlooked components fail to function then overall system failure and vehicle downtime is inevitable. By focussing on these vital parts, operators of mining plant and equipment can realise significant cuts in operating and maintenance costs, while maximising equipment performance and life in service
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With this in mind, component manufacturers have been working to develop a new generation of parts, specifically for use in the mining industry that are virtually maintenance free and offer a far longer operating life under a wider range of demanding environmental conditions than has previously been possible. The introduction of these dedicated technologies means that plant and maintenance engineers can now implement a range of devices that will help them to reduce maintenance costs, while improving machine reliability and overall plant productivity. Equally important are the considerable contributions that these new products can make to both health and safety, and environmental protection.
As these latest technologies cut the overall maintenance and repair demands they also eliminate the hazards that accompany them. This is particularly pertinent in the light of recent findings which indicated that 32% of all mineworker injuries occur during machine maintenance and repair operations. Correspondingly, the increased safety means that the lost productivity and inflated health and insurance costs that come as a result of accidents can also be cut to an absolute minimum.
For instance, oil injection mounting and dismounting tools enable engineers to safely mount and dismount bearings, couplings and other mechanical components without hammers, bars and torches, thereby reducing the risk of injuries that can come with the use of such tools. Laser alignment tools, on the other hand, help make motor and drive alignments safer due to the fact that engineers are no longer required to take manual measurements, eliminating the need for close contact with moving machinery.
As far as carbon footprints go, this new generation of components has been designed with environmental pressures in mind, helping mining operations overcome the rising energy and waste disposal costs, while complying with the stringent government environmental standards.
Ideal for use on conveyors, crushers and screens, the latest self-aligning bearings accommodate the axial thermal expansion and movements in bearings and housing arrangements commonly found in mining equipment, thus achieving more consistent, reliable and efficient operating performance.
For example, a new bearing system from SKF has been designed to incorporate an SKF Explorer spherical roller bearing in the locating position and a CARB toroidal roller bearing in the non-locating position. The CARB bearing is a self-aligning radial bearing with an inner ring that moves independently of the outer ring, similar to a cylindrical roller bearing.
This unique construction allows the system to accommodate shaft elongation within the bearing without inducing internal axial loads, resulting in considerably less friction and lower operating temperatures. In addition, it operates with reduced vibration and noise levels and enables safer, more efficient designs. Ultimately, this leads to extended re-lubrication intervals and extended bearing service life.
In addition, as the radial clearance of the bearing is small and does not change during its operating life, it does not affect the long term accuracy or repeatability of high performance equipment. The CARB bearings are also packed with high performance grease, allowing significant savings to be made in both the time and money spent on maintenance and repair.
Similarly, the latest high performance seals are perhaps more effective than ever at providing protection against the intrinsically harsh operating environments of mining applications, preventing system contamination resulting from the ingress of particulate matter and moisture. Furthermore, a correctly specified seal provides low levels of friction, retains the lubricant and essentially extends bearing service life.
There is a wide assortment of seals available on the market today, manufactured in various materials and designed to withstand both high and low operating temperatures, as well as resisting different chemicals. These sealing solutions include radial shaft seals, piston seals, mechanical seals and v-ring seals that offer exceptional reliability, minimal maintenance requirements and low maintenance costs. In addition, the SKF SPEEDI-SLEEVE has been specially designed to repair seal worn shafts. This solution can be easily mounted onto worn shafts and provides an excellent matching surface for the seal.
Likewise, the latest large diameter seals, such as the HDSF2 seals from SKF, feature a PTFE excluder lip, which is integrated within the body of the seal, to protect bearings from the ingress of abrasive dust and particles in a wide range of mining applications. This enables the typical operating life of bearings in horizontal grinding mills, coal pulverisers and vertical rolling mills to be more than doubled, helping operators to improve productivity while reducing repair and maintenance costs.
While it is essential for the right components to be specified for an application, the correct installation and alignment of these parts is critical in order to realise the benefits of extended machinery operating life and improved plant reliability. Indeed, misaligned shafts are estimated to be responsible for up to half of all the costs related to rotating machinery breakdowns. However, to overcome this problem a new generation of laser shaft and belt alignment tools have been developed to offer quicker and more accurate results than traditional methods.
As an example, the SKF shaft alignment TMEA series of instruments are easy to set up and use, allowing for a simple three stage process of measuring, aligning and documenting. They consist of two self-contained units, mounted opposite each other on the two shafts to be checked. Laser beams are transmitted from one to the other, with a handheld LCD display unit showing the actual alignment status. As adjustments are made, normally by inserting shims under the machinery feet, the display counts down to zero, indicating the correct alignment. The system also allows for documentation to be produced recording a machine’s condition over its working life and providing maintenance engineers with an essential tool for extending operating life still further.
To further ensure the optimum performance of mining equipment over extended service lives, condition monitoring and predictive maintenance can also be used. One such system is the SKF Copperhead programme which enables early detection of imbalances, mechanical looseness, bearing faults or high temperatures. This allows remedial action to be taken promptly before performance is degraded and so eliminating downtime. Furthermore, a range of handheld analysers are available for simple analysis and reporting.
In summary, what is needed is a combination of the latest generation of high performance components and a preventative approach to maintenance if mining companies are to maximise output at the lowest possible cost. By adopting these technologies, reliability and uptime can be optimised, health and safety improved and environmental impact minimised, leading to increased plant productivity and, above all, better returns and profitability.
Phil Burge, Communication Manager, SKF (UK) Limited. www.skf.co.uk.
