Bearings are an integral part of equipment which increase efficiency by reducing friction, while maintaining the operational requirements.
In this fast moving age of industrialisation, efficiency is the key to success. Construction equipment operates in very demanding environments, and so the design of such equipment requires components which can withstand such demanding environments with efficiency. Construction segment applications have to deal with heavy loads and harsh conditions. Also, there is increasing pressure on the operators to push equipment for higher productivity and reduced downtime. This in turn has resulted in need for construction equipment with better performance and functionality which will comply with the emission regulations. For such conditions, the various ranges of bearings like cylindrical roller bearings, spherical roller bearings, tapered roller bearings, plain bearings and slew ring bearings are used as per the application within the equipment.
With customers now looking for more than just a bearing supplier, most of the bearing manufacturers are looking forward to improving the product features to live up to the expectation from customers.
Hrishikesh Kulkarni, Head ¨ Drives and Off-highway Business Unit, SKF India Ltd, elaborates on the products and solutions offered by his company, ¨SKF manufactures different ranges of these bearings, and we also have world-class unique offerings like Y-bearings, SKF Explorer class spherical roller bearings and application-specific sensorised bearings, all of which ensure reliability and energy-efficiency to OEMs and end users alike.¨
He adds, ¨SKF upgraded Explorer spherical roller bearings are a result of our detailed application understanding by working closely with the construction segment. Tests conducted in SKF laboratories show that upgraded SKF Explorer spherical roller bearings can last up to twice as long as previous bearings under contaminated or poor lubrication conditions.¨ SKF is also focusing on new generation smart products. ¨By integrating mechanical, electronic, and information technologies, SKF engineers are helping customers design a new generation of smart products through mechatronics. Employing sensor-equipped bearings or sensorised linear systems, mechatronic systems can measure speed, temperature, load, vibration, and position. At the same time, they can be used to integrate Global Positioning Systems (GPS) into drive-by-wire systems. They can also simplify designs, reduce weight and maintenance and minimise environmental impact. There are also some application-specific solutions that are used like the SKF spherical roller bearings for vibratory applications, which are designed to withstand high acceleration forces while operating at cooler temperatures.¨
Globally, NTN is a leading supplier of bearings to the construction equipment segment. Says Ramnath Shenoy, Director, NTN Bearing India Pvt Ltd, ¨We are OEM to all the large equipment makers like Caterpillar, BEML, Komatsu, Tata Hitachi, L&T Equipment and others. We have the Ultage series of bearings for this segment, which offers high performance and reliability under tough operating conditions that this segment demands.¨
As one of the leaders in the bearing sector, NRB has been providing cylindrical roller bearings, roller thrust bearings, sealed ball bearings, tapered roller bearings, spherical roller bearings and pillow block units. Says Harshbeena Zaveri, Vice Chairman & Managing Director, NRB Bearings, ¨NRB´s strategy is to carve out a niche in applications that are extremely difficult and therefore have historically been the domain of the world´s most respected technology-driven engineering product supplier. We specialise in customised friction solutions to meet the exacting needs of our customers.¨
Bajaj Bearings Pvt Ltd is a manufacturer and exporter of bearings under the brand ´Bajaj´, having the largest range of all types of bearings, especially for CE applications. Says Shailesh Lall, Managing Director, Bajaj Bearings Pvt Ltd, ¨We manufacture bearings not only for CE applications but also for heavy trucks and trailers: Volvo Trucks, Scania, IVECO, MAN Truck etc.¨
Standard & specialised bearings
Rolling bearings are also known as ´anti-friction bearings´, but of course, some frictional losses occur in the bearing. A contributing factor to rolling friction in a bearing is the result of elastic deformation of the rolling elements and raceways under load. Says Kulkarni, ¨Apart from a wide range of standard and specialised bearings, SKF also manufactures application-specific bearings for the construction industry including the Upgraded Explorer class, Energy Efficient (E2) class and localised Full Complement Cylindrical Roller Bearings (FCCRBs), amongst others.¨ Shell bearings are basically plain bearings which consist of a shaft or journal which rotates freely in a supporting metal sleeve or shell. There are no rolling elements in these bearings. According to Kulkarni, SKF manufactures a wide range of standard plain bearings and also has specific solutions like the SKF Explorer steel/steel plain bearings, SKF composite plain bearings, high performance TX spherical plain bearings and heavy duty SKF spherical plain bearings, for specific demanding application requirements.
He adds, ¨SKF Explorer steel/steel plain bearings are virtually maintenance-free and extremely robust - the optimal combination for reducing costs and improving reliability. SKF also has the SKF Extended Life Plain Bearings which feature high-grade, carbon chromium steel to minimise the risk of corrosion and offer a re-lubrication-free alternative to frequent re-greasing, thereby making them virtually maintenance-free and ideal for construction applications.¨
According to Zaveri, NRB supplies a wide range of anti-friction bearings for all mobility applications.
¨NTN makes a wide range of anti-friction bearings not only for the CE industry but also for the aerospace, railways and wind turbine industries. Besides the regular range, we have other specialised products such as large size bearings, dust-cover type bearing units, Triple Lip sealed bearings, etc,¨ states Shenoy.
Design and shape for applications
The basic dimensions for bearings are standardised and equipment designers can easily pick standard products for the equipment they design. Says Shenoy, ¨However, the extra edge is provided by NTN where we optimise the internal design and other parameters to give performance beyond the regular standards. For example, our special 4T type, case-hardened taper roller bearings offer better life for CE equipment.¨ He adds, ¨One of the reasons NTN is globally strong in the CE segment is because historically we have worked very closely with the CE OEMs to develop products that can meet their critical needs.¨
According to Zaveri, bearing type selection mostly depends on the type of loads the bearing is supposed to carry and the mounting arrangement in particular. For a particular type of loading, there can be different bearing types which can fulfil the designer´s intent of bearing selection. For example, cylindrical roller bearings only take radial loads. However, there are some modern designs in which limited axial load taking capability is present in the cylindrical roller bearing. For pure thrust loads, needle thrust bearings, tapered thrust bearings and even tapered roller bearings can be considered.
When the loads are very high and radial space available is low, a combination of ball bearing to take the axial load and the cylindrical roller bearing to take the radial load can be considered as a unit. ¨When a particular type of bearing is selected, the designer´s decision is further screened down to a further specific type of the bearing due to several other factors like available space, load, material used, environment and its cleanliness, heat treatment of mating components, end customer´s durability requirements and type or method of lubrication,¨ she adds.
Mitul Doshi, Director, MRS Bearings explains, ¨The selection of the correct type and capacity (load and speed) is of utmost importance in getting the best out of the equipment. There are additional parameters which also need to be considered like whether the bearing is exposed to dusty/humid/wet environments or the possibility of lubrication/re-lubrication, the constraining factors like housing size/shafts sizes or the restriction on the mating component sizes, temperature of operations etc. For e.g., a point of application in which the speed at which the power is transmitted is high and the load applied at the point of the bearing installation space is low, a normal ball bearing can be used. But in the same case, if the point of bearing installation is in a dusty area, the bearing to be selected will be a sealed ball bearing.¨
In any industry segment, be it is automobile, power, or industrial machinery, the concept of lightweighting is fast gaining momentum as it leads to fuel saving, resulting in overall economy. In today´s world where the customer´s demands are ever increasing in terms of performance and value, companies have to come up with new technologies which have to be greener while providing an increased price-to-performance factor. With this view, most of the CE manufacturers are looking at lightweighting their equipment while increasing its efficiency. Bearings play a major role in lightweighting. Says Shenoy, ¨Our Ultage range of products has higher load ratings and this can contribute in downsizing the bearings at the time of design. Hence we are helping the industry in their objective of lightweight concept. This range is available in spherical roller and taper roller bearings. We are also expanding the range into cylindrical and ball bearings too.¨
NRB has also engineered cost-effective, lightweight friction solutions for a host of applications that resulted in increased fuel efficiency, noise reduction for engines and transmissions, and enhanced life. Zaveri gives the highlights, ¨We employ the frugal innovation approach wherein we devise smart solutions using sustainable design that preserves resources. The concept currently is applied to drawn cup cylindrical roller bearings and has replaced solid race bearing products not only like CRBs but also ball bearings.¨
Says Doshi, ¨We at MRS are working on designs that will provide customers with weight reduction through use of recyclable materials (e.g., replacing casting parts with engineering plastics) which will sustain the same load capacities while reducing the weight of the components which in turn saves on energy consumption and logistics costs, and which indirectly also contributes to the carbon footprint of the product.¨
For prolonged service of equipment
Bearings are the first component to fail during operation in any construction equipment, and hence are of critical importance. Bearings facilitate effective functioning of the equipment and the right bearing type will increase the efficiency of the equipment. According to Kulkarni, there are various parameters within the bearing that govern its quality and functionality. These include the type of steel, the seals used to keep the contaminants out and the grease which ensures proper lubrication. He adds, ¨SKF bearings are specially designed and manufactured considering all these parameters as per the application need. Using the right bearing type will ensure long life, which in turn will ensure increased efficiency and service life of the corresponding equipment.¨
Says Shenoy, ¨Bearings are a key component in any machinery. They limit the relative motion and reduce friction between the moving parts. Hence it is important to fit and maintain them properly. Well-maintained bearings can work for a long time and thus extend the service life of any machinery. In addition to this, our Ultage range further helps to prolong the service life of the equipment.¨
According to Doshi, bearings are an integral part of the science of Tribology, which studies interaction between two moving parts. ¨CEs require high efficiency not only in terms of operations, but also to operate without breakdown or need for service for a longer time. The selection of the right type (design) and capacity of bearings provides the equipment the needed efficiency to operate with long service intervals,¨ he adds.
Lubrication plays a vital role in extending the life of bearings. Proper and timely lubrication reduces the problems associated with bearings. Greases are mostly used to lubricate the bearings. Grease has to be applied to avoid the wear and tear, reduce corrosion and protect from rust.
Says Pulkit Khemka, Vice President, Pensol Industries Ltd, ¨Bearing failure is majorly due to inappropriate or wrong grease being charged. Less greasing increases the wear of bearings, and over-greasing also reduces the bearing´s life due to churning effect and increase in the operating temperature. Overall, 70 per cent of bearing failure is due to inappropriate and wrong grease selection.¨
He adds, ¨Our products are able to cater to all the applications in earthmoving equipment. For medium-large to very large bearings used in construction equipment applications, we recommend Pensol Lithonex EP Grease. For wheel bearing applications, we recommend Pensol WB Grease. For general-purpose lubrication, we recommend Pensol AP-LR 30000 Grease and Pensol AP3 Grease.¨
Says Shenoy, ¨Lubricants play a key role in the life of bearings. In fact, the life of the lubricant can sometimes decide the life of the bearing. NTN works very closely with lubricant makers. We offer a choice of over 400 lubricants for cases where the bearing is supplied with pre-filled lubricant.¨
According to Zaveri, energy-efficient lubricants aim at reduction of oil viscosities and improvement of lubricity by addition of extreme pressure additives. She says, ¨While working with such lubricant bearing products, especially those containing nonferrous material, we have to study their chemical compatibility and aging stability with energy efficient lubricants. NRB´s engineering centre has a state-of-the-art chemical laboratory for such studies and to conform product performance with different compositions of energy-efficient lubricants.¨
The lubricant and lubrication system are often integrated into the bearing system where specific greases are chosen, dedicated to the application. ¨Application engineering, consultancy services, training, lubrication management, condition monitoring, reliability maintenance, technical support, tools, products and systems together form the complete lubrication solution,¨ explains Lall.
He adds, ¨The perfect bearing would be lubricant-free. However, lubricant is needed to separate the rolling elements from the raceways in order to prevent damage due to (micro) slip. The ideal separating medium is liquid, which is able to accommodate shear with low frictional losses and may replenish the bearing surfaces (self-healing action).¨
Trends in bearing lubrication
There has been a tremendous advancement in bearing technology over the past 10 years. The bearing industry is now using high-hardness coatings, ceramics and new specialty steels with bearings. These specifications were not available a few years ago.
According to Khemka, currently, bearing lubrication has to withstand a wide temperature range. At the same time, greases have to withstand the load and temperature simultaneously during operations. Through vast and dedicated research on new resources, grease technology helps us to cater to the all the areas from low temperature application to high temperature application, low load to high load, normal condition to extreme environment condition. Major grease manufacturers make customers aware about new technology in the greases and newer thickeners, that will replace lithium grease to overcome various issue.
¨Pensol, being one of the leading grease manufacturers in India, invests a lot in R&D. Over the years, we have successfully launched products that have set milestones in the industry. Recently we have introduced Pensol AP-LR GEL grease in the market, which is again one of its kind in India. This grease further enhances the life of bearings and guarantees high drain interval of 1,00,000 km or more under ideal operating conditions,¨ claims Khemka.
The expectation level from customers has been increasing. They are now looking for more than just a bearing supplier. Says Shenoy, ¨Our engineering team in India works closely with the actual user of the product, identifying the root causes and offers a range of solutions, from new technology products, auto-lubrication solutions, maintenance tools and more.¨
Kulkarni elaborates on the innovations in SKF, ¨One of the key innovations is the SKF Extended Life Plain Bearings which are lubricated for life and are virtually maintenance-free. Combining a virtually maintenance-free design with the robust performance of conventional steel/steel spherical plain bearings, the new SKF Extended Life Plain Bearings offer a re-lubrication-free alternative to frequent re-greasing. For applications with moderate contamination levels, SKF Extended Life Plain Bearings will last at least as long as standard steel/steel spherical plain bearings, even if those standard bearings are re-lubricated in accordance with recommended maintenance schedules.¨
Zaveri explains, ¨The key to success in this industry is product and process innovation, research on cutting-edge technology development and lightweighting. Our range of bearings has equal stress distribution. The lubricants used are specially selected and the bearing material is custom made for extra fatigue life. We reduce the friction by reducing relative contact speeds and slips of bearing elements. This helps us maintain quality and extend life of our bearings.¨
¨For the last few years, we have been expanding our Ultage range of bearings. The word ´Ultage´ is a combination of ´ultimate´, signifying refinement, and ´stage´. It is the general name for NTN´s new generation of bearings with the world´s highest standards of performance,¨ explains Shenoy.
He adds, ¨NTN´s Ultage Series spherical roller bearings are designed to work under extreme operating temperature of 200¦C and at the same time have the highest dynamic and static load carrying capacity in the industry. They also support much higher speeds than the conventional type of spherical roller bearings. All this is available at the cost of a standard spherical roller bearing. In comparison, the rest of the bearing industry offers high temperature bearings at a premium as compared to its standard range which can operate up to 120°C only.¨
Doshi states, ¨MRS has successfully innovated special seal designs, special internal design of the rolling elements and its arrangement to provide a very high reliability of bearings in the operating application. MRS-designed products are tested to the stringent endurance testing criteria which are normally rated higher than the application requirements.¨
Lall elaborates, ¨In an effort to increase bearing life, to improve bearing performance and extend maintenance periods, we use high quality oil and grease. We have focused on quality and technical development. Bajaj bearings are manufactured from bearing steel Grade SAE 52100 (as per international standards), with modern technologies and skilled workforce.¨
Make in India: Opportunities & challenges
According to Doshi, Make in India is a promising initiative by the Government of India on a long-term basis. It can attract foreign investments, increase job opportunities, grow demand for the component/support industries, and act as an avenue for generating revenues for the government, which can be pumped back into the economy through infrastructure development. He adds, ¨Though the initiative has its advantage, it will also create challenges like competing against low-cost funded investments from overseas, more competition in terms of product offerings, prices and reduction in profit margins in the short term. We at MRS are well prepared to address these challenges, by making our operations more efficient, getting close to customers, and we´ll focus on providing solutions which give a win-win output for us and our customers.¨
Shenoy comments, ¨Make in India is a great initiative by the government and we hope to benefit from the same. NTN has a manufacturing base in India since 2006. We have two plants: one is at Bawal, Haryana and a new one was set up in 2012 at Chennai. Our long-term plans are to increase our footprint in India and cater to every kind of industrial segment.¨
Zaveri also sees opportunities on one side and challenges on the other as she says, ¨The Make in India initiative aims at self-sufficiency of Indian industries to cater to their own requirements and create a brand image worldwide. One of the major challenges in this regard is import substitution and indigenisation of raw materials. However, the Indian auto component industry is set to become the third largest in the world by 2025 with exports quadrupling to $40 billion by 2020. This allows us plenty of opportunities to secure a greater share of business in the growing domestic market.¨
With all the respondents positive on the emerging scenario, no doubt that the bearing industry will show considerable growth in the coming years.
Types of Bearings Used in Equipment
Bearing lubricants: Selection parameters
- Pulkit Khemka, Vice President, Pensol Industries Ltd
The right lubricant needs to: