Influence of hydraulic pressure on pipe ovality in the CNC machine threading process

Abstract

Abstract— Threading using CNC machining is widely used in the manufacturing industry to produce pipe threads. The hydraulic pressure applied during the threading process plays a crucial role in determining thread quality. Inappropriate hydraulic pressure can cause pipe crosssectional deformation, known as pipe ovality, which reduces dimensional accuracy and product quality. This study aims to analyze the effect of hydraulic pressure on pipe ovality in the CNC threading process. The experimental method was carried out by measuring pipe ovality at various hydraulic pressure levels, and the data were analyzed using one-way ANOVA with hypothesis verification. The results show a clear relationship between hydraulic pressure and pipe ovality. At low pressure levels (400–700 psi), the ovality remains within acceptable tolerances. At medium pressure levels (850–1150 psi), the ovality approaches or exceeds the tolerance limit of 0.004 inches. At high pressure levels (≥1300 psi), excessive clamping force causes significant pipe deformation, so that the ovality value exceeds the allowable limit and causes rejection criteria.