Ultrasonically-assisted turning of metallic alloys: experimental analysis

Experimental analysis of Ultrasonically Assisted Turning (UAT) for metallic alloys with the aim of producing a set of empirical formulas to predict the value of cutting forces as well as chip compression ratios, is of great impact to any future research related to metal cutting field.

Such empirical formula could also predict the value of surface roughness and machining accuracy for produced parts under both conventional cutting (CT), and UAT domains. While UAT has been around for many years, no much improvement has been done to enhance UAT system for force reduction as well as system stability application. The reason behind this is the lack of information regarding the quantifying of underlaying mechanisms in UAT.

In recent years, with the advancement of better control systems as well as enhanced UAT systems, a new unique system was improved and constructed at Loughborough University (LU) for better understanding of UAT performance for hard alloys. Yet this system was not tested with conventional materials. Those materials represent engineering materials used day-to-day in almost all manufacturing plants. Stainless steel, cast iron, aluminium, brass, and bronze were chosen to represent various categories of ferrous and nonferrous metals.

Materials used in this study represent a variety of traditional engineering materials. They include both ferrous and nonferrous; stainless steel (SS), cast iron (CI), aluminium (Al), brass (Br) and bronze (Bro). The objective was to present the behaviour of UAT vs. CT with well-established materials to try to broaden the knowledge of UAT. As forces are reduced, the proposed mechanisms include an interconnected effect of several mechanisms - hardening and softening ones. Hardening mechanisms are a term used to describe the interaction of the tool and workpiece under UAT, which results in workpiece material being hardened. Softening mechanisms are a term used to describe the interaction of the tool and workpiece under UAT, which results in workpiece material being softened. So, by introducing well-established materials for the UAT study, models could be enhanced more easily to be able to quantify both the hardening and softening mechanisms.

In this thesis, titled “Ultrasonically Assisted Turning of Metallic Alloys: Experimental Analysis”, it introduces the development of model to predict cutting forces, chip compression ratio, surface roughness, and machining accuracy for produced surfaces using both UAT and CT. Experimental research has resulted in new contributions to knowledge in the following ways: (1) one-dimensional UAT is more advantageous when it comes to machining common engineering materials, (2) development of a model to predict process parameters under both UAT and CT, (3) Demonstrate the behaviour of force reduction and surface roughness improvement for a number of materials under UAT.

Up to the time of writing this thesis no such model exists, and the motivation to develop such model - to fill a knowledge gap in this area - is to better quantify the one-dimensional UAT improvements as a machining method.