Sagar
Stepper motor and solenoid are overkill and somewhat expensive. There are plenty of surplus DC gearmotors, you can use a scissor jack powered by a gearmotor to crush the cans. To automate the process use a relay for the motor control and a switch that reverses the motor when it is done crushing the can. You can probably add some sort of linear actuator to push one can at a time into the crusher to make it even more automated.
I know one thing that helps when crushing a can is too slightly crease the sides of the can before hand. Maybe make the cylinder that holds the cans have a bar smack the sides before crushing the can.
I know one thing that helps when crushing a can is too slightly crease the sides of the can before hand. Maybe make the cylinder that holds the cans have a bar smack the sides before crushing the can.
Charles has the right idea. The intial resistance to crushing will be very high, but once the thin wall start to buckle it will collapse quickly. So, you need to hit the can first from the sides to pinch it in, then hard down the axis. Inertia will be your friend, and keep in mind that work is define as force over distance. So accelerate the "hammer" for a longer distance to store more kinetic energy.
I like Warren's idea as well, but the cans still should be dented on the sides before trying to crush them betweem wheels/rollers.
Keeping Occam's Razor in mind, a simple dent on the side of the can should compromise it enough to have the 2nd version of the electromagnetic cylinder work (it appeared to have enough smashing power anyway).