The automation of high volume production in fibre-reinforced polymer composite (FRPC) manufacturing is a key issue to lower manufacturing costs. In terms of injection technologies, the solvent free processing of fast curing resin systems is a key to reduce both labor work and waste production. Two types of injection machines with corresponding strategies are pursued today. Low-pressure injection machines are based on static or dynamic mixing devices that shear the material by their elements. This principle leads to high operation costs by using solvents or cleaning agents to flush the mixing chamber. High-pressure injection machines induce turbulent streams to mix the components. Enabling an efficient ejection of the reactive resin system, the necessary high pressure leads to complex and cost intensive plants. In this paper, the acoustic cavitation effect is applied to enable a solvent free Low Pressure Resin Transfer Molding (LP - RTM) production based on a moving ultrasonic horn. During injection, the micro scale turbulent streams enable a uniform homogenization of a three component fast curing resin system including an internal release agent at low mixing pressure. The use of an internal release agent eliminates the need of an external, manually applied release agent. Further, the poor contact principle enables a self-cleaning of the mixing chamber after the injection. The investigation of this Ultrasound Mixing Head is done in three steps: First, the integration, guidance and control of the ultrasound device during a LP - RTM injection are examined. Second, the process and material characteristic of parts produced with the Ultrasound Mixing Head and a Static Mixing Head are compared. Third, results of demolding tests performed with specimens produced with both Mixing Heads at various process conditions are presented.