Fabrication of microplastic parts with a hydrophobic surface by micro ultrasonic powder moulding

Abstract Microstructures with hydrophobic surfaces have been widely used in industrial fields such as self-cleaning and drag reduction. With the aim of fabricating microplastic parts with a hydrophobic surface, the paper processed the mould insert with micro-groove arrays from 304 stainless-steel plate through low-speed wire electrical discharge machining (LS-WEDM). And the micro-groove arrays were designed to U shape with bottom radius of 70 μm and depth of 110 μm. Ultra-high molecular weight polyethylene (UHMWPE) powders were used as raw material to fabricate microplastic parts with hydrophobic surface structures by micro ultrasonic powder moulding (micro-UPM). The parameters of the micro-UPM process were obtained by the single-factor test method. Under the ultrasonic energy of 1200 J, welding pressure of 100 kPa and pressure holding time of 8 s, microplastic parts with well surface morphology (Ra =1.36 μm) and replication rate (97.76 %) were successfully fabricated. The surface contact angle of the microplastic part was 135.4°, which indicated well surface hydrophobicity.