In ultrasonic

machining Machining is a process in which a material (often metal) is cut to a desired final shape and size by a controlled material-removal process. The processes that have this common theme are collectively called subtractive manufacturing, which utilizes ...

, welding and mixing, a sonotrode is a tool that creates ultrasonic vibrations and applies this vibrational energy to a gas,

liquid A liquid is a nearly incompressible fluid that conforms to the shape of its container but retains a (nearly) constant volume independent of pressure. As such, it is one of the four fundamental states of matter (the others being solid, gas, a ...

, solid or tissue. A sonotrode usually consists of a stack of piezoelectric transducers attached to a tapering metal rod. The end of the rod is applied to the working material. An alternating current oscillating at ultrasonic frequency is applied by a separate power supply unit to the piezoelectric transducers. The current causes them to expand and contract. The frequency of the current is chosen to be the

resonant frequency Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscillatin ...

of the tool, so the entire sonotrode acts as a half-wavelength resonator, vibrating lengthwise with

standing wave In physics, a standing wave, also known as a stationary wave, is a wave that oscillates in time but whose peak amplitude profile does not move in space. The peak amplitude of the wave oscillations at any point in space is constant with respect ...

s at its resonant frequency. The standard frequencies used with ultrasonic sonotrodes range from 20 kHz to 70 kHz. The amplitude of the vibration is small, about 13 to 130 micrometres. Sonotrodes are made of titanium, aluminium or

steel Steel is an alloy made up of iron with added carbon to improve its strength and fracture resistance compared to other forms of iron. Many other elements may be present or added. Stainless steels that are corrosion- and oxidation-resistant ty ...

, with or without heat treatment ( carbide). The shape of the sonotrode (round, square, with teeth, profiled ...), depends on the quantity of vibratory energy and a physical constraint for a specific application. Its shape must be optimized for the particular application. Sonotrodes of small diameter are sometimes called probes. For an ultrasonic welding or cutting application, the sonotrode gives energy directly to the welding contact area, with little

diffraction Diffraction is defined as the interference or bending of waves around the corners of an obstacle or through an aperture into the region of geometrical shadow of the obstacle/aperture. The diffracting object or aperture effectively becomes a s ...

. This is particularly helpful when vibrations ( wave propagation) could damage surrounding electronic components.Design of ultrasonic devices
/ref>

References

See also