Ultrasonic Machining Operation

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Ultrasonic Machining, also known as ultrasonic impact grinding(2), is a cold-cutting operation(1) in which an abrasive slurry freely flows between the workpiece and the vibrating tool. The tool never contacts the workpiece and as a result the grinding pressure is rarely more than 2 pounds(1), which makes this operation perfect for machining extremely hard and brittle material; such as glass, sapphire, ruby, diamond, and ceramics(3).

[edit] Surface Finish

The surface finish of ultrasonic machining depends upon the hardness of the workpiece/tool and the average diameter of the abrasive grain used. Up close, this process simply utilizes the plastic deformation of metal for the tool and the brittleness of the workpiece. As the tool vibrates, it pushes down on the abrasive slurry (containing many grains) till the grains impact the brittle workpiece. The workpiece is broken down while the tool bends very slightly(3). Commonly used tool material consist of nickel and soft steels(3).

[edit] Machine Time

Machine time depends upon the frequency at which the tool is vibrating, the grain size and hardness (which must be equal or greater than the hardness of the workpiece(3)), and the viscosity of the slurry fluid(3). Common grain materials used are silicon carbide and boron carbide, because of their hardness(3). The less viscous the slurry fluid, the faster it can carry away used abrasive(3).

(1) http://www.sonicmill.com/ultrasonic.htm

(2) http://www.bullen-ultrasonics.com/UltraMachine.html

(3) Media:www.ligo.caltech.edu/docs/T/T020198-00/T020198-00.doc