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  • Analysis of burr formation in finish machining of nickel-based superalloy with worn tools using micro-scale in-situ techniques

This content will become publicly available on June 1, 2024

Title: Analysis of burr formation in finish machining of nickel-based superalloy with worn tools using micro-scale in-situ techniques
The formation of burrs is among the most significant factors affecting quality and productivity in machining. Burrs are a negative byproduct of machining processes that are difficult to avoid because of a limited understanding of the complex burr formation mechanisms in relation to cutting conditions, including both process parameters and tool condition. Thus, the objective of this work was to characterize burr formation under finish machining conditions via a high-speed, high-resolution in-situ experimental method. Various parameters pertaining to burr geometry such as height, thickness, and initial negative shear angle were measured both during and after cutting. Results showed that varying the conditions of uncut chip thickness, tool-wear, and cutting speed all have a significant effect on burr formation, although certain burr metrics were found to be insensitive with respect to different process conditions because the difference was statistically insignificant. This study provides new insights into the relationships between the workpiece material’s microstructure, machining parameters, and tool condition on both crack formation and propagation/plasticity during burr formation. Using digital image correlation (DIC) and a physics-based process model not previously utilized for burr formation analysis, the displacement and corresponding flow stress were calculated at the exit burr root location. This novel semi-analytical approach revealed that the normalized stress at the exit burr root was approximately equal to the flow stress for a variety of different conditions, indicating the potential for model-based prediction of burr formation mechanics. Finally, this study investigates factors that influence fracture evolution during exit burr formation. It was found that negative exit burrs are a direct result of high strain rate and high uncut chip thickness, which was expected, but also a microstructural size effect and a tool-wear effect, neither of which have been previously reported. By harnessing ultra-high-speed imaging and advanced optical microscopy techniques, this manuscript deals with the fundamentals of burr formation, including new insights into material response at the grain-scale to the loads imposed with both sharp and worn tools.  more » « less
Award ID(s):
2143806
NSF-PAR ID:
10488567
Author(s) / Creator(s):
;
Publisher / Repository:
International Journal of Machine Tools and Manufacture, Elsevier
Date Published:
Journal Name:
International Journal of Machine Tools and Manufacture
Volume:
189
Issue:
C
ISSN:
0890-6955
Page Range / eLocation ID:
104030
Subject(s) / Keyword(s):
["Burr formation, Inconel 718, Machining, Tool-wear, In-situ characterization, Digital image correlation (DIC)"]
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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