Lubrication and Reliability Handbook 2010 Part 1 pptx

[...]... finish and shape R E Reason DSc, ARCS, FRS Shape tolerances of components J J Crabtree BSc(Tech)Hons S.I units and conversion factors M J Neale OBE, BSc(Eng), DIC, FCGI, WhSch, FEng, FIMechE Selection of lubricant type Table 1. 1 Importance of lubricant properties in relation to bearing type Figure 1. 1 Speed/load limitations for different types of lubricant A1 .1 A1 A1 Selection of lubricant type Figure 1. 2... characteristics of various oils A1 The effective viscosity of a lubricant in a bearing may be different from the quoted viscosity measured by a standard test method, and the difference depends on the shear rate in the bearing Figure 1. 6 Variation of viscosity with shear rate A1.3 A2 Mineral oils CLASSIFICATION Traditional use Mineral oils are basically hydrocarbons, but all contain thousands of different types... (e.g below about 0. 01 Ns/m2 at 60°C,) suitable for the lubrication of high-speed bearings such as textile spindles Medium viscosity oils (e.g 0. 01 0.02 Ns/m2 ) at 60°C, suitable for machinery running at moderate speeds Higher viscosity oils (e.g 0.02–0 .10 Ns/m2 ) at 60°C, suitable for slowmoving machinery Suitable for the lubrication of steam engine cylinder; viscosities from 0 .12 to 0.3 Ns/m2 at 60°C... 0 and 10 0 only, the higher figures representing lower degrees of viscosity change with temperature, but nowadays oils may be obtained with KVIs outside these limits They are generally grouped into high, medium and low, as in Table 2 .1 Table 2 .1 Classification by viscosity index The various hydrocarbon types are classified as follows: (a) Chemically saturated (i.e no double valence bonds) straight and. .. solvent extracted and dewaxed distillate It should be noted, however, that in Table 2.5 viscosity index has been determined from dynamic viscosities by the method of Roelands, Blok and Vlugter ,1 since this is a more fundamental system and allows truer comparison between mineral oils Except for low viscosity oils, when DVIs are higher than KVIs, there is little difference between KVI and DVI for mineral... a predominant influence on the VI of the oil In paraffinic oils the VI of the saturates may be 10 5 12 0 and 60–80 in naphthenic oils A2 .1 Mineral oils A2 Structural group analyses This is a useful way of accurately characterising mineral oils and of obtaining a general picture of their structure which is particularly relevant to physical properties, e.g increase of viscosity with pressure From certain... ‘natural inhibitors’ Top-up rate Oil type Table 2.6 Effects of oxidation and methods of test A2.5 Rate doubles for every 8 10 °C temperature rise Degree of agitation of the oil with air Particularly iron and copper in finely divided or soluble form Replenishment of inhibition (natural or added) Proportions and type of aromatics and especially on the compounds containing nitrogen, oxygen, sulphur Mineral... paraffinic groups (% CP ), and the total number (RT ) of naphthenic and aromatic rings (RN and RA ) joined together Table 2.3 presents examples on a number of typical oils Table 2.3 Typical structural group analyses (courtesy: Institution of Mechanical Engineers) REFINING used as such on some plain bearings subject to high temperatures and as blending components in oils and greases to form very viscous... engine oils, cutting oils, gear oils, hydraulic oils, turbine oils, and so on, with superior properties to plain oils, as discussed below The tolerance in blend viscosity for commercial branded oils is typically ±4% but official standards usually have wider limits, e.g 10 % for ISO 3448 PHYSICAL PROPERTIES Viscosity-temperature Figure 2 .1 (courtesy: Institution of Mechanical Engineers) Figure 2.4 illustrates... service by: oxidation, thermal decomposition, and contamination Temperature Oxygen access Catalysis Oxidation Mineral oils are very stable relative to fatty oils and pure hydrocarbons This stability is ascribed to the combination of saturated and unsaturated hydrocarbons and to certain of the hydrocarbon derivatives, i.e compounds containing oxygen, nitrogen and sulphur atoms – the socalled ‘natural inhibitors’ . 7506 515 4 7 1. Lubrication and lubricants – Handbooks, manuals, etc. 2. Reliability (Engineering) – Handbooks, manual, etc. I Neale, M. J. (Michael John) TJ1075.L 812 2000 6 21. 8'9–dc 21 00–049378 British.