Due to intensive research in the field of material development considerable progresses in terms of processing and performance characteristics could be achieved during the last years. Therefore bio-based plastics are increasingly being used for the production of durable injection moulded components. Several applications can be found in the automotive sector, in the field of consumer electronics or the sports industry. For an economic production, the joining technology often plays a key role to realise modular designed components. Detachable connections, which are frequently used in plastics processing (e. g. snap hooks or screw connections), often reach their limits with respect to the reliability and tightness of the joint. In order to meet the increasing requirements to the joint, plastics joining processes can allow a suitable component assembly. Bio-based plastics may differ from conventional plastics regarding their processing properties, such as the melting and solidification behaviour. Therefore investigations at IKV were carried out to get an extensive process knowledge in welding of bio-based plastics. To perform a scientific examination of the influence of the moulding process on the weld seam quality, cellulose and lactic acid based plastics were selected and injection moulded with varying parameters like mass temperature, mould temperature and injection speed. In subsequent welding experiments using the infrared and ultrasonic welding method connections have been produced and analysed with regard to mechanical and morphological properties. The investigations show that all of the selected bio-based plastics can be welded. Depending on the material and the welding method the choice of the moulding parameters can have different influences on the weld seam strength. For example, a higher mould temperature during injection moulding leads to higher weld seam strengths for ultrasonic welded test specimens made of lactic acid-based plastics.