Thesis
Tool wear and hole quality in drilling carbon fiber reinforced plastics and titanium stacks
Washington State University
Master of Science (MS), Washington State University
2011
Handle:
https://hdl.handle.net/2376/100326
Abstract
Over that past decade, carbon fiber reinforced plastics (CFRP) have become increasingly popular, due to their unique and tailored properties. Often, CFRP is stacked with metals such as aluminum and/or titanium (Ti) and used in the design of structural members of aircraft today. CFRP-Ti stacks are highly attractive to the aerospace industry because of their high strength-toweight ratio and excellent corrosion and heat resistance. The stacked materials are being drilled using a one shot procedure. One shot drilling can reduce cycle time and increase production, which is very beneficial to manufacturing companies. However, the dissimilar mechanical and thermal properties of the materials makes one shot drilling a difficult process that significantly decreases tool life and hole quality. Recently, many researchers have concluded that tool life and hole quality, in drilling, are highly dependent on process parameters and the rate of tool wear. To study tool wear rates and process parameters, three twist drills with different material properties were used at two different spindle speed conditions to conduct the experiments. Tungsten carbide (WC, 9% Co ultra-fine grain), polycrystalline diamond insert (PCD; bimodal grade), and Aluminum magnesium boride, a.k.a. BAM, (AlMgB14) coated WC are the drill bits selected for the study. A high and low spindle speed condition was chosen for the drilling of CFRP-Ti stacks. CFRP contains highly abrasive carbon fibers, which produce severe abrasive tool wear and tool edge chipping. Ti possesses low thermal conductivity and strong chemical affinity to tool materials, which leads to flank wear and reduction in tool life. In addition, the formation of a titanium built-up-edge on the cutting edges of the tools leads to tool chipping and premature failure. Overall, the PCD tools were to most resistant to tool wear and produced the most consistent and low hole quality defects. Hole quality parameters that were inspected are hole diameter and roundness, hole profile, CFRP entry hole delamination, titanium burr height and profile, CFRP-Ti inter-plate damage, and inner-hole surface defects. Heat generation, hot titanium chip evacuation, tool instability, Ti burr formation, Ti built-up-edge, and tool wear are the root causes of hole quality defects in CFRP-Ti drilling.
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Details
- Title
- Tool wear and hole quality in drilling carbon fiber reinforced plastics and titanium stacks
- Creators
- Aaron Lyle Beal
- Contributors
- Dave Kim (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Mechanical and Materials Engineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525190401842
- Language
- English
- Resource Type
- Thesis