Difficulties in drilling of carbon fiber composites

Carbon fiber composite material as a high-end material, with the characteristics of hard and high strength, although superior performance, but two times more difficult to process. In the carbon fiber composites material products drilled, it is easy to appear empty perimeter tearing, layering, uneven appearance. Large carbon fiber products need to coordinate the structural characteristics of the parts to determine the hole, it must be manually drilled by the fitter, but in the manual drilling, the processing state is very unstable, there are many uncertainties and human effects, resulting in manual drilling quality is not stable, the work piece wall around the material defects than the equipment processing serious, Especially the hole exit tearing is more serious. Large-scale carbon fiber composite parts manufacturing cost high, usually the number of hole processing is more, any quality problems in drilling will form a product defect, directly affect the assembly quality of the parts, the serious cause of the part scrap, resulting in huge losses.

Technical difficulties in manual drilling of carbon fiber composites:
Because the carbon fiber overlay each angle produces each same dissimilar, the inter layer strength is low, at the same time the carbon fiber composites material hardness is high, the performance is brittle, the intensity are high and the heat conduction ability is poor, causes the drill bit to wear seriously, produces the cutting torque and the cutting heat big, the part material under the action of the cutting force is prone to the In the diameter of the drill, the cutting edge of the parameters of the case, the drill speed and feed speed will be the main factors affecting the size of the axial force, the axial force with the increase in speed and decrease, with the increase in feed, and the impact of the feed is far greater than the impact of rotational speed, so the feed is a key factor to control axial Hole exit tearing occurs at the most surface layer on one side of the hole exit, the most common flaw in drilling is that when drilling is close to drilling, the decrease rate of axial force is less than the decrease of material strength, which causes the cutting material not to enter the cutting layer, causing damage and tearing, so it is necessary to reduce the feed when drilling close to drilling. In this way, the drilling force is less than the critical cutting force produced by the defect, reduce the hole exit tearing phenomenon, and because the drill edge sharpness is not enough, composite fiber is not completely cut off has drilled through, resulting in hole exit tearing, raw edges. Therefore, the carbon fiber composite hole processing, especially near the drilling pass, should choose a smaller feed.

In the production of carbon fiber composites manual drilling, hand-held pneumatic drill, but processing state is very unstable, the center position of the drill bit, vertically and other errors and changes, the operator’s work experience directly affect the processing quality of the hole, manual drilling process, the feed is not easy to control drilling quality instability of the main factor, In particular, when the holes are closed out by the dry cutting material suddenly reduced, instantaneous material itself, the drilling back force suddenly greatly reduced, resulting in a sudden increase in feed, the drill bit impact drill bit phenomenon, resulting in the hole tearing more serious.

Post time: Sep-17-2018

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