Geometric Criterion of Minimum Zoneof Cylindricity Error

Theory of minimization of extreme difference is used to reveal the geometric feature of minimum zone of cylindricity error.Based on the algebraic criterion, the geometric criterion for the minimum zone of cylindricity error under the condition of non-degeneration has been found out.The congruence of the two kinds of criteria has been proved experimentally. An exchange algorithm by way of the geometric criterion can be used to evaluate the cylindricity error.