A: The following points should be noted: (1) coordinate boring work environment should be a constant temperature, temperature controlled within 20 ± 1 ℃. (2) Before machining a workpiece to be machined, should be pre-placed in the heated indoor, no less than 8h, to ensure that no temperature difference between the workpiece and the machine. (3) machine work should be preceded by the air operation, to be at or near thermal equilibrium after processing. Without cutting the intermittent time, still let the machine run empty in order to maintain the heat balance of the machine. (4) should be roughing, semi-finishing, finishing operations strictly separated, the time interval between each process should be not less than 8h. (5) to strictly control the amount of cutting, the cutting depth of not more than 0.5 ~ 1mm, the feed rate of not more than 0.05 ~ 0.07mm / r. Around (6) does not allow the crowd of onlookers machine, machine lighting arrangement should be reasonable, so as not to affect the ambient temperature of the machine.