Abstract
Measuring and characterizing of surface roughness of machined surfaces of carbon fiber reinforced polymer (CFRP) composites are difficult due to the occurrence of special surface damages (delamination, uncut fibers, fiber pull-outs or micro-cracks, etc.). The main objective of the present study is to analyze the characteristics of surface roughness of machined unidirectional CFRP in detail. Numerous conventional drilling, helical milling, and edge trimming experiments were carried out with different cutting tools in order to analyze the influence of them on the average surface roughness (Ra), on the roughness depth (Rz) and on the Rz /Ra parameter. The surface roughness was measured by a Mitutoyo SJ-400 contact profilometer and an Alicona Infinite Focus confocal microscope. The usability of the contact profilometer was experimentally tested and compared its results with the results of the confocal microscope. Experimental results show that the contact profilometer is suitable for measuring surface roughness of CFRP, furthermore, values of Rz /Ra of drilled and edge trimmed surfaces of unidirectional CFRP are changing in a wide interval: from 5 to 14 μm/μm due to the special surface damages. Based on this research, the machinability analysis of CFRP is suggested to be extended to the analysis of the Rz /Ra parameter.
Highlights
The application range of carbon fiber reinforced polymer (CFRP) composite materials increases in the high-tech industries like automobile, marine, aerospace or space industry; mostly due to the excellent specific mechanical properties of CFRP
Experimental results show that the contact profilometer is suitable for measuring surface roughness of CFRP, values of Rz /Ra of drilled and edge trimmed surfaces of unidirectional CFRP are changing in a wide interval: from 5 to 14 μm/μm due to the special surface damages
2 Experimental setup Epoxy resin-based, unidirectional carbon fiber reinforced polymer (UD-CFRP) composite was manufactured by a hand laminating process in order to analyze its machinability by experimental work
Summary
The application range of carbon fiber reinforced polymer (CFRP) composite materials increases in the high-tech industries like automobile, marine, aerospace or space industry; mostly due to the excellent specific mechanical properties of CFRP. Manufacturers try to laminate CFRP parts ready-to-shape, there is often necessary to mechanically machine them in order to: (i) machine difficult-to-mold features like pockets and holes, (ii) increase surface quality by edge trimming or (iii) meet other dimensional requirements [3,4,5,6,7,8]. CFRP is a difficult-to-cut material because of its inhomogeneous and anisotropic features, carbon fiber reinforcements have a strong abrasive wear effect, carbon chips have to be removed from the cutting zone (usually by a vacuum device) [9]. The influence of fiber cutting angle has been widely investigated by many researchers [6, 10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26] in order to describe chip removal mechanisms in unidirectional CFRP
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