The milling of glass and carbon fibre reinforced plastics provides manufacturers from the automotive and aerospace industry with major challenges. The high carbon and glass fibre content increases the risk of insufficient production qualities. The abrasive fibres cause cutting edge rounding which results in the issue that the comparatively thick glass fibre cannot be reliably cut, while the carbon fiber is being less of a challenge. One approach to improve the production quality is the use of ultrasonic assisted milling. At the IWF tests have been undertaken to study the influence of ultrasonic assistance on workpiece quality, cutting forces and dust generation