Tips for Machining Carbon Fiber

BY HAN'S YUEMING LASER GROUP

POST ON:2020-04-29

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The use of carbon fiber reinforced polymers is rising in many industries and as an outcome there is a higher demand of mechanical testing of composites. To get right and repeatable outcomes, precisely machined test specimens are needed. Due to the nature of the stuff, Carbon Fiber Cutting Machine shops with new challenges, as matched to machining traditional materials like metals.

Waterjet

Waterjet cutting is a quick and perfect way to cut carbon fiber. One benefit of waterjet cutting is that no unique tools are needed. It is excellent to drill a starting hole, otherwise the waterjet can cause delamination. When strong tolerance  are needed, it may be top to waterjet the part oversized and machine to final dimensions.

Milling

Machining of carbon fiber is usually done with router, anyway, standard metal machining technique can be used. Machining carbon fiber needs higher spindle speed than metals, but lower feed rates. The feed rates need to be managed to reduce the heat in the part while lower feed rates. The feed rates need to be managed to reduce the heat in the part while machining. Carbon fiber has a low thermal conductivity and the majority of the heat remains in the part since there are no chips to support dissipate the heat when machining. This heat from cutting can lead to damage to the resin. Since coolant might not be allowed when machining carbon fiber, the tool path and tool must be used to manage the heat in the part while machining.

Tooling

Carbon fiber is rough and will wear down tools fast. When a tool loses its sharpness, it can catch fiber and pull them from the part instead of cutting them. To reject this, tool life must be monitored during machining as cut standard will reduce fast.  The top way to do this is to check the machining time on the tool and replace it before it becomes dull.

There are several types and shapes of cutters for various applications, but they are usually made from 2 materials:  polycrystalline and carbonize diamond (PCD). Carbide offers best wear resistance, but is more applicable to little jobs. PCD cutters provide better wear resistance and are the cutter of choice for many composites machine shops. Anyway, the advantage of PCD cutters does come at a very higher cost matched to carbide.

Diamond coated grinding wheels are also clip of the well-rounded composite machine shop. They permit right dimensional control, best tool life-expense ratio, and right heat management.