Author ORCID Identifier

https://orcid.org/0000-0001-9229-3119

Year of Publication

2020

Degree Name

Master of Science in Mechanical Engineering (MSME)

Document Type

Master's Thesis

College

Engineering

Department

Mechanical Engineering

First Advisor

Dr. Julius M. Schoop

Abstract

Finish machining is an essential manufacturing process that is used to enhance the mechanical characteristics of critical components. The deformation that occurs at the tool and workpiece interface in finish machining significantly affects a host of component properties, commonly referred to as “surface integrity” properties. Surface roughness is a machining deformation-affected characteristic that is of high relevance in contemporary manufacturing. However, over recent decades it has been made clear that the material properties of the deformed surface layers are relevant to component performance as well. Predicting the overall surface quality of a machined component is of great relevance to the manufacturing industry.

Current state-of-the-art predictive models in the area of machining-induced surface integrity are typically founded in two-dimensional F.E.M. analysis. These investigations frequently show the advantages of tool geometry manipulation. However, most efforts focus solely on the prediction of two-dimensional surface integrity qualities such as those found in orthogonal machining. Indeed, most recent models largely ignore three-dimensional properties such as surface roughness, and do not incorporate three-dimensional machining parameters that are highly relevant to the surface integrity state of typical finished components. In light of these shortcomings, the nature of surface integrity in three-dimensional machining is explored, and a physics-based geometric model of surface generation is applied to some areas of surface integrity prediction.

The main focus of this work is to investigate and model the relationship between the more dominant parameters in finish turning (feed, nose radius, and edge geometry) and the surface generation phenomena that occur in the application of tools with varied geometries of this scope. The presented geometric model is derived from unique assumptions that allow for the close approximation of surface generation. The model is subsequently validated with experiments that utilize modified turning inserts of precise edge geometry, as well as pedigreed data from previous literature. Good agreement with experimental roughness results is obtained, thus verifying the validity of the surface generation assumptions. In addition, subsurface properties are found to correlate well with the geometry of ploughed areas predicted by the modeling methodology presented in this text.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.361

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