Injection Moulding Asia

Combined technique for lighter automotive parts

S

Calling it GK LIPfibre (Georg Kaufmann Lightweight Integrated Process fibre), the company says parts produced are lighter than comparable metal components. At the K exhibition, the company says interest was shown by visitors from the automotive and aviation industries. The K show demonstration was realised together with Audi, KraussMaffei, Lanxess, Bond-Laminates and Jacob Composite.

For the production of this dynamic impact modifier, a flat pre-heated sheet of fabric and glass fibre-reinforced thermoplastic is first thermoformed and remains in the now closed mould. Then in a second step, in the same mould, it is enhanced by adding reinforcement ribs, corners, and edges. The material for the ribs is a glass fibre-filled polymer.

The combination of thermoforming and injection moulding requires a production system in which the individual process steps are coordinated and synchronised with each other, to guarantee the required product quality and process reliability.

The first stage of the process - the thermoforming of the glass fibre-reinforced thermoplastic composite sheet - begins with a special cavity insert that presses the sheet onto the core and holds it in place. During the thermoforming the sheet may not develop any creases. Also important is the orientation of the fibres in the now formed sheet, which is predetermined according to the functionality of the part.

The mould remains in its closed position at the end of the thermoforming process. The melt for the overmoulded ribs, consisting of a glass fibre reinforced-polymer, is injected via a hot runner system and bonds completely with the thermoformed sheet. In addition the melt flow ensures that all sections of the part are fully formed and filled.

The research production mould was equipped with several sensors for pressure and temperature measurements, monitoring the various process stages, the shaping of the glass fibre-reinforced sheet during thermoforming, the injection of the polymer melt and the complete filling of all corners and edges of the part. The recording of the measurements during these operations will help to better understand the requirements for future applications.

Future moulds of this type will be equipped likewise with considerably fewer sensors to monitor the different steps in the process.