Yamaha Technology 1996: Forged Aluminum Pistons - Controlled Forging Technology

 

A technology for forged aluminum pistons and their mass production that enables lightweight design. First adopted on the ’96 model YZF1000 ThunderAce. Used since on large-displacement sports models from the YZF-R series to the Midnight Star.

Summary
This is an aluminum piston forging technology and its mass production method that involves heating aluminum alloy to a set temperature and putting it in a temperature-controlled metal mold and forging it under pressure into the piston shape. It can make use of strong aluminum alloy material which does not have to be heated until it melts so that it maintains its original even solidification matrix. This makes possible a thinner-walled piston design, thus reducing the piston’s reciprocating inertial weight.
The primary merit is that stronger aluminum alloys can be used in the forging process.

Furthermore, a program was developed by which the aluminum alloy is heated to a specified temperature, inserted into the mold with the best timing and forged with just the right amount of pressure. This is called our “Controlled Forging Technology”.
It involves comprehensive control of
(1) optimum heating of the aluminum alloy,
(2) the temperature of the metal mold,
(3) optimum use of the mold freeing agent and
(4) control of the pressure applied.
In this way it is possible to achieve mass production of aluminum forged pistons that until now had proved difficult.

Effect 
1) Design of thinner-walled pistons due to the use of stronger aluminum alloys,
2) reduction of reci-procating inertial weight due to the piston’s lighter weight, and
3) improved piston durability and reliability.