Understanding the Influence of Parameter Modulation in Machining-based Processing
Open Access
- Author:
- Norman, Joshua Michael
- Graduate Program:
- Mechanical Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- April 24, 2013
- Committee Members:
- Dr Christopher Saldana, Thesis Advisor/Co-Advisor
- Keywords:
- orthogonal
cutting
machining
modulation
MAM
specific energy - Abstract:
- It is widely believed that the parameters of cutting speed and undeformed chip thickness can be used to influence the specific energy consumption of traditional machining processes. The purpose of this study was to further investigate the degree to which these two parameters affect the system load response (e.g. force, power consumption) – and in turn the specific energy consumption – when they are applied quasi-statically as well as dynamically. This was carried out experimentally using a CNC planer (to study the effects of cutting velocity) and a CNC lathe (to study the effects of undeformed chip thickness). Furthermore, this study purposed to ascertain whether the loading response of a system to dynamic parameter manipulation can be predicted based on a characterization of the system’s response to static changes in the same parameter. This involved discretizing the time-varying cases and treating them as a continuous series of static cutting instances, each of which could then be assigned a predicted force value. Obviously, such a technique would only be effective if there is close agreement between the static and dynamic loading responses of the given system. As a result of empirical testing, close agreement was found between the loading responses for static and dynamic variations in cutting speed for both AA6061-T6 and OFE Copper. When similar variations were applied to AA6061-T6 and Ti3Al2.5V in the direction of undeformed chip thickness, close agreement between static and dynamic loading responses was again found, but for low to moderate values of the processing parameter. These observations suggest that, for many materials, the nature of material response in low-frequency, modulation-assisted machining (MAM) is similar to that which occurs in conventional machining. Based on this similarity, it was also found that the general shape of the characterized load response to static parameter manipulation could be used to predict whether MAM would consume more or less specific energy than its conventionally cut counterpart. Specifically, MAM will generally require slightly more energy for dynamic changes in cutting velocity but significantly less energy for dynamic changes in undeformed chip thickness, as compared to conventional cutting. It is suggested that further research be performed which incorporates dynamic changes in cutting speed and rake angle into the energy prediction model for MAM as applied in the direction of undeformed chip thickness. Finally, a further study may also make use of an intermediate variable, such as thickness of the primary deformation zone, as the predicted quantity for the dynamic cases. Such might provide insight as to the existence of a common physical mechanism underlying the energetics of both modulated machining configurations and would act as an extension of the research performed by Kececioglu [2,14].