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How does ultrasonic cleaning work

How does ultrasonic cleaning work?

Ultrasonic cleaning is considered a highly effective method for removing dirt, debris, and other contaminants from various surfaces due to its use of high-frequency sound waves that create microscopic bubbles which implode, generating a powerful cleaning action that can reach into tight crevices and complex shapes.

Technical details of ultrasonics

Ultrasonic cleaning energy exists in a liquid as alternate rarefaction’s and compressions of the liquid. During rarefaction, small vacuum cavities are formed which collapse, or implode, during compression. This continuing rapid process, called cavitation, is responsible for the scrubbing effect, which produces ultrasonic cleaning. Three factors affecting the scrubbing action are the degree of liquid degassed, the ultrasonic frequency and the chemical characteristics of the liquid at specific temperatures.

Ultrasonic Cavitation

The process of Ultrasonic cavitation, which plays a crucial role in ultrasonic cleaning, is detailed in the below breakdown of the concepts involved:

  1. Cavitation:
    • Cavitation occurs when ultrasonic waves pass through a liquid, causing rapid changes in pressure. In areas of rarefaction (low pressure), microscopic vacuum bubbles or cavities form in the liquid. When these cavities encounter compression (high pressure), they collapse or implode. This rapid collapse generates intense local energy, creating shockwaves and producing extreme heat and pressure in a tiny area, which leads to the cleaning effect.
  2. Scrubbing Effect:
    • The scrubbing effect, essential to ultrasonic cleaning, refers to the physical action of these imploding bubbles. As the bubbles collapse, they generate microjets of fluid that can dislodge contaminants from the surfaces of objects being cleaned. This action is highly effective for cleaning intricate or delicate parts that are difficult to clean through traditional methods.
  3. Factors Affecting Cavitation and Cleaning Efficiency:
    • Degree of Liquid Degassing:
      • If the liquid is degassed (i.e., dissolved gases are removed), cavitation tends to be more consistent and efficient. Dissolved gases can dampen the formation and collapse of bubbles, reducing cavitation intensity.
    • Ultrasonic Frequency:
      • Higher frequencies (e.g., 40 kHz) typically create smaller, faster cavitation bubbles, which are better for cleaning delicate items. Lower frequencies (e.g., 25 kHz) produce larger, more powerful bubbles, which are more effective at removing heavy, stubborn contaminants.
    • Chemical Characteristics of the Liquid:
      • The presence of certain chemicals in the cleaning solution can enhance or hinder cavitation. For instance, surfactants can reduce surface tension and improve the penetration of bubbles into contaminants. Additionally, the temperature of the liquid plays a role—higher temperatures often increase cavitation intensity but must be balanced to avoid damage to sensitive materials.

These factors are carefully controlled in ultrasonic cleaning systems to optimize cleaning efficiency, particularly in industrial applications like cleaning precision parts, medical instruments, or electronics.

Degassing

Degassing is the removal of unwanted air from the liquid. As the cavities form, they fill with air, forming bubbles, which resist collapse and tend to remain suspended in the liquid. These bubbles act as ‘ shock absorbers ‘ which materially reduce cleaning efficiency. The amount of air can be reduced by periodically switching off, or modulating, the sound energy to permit adjacent bubbles to coalesce, float to the surface, and escape. The type of modulation is important, for the correct balance between degassing and cleaning efficiency must be selected for each ultrasonic cleaning application.

The process of Degassing is detailed in the below breakdown of the concepts involved:

Degassing in Ultrasonic Cleaning

Degassing refers to the process of removing unwanted air or dissolved gases from a liquid, which is a critical step in optimizing ultrasonic cavitation. Here's why this is important:

  • Air Bubbles and Cavitation:
    • When ultrasonic waves are applied to a liquid, they create areas of high and low pressure. In the low-pressure areas (rarefaction), small cavities or bubbles form. If the liquid contains dissolved air or gas, these cavities can fill with air, creating bubbles.
    • These air-filled bubbles are less effective in the cavitation process because they resist collapse. The bubble collapse, which is essential for generating the cleaning effect, is less violent when the bubbles are filled with air rather than vapor or liquid. This reduces the intensity of the cavitation and, consequently, the cleaning efficiency.
  • Shock Absorber Effect:
    • The air bubbles act as "shock absorbers." Instead of collapsing rapidly and generating the microjets of fluid and shockwaves needed for cleaning, the bubbles dissipate energy as they collapse more gently. This significantly weakens the cavitation process, leading to poorer cleaning results.

Degassing Process

To maximize cavitation and improve cleaning efficiency, it's important to remove as much air from the liquid as possible:

  1. Modulating the Sound Energy:
    • One way to degas the liquid is by periodically switching off or modulating the ultrasonic energy. This allows air-filled bubbles to coalesce (merge together) and rise to the surface of the liquid. Once they reach the surface, the air bubbles escape from the liquid, reducing the amount of dissolved gas.
  2. Effect on Cavitation:
    • With less dissolved gas, the cavitation bubbles that form are more likely to collapse properly, generating the powerful shockwaves needed for effective cleaning. As a result, the liquid's ability to clean objects improves.
  3. Balancing Degassing and Cleaning Efficiency:
    • It's important to find the right balance between degassing and cavitation intensity. If the modulation is too strong or too frequent, it might reduce the cavitation time, while insufficient modulation could leave residual air in the liquid, reducing cleaning effectiveness.
    • The correct type of modulation depends on the specific ultrasonic cleaning application. For example, delicate cleaning may require less intense modulation, while heavy-duty cleaning may benefit from more aggressive degassing.

Optimizing Degassing for Cleaning Applications

  • Temperature: Higher temperatures can aid in degassing because gases are less soluble in warm liquids. However, care must be taken to avoid damaging sensitive materials.
  • Duration: Allowing the ultrasonic unit to run without cleaning objects (a "cleaning cycle" without items) can help remove gases from the liquid before the cleaning process begins.
  • Frequency of Modulation: The frequency and timing of modulation depend on the type of contaminants and materials being cleaned. For some applications, periodic pauses to allow bubbles to escape may be essential for optimal cleaning.

In summary, effective degassing improves cavitation by minimizing air bubble formation, allowing for more efficient collapse of cavitation bubbles, which results in a stronger scrubbing action and better cleaning performance. This process is an essential component of optimizing ultrasonic cleaning systems.

Frequency

Frequency affects ultrasonic cleaning efficiency by determining the cavity size. Low frequencies generate large but relatively few cavities with high cleaning power. High frequencies generate a great number of small cavities with good penetrating capability. The selection of the correct frequency is difficult, for it varies with each cleaning application. The frequency also affects degassing, with 40 kHz nearly optimum.

Impact of Frequency on Cavitation and Cleaning Efficiency

  1. Low Frequencies (e.g., 25 kHz):
    • Cavity Size: Low frequencies generate larger cavitation bubbles. The bubbles are more powerful when they collapse, creating more intense shockwaves and microjets of fluid.
    • Cleaning Power: Due to the larger bubbles, low-frequency ultrasound produces greater cleaning power. This is beneficial for removing heavier, more stubborn contaminants like grease, oils, and dirt that are strongly adhered to surfaces.
    • Cleaning Detail: While low frequencies are effective at removing tough contaminants, their larger bubbles can be less effective at cleaning very fine or intricate details. The large bubbles may not reach into small crevices or delicate areas as efficiently.
    • Cavitation Density: Because fewer, larger bubbles are created, the cavitation density (number of bubbles per unit volume) is lower compared to higher frequencies.
  2. High Frequencies (e.g., 40 kHz or 100 kHz):
    • Cavity Size: High frequencies generate smaller cavitation bubbles. These smaller bubbles are less powerful in terms of shockwaves and microjets but can collapse with much greater precision.
    • Penetration Ability: The smaller bubbles produced by higher frequencies are much more capable of reaching into tiny crevices, delicate components, or fine surfaces. They can clean more thoroughly in intricate areas, making them ideal for cleaning delicate or complex objects, such as electronic components, medical instruments, or fine jewelry.
    • Cleaning Power: While the cleaning power is lower in terms of raw force, the increased number of cavitation bubbles means that the cleaning action can be very effective at dislodging fine particles or contaminants that are lightly adhered to surfaces.
    • Cavitation Density: Higher frequencies produce a greater number of bubbles, leading to a higher cavitation density, which can result in more uniform cleaning across the entire surface of an object.
  3. Optimal Frequency (e.g., 40 kHz):
    • The frequency of 40 kHz is often considered near-optimal for most general ultrasonic cleaning applications because it strikes a balance between cleaning power and cavitation precision. It produces a good number of medium-sized bubbles that collapse with enough force to provide effective cleaning, while still being small enough to reach detailed areas and penetrate intricate surfaces.
    • This frequency is effective for cleaning a wide variety of items, from industrial parts to sensitive electronic devices, and is typically used in many commercial ultrasonic cleaning systems.

Frequency and Degassing

  • The frequency of the ultrasound also affects the degassing process. At around 40 kHz, cavitation bubbles are small enough to allow for efficient degassing without disrupting the cavitation process itself. This frequency provides a good balance between degassing the liquid (by allowing bubbles to coalesce and rise to the surface) and generating effective cleaning power through cavitation.
  • Lower frequencies (such as 25 kHz) are more aggressive and can produce larger bubbles that don't degas as efficiently, potentially leading to less effective cavitation.
  • Higher frequencies (e.g., 100 kHz) may lead to smaller, more numerous bubbles but can reduce the overall energy for degassing, making it slightly less effective for removing dissolved gases from the liquid.

Selecting the Right Frequency

  • Application-Specific: Choosing the correct frequency for ultrasonic cleaning depends on the nature of the cleaning task:
    • For heavy-duty cleaning of parts with large surface areas or tough contaminants, a low frequency (e.g., 25 kHz) is preferred.
    • For delicate cleaning, such as fine jewelry, electronics, or medical instruments, a high frequency (e.g., 40 kHz or higher) is better, as it will clean efficiently without damaging sensitive components.
    • 40 kHz is often the gold standard because it offers a balance of cleaning efficiency and precision for a wide range of applications.

Conclusion

In summary:

  • Low frequencies (e.g., 25 kHz) are suitable for cleaning larger, tougher contaminants with higher cleaning power but less penetration.
  • High frequencies (e.g., 40 kHz or 100 kHz) provide better penetration into intricate areas and are ideal for cleaning delicate or complex objects.
  • The 40 kHz frequency is often the best balance for general ultrasonic cleaning, offering both effective cleaning and adequate degassing capabilities.

Ultimately, the choice of frequency depends on the specific cleaning needs, the type of contaminants, and the sensitivity of the items being cleaned.

Cleaning efficiency is also effected by the chemical and physical characteristics of the liquid. For best cleaning, the liquid must chemically soften the soil, yet maintain effective cavitation and provide the desired characteristics for rinsing and drying the cleaned parts. Ultrasonic cleaning solutions are broadly characterised as aqueous or non-aqueous. Final selection is dependent upon the overall process considerations for the cleaning application.

The ultrasonic energy is created within a liquid by means of transducers which convert electrical energy into acoustic energy.

Chemical Characteristics of the Cleaning Liquid

  1. Soil Softening:
    • For ultrasonic cleaning to be effective, the cleaning solution should be able to chemically soften or break down the contaminants (e.g., oils, grease, dirt, and other soils). Surfactants, detergents, and other cleaning agents are often added to the liquid to lower the surface tension of the contaminants, making it easier for cavitation bubbles to dislodge them.
    • Surfactants or detergents allow for better interaction between the liquid and contaminants, facilitating their removal by ultrasonic cavitation. The right chemical formulation can make a significant difference, especially for sticky or stubborn contaminants.
  2. Compatibility with Cavitation:
    • The cleaning solution must maintain effective cavitation throughout the cleaning process. Some chemicals might interfere with cavitation by affecting the liquid’s viscosity or surface tension. It’s crucial to ensure that the solution allows for proper bubble formation and collapse during the ultrasonic process.
    • If the liquid is too thick, it may dampen the cavitation effect, reducing cleaning efficiency. Conversely, a solution that is too thin or lacks proper chemicals may not remove contaminants effectively.
  3. Rinsing and Drying Properties:
    • After cleaning, the solution must allow for easy rinsing to remove any residual cleaning agents or dislodged contaminants from the parts. Some cleaning solutions may leave behind residues, which can interfere with further processes (such as coating or assembly).
    • Additionally, the solution should ideally facilitate drying of the cleaned parts. Some cleaning solutions contain agents that promote faster drying by preventing water spots or residue from forming on the surface of the items being cleaned.

Types of Ultrasonic Cleaning Solutions

  1. Aqueous Solutions:
    • Water-based solutions are the most commonly used in ultrasonic cleaning. They can be further classified based on their chemistry:
      • Surfactant-based aqueous solutions: These are commonly used for cleaning oils, greases, and particulate matter. Surfactants lower the surface tension of the liquid, allowing it to penetrate contaminants more effectively.
      • Alkaline solutions: Alkaline cleaning solutions are used for tougher, more stubborn contaminants like oils, heavy grease, or carbon residues.
      • Acidic solutions: These are used for specific cleaning tasks, such as removing rust, scale, or mineral deposits from metal surfaces.
    • The advantages of aqueous solutions include ease of use, non-toxic properties (in many cases), and lower cost. They are ideal for cleaning a wide range of materials, from delicate to industrial components.
  2. Non-Aqueous Solutions:
    • Solvent-based solutions are used when water-based solutions cannot effectively clean certain contaminants. These are typically used for cleaning materials that are water-sensitive, such as certain metals or plastics, or for removing specific oils and greases.
    • Common non-aqueous cleaning agents include organic solvents, petroleum-based liquids, or fluorinated fluids. These can provide better cleaning power for oil, grease, or other non-polar contaminants.
    • However, non-aqueous solutions can be more expensive, have safety concerns (e.g., flammability), and may require special disposal or recycling methods.

Physical Characteristics of the Liquid

  1. Viscosity:
    • The viscosity of the cleaning solution influences its ability to transmit ultrasonic energy. A thicker solution can absorb more of the ultrasonic energy, reducing the cavitation efficiency. Ultrasonic cleaning solutions must have an appropriate viscosity to allow cavitation to occur effectively.
    • A solution with optimal viscosity ensures that cavitation bubbles can form and collapse as intended, generating the scrubbing action necessary for cleaning.
  2. Density:
    • The density of the cleaning liquid can also affect how well it transmits ultrasonic energy. Solutions with higher density may transmit sound waves more efficiently, enhancing cavitation. However, if the density is too high, it might interfere with the cavitation process, limiting cleaning performance.
  3. Temperature:
    • Temperature plays a significant role in the efficiency of ultrasonic cleaning. As the temperature of the solution increases, the activity of cavitation bubbles becomes more energetic. However, too high of a temperature can damage sensitive materials or cause the cleaning solution to degrade.
    • Typically, ultrasonic cleaning is done at temperatures between 40°C and 60°C (104°F to 140°F), though some applications may require higher or lower temperatures depending on the materials being cleaned.

Role of Transducers in Ultrasonic Cleaning

  • Transducers are devices that convert electrical energy into acoustic energy (sound waves) in the ultrasonic cleaning system. They are typically made from materials like piezoelectric ceramics, which generate vibrations when an electrical current passes through them.
  • These vibrations create ultrasonic waves (usually between 20 kHz to 400 kHz) that travel through the cleaning liquid. As these waves propagate, they create alternating high and low-pressure zones, leading to the formation of cavitation bubbles in the liquid. These bubbles implode with great force, generating the scrubbing action that cleans the surfaces of the items being treated.
  • The transducers need to be properly tuned and aligned to ensure uniform distribution of ultrasonic energy across the liquid. If the transducers are not optimized, certain areas of the cleaning tank may experience lower cavitation intensity, resulting in uneven cleaning.

Selecting the Right Cleaning Solution and Transducer Configuration

  • The choice between aqueous or non-aqueous solutions, along with the right chemical additives (such as surfactants), will depend on the nature of the contaminants and the type of materials being cleaned.
  • The effectiveness of cavitation can also depend on the placement and configuration of the transducers. Ensuring that the ultrasonic waves are evenly distributed throughout the cleaning solution will maximize cleaning efficiency.

Conclusion

For optimal ultrasonic cleaning efficiency, the cleaning solution must be carefully selected to achieve the right balance between:

  • Soil softening (ability to break down and remove contaminants),
  • Cavitation effectiveness (solution characteristics that allow efficient bubble formation and collapse),
  • Rinsing and drying (post-cleaning characteristics),
  • Physical properties (such as viscosity, density, and temperature).

By matching the solution's chemical and physical properties to the specific cleaning task and using well-tuned ultrasonic transducers, the cleaning process can be highly effective.

These transducers are similar in function to a radio speaker except they function at ultrasonic frequencies (40,000 Hz) and transmit acoustic energy to a liquid rather than air. The transducers consist of vibrating elements (piezoelectric disc) bolted between thick metal plates. The transducers are bonded to the under side of the active face of the tank containing the cleaning liquid or can be encased in stainless steel for immersion within a liquid. For reliability, many transducer modules are uniformly distributed over the tank base rather than having a single transducer in the centre of the tank working very hard. An electronic generator energises the transducers. The generator transforms the electrical energy from the wall outlet into a suitable electrical form for efficiently energising the transducers at the desired frequencies. All ultrasonic cleaning systems consist of the four fundamental components of transducer, generator, container for liquid and cleaning liquid.

Below is an overview of the fundamental components and working principles of an ultrasonic cleaning system and information to provide  a better understanding of how they all function together in the cleaning process:

  1. Transducers
  • Function: Transducers are the heart of an ultrasonic cleaning system. They convert electrical energy into ultrasonic sound waves (acoustic energy) at ultrasonic frequencies (typically around 40 kHz, but it can range from 20 kHz to 400 kHz).
  • Components:
    • Piezoelectric Disc: At the core of the transducer is a piezoelectric material (often a ceramic disc). When an alternating electric current is applied, the piezoelectric material vibrates at high frequencies, generating the ultrasonic sound waves.
    • Metal Plates: The piezoelectric disc is usually mounted between thick metal plates (often made of brass or steel), which help to amplify the vibrations and transmit the ultrasonic energy more efficiently into the cleaning liquid.
  • Mounting:
    • Under the Tank: In most ultrasonic cleaning systems, the transducers are bonded to the underside of the tank holding the cleaning liquid. The vibrations they generate are transmitted directly into the liquid.
    • Encased in Stainless Steel: In some designs, transducers are encased in stainless steel, allowing them to be immersed directly in the cleaning liquid. This helps to protect the transducer and improve its longevity.
  • Distribution of Transducers:
    • To ensure uniform cavitation across the entire tank, many ultrasonic cleaning systems use multiple transducer modules distributed evenly across the tank base. This prevents uneven cleaning, which might occur if only one transducer is placed in the center, leading to a concentration of ultrasonic energy at that point.
  1. Generator
  • Function: The electronic generator is responsible for powering the transducers. It converts the electrical power from a standard wall outlet (typically 120V AC or 240V AC) into an alternating current (AC) that is suitable for the transducers to generate ultrasonic frequencies.
  • Frequency Control:
    • The generator is responsible for adjusting and maintaining the frequency of the ultrasonic waves, which can be set to specific levels depending on the cleaning requirements. For example, a common frequency for general ultrasonic cleaning is 40 kHz, but higher or lower frequencies may be used for specialized tasks.
    • The generator also ensures that the transducers operate efficiently, producing the correct type of energy required to create cavitation in the cleaning solution.
  1. Tank (Container for Liquid)
  • Function: The tank holds the cleaning liquid and is designed to allow sound waves to travel through the liquid efficiently. The tank is typically made from durable materials like stainless steel to withstand the forces created by the ultrasonic waves and to prevent corrosion from the cleaning solutions.
  • Design Considerations:
    • The tank needs to be deep enough to ensure that the items being cleaned are completely submerged in the liquid.
    • Vibration Resistance: The material and structure of the tank must also be able to handle the vibrations generated by the transducers without causing any damage or significant energy loss.
  1. Cleaning Liquid
  • Function: The cleaning liquid (or cleaning solution) plays a key role in the cleaning process. Its chemical composition is designed to enhance cavitation and remove contaminants effectively. The liquid must allow the formation of cavitation bubbles and facilitate their collapse with sufficient energy to clean the surfaces of the items.
  • Types of Cleaning Liquids:
    • Aqueous Solutions: Water-based solutions that may contain surfactants, detergents, or other chemicals to aid in breaking down oils, dirt, and other contaminants.
    • Non-Aqueous Solutions: Solvents used for cleaning materials that may be damaged by water, or for contaminants that are not easily dissolved in water.
  • Effect on Cavitation:
    • The properties of the liquid, such as viscosity, density, and temperature, directly affect cavitation. A liquid with the correct balance of these properties will allow the ultrasonic waves to create and collapse bubbles efficiently, resulting in effective cleaning.

How These Components Work Together

  • The generator sends electrical energy to the transducers, which convert it into high-frequency ultrasonic waves.
  • The transducers transmit the sound waves into the cleaning liquid.
  • As the ultrasonic waves propagate through the liquid, they create alternating high-pressure and low-pressure zones. In the low-pressure zones (rarefaction), cavitation bubbles form, which grow and collapse as the pressure fluctuates.
  • These rapidly collapsing bubbles generate high-energy microjets of fluid that dislodge contaminants from the surfaces of the items being cleaned.
  • The tank holds the cleaning solution and items being cleaned, ensuring uniform distribution of the ultrasonic waves and protecting the transducers.

Conclusion

An ultrasonic cleaning system relies on four main components: transducers, generators, tanks, and cleaning liquids. Each plays an essential role in ensuring the system operates efficiently:

  • Transducers convert electrical energy into acoustic energy to create cavitation.
  • The generator controls and powers the transducers at the correct frequency.
  • The tank holds the liquid and facilitates the transmission of ultrasonic energy.
  • The cleaning liquid provides the right environment for cavitation to occur and aids in the removal of contaminants.

By understanding how these components work together, you can ensure that ultrasonic cleaning systems perform optimally for a variety of cleaning applications.

The performance and reliability of the system depends on the design and construction of the transducers and generators. The overall effectiveness of the cleaning is dependent on the cleaning liquid. The size of the tank is dependent upon the size or quantity of the parts being cleaned. The number of transducers and generators is determined by the tank size. The choice of cleaning liquid depends upon the parts being cleaned and contaminants to be removed.

There are some essential factors that contribute to the performance and reliability of an ultrasonic cleaning system. These factors involve the design and construction of the key components (transducers, generators, tank, and cleaning liquid), as well as their relationship to each other. Here's a deeper look at how each factor influences the overall system:

  1. Transducer and Generator Design and Construction
  • Transducers:
    • The quality and construction of the transducers directly affect the ultrasonic cleaning efficiency. The piezoelectric material used (typically ceramic) and its mounting between the metal plates should be of high quality to ensure proper vibration transmission. A high-quality transducer will produce consistent and uniform cavitation throughout the liquid, ensuring effective cleaning.
    • The placement and number of transducers in the tank are also important. Multiple transducers distributed across the tank ensure even coverage, preventing areas where cavitation may be weak, which could lead to uneven cleaning.
  • Generators:
    • The generator is responsible for converting electrical energy into the correct ultrasonic frequencies (usually between 20 kHz to 400 kHz). A well-designed generator will provide a consistent and stable power output to the transducers, ensuring that the ultrasonic waves are at the correct frequency and strength for optimal cleaning.
    • The generator's efficiency is crucial because it determines the amount of energy that gets converted into acoustic energy. Any inefficiency in this process can reduce the cleaning power and lead to inconsistent cavitation. For best results, the generator must be tuned to work well with the transducers' specifications.
  1. Cleaning Liquid
  • The choice of cleaning liquid is perhaps the most important factor in determining the overall cleaning effectiveness. The liquid needs to facilitate the cavitation process and aid in contaminant removal without damaging the parts being cleaned.
    • Chemical Composition:
      • The liquid should have the right balance of surfactants, detergents, or other chemicals that break down or emulsify the contaminants (e.g., oils, grease, particulate matter).
      • The cleaning solution should also be compatible with the materials being cleaned. For example, some metals or plastics may require special cleaning liquids to avoid corrosion or surface damage.
    • Effect on Cavitation:
      • A liquid that is too viscous can dampen the cavitation process by reducing bubble formation and collapse efficiency. Conversely, a liquid that is too thin may not have enough energy to effectively dislodge contaminants.
      • The temperature of the cleaning liquid also plays a role in cavitation. Higher temperatures generally improve cleaning by increasing the energy of the cavitation bubbles, but excessive heat could damage delicate parts.
    • Type of Solution:
      • Aqueous solutions (water-based with detergents, solvents, or alkalines) are typically used for general cleaning, especially for items that can tolerate water.
      • Non-aqueous solutions (solvents or oils) are used for specific contaminants or sensitive parts that cannot be exposed to water.
    • Rinsing and Drying: After the cleaning process, the liquid must be able to facilitate easy rinsing of the cleaned parts and not leave any residue behind. The drying characteristics of the liquid also affect the final result, particularly for sensitive components.
  1. Tank Size and Capacity
  • The tank size is determined by the size and quantity of the items being cleaned. The tank must be large enough to hold the parts and the cleaning liquid while ensuring uniform cavitation. A larger tank may require multiple transducers and generators to ensure consistent energy distribution throughout the liquid.
  • Tank Dimensions:
    • The depth, width, and length of the tank affect the path that the ultrasonic waves travel. A well-designed tank ensures that the ultrasonic waves reach all areas of the liquid and the items being cleaned.
    • For larger parts or greater quantities of parts, a larger tank with a higher number of transducers is necessary to maintain effective cavitation throughout the cleaning process.
  • Transducer and Generator Placement:
    • As the tank size increases, the number of transducers and generators must also increase to ensure that ultrasonic energy is evenly distributed throughout the tank.
    • In larger tanks, multiple transducer modules are placed across the tank base to avoid the creation of "dead spots" where cavitation might be weak, leading to uneven cleaning.
  1. Number of Transducers and Generators
  • Transducer Number:
    • The number of transducers directly correlates with the size of the tank. A larger tank requires more transducers to ensure uniform cavitation, especially when cleaning large or numerous parts. The transducers should be distributed evenly across the tank base to prevent concentrated areas of intense cavitation and weak spots.
    • More transducers lead to a more uniform distribution of ultrasonic energy, which results in more effective and thorough cleaning.
  • Generator Power:
    • The number of generators is also determined by the size of the tank. Larger tanks or systems that require higher ultrasonic power might need multiple generators to provide the necessary power for the transducers.
    • Each generator typically energizes a specific set of transducers. Using multiple generators ensures that each set of transducers receives the correct amount of power to produce effective cavitation.
  1. Determining the Cleaning Liquid Based on the Parts and Contaminants
  • The choice of cleaning liquid depends heavily on two main factors:
    • Material of the Parts: Different materials (e.g., metals, plastics, ceramics) react differently to cleaning solutions. For example, certain metals may require acidic solutions to remove rust or scale, while plastics may need milder, non-water-based solvents to avoid damage.
    • Type of Contaminants: The type of contaminants on the parts (e.g., grease, oils, particulate matter, rust, or scale) determines the appropriate liquid. Alkaline solutions are good for removing oils and grease, while acidic solutions are better for mineral deposits and corrosion.

Conclusion

The performance and reliability of an ultrasonic cleaning system depend on the coordination and design of its components:

  • Transducers must be efficiently designed and distributed to ensure consistent cavitation.
  • The generator must provide reliable and efficient power to the transducers.
  • The tank must be appropriately sized and configured to handle the parts being cleaned.
  • The cleaning liquid must be tailored to the specific needs of the materials being cleaned and the contaminants being removed.

All these factors work in concert to determine the overall cleaning effectiveness, and any imbalance in the design of one component can affect the overall efficiency and reliability of the cleaning system.