During the processing of carbon fiber tubes, not only geometric defects but also unique processing defects of carbon fiber composite materials will appear, which can be mainly divided into several damage forms such as burrs and delamination.
1. Glitch
The burr means that when the hole is made, the fiber layer has no binding force, and the axial force pushed outward by the drill bit makes some uncut fiber burrs appear at the bottom. Careful observation reveals that the burrs have distribution characteristics in a certain area, mainly because the carbon fiber tube is subjected to both shearing and stretching forces during the drilling process. At the same time, in the processing process, the constantly worn tool cannot cut the fiber instantly, which will aggravate the generation of burr defects.
2. Layering
Delamination refers to the phenomenon of degumming, separation and damage between carbon fiber prepreg plies. The main cause of delamination is the normal stress between layers when bearing static load and dynamic load, and secondly, when the vertical stress generated during cutting exceeds the bonding strength between matrix and fiber, interlayer delamination will occur. During the drilling process, the friction between the cutter head and the carbon fiber tube generates heat, and the thermal effect formed around the hole wall will also cause delamination.
So how do we fix these flaws?
Regarding the burrs, after processing the carbon fiber tubes, we can use sandpaper to repair the burrs on the carbon fiber tubes to minimize the burrs on the surface of the carbon fiber tubes.
Regarding delamination, we can slow down the processing speed as much as possible to reduce the heat generated by the friction between the cutter head and the carbon fiber tube during the drilling process.