Vacuum Technology in use during the Hot Pressing of Prepreg Materials

Before the prepreg materials can be processed, which is usually done through hot pressing, the adhesive material is cut to the appropriate size on a cutting table (1) . To ensure that the prepreg does not stick together during storage, there is a protective film on the material that is often removed manually before the hot pressing. Afterwards, the gripper picks up the cut prepreg pieces and stacks them on top of each other in a specific order (2). The various layers thus form a kit. The tacky surface is a challenge for the gripper in this process step because sticking of individual layers to the gripper during handling needs to be avoided.

A gripper precisely sets down the kit in the mold of the press (3), where it is then pressed and cured (4). This produces a three-dimensional FRP part (5), which can be removed by specific "non-marking" suction cups.

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Requirements

Requirements for Vacuum Technology

Adhesiveness of the workpiece
A feature of prepreg materials is their tacky surface due to their prior impregnation with reactive resins. It is a challenge for the gripper to ensure that the cut piece does not remain stuck on the gripper during the handling process and can be released precisely. Furthermore, it is better if the gripper does not become too heavily contaminated.

Gently handling sensitive workpieces
The orientation of the textile fibers is crucial for the result of the pressing and hardening of the workpiece. The suction plates SPL POM-NBR use an even vacuum distribution and their flat design to prevent the workpiece from being drawn into the gripper and protect the semi-finished products from permanent deformation.