Machining Damage in Edge Trimming of CFRP

Conventional machining processes such as turning, milling, drilling, abrasive cutting, and grinding are commonly used to bring composite parts to final shape and assembly requirements. However, due to the layered nature of these materials, their machining may generate undesirable defects such as delamination and high surface roughness. The service life of composite components is believed to be highly dependent on machining quality and damage due to machining may result in scraping expensive parts. In this work, an experimental investigation was conducted to determine the effect of spindle speed, feed rate, and tool condition on machining quality of carbon fiber reinforced polymer (CFRP) composites during edge trimming operation. Machining quality was quantified in terms of average delamination depth and surface roughness. Delaminations were also characterized by their type and frequency of occurrence. It was found that average delamination depth and surface roughness increase with an increase in feed rate and an increase in cutting distance and decrease with an increase in spindle speed. There is a strong relationship between delamination damage and effective chip thickness. The cutting conditions for best machining quality are high spindle speed and low feed rate, which correspond to small effective chip thickness. The most frequent delamination type was found to be Type I/II.