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 Engine cylinders bear enormous heat in the combustion chamber, so excess heat
must be swiftly dissipated to maintain thermal efficiency. That is especially
important in motorcycle engines, which generate higher engine revs than automotive
engines.“Improving motorcycle performance requires ever more lightweight and heat-resistant materials for engine components,” said Kazutatsu Suzuki, Assistant Manager of Group I, Motorcycle Division I, Design Department. “Although today’s high-performance motorcycle engines feature aluminium die-cast cylinder blocks and aluminium pistons, most also have heavy steel cylinder liners to prevent wear. So we engine designers prefer to employ special plating for cylinder walls.” But the plating methods commonly used for engines of expensive sports bikes and Formula One competition racecars formerly required extremely costly and complicated processing procedures in huge facilities, until Suzuki succeeded at developing a unique high-speed plating method: the Suzuki Advanced Plating (SAP) system. “Suzuki has led the field since the 1970s, so by 1996 we were ready to develop an entirely new plating system which doesn’t require multi-stage pre-treatment processes and features a highly efficient composite plating method,” said Hitoshi Muramatsu, Assistant Manager of Group I, Development Department and plating technology expert. “Our SAP has reduced pre-treatment processes from five to one, and improved plating speed to a fifth of the time required for conventional plating. The result is dramatic reductions in production costs, facility space, maintenance manpower and harmful waste fluids.” Figure 1 compares the procedures of a conventional plating method to SAP. After degreasing of the cylinder surface, conventional pre-treatment starts with alkaline etching to eliminate oxide coating, then repeats the process of mixed acid desmutting and zincate conversion twice, using such deadly poisons as concentrated alkali and acid. In contrast, pre-treatment of SAP requires only electrolytic etching with phosphoric acid. “This innovative pre-treatment process unique to Suzuki reduces use of poisonous fluids by about 80%. Furthermore, we endeavour to recycle up to 70% of the waste fluids. Finally, we’re able to reduce fluid use to only 6% as much as conventional pre-treatment processes, which reduces costs and minimizes environmental impact as well,” Muramatsu related proudly. After pre-treatment, the plating process begins. Figure 2 illustrates the difference between a conventional dipping method and SAP in Ni-P-SiC composite plating. The dipping method employs a soluble anode consisting of nickel pellets in a titan tube dipped in electrolytic bath. To increase the plating speed, you have to feed nickel pellets quickly and continually using huge machinery. In contrast, the high-speed plating by SAP operates in a compact circular system which runs sulphuric-acid based nickel-plating fluid through the engine cylinder. An insoluble anode is set inside the cylinder, and nickel is fed by adding NiCO3 powder so that elements other than nickel evaporate as CO2, keeping the plating fluid unchanged. “With this efficient, maintenance-free system, you can increase fluid speed to one-fifth of the time required for existing methods, which raises productivity by five times.”  An engine manufactured using SAP debuted this February in the new Choinori 50cm3 scooter for the Japanese market, astonishing motorcycle fans with its high performance and low price. “With SAP, we achieved excellent heat dissipation and high wear-resistance, as well as compact, lightweight engine structure, at quite low cost,” continued Suzuki. “It’s an engineering breakthrough, and I look forward to applying this technology in more and more Suzuki products.” |
