Konzeptionierung und Aufbau eines Prototyps für die Förderung und Mischung von Duroplastgranulat für eine Tablettenpresse

The most common procedure for encapsulation of electronics and electric drives for use in harsh surroundings, like in medical products, at the company Ottronic is the “Resin Transfer Molding” process. This requires B – Stage – thermoset tablets, which are no longer provided by a lot of suppliers. Therefore, this master’s thesis covers the conception and validation of a conveying system to the tablet press for the granulate.
It is important to protect the material from external influences, such as pressure and temperature, to avoid early ageing (pre – crosslinking), which has a negative influence on the processability. Additionally, the safety of the production workers need to be considered due to the arising dust exposure.
This master’s thesis examines various conveying and mixing options of coarse and fine thermosets by using different geometries of conveying screws and mixers. The target aims at finding the best combination for the process.
The validation of the different concepts is based on DSC – Analyses (Differential Scanning Calorimetry) and practical studies, which are carried out on RTM – machines (Resin Transfer Molding). Thereby, the main focus lies on the free enthalpy of reaction and the visual evaluation of the practical samples within a rating matrix. Additionally, sieve tower analyses were performed to examine the gain decay, or rather the grinding, of the thermoset during various conveying options. During the test procedure, the occurring dust load is recorded.
Based on the analyses, a suitable conveying and mixing concept was determined. This variant shows a low influence on the material interactions and therefore the thermoset granulate remains good for processability. Depending on the position of the dust measuring system, it detects different values of the dust exposure. However, there is no need for concern, since an automatization of the tableting process is planned.