Ultrasonic Cleaner Basics: Types, Working Principle, and Benefits

This article provides a comprehensive overview of ultrasonic cleaners, covering their components, working principles, types, and applications. It delves into the advantages of using ultrasonic cleaning methods compared to traditional approaches.

Ultrasonic Cleaner Definition

An ultrasonic cleaner is a device that utilizes ultrasonic frequency waves to clean objects. This cleaning process is known as ultrasonic cleaning.

The ultrasonic frequency range typically spans from 20 kHz to 200 kHz, which falls outside the audible range of human hearing. This method is highly effective for removing dust, dirt, grime, and other contaminants from both outer and inner surfaces of objects without causing physical damage.

Ultrasonic cleaners find applications in diverse fields, including microelectronics, medical devices, hard-disk drives, biomedical engineering, optics, automotive component manufacturing, and jewelry cleaning.

Typical Applications:

• Cleaning oil, grease, and other contaminants in metal industries. Also used to polish compounds before plating.
• Removing flux from PCBs and cleaning them from dust.
• Cleaning jewelry and ornaments.
• Cleaning dental tools by dentists.
• Cleaning glasses, watches, screws, etc.

Ultrasonic Cleaner Components and Working Principle

Image Alt: How Ultrasonic Cleaner Works

The ultrasonic cleaner operates by harnessing ultrasonic energy within the specified frequency band. The process involves the creation of bubbles in a liquid medium using specialized ultrasonic devices. These bubbles rapidly expand and implode against the surface of the object immersed in the tank.

The energy released during the implosion dislodges contaminants from the surface, even in the most inaccessible recesses. The energy required to form these cavitation bubbles is directly proportional to the surface tension and vapor pressure of the liquid.

Figure 1 illustrates the typical components found in an ultrasonic cleaner:

• Ultrasonic generator
• Transducers
• Radiating diaphragm
• Metal tank
• Cleaning agent or aqueous solution

Let’s explore the functions of each of these components:

• Ultrasonic Generator: The generator converts electrical energy from a 50/60 Hz power source into electrical energy at higher ultrasonic frequencies, thereby energizing the transducers. Each transducer requires a minimum voltage (approximately 75%) to become active. Generators are typically equipped with power and frequency sweep controls. Transducers operate within the 18 kHz to 120 kHz range, with an energy density of approximately 100 watts per gallon of fluid.

• Transducers: Electrical energy at ultrasonic frequencies is applied to transducers, which are mounted on the bottom, sides, or both. Two primary types of transducers exist: piezoelectric and magneto-strictive. Both types generate mechanical energy in the form of vibrations, which are then transmitted through the liquid via a radiating plate or diaphragm.

  • Magnetostrictive Transducers: These transducers leverage the principle of magnetostriction, where certain materials expand and contract when exposed to an alternating magnetic field (H-field).

  • Piezoelectric Transducers: These transducers directly convert alternating electrical energy into mechanical energy through the piezoelectric effect. Certain materials undergo dimensional changes when an electrical charge (Q) is applied.

  For more details, refer to the section on Ultrasonic Cleaner Working.

Ultrasonic Cleaner Types

Image Alt: Ultrasonic Cleaner basics and Types

Figure 2 showcases two primary types of ultrasonic cleaners:

• Industry-grade Ultrasonic Cleaner: Typically larger and more powerful for heavy duty cleaning.
• Portable/Desktop Ultrasonic Cleaner: These models are lightweight and compact.

These cleaners are available in various sizes, each operating at different frequencies within the ultrasonic range. Desktop versions typically operate between 20 kHz to 40 kHz and 40 kHz to 70 kHz.

• The 20-40 kHz version is used for cleaning engine blocks, heavy metal parts, and removing greasy oils.
• The 40-70 kHz version is used for cleaning optics, machine parts, dental tools, and other components.
• More powerful versions operate from 70 kHz to 200 kHz and are used for cleaning jewelry, watches, and contact lenses.

Some ultrasonic cleaners offer control over timing and temperature, while others are equipped with power and frequency control.

Benefits of Ultrasonic Cleaning

The following are key benefits of utilizing ultrasonic cleaning:

• Fast Cleaning: Saves valuable time.
• Environmentally Friendly: Reduces the need for harsh chemicals.
• Safe Working Environment: Minimizes exposure to hazardous substances.
• Perfect Removal of Contaminants: Cleans even hard-to-reach areas.
• Energy Efficient: Uses less energy compared to some traditional methods.