Design for Manufacturing of Variable Microgeometry Cutting Tools

Cutting edge microgeometry has gained special attention of late in the machining research community. Machine tool vibration, tool life, and workpiece surface integrity are all influenced by cutting edge size/shape. To optimize the machining process, variable microgeometry (VMG) cutting tools, in which the edge microgeometry varies along the edgeline with respect to specific variables (such as machining parameters or expected tool wear), are manufactured. Despite the advantages of VMG tools, a major hindrance in their development is the manufacturing complexity that demands high precision multi-axis edge preparation processes following extensive machine setup, fixturing, and programming. This paper details the proof of concept of a design criterion, which leads to the manufacturing of VMG cutting tools by only traditional edge preparation processes. The present method relies on the existing relationship between the edge radius subsequent to the edge preparation process and the tool wedge angle. The validity of the proposed method is first examined by a numerical simulation of the edge preparation. Carbide cutting tool inserts are then designed based on the proposed idea. Robust VMG generation subsequent to edge preparation by microblasting is demonstrated through microgeometric measurements. VMG chemical vapor deposition-coated carbide tools manufactured by the proposed approach are evaluated for turning hardened steel, and optimal designs are identified with respect to tool life and workpiece surface roughness. To address the design consideration, finite element (FE) modeling provides valuable insight into the machining process. FE modeled stress and temperature distribution clarify the experimental observations and reveal the design constraints.