Machining characteristics of graphite/epoxy composite. Ph.D. Thesis
The first part of this study dealt with tool wear of Carbide and Polycrystalline Diamond (PCD) inserts for machining Graphite/Epoxy (Gr/Ep) composite materials. Two different cutting modes, continuous and interrupted, were applied for carbide inserts under dry cutting conditions. In the interrupted cutting mode, a wave form of flank wear was observed with one third peak-to-peak value of one-ply thickness. In the continuous cutting mode, severe nose wear and rounding of cutting edge wear was observed due to the high temperature around the nose region, which accumulated heat on the cutting edge. Heat generation was found to influence the carbide life both under continuous cutting and interrupted cutting modes. The flank wear of PCD inserts was below 100 mu m for 60 minutes of cutting time, whereas that of carbide inserts exceeded 300 mu m within 5 seconds of cutting time. Therefore, it was found that PCD inserts have excellent tool life when compared to carbide inserts. Based on these experiments, flank wear models were constructed to predict tool life for given cutting conditions. The second part of this study dealt with orthogonal cutting characteristics of machining unidirectional and laminate Gr/Ep and unidirectional model Carbon Fiber Reinforced Plastic (CFRP) composites. Chip formation, cutting force, and surface morphology were considered as cutting characteristics. Powder-like chips for Gr/Ep composites and ribbon-like chips in small depths of cut for CFRP composites were observed. Chip formation was found to be dependent on fiber orientation. Four common fiber orientations, 0 deg, 45 deg, 90 deg, and {minus}45 deg, had different cutting mechanisms of chip formation. Bending, peel fast fracture, and fracture perpendicular to the fiber direction were the general cutting mechanisms for the 0 deg fiber orientations when machining unidirectional and laminate composites.
- Research Organization:
- Washington Univ., Seattle, WA (United States)
- OSTI ID:
- 237317
- Report Number(s):
- N-96-23091; NIPS-96-07520; TRN: 9623091
- Resource Relation:
- Other Information: TH: Ph.D. Thesis; PBD: Jan 1993
- Country of Publication:
- United States
- Language:
- English
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