When a car buyer makes the decision to buy a vehicle made by a premium manufacturer, it is not only the performance and design of the vehicle that must be right but also the feel. The same is true for many products. It is particularly true for components that are subject to regular handling such as door handles. Robot deburring using plasma torches provides an effective option for one maker.
Plastic handles are produced in pairs using injection moulding that can leave a flash from the mould-seam or gate. The same is true in metal casting. Left untreated they give an image of poor quality and make paint or finishing more difficult. Moreover, removing the flash requires an additional deburring process and cost.
In the case of one automotive supplier, the flash was removed manually using a grinding machine. This process was inefficient and time-consuming. It was also cost-intensive due to number of employees involved, and the high scrap levels. Investigations identified plasma deburring as the best way of achieving a high-quality finish.
Robot controlled plasma torches
Increased automation was important to provide the desired throughput. The machine manufacturer and the programming company developed a solution using Mitsubishi Electric. The result was a highly accurate and fully automated process using a robot and two plasma torches operating in parallel with each other.
Firstly, trials using Mitsubishi Electric automation products determined the most appropriate robotic technology. After the positive test run, they decided to build the installation. To avoid disruption they established a temporary replacement system with help from Mitsubishi.
In the finished system, the MELFA RV 6 SD 6-axis overhead articulated arm robot takes care of surface finishing by guiding the two plasma torches. An additional SCARA RH 12 SDH robot automatically replenishes the feeder systems. Operator control was through a GOT 1000 HMI touch panel, and MELSEC FX3G 60M PLC handles machine control. The system uses a light sensor to differentiate between trays containing right and left door handles. The information is passes to the robot controllers which adapt the programs accordingly.
Markedly, the system can process a tray containing 28 handles in six minutes. Besides reducing the scrap levels, robot deburring has improved throughput and reduced, personnel and cost. The machine operates on three-shift basis to further improve overall productivity.