WNT (UK)’s tooling cuts weight of racing powerboat

F2, the fastest class of Royal Yacht Association national inshore circuit racing, uses standard 227 hp (1,692 kW) Mercury V6 two-stroke engines of to achieve speeds of greater than 120 mph. WNT (UK) recently machined new steering arms for the engine. The parts were machined at WNT (UK)'s Technical Centre in Sheffield where WNT's Internal Technical Sales Engineer Billy Poore made full use of the latest WNT cutting tool technology to produce a lightweight, yet strong, steering arms from aerospace grade aluminium. The steering arm was machined on the XYZ Machine Tools installed at the technical centre and involved a number of cutting tool strategies, covering face milling, profiling, pocket milling, fine finishing and drilling. WNT used a variety of indexable and solid carbide cutters on the project, with face milling carried out using its A2790 style 50 mm diameter indexable insert cutters running at 400 m/min at a feedrate of 0.2 mm/rev and a depth of cut of 1.0 mm and width of cut of 60% of the cutter width. An indexable insert cutter was also used for the rough profiling operations running at 240 m/min, feedrate 0.25 mm, depth of cut 5.0 mm and 100% cutter width engaged. The milling of the pockets and finish profiling was completed using WNT's HPC solid carbide 90 degree approach and ball nose end mills, running typically at 230 m/min, with the drilled holes being achieved with the latest WNT WTX solid carbide high performance drills at cutting data of 300 m/min and a feedrate of 0.5 mm/rev. The objective of this exercise was to reduce the overall weight to aid performance, while maintaining the structural integrity of the part. Billy Poore says: "The original steering arm weighed 1400 g. By machining from a billet we have achieved a weight of 850 g each, so a total saving of 1100 g for the pair of arms. In addition, we have created a component that is stiffer, so its performance has increased. While taking 1100 g from a powerboat weighing 475 kg may not sound much, when combined with other weight saving measures taken by the team a total of 26 kg has been taken away, which should add greater speed and improve overall performance when the next season starts." Since the parts are fully exposed when installed, a secondary target for WNT (UK) was to make them look good.