Rolling-element bearings: A review of the state of the art

Some of the research conducted which has brought rolling-element technology to its present state is discussed. Areas touched upon are material effects, processing variables, operating variables, design optimization, lubricant effects and lubrication methods. Finally, problem areas are discussed in relation to the present state-of-the-art and anticipated requirements

Wear of Bainite-transformed AISI 1045 Steel in Comparison with Nitriding and Boriding Treatments

The purpose of this work is to develop a bainitic heat treatment procedure for wear reduction in a medium carbon steel and compare the efficiency of this heat treatment with gas nitriding or electrochemical boriding surface treatments. Heat treatments were conducted on AISI 1045 steel blocks taken from an automotive component, namely an overrunning alternator decoupler (OAD) pulley bore using an induction heater. The samples were quenched in different quenching media of oil, melt salt and water. The hardness and microstructural transformation results were represented with cooling curves superimposed on the Continuous Cooling Transformation (CCT) diagram of the 1045 steel. The heat treated results indicate 820 °C induction heating for 2 minutes followed by 160 °C oil quenching for 15 seconds resulted in the lower bainitic and martensitic structures and the highest bainite percentage (~19.5 %). The sliding wear test was conducted with block-on-ring tribometer under dry, lubricated and humidity conditions. Volumetric wear loss was measured and calculated at different sliding distances. The relationship between the volumetric loss and working conditions showed that induction hardened steel followed by 160 °C oil quenching resulted in the lowest wear rate in both dry and lubricated condition due to the higher hardness and toughness of bainitic and martensitic structures compared to the untreated, nitrided and borided 1045 steel. In addition, it was found that the gas nitriding process produced the lowest surface roughness (0.35 - 0.37 μm) and the electrochemical boriding process produced the highest surface microhardness (1100 - 1300HV). The boric acid film was formed on the surface of borided steel after the SAP process (annealing at 750 °C followed by cooling in 40 % RH environment). It can be considered as a self-lubricated film to make the surface withstand sliding wear damage

Analysis Of Vibration Signals And Surface Characteristics Of Cylindrical Roller Bearing

This work aims to establish the relation between the vibration level and the surface roughness of the bearing running under lightly oiled, greased and dry conditions. Kajian ini dijalankan untuk mengesahkan kaitan antara paras getaran dan kekasaran permukaan galas yang dijalankan pada keadaan minyak yang nipis, pelinciran gris dan kering

Bearing fatigue investigation 3

The operating characteristics of large diameter rolling-element bearings in the ultra high speed regimes expected in advanced turbine engines for high performance aircraft were investigated. A high temperature lubricant, DuPont Krytox 143 AC, was evaluated at bearing speeds to 3 million DN. Compared to the results of earlier, similar tests using a MIL-L-23699 (Type II) lubricant, bearings lubricated with the high density Krytox fluid showed significantly higher power requirements. Additionally, short bearing lives were observed when this fluid was used with AISI M50 bearings in an air atmosphere. The primary mode of failure was corrosion initiated surface distress (fatigue) on the raceways. The potential of a case-carburized bearing to sustain a combination of high-tangential and hertzian stresses without experiencing race fracture was also investigated. Limited full scale bearing tests of a 120 mm bore ball bearing at a speed of 25,000 rpm (3 million DN) indicated that a carburized material could sustain spalling fatigue without subsequent propagation to fracture. Planned life tests of the carburized material had to be aborted, however, because of apparent processing-induced material defects

A bibliography /with abstracts/ on gas-lubricated bearings Interim report

Gas lubricated bearings - annotated bibliograph

Morphology of surface damage resulting from static and dynamic contacts

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Contact fatigue damages resulting either from static or dynamic contact are of interest for understanding the failure modes and mechanisms leading to improvement of the components’ performances in tribological applications. The objective of this research was to ascertain how and to what extent the counterface materials, loading conditions, contact configuration, lubrication, and the environment affect the failure behaviours of material under static and dynamic contact fatigue loading. An experimental ball-on-flat test configuration was employed for both static and dynamic contact fatigue testing. In house designed test rig was used to study static cyclic loading contact fatigue behaviours of brittle polymethylmethacrylate (PMMA) in contact with balls made of different materials, i.e. Si3N4, steel, aluminium, bronze and PMMA in dry and oil-lubricated conditions. A modified four ball test machine was used to study dynamic rolling contact fatigue behaviours of thermally sprayed molybdenum and titanium coatings in contact with steel balls in dry and seawater conditions. The static contact fatigue and the dynamic contact fatigue test results revealed that counterface material, loading magnitude, lubricant and the environment play a vital role in controlling failure modes and the extent of damage. In static contact fatigue, adhesive strength of the interface was the key factor controlling damage of the PMMA plate in both dry and oil-lubricated conditions. In dry conditions, three failure modes, i.e. adhesive wear, ring cracks, and radial cracks controlled the damage of PMMA to a different degree for each combination of materials. Whereas, the damage of each combination in oil-lubricated conditions was affected by the extent of three failure modes, i.e. adhesive wear, radial cracks and abrasive wear. In dynamic contact fatigue tests, adhesive wear and inter-lamellar cracking were the major failure modes controlling damage of molybdenum coating and titanium coating in dry contact conditions while abrasive wear, corrosion and lubrication controlled damage processes in seawater conditions

Electrical Bearing Damage, A Problem in the Nano- and Macro-Range

Rolling bearings face different damaging effects: Besides mechanical effects, current-induced bearing damage occurs in electrical drive systems. Therefore, it is of increasing interest to understand the differences leading to known electrical damage patterns. It is of utmost importance not to consider the harmful current passage in the machine element as an isolated phenomenon but to take into account the whole drive system consisting of the machine elements, the electric motor and the connected power electronics. This publication works toward providing an overview of the state-of-the-art of research regarding electrical bearing currents

Aluminium recycling activity on construction site: Malaysia case study

Aluminium is largely used in transportation industry to make vehicles, but not all country has their own transportation industry. But nearly all country has their construction industry. With the rise of aluminium usage in the effort to save the environment, it is wise to identify the recycling activity on a construction site. This paper is about the identification of aluminium recycling activity on a construction site. Construction site is second to transportation in term of aluminium usage. A case study is conducted to identify the aluminium recycling activity on the construction site.This study is explorative in nature as different country has different conduct of recycling on site. Fromconducted case study, one main recycling activity is in the light which is collecting. Even though it is only one activity, it appears in many stages of the aluminium recycling activity. By having this knowledge, it might help the responsible party to set up standardised recycling procedure on the construction site while at the same time encourage the recycling activity

Government review of the Mod-2 wind turbine (as-built)

The findings and recommendations of the Government committee formed to conduct an as-built review of the three Mod-2 wind turbine units at Goldendale, Washington are given. The purpose of the review was to identify any critical deficiencies in machine components that could result in failure, and to recommend any necessary corrective action before resuming safe machine operation. The review concluded that one of the deficiencies identified would preclude planned attended or unattended operation, provided that certain corrective actions were implemented