Yamaha R15: forged pistons

Bits and pieces of the R15 coming out as press releases, it would seem...

New Delhi, March 19, 2008: Keeping up with new technology and constantly bringing it to the next level, Yamaha Motor India is set to introduce forged piston which enables lighter piston design and excellent power development, in the Indian market. The forged piston is used on the new 150cc YZF-R15, which was unveiled at Auto Expo 2008, as the first on an Indian market model and a feature that reduces the reciprocating mass of the piston by approximately 20%.

Introduced in 1997, Yamaha "controlled forging technology" has been used successfully for over a decade for the mass production of forged aluminum pistons because it utilizes a system of precise control of the piece temperature, mold temperature and the forging force. Yamaha's controlled forging technology tightly controls the forging conditions, including (1) the initial heating of the work piece, (2) controlling the temperature of the mold so that it keeps the work piece in the ideal 400 to 500 ℃ range (3) applying just the right amount of pressure to the mold in the forging process and many more factors.

According to Mr. Sanjay Tripathi, Head of Dept- Product Planning & Strategy, "Pistons for car and motorcycle engines are usually cast by pouring molten aluminum alloy into a mold. The other type of piston is the forged piston, with which the alloy is not melted but heated to the point where it can be forged into a mold under pressure. Since the
aluminum is not melted in the forging process, it retains a stronger metallurgic quality. This makes possible a thinner, and thus lighter, piston that has less reciprocating mass and also contributes to weight reduction. The result is better revving and lesser engine vibrations."

"However, there are exacting requirements involved in manufacturing a complex shaped piston and difficulties in maintaining precise temperature in the "forging" process. Due to which such pistons are expensive to produce. But Yamaha's "controlled forging technology" enables production of the forged pistons at a lower cost", he adds further.

The forged pistons made with Yamaha "controlled forging technology" have excellent strength characteristics that enable the design of a thinner, lighter piston with smaller reciprocating mass achieve higher rpm and performance as well as providing the greater reliability of the higher strength aluminum. For this reason they are used in YZF-R15 and many Yamaha motorcycles.