Article on Bearing Special - by Mr. Ajay K. Gupta, The Managing Director of Kamtech Associates Pvt. Ltd.

"Presently Indian bearings market is quite bullish with excellent growth prospects, thanks to the enormous grow in the automobile sector giving rise to demand for bearings. Most of the major manufacturers have got their capacities booked till 2014. Understandably, companies are looking for alternate sources for bearing supplies. This offers a huge opportunity for more and more international brands exploring India manufacturing base. The market is hot, in The automotive industry, more than 30 lakh vehicles are coming every year. Every vehicle requires bearings. When these vehicles start requiring maintenance after five years, there is again a demand for bearings. In the automotive sector the requirement for bearings will never get exhausted", revealed industry specialist Ajay K. Gupta, who is also the Managing Director of Kamtech Associates Private Limited. Read more


  • Ajay Kumar Gupta (MD, Kamtech Associates Pvt. Ltd.)

  • Industrial Bearings Market in India : Issues and problems

  • (Delivered at Global Bearing Conclave 2007 held at Jaipur, (India)

Bearings Industry

  • Harish Hirani (Assistant Professor - IIT Mumbai)

  • Bearing Failures-An Overview

  • Bearing Lubrication

  • Failure Analysis of Roller Bearings-Part I

  • Failure Analysis of Roller Bearings-Part II

  • Overview of Bearing Technologies

  • Hydrostatic Bearings-An Introduction

Bearings Industry

Electrically-insulated Rolling Bearings

Bearings Industry
Bearings Industry

The Problem

The passage of electrical current under unfavourable circumstances may damage rolling bearings used in electrical machines.

Such a passage of electric current may be caused by faulty or damaged insulation of the bearing shields or by an ineffective earth connection of the machine.

Particularly in the case of modern electrical machines that feature a high degree of performance and increased customer requirements, in terms of high reliability and a long service life, such damage may cause considerable and expensive problems.

Defect Mechanisms

The amount and appearance of bearing damage, due to passage of electrical currents, is dependant upon the individual operating conditions, e.g.,

the actual effective voltage.

The appearance of the damage may vary between single craters (that can be easily identified by a visual inspection), and a continuous row of shallow flutes with discolorations around the actual areas.

In a somewhat simplified form, the development of damage caused by electro corrosion may be described as follows (Figure 1):

The user may notice this process only by symptoms such as an increase in the levels of running noise and/or vibrations, until the bearing fails prematurely.

The Solution

The effective electrical insulation of the end shields is, in most cases, only possible with great care and additional efforts. In the case of existing designs, any improvement of electrical insulation could also be difficult from a technical point of view.

The simplest solution is provided by the use of NKE Electrically Insulated Rolling Element Bearings.

These are bearings that have an extremely efficient electrical insulation integrated that avoids the passage of electric current through the bearing.

For this reason, the additional electrical insulation of the end covers may be omitted. This means, in addition to the total cost savings by the removal of the conventional insulation, an increase in reliability and actual service life can occur.

Design Variants

SQ77: Bearings with an oxide ceramic insulating layer applied to the outer ring.

The application of the thin-layer of insulation coating is completed by a plasma spraying method.

The guaranteed minimum breakdown resistance of this insulating layer is 1000V alternating or direct current.

SQ77B: Bearings with rolling elements made from oxide ceramic (hybrid bearings).

This alternative method of insulating should be applied, preferably, to smaller bearings. The theoretical breakdown resistance of insulating rolling elements is ¥.

Technical Characteristics of NKE Electrically-insulated Bearings

Standard Range

“Economic Efficiency through Innovation"

Wide Performance Spectrum for the Rail Vehicle Industry

WÜRZBURG / SCHWEINFURT, December 11, 2002. At a two-day press symposium in Würzburg and Schweinfurt, the Schweinfurt rolling bearing specialist FAG Kugelfischer Georg Schäfer AG provided ample proof of its competence as a development partner to the rail vehicle industry. Focusing on economic efficiency and innovation, the FAG railway specialists presented new solutions for the rail vehicle industry and showed that they are well prepared to respond to the challenges of this growing market. The INA solutions for tilting technology and rail gage adjustment were also subjects of the presentations.

Dr. Raimund Abele, Head of the FAG segment Railway and Transport assumes that the worldwide transport volume will increase by five to seven percent in the next two decades. “In Germany alone the freight volume in the coming 15 years will increase by more than 60 percent.“ International growth markets are above all to be found in the Asia/Pacific area and in North America. “FAG has geared up for that. We offer an innovative, powerful and customer-friendly product portfolio “, said Abele.

In addition to FAG’s technological solutions and more than 100 years of rolling bearing knowhow, the unique test competence plays a very important role in this context. “FAG is the only rolling bearing manufacturer to be approved as an inspection station for the rail vehicle industry by the Federal Railway Office, EBA,” says Abele. This has also become possible thanks to the FAG-developed test rigs that are available at the Schweinfurt test center. The latest test rig permits the inspection of complete wheelset bearings under quasi-field mounting and test conditions.

In further reports, FAG development and application engineering specialists dealt with the latest products and findings regarding material research, calculations and lubricant development. Based on improved calculation methods (“Bearinx” – the new calculation standard within the INA Group) and simulation models (CAD, Finite Elements, BEM), it had for instance been possible to develop the Y25/25t wheelset bearing for freight wagons. With their higher load carrying capacity, these bearings permit a cost-efficient increase of the admissible axle load, a simultaneous reinforcement of other bogie components provided.

"New manufacturing methods and materials"

Prof. Edgar Pröschel, Chief Designer of the FAG Railway segment, and Dr. Klaus Baalmann, Head of Product Research, provided information about new trailblazing manufacturing technologies (milled, spiral-turned cages), new materials (high-nitride chromium steel for bearing rings, ceramic material for balls and rollers) as well as coated surfaces against fretting corrosion, and showed how these can ensure enhanced economic efficiency. Here it is in particular X-life bearings with their optimized materials that offer progressive solutions with tangible economic advantages in the form of significantly extended inspection and maintenance intervals and extremely long service life.

For instance, the high-nitride chromium steel “Cronidur30” admits a multiple extension of the material fatigue life. In addition, it admits higher contact pressure, is corrosion-resistant and insensitive towards conditions of mixed friction or contamination. The rolling elements of ceramics have a significantly lower mass, permit higher speeds, prolong the grease life, can be operated at elevated temperatures and are insensitive to starved lubrication. Their combination with specially developed lubricants and seals completes these positive features.

X-life bearings in traction motors too have significantly extended inspection and maintenance intervals. Owing to their ceramic rolling elements they even have a built-in current insulation.

"FAG wheelset bearings with integral sensor technology"

The integration of mechatronic components in wheelset bearings opens up a new dimension. On the road to “intelligent wheelsets”, experienced by passengers as enhanced traveling comfort, ready-to-mount FAG wheelset bearings with integral sensor technology represent an important factor. The sensor technology stands out for its low space requirements, low masses, easy maintenance and handling as well as high reliability and measuring accuracy. Inspection and replacement of the sensors can be carried out with ease. In addition to temperature and speeds, they now also measure acceleration values during operation. These values are monitored in all three spatial axes (longitudinal, vertical and axial). In conjunction with the readings for bearing temperature and speeds, the operating condition is ascertained and recorded. The documented measurements also serve as basis for demand-oriented maintenance. According to Dr. Baalmann, the medium-term goal is to arrive at a complete “on-board condition monitoring”.

"Electric power from the wheelset bearing: The FAG generator bearing"

With the new generator bearing, FAG offers a convincing, innovative solution for vehicles that have no power supply of their own, like freight cars. The bearing is able to supply the required electric power to both the sensors monitoring the operating condition (temperature, speeds, acceleration) and the systems monitoring the loading condition as well as to anti-theft devices. In addition, signal emitters and receivers in satellite navigation systems (GPS) can draw the required electric power from the bearing.

The FAG generator bearing can generate an output of more than 100 Watts. This is more than sufficient for a reliable supply and activation of, for instance, electro-pneumatic brakes. To ensure that the electricity is kept flowing even in stationary wagons, it is stored in a heavy-duty battery that can supply it to the vehicle over a long period of time. FAG generator bearings are the ideal choice especially where large distances have to be covered on non-electrified sections, as e.g. in China.

"INA products for tilt, closing and rail gage adjustment"

Klaus Becker, Head of INA Railway Technology, presented the latest yoke type track roller units for electromechanical tilting systems that are currently being mounted in series into Swiss Rail’s ICN for the first time. INA also offers the appropriate solution for hydraulic tilting systems, in the form of corrosion-resistant cylindrical roller bearings with “Corrotect” coating. Brand new components used for rail gage adjustment are currently being put into operation on test trains of Deutsche Bahn AG and Polish Railways. According to Becker, INA rolling bearing systems ensure the precise and smooth closing of doors and windows.