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The process of finding the ultimate grease is described in this report using an example from railway applications. This example includes steps such as a requirement list, field tests, laboratory tests and an evaluation method. The example deals with the problems discovered in a field test performed to determine the best grease for tapered roller bearings in railway wagon wheels and to increase the knowledge of grease lubrication. Seven different fully formulated commercial greases were examined in the wheel bearings of one ore wagon, used for transporting ore commercially by railway from the Kiruna Mine in northern Sweden to Narvik in northern Norway for shipping to foreign markets. The steps performed in this study are recommended in all problems associated with finding the optimal grease for different types of applications.

PREVIOUS articles in this series have dealt with the duties and properties of the lubricant with regard to both grease and oil lubrication. We shall now consider methods of applying the lubricant. Commencing with application of grease, it will be seen that various points of bearing housing design will be mentioned as they affect lubrication.

The purpose of this paper is to formulate heavy-duty lithium complex grease using low molecular weight poly tetra fluoro ethylene (PTFE) micro-particles as extreme pressure (EP) additive manufactured by E-beam scissoring and ultra-high speed grinding process of pre-sintered PTFE scrap.

Lithium complex grease is formulated with PTFE micro-particles, and optimum treat rate was studied by standard bench tests by ASTM D 2266 and IP-239 for tribological properties and compared with commercially available Molybdenum Di sulphide (Moly)-based lithium complex grease. The performance of the grease was further evaluated by a cyclic load test at varying speeds and loads to simulate the operational field conditions.

The lithium complex PTFE grease was manufactured using PTFE micro-particles as EP additive. The PTFE micro-particles dispersed in the lithium complex grease significantly improve the anti-wear performance and load bearing properties. Further, when the product was tested under a cyclic load conditions on standard tribological bench test against commercially available Moly lithium complex grease, shows stable anti-wear properties and reduced coefficient of friction.

The low molecular weight PTFE micro-particles, manufactured in the in-house electron beam (E-beam) and ultra-high speed micronizer facility from a pre-sintered PTFE scrap has been used as EP additive for grease applications for the first time. The results on the cyclic load tests indicate significant performance improvement in retaining the anti-wear and friction properties. Thus, value addition is done in formulating superior performance grease and evaluating under cyclic load conditions similar to field operating conditions and also in creating value added additives by converting the pre-sintered PTFE scarp which is environmental hazard due to poor biodegradability, creating a cyclic economy and a sustainable concept.

SELECTING the correct bearing for any particular application involves more than the determination of the correct type and size. It is true that the calculation of the nominal working life will give an indication of the operational life before failure, but this calculation only takes into account the fatigue life of the material. If this theoretical life is to be obtained—and perhaps exceeded—then additional factors must be taken into account when initially designing the bearing arrangement. Lubrication and protection from the operating environment are two very important considerations.

The purpose of this study is to reduce the use of Zinc dialkyl dithiophosphates (ZDDP) and improve the frictional properties and thermal oxidation stability of Perfluoropolyether (PFPE) grease by adding antioxidant additives. The addition of antioxidants can reduce the consumption of ZDDP as an antioxidant, thus improving the anti-wear efficiency of ZDDP and reducing the excess phosphorus element in the grease.

In this study, an antioxidant with good comprehensive performance was selected from several antioxidants by tribological tests and high-temperature tests. Then, the effect of its combination additive with ZDDP on PFPE grease was investigated. The anti-wear property, anti-friction property, thermal oxidation stability and extreme pressure property of greases containing different proportions of ZDDP and antioxidant were tested by four-ball tester and synchronous thermal analyzer (STA). The effects of additives on properties of grease were analyzed by SEM, EDS, LSCM, XPS and FT-IR.

The research shows that 2,6-Di-tert-butyl-4-methylphenol (BHT) can be used as an antioxidant in combined additives to reduce the antioxidant reactions of ZDDP, thus improving the anti-wear efficiency of ZDDP and further enhancing the anti-wear performance of the grease. Moreover, BHT and ZDDP have a synergistic effect on the high temperature performance of the PFPE grease due to their different antioxidant mechanisms.

In this paper, the problems related to PFPE grease are studied, which has a certain guiding effect on the industrial application of fluorine grease and the related formulation design.

In this paper, the properties of PFPE grease under different lubricating condition were studied. The synergistic lubrication effect of antioxidant and ZDDP are discussed. It provides experimental and theoretical support for reducing the content of ZDDP and improving the performance of additives.

Describes the requirements for biodegradability, defines the different terms and lists the various tests used. Outlines how greases can cause pollution. Details the main primary biodegradability test for lubricants and how to formulate greases to optimize breakdown in the environment and still lubricate well. Gives examples of commercial biodegradable greases.

This paper aims to investigate and prepare the composite polyurea greases with excellent thermal stability and tribological properties.

In this paper, composite Ba-based (Ba, barium) tetra-polyurea lubricating greases were prepared with two different methods: mixing Ba-based gelatinizer and tetra-polyurea gelatinizer by a physical method; and introducing barium carboxylate into tetra-polyurea molecules by a chemical method. The properties of the products, such as heat stability, water resistance and friction performance, were analyzed with thermogravimetry, water-resistance test and four-ball friction test.

The results indicated that the products obtained by chemically introducing barium carboxylate into tetra-urea molecules showed better elevated temperature tribological properties, and the disadvantages of the polyurea greases with high temperature hardening were also obviously improved. The cone penetration rate at 180°C for 24 h is only 3 per cent. The friction coefficient can be decreased to 0.44 and the last non-seizure load value was increased from 560 N to 1,120 N without any other additives.

The research is significant because the prepared composite grease showed excellent performances, such as the outstanding thermal stability, water resistance and excellent extreme pressure and anti-wear properties, which may be widely applied in steel, metallurgy, bearings and other industrial fields.

The author gives a review of developments over the past decade in new compositions and application practices for ball and roller bearing grease.

Bismuth is relatively little known in general; however, it has been known since the fifteenth century in Germany and was called by Paracelsus “Bismutum”. With very similar properties to lead, it could be called the “twin brother of lead”, but bismuth is considered non‐toxic and used in cosmetics and pharmaceuticals. It is really a unique metal, considered as a metal within the periodic table of elements, but has more similarity to semimetals than to metals. Bismuth replaces the formerly and widely used lead in EP‐greases and EP‐lubricants giving better properties to them, even using down to half of the metal concentration. Bismuth has very high synergism to sulphur, the oldest known element. So, the combination of the oldest known element sulphur with the newest “green and ecologically clean” metal Bismuth – is actually the modern and metallic extreme pressure technology – that follows the formerly used, during many decades, sulphur‐lead‐technology – but being non‐toxic.