With the rapid development of CNC technology, "complex, high-speed, intelligent, sophisticated, environmental-protection" has become the major trend for nowadays development of machine tool industrial technology. Among them, high-speed processing can improve the efficiency of machine tools, also shorten the processing cycle, which requires machine tool spindle and associated components to meet the requirements of high-speed processing. Similarly, precision bearings equiped on high precision & high speed CNC processing center spindle and feed parts must meet machine tools’ requirements of high-precision, high speed, low noise, trouble-free, high-reliability, etc. Assembly quality for precision bearings directly affect the work status and service life, many failures in CNC processing center are caused by improper assembly, so the assembly technology for precision bearings should be given adequate attention. Followings are the assembly points for high-speed precision bearings.
　　Firstly, removing and cleaning of precision bearings
　　1. Keep hands clean and dry
　　Operators’hands should keep clean and dry when removing precsion bearings from the package, because sweat on the hands can cause rust, if necessary, operators should wear gloves.
　　2. Ensure good lubrication
　　Precison bearings removed should be immediately loaded grease and coated with oil, while precison bearings with grease should make pullution-free installation after removed rather than treating with grease and oil. Grease must be added between the gap of cage and bearings’ outer ring, for examle, grease for precision bearings should be added to 30% of the cavity, while 20% for high speed precision bearings.
　　3. To seal the package
　　Precision bearings can only be cleaned from the original packaging before assembly. After taking out several sets of bearings from the multiple precision bearings package which sealed with volatile corrosion inhibitors, it should be sealed immediately, because the protective gas of VIC paper can only be maintained in the sealed packaging.
　　4. Correct cleaning
　　Precision bearings with grease cannot be cleaned before assembly, while precision bearings without grease must be cleaned before assembly, then immediately coat anti-rust oil or grease after cleaned and dried to prevent corrosion. Degreasing and cleaning for precision bearings could adopt the following detergent: aqueous detergent - neutral, acidic or alkaline detergent, examining the compatibility of alkaline detergent with aluminum parts before cleaning; organic detergent - acid and anhydrous kerosene, benzine (non-automotive gasoline), Freon 12 substitutes or chlorinated hydrocarbons detergent. Pay attention to the following note when clean precision bearings: environmental protection, health and work safety; methods of operation for detergent must comply with product descriptions so as to avoid danger.
　　Secondly, mounting and installation tools for precision bearingsbr /> 　　As the basic component parts for machine tools, performances of spindle & screw bearings can directly affect machine tools speed, rotary accuracy, rigidity, anti-vibration cutting performance, noise, temperature rise, thermal deformation, etc, thereby to affect the accuracy and surface quality for machining parts.
　　1. Mounting notes for precision bearings
　　Precision bearings assembly site should be kept clean as possible to avoid pullution or foreign matters to enter, contamination has great adverse effect on bearings’ operation and service life; checking the geometric accuracy, dimensional accuracy and cleanliness of the bearing housing bore and the matching surface of shaft; coating with a small amount of oil or grease at the matching surface of the ring when installation, precision bearings are easier to install in the design position; there should has a 100 to 150 installation guide chamfer when designing the bearing housing bore and shaft; do not cooling bearings excessively because condensation can lead to corrosion for bearing and the matching surface; assembly for bearings’ inner ring and the spindle should adopt directional fitting method or point matching method, i.e., to artificially control the direction of radial runout error for each assembly, so that to offset errors instead of cumulation; bearings should flexibly rotate when pressing into the shaft without sense of block; checking whether precision bearings could properly work after the installation had completed.
　　2. Rational use of installation tools
　　(1) When the interference is too large, it can use heating box, oil bath heating or sensor heating bearings to install, the heating temperature range is 80 ℃ ~ 100 ℃ with the maximum can not exceed 120 ℃. Meanwhile, one should fasten the bearing by nut or other appropriate means to prevent contraction in the wide direction after bearing cooling, thus to produce clearance between ring and shaft shoulder.
　　(2) When install bearings, pressing the ring on the circle of the ring end with equal force, do not directly hit the bearing end with Lang or other tools in order to avoid injury. In the case of small amount of interference, it can suppress bearing ring’s end by sleeve under normal temperature, slightly hit the centre of assembly sleeve with Lang, then evenly press the ring through the sleeve. Assembly force can not pass through the rolling, to avoid directly hammering bearing rings. When pressed, it should ensure that there is no gap between outer ring end & shell shoulder and inner ring end & bearing shoulder.