The effects of the process parameters on shoulderless friction stir processing on the tribological properties of polylactic acid/basalt composites

The limitations of traditional metallic biomaterials motivated the development of polymer matrix composites to fabricate various biomedical implants. The wear resistance of the composites can be enhanced by modifying the surface properties, using a surface modification process to increase the components' lifespan. Friction stir processing (FSP) is one of the best solid-state processing techniques for fabricating polymer composites. In the present study, a new, shoulderless tool has been developed to perform FSP to understand the process parameters' influence to produce an effective processing zone. It may be called 'Shoulderless Friction Stir Processing'. Therefore, for this research work, the tool rotational speeds of 500, 600 and 700 rpm and traverse speeds of 10, 15 and 20 mm/min have been selected as the process parameters to conduct the FSP on the developed basalt fibre-reinforced polylactic acid composite materials. The obtained result reveals that the tool rotational speed is the most influencing processing parameter, as it affects the surface of the composite. A high rotational speed leads to a high material removal rate, whereas a low rotational speed leads to the burning of the polymer. In addition, the specific wear rate (SWR) is also found to be minimal for the specimen processed at 600 rpm with 20 mm/min traverse speed compared to the other processing parameters.