Firstly it should be clear that, the straightness of some axis refers to two planes. For example, the straightness of X axis refers to the straightness in X, Y plane and X, Z plane.

The carrier of machine tool bears the weight of guide rail, therefore the straightness of movement decides on the straightness of guide rail. There are two reasons for losing the straightness, one is the straightness of guide rail’s condition; the other is the straightness of guide rail’s installation datum plane. The guide rail, carrier and machine tool with high accuracy and steady condition when combined together is the basic condition to guarantee the straightness. The goal of high-low temperature and aging treatment of guide rail, carrier and machine tool also lies in this.

It’s obvious that the non-conformability of roller (steel ball) will cause few stress point and teeterboard phenomenon.

Must note that, because the nonstandard movement of lead screw can affect the guide rail, for example, the axial direction of lead screw is not parallel with guide rail, the center height of lead screw is inconsistent with nut, a torsion force is between the lead screw and nut as well as the lead screw is curving and so on, could disturb and destroy the rectilinear movement of guide rail while the lead screw is moving.

No matter "V" shape or "一" shape, both the guide rail and roller conveyer should not contaminate any contamination or impurity, which not only affects the guide rail’s moving straightness, moreover it causes the guide rail’s damage and distortion. The guide rail requests spotless, this is one of the rules for maintaining the machine tool and keeping long-time precision.