Abstract
This paper presents an analytical model of the 3-D curled chip that is commonly produced in oblique machining. The chip model is based on a 3-D spiral with continuously varying center and curl radius. Stresses in the chip are analyzed by an energy-based approach. Bending and torsional shear stresses in the chip are generated based on input reaction forces. A case study with typical input values of reaction forces is analyzed for finding the magnitude and location of the maximum stresses. Also, the octahedral shear stress is proposed as a comprehensive 3-D chip failure criterion, because it combines the individual effects of the bending and shear stresses.