CFRP injection moulded composite replaces aluminium in oil control valve
Metal-to-composite conversion reduces cost, weight, improves engine performance
AN Asian automaker has replaced machined aluminum with a unique carbon fibre-reinforced composite in an injection moulded oil control valve within the variable valve timing system that controls engine intake and exhaust. The high-performance thermoplastic valve (2-8 valves per vehicle depending on engine size) reduces cost and weight and improves engine response time, hence engine performance.
Called Sumiploy™ CS5530 resin, the polymer is produced by Sumitomo Chemical in Tokyo. Sumiploy resin is a unique formulation of Sumitomo’s SumikaExcel™ polyethersulfone (PES) resin plus chopped carbon fibre and a proprietary additive package that boosts wear resistance and dimensional stability. The resulting high-performance composite offers excellent thermal resistance, good dimensional stability and long-term creep resistance over a broad temperature range, good impact strength, chemical resistance to aromatic hydrocarbons like gasoline, ethanol, and engine oil, inherent flame retardance, and high environmental stress-crack resistance (ESCR). Unlike many other high-temperature thermoplastics that are challenging to mould, Sumiploy CS5530 resin is high-flow, making it easier to molud high-precision 3D geometries in thin walls.
For the oil control valve application, key engineering requirements that Sumiploy CS5530 composite had to pass include ultra-high dimensional accuracy (10.7mm ± 50μm or 0.5%), thermal stability from -40 to 150C, low coefficient of friction, chemical resistance to engine oils, and excellent fatigue strength and creep resistance. Drivers for making the change from machined aluminium to an engineering thermoplastic composite include lowering manufacturing costs, improving engine performance, and lowering weight. The part has been in commercial use since start-of-production (SOP) in 2015, thus establishing a proven record of performance. Being a thermoplastic, it is fully recyclable (melt reprocessable) at the end of vehicle life.