Advanced in mould assembling technologies for high precision polymer based optical component

In recent years, the worldwide economic crisis and the continuing trend toward globalization have forced companies worldwide to seek to improve existing production systems or implement new manufacturing processes. It was based on this problem that this project was initiated. This PhD had the objective of developing a new process capable of producing a functional automotive component in an optimized way and with a lower cost compared to existing processes. To achieve this objective an intensive study was made into the concept of a manufacturing process utilizing injection molding processes allied with laser welding technologies. These two processes were chosen due to their capability of producing different components in a single process. To achieve the desired end, several tasks were undertaken. In the first instance a market research study was done so as to define which automotive component case study warranted particular examination. An in-depth appraisal of the state-of-the-art of the technologies involved in the projected manufacturing process. Following on identification of the optimal component case study, initial design of a mold and assembling process was undertaken, this ultimately leading cost analysis. This PhD was made in collaboration with PIEP and Olesa. After preliminary studies it was decided to focus on the rear lamp. To adapt the existing rear lamp to be produced through this new process it was necessary to develop a new electric circuit and to change the resistive lamp to LEDs. To produce the electric conductive circuit, it was decided to use conductive polymers. The modification made to the existing rear lamp was made according to legislation UNECE Vehicle Regulations - 1958 Agreement; Regulation No. 50 -Rev.2. To ensure the success of the new electric conductive circuit, several conductive additives were mixed with PC and PP and then tested. These comparative conductive tests showed that the material with the best electric conductivity was PC with 5% of carbon nanotubes. In this project was to examine the application of laser welding as the joining process. To study their viability in joining several materials were studied - PC, PMMA and PP. The seams of the joins made were characterized in terms of the mechanical resistance. The best combination of materials obtained would seem to be PMMA with PC while the best welding conditions are available with a minimum velocity of 20cm/min, a minimum power of 20W and a laser emitter 1mm in diameter. A comparative cost analysis examining and contrasting the comparable unit costs of production under the current manufacturing/ assembling process. The current process produces component subsystems with a lower cost when compared to the hybrid process for production batches smaller than 2800 units. After this batch size, the hybrid process produces subsystems with lower cost. In the thesis, a number of factors that influence the final price were also studied and evaluated. In particular, the possibility to produce component subsystems with two injection machines in contra-cycle with one laser and robot was examined; this production process seems capable of producing component subsystems with a lower cost and double the productive capacity when compared to the process initially studied.