ntn bearphite oil-impregnated sintered bearings 1 features of ntn bearphite and hydrodynamic bearphite bearings 1-1 features of ntn bearphte 1 ntn bearphite bearings incorporate a unique material comprising a metal combined with a fine powder of quality natural graphite this composition contributes to excellent bearing performance across a wide variety of applications 2 ntn bearphite oil-impregnated bearings are manufactured from sintered metal which has a porous metal structure as a result these bearings retain lubricant efficiently helping to keep the bearing continuously lubricated 3 thanks to their stable lubrication function ntn bearphite bearings provide a longer life and excellent performance across a wide temperature range 1-2 features of hydrodynamic bearphte bearings 1 the herringbone-shaped hydrodynamic grooves located on the bearing bore greatly improve bearing rigidity and promote the formation of an oil film 2 the hydrodynamic bearing design incorporating sintered metal h
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ntn bearphite oil-impregnated sintered bearings 2 product types and applications table 1 types and typical applications of ntn bearphite 4
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ntn bearphite oil-impregnated sintered bearings 4 material characteristics and applications for ntn bearphite 4-1 material characteristics and applications for sintered oil-impregnated bearings table 3-1 ntn bearphite material characteristics and applications residual amount residual amount 6
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ntn bearphite oil-impregnated sintered bearings 4-2 applications and characteristics of materials used for sintered mechanical components table 3-2 characteristics of materials used for sintered mechanical components and typical applications 8
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ntn bearphite oil-impregnated sintered bearings 5 bearing selection 5-1 allowable load and speed the performance of ntn bearphite bearings is limited by the allowable pv value which is the product of bearing load p mpa and sliding velocity v m/min table 4 summarizes the generally recommended allowable pv values table 4 allowable pv values 5-2 bearing life the life of oil-impregnated bearings can vary depending on the rate of consumption of the lubricating oil in the bearings once 40 of the impregnated oil has been consumed bearing wear begins to accelerate and bearing performance deteriorates accordingly for this reason once the residual lubricating oil drops to 60 the bearing in question is regarded as having reached the end of its service life lubrication is adversely affected by high temperatures the maximum allowable temperature for lubricating oil is usually 80°c fig 3 summarizes the effect of typical bearing temperatures on bearing life fig 2 interrelation between bearing load a
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ntn bearphite oil-impregnated sintered bearings 5-5 recommended shaft specifications 5-5-1 shaft composition the shaft is typically made from carbon steel an alloy steel or stainless steel for special applications 5-5-2 shaft hardness the minimum allowable shaft hardness is hv300 improved performance can be obtained with higher shaft hardness 5-5-3 shaft surface roughness the recommended shaft surface roughness is 0.4ra for stricter sound requirements a finish of 0.2ra is suggested 12
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6 recommended housing fits and mounted clearance sleeve-type and flange-type bearings are usually mounted in a housing with an interference fit in order to ensure optimal mounted clearance the reduction in the bearing bore diameter due to the interference fit must be considered 6-1 recommended housing fits when pressing the bearing into the housing the smallest amount of interference is preferred to avoid damage to the bearing however sufficient interference must be kept between the housing and the bearing so they remain fixed to each other fig 5 graphically illustrates the appropriate interference ¡situations requiring increased interference 1 higher bearing load 2 smaller bearing length 3 higher expansion coefficient of the housing material ¡situations requiring reduced interference 1 larger bearing length 2 higher bearing wall thickness generally the reduction in the bearing bore diameter increases with a larger bearing outside diameter a thinner bearing wall thickness a greater int
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7 care handling of bearings 7-1 bearing handling precautions when mounting a bearing be aware of the following 1 handle the bearing only in a clean dust-free location 2 avoid using any tools that generates debris 3 make sure that the fitting surfaces of the shaft and housing are free of dents burrs and dust 4 never use a hammer to install a bearing 7-2 bearing maintenance when performing bearing maintenance be sure to remember the following 1 relubrication is recommended to ensure smooth continuous operation relubrication intervals vary depending on operating conditions as a guideline relubrication should be performed every 500 to 1,000 operating hours 2 to impregnate a bearing with oil immerse the bearing in an oil bath heated to approximately 60°c and heat the bearing uniformly for 1 to 2 hours when bubbles are no longer released allow the bath to cool down with the bearing in it or immerse the bearing in cool oil 7-3 storage when storing a bearing observe the following 1 avoid stor
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8-3 dimensional accuracy of hydrodynamic bearphite bearings 8-4 materials used in hydrodynamic bearphite bearings 8-5 lubricating oil used for hydrodynamic bearphite bearings 17
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9 applications 19
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