Angular contact ball bearings rolling the ball , because it is a point contact (as distinguished line contact roller bearings ) , they are able to provide higher speed , smaller heat and higher rotational accuracy. In some super- high-speed spindle applications, but also the use of ceramic balls ( usually Si3N4 or Al2O3) hybrid bearings. Compared with the traditional full hardenability steel balls, ceramic balls gives the material itself features ceramic ball bearings with high rigidity , high speed , high temperature, long life , to meet customer demand for high-end products bearing the machine .

 

    Angular contact ball bearings contact angle of the more popular is the contact angle of 15 and 25 ; contact angle is usually 15 has a relatively high speed performance, and has a contact angle of 25 high axial load carrying capacity. Due to the impact of the choice of preloaded precision angular contact ball bearing applications is very large, such as in high-load , high rigidity of the occasion , the general will choose medium or heavy bearing preload ; while for some high- speed , high-precision applications, in the early selection of the bearing , the need to pay attention to choose the right preload. Preload is generally divided into light, medium and heavy are three general light preload more common. In order to facilitate the use of customers , the current major bearing manufacturer in the world are generally available and add pre-ground bearing end face of the bearing preload , which is commonly referred to as universal matching precision angular contact ball bearings form . This kind of bearing preload adjustment eliminates the customer , thus saving installation time.

 

    In some overloaded and there are certain requirements on the speed of the machine tool applications, such as the shortage of forging mill, oil pipeline threading machines, lathes and milling machines and other heavy-duty , choose precision tapered roller bearings are an ideal solution. Since the roller tapered roller bearings are designed line contact , so it can provide high rigidity and load bearing spindle ; addition, tapered roller bearing is a pure rolling bearing design , it is a good way to reduce bearing operation torque and heat, and to ensure the accuracy of the spindle speed . As the tapered roller bearings can adjust the axial preload during installation ( clearance ) , which allows customers bearing the entire life cycle to better optimize the bearing clearance adjustment.

 

    Furthermore, in some inner block edges faster than 30m / s high-speed applications, tapered roller bearings are also some special design to meet the requirements, such as Hydra-Rib TSMA hydrodynamic bearings or bearing a floating wall bearing wall TSMA a plurality of oil holes in the axial direction , can be circulating oil lubrication or oil mist lubrication , the oil can be distributed to the centrifugal roller in contact with the wall region , which can more adequately lubricated bearings, bearing speed increase . The Hydra-Rib hydraulic floating wall is designed to optimize the bearing preload spindle system designed to float bearing wall , in contact with the roller large end , unlike the common bearing a fixed inner wall ; and the floating ribs by a "pressure" system location , so that we can ensure the bearing under various operating conditions can play a most excellent performance , and has been successfully used in the domestic customers.

 

    For precision tapered roller bearings in terms of choice , ISO P5 grade bearings are used in conventional lathes and milling machines ; If machining centers , grinders and other applications , usually choose ISO P4 or higher precision bearings . Spindle design, more common tapered roller bearings have two layouts . The first is the use of a front-end and back-end of each tapered roller bearings , and the use of face- installation, compact design of such structures , high rigidity and ease of installation and adjustment.

 

    The second is the use of two tapered roller bearings mounted facing the front end of the main shaft , and the rear end of the outer ring using one pair of two single- bearing inner ring (TDO) is used as a floating end ; because a floating capacity , the design can be such well withstand the axial thermal expansion of the spindle , and high stiffness, to ensure the accuracy of the machine.

 

    In the machine tool spindle applications, precision double row cylindrical roller bearings are also being used to normally contact ball bearings or thrust bearings and precision angle composite applications . Such bearings can withstand higher radial loads and allows a higher speed. Bearing in two rows of rollers arranged in a cross pattern , rotation fluctuation frequency significantly higher than single row bearings , the amplitude reduced by 60 % to 70 %. Such bearings are usually two forms : NN30, NN30K two series with a wall bearing inner and outer rings separable ; NNU49, NNU49K two series bearing outer ring with ribs , separable inner ring , which NN30K and NNU49K Series inner ring tapered bore ( taper 1:12 ) , and with the spindle taper journal , axial movement of the inner ring , the inner ring can swell, so the bearing clearance can be reduced even preload bearing ( negative clearance state ) . Cylindrical bore bearings are usually installed using heat , reduce the use of interference fit bearing clearance or preload the bearings. NNU49 series on inner separable bearings , usually in the inner ring mounted on the spindle before finishing on the raceway to improve spindle rotation accuracy.