(4) parallel error between the guideways and the spindleIf the error is in the horizontal plane, the cylindrical surface will havetaper error;If it is in the vertical plane,the cylindrical surface willbecome a hyperbola shape(shown as figure). Because it is in the non-sensitivedirection,itcanbeignored
（4）parallel error between the guideways and the spindle If the error is in the horizontal plane, the cylindrical surface will have taper error；If it is in the vertical plane, the cylindrical surface will become a hyperbola shape(shown as figure). Because it is in the nonsensitive direction,it can be ignored
3.2.2.3 transmission errorWhenmachiningsomesurfacessuchashelicalsurface,gear,wormwheel,the constant motional relationshipbetweenthecuttingtool andtheworkpiece is ensured by the transmission system of themachine tool.Transmissionerrorreferstotherelativemotional erroroftheelementsatthetwoendsofthetransmissionchain
3.2.2.3 transmission error When machining some surfaces such as helical surface, gear, worm wheel, the constant motional relationship between the cutting tool and the workpiece is ensured by the transmission system of the machine tool. Transmission error refers to the relative motional error of the elements at the two ends of the transmission chain
3.2.3 deformation of the machining systemthe machining system will deform under the cutting force, clampingforce,transmission force, weight and inertial force,which will damagethecorrect positionbetweenthe cuttingtool and the workpiece and causemachiningerror.ThisphenomenacanbeexplainedbyFig.3.12(a),(b09c)
3.2.3 deformation of the machining system the machining system will deform under the cutting force, clamping force,transmission force, weight and inertial force，which will damage the correct position between the cutting tool and the workpiece and cause machining error. This phenomena can be explained by Fig.3.12(a),(b09c)
Fig 3.12 error caused by deformation of the machining system(a)slimshaftdeformationmovie(b)short andbigdiameterworkpiecedeformationmovie
Fig 3.12 error caused by deformation of the machining system （a）slim shaft deformation movie （b）short and big diameter workpiece deformation movie
Thestiffnessofthemachiningsystemreferstothetheratiobetween the resultantnormal cuttingforces F.on the machiningsurface and the deformation value Yystem in the normal direction :FyKsystemYsystemKwherethestiffnessoftheprocesssystemN/mm;systemFynormal cutting force N;Y-normaldeformationmm。system
system Y system Y F K = where ——the stiffness of the process system N／mm； ——normal cutting force N； ——normal deformation mm。 Ksystem FY Ysystem The stiffness of the machining system refers to the the ratio between the resultant normal cutting forces on the machining surface and the deformation value Y system in the normal direction ： Fy