7.2.2 Error of the machine tool
Errorofthemachinetoolreferstothemanufactureerror,setuperrorandwearcome
fromthemachinetoolwithoutcuttingforce.
7.2.2.1spindlerotationalerror（1）conceptofspindlerotationalerror
Theoretically,the position of the rotational axis of the spindle in the space is fixed, or in another word, the instant speed is zero.But in
practice,there are a lot of factors influence the position of the spindle and make the spindle position change instantly. We call the maximum floating value in the sensitive direction of the error the rotational error of the spindle.
There are three types of spindle rotational error, shown below：movieFig.1 the three types of the spindle error of the machine tool(a) Pure radial jump (b) pure axial jump (c) pure angular move
Pure radial jump ：The practical axis is parallel to the desired axis, but jump in constant amplitude
Pureaxialjump：Thepracticalaxismovesalongthedesiredaxiswith
constantamplitude.
Pureangularmove：Thepracticalaxismovesinclinedtothedesiredaxiswitha
constantamplitude,andthejointpointkeepsconstant.
（2）influence of the spindle error on machining accuracy
Differentrotationalerrorofthespindlehasdifferentinfluenceonthemachiningaccuracy,eventhesamerotationalerrorhasdifferentinfluencewhenthemachiningmethodisdifferent,shownasFig.6.5、6.6、6.7、6.8andtable6.1.
(a) Turning influenced by radial jump(b) Boring influenced by radial jump
moviemovieEnd surface influenced by Angular move
Boring influenced by Angular movement error
movieTable 1 influence of the spindle error on the surfaces under different machining method
