Mechanics of Saw-Tooth Chip Formation in Metal Cutting

Abstract

The saw-tooth chip was the last of the major types to be identified. This occurred in 1954 during machining studies of titanium alloys which were then being considered for aerospace applications because of their large strength-to-weight ratio and corrosion resistance. This is a type of chip that forms when very hard brittle materials are machined at high speeds and feeds. Since this is an area of machining which will be of increasing interest in the future, particularly in hard turning, it is important that the mechanism and mechanics of this type of chip formation be better understood. At present, there are two theories concerning the basic origin of saw-tooth chips. The first to appear assumed they are of thermal origin while the second assumes they arise due to the periodic development of cracks in the original surface of the work. The thesis presented here is that the root cause for saw-tooth chip formations is cyclic cracking. This is followed by a discussion of extensive experimental data that supports this point of view.

A new material model for 2D numerical simulation of serrated chip formation when machining titanium alloy Ti–6Al–4V

“…Vyas and Shaw [4] and Hua and Shivpuri [5] explain the titanium alloy chip segmentation by a crack initiation followed by propagation inside the primary shear zone.…”

Cutting force and chip formation in end milling operation when machining nickelbased superalloy, Hastelloy C-2000

“…A compressive stress ahead of the cutting edge was the reason for the formation of the cracks at the free surface, creating the brittleness of the workpiece). The cracks produced during the formation of chips cannot be entirely repaired by plastic deformation [36][37][38]. Therefore, their tips can be perceived at high magnification.…”

A Study on Ultrasonic Elliptical Vibration Cutting of Inconel 718

“…The theoretical surface roughness formed by the feed marks was introduced by Vyas and Shaw in 1999 [9]. It can be expressed as…”

“…Through constant development in the last decade, this technique has been proven to be a promising method in terms of almost all cutting performances in cutting of various difficult-tocut materials [6][7][8][9]. Compared with the conventional cutting (CC) and ultrasonic vibration cutting, the UEVC have many advantages such as less cutting forces, longer tool life, and better surface finish [10,11].…”