Turbulent Cleaning vs. Targeted Cleaning: Understanding Two Core Industrial Cleaning Processes

Overview

Turbulent cleaning and targeted cleaning are two common process stages used in modern industrial cleaning systems. They are not competing technologies. Instead, they serve different purposes and are often combined in the same cleaning system.

In simple terms, turbulent cleaning provides broad surface coverage, while targeted cleaning focuses cleaning force on difficult-to-reach or critical areas.

This article explains the operating principles, application boundaries, and combination logic of these two industrial cleaning processes, including insertion cleaning and plug-sealing cleaning for internal passages and cavities.

1. Turbulent Cleaning: Broad Coverage Across the Workpiece

Turbulent cleaning uses high-flow cleaning fluid to create a strong turbulent flow inside the cleaning chamber. The fluid moves in multiple irregular directions, continuously flushing the surfaces of the workpiece.

Compared with laminar flow, turbulent flow creates more complex fluid movement and multidirectional mechanical impact. This helps loosen and remove contamination attached to the workpiece surface.

How Is Turbulent Cleaning Achieved?

Turbulent cleaning is commonly implemented in two ways:

• High-flow pump and nozzle systems: A high-flow pump and specially arranged nozzles create fluid circulation inside an enclosed cleaning chamber.
• Robot-assisted workpiece movement: A robot moves and rotates the workpiece through different orientations so that multiple surfaces are exposed to the cleaning flow.

The second approach is commonly used in robotic industrial cleaning systems, especially when the workpiece has complex external geometry.

Advantages and Limitations

The primary advantage of turbulent cleaning is overall coverage. As long as a surface is exposed to the cleaning flow, it can receive mechanical cleaning action, even when the workpiece has a relatively complex shape.

However, the cleaning force is distributed across a relatively large area. This means turbulent cleaning alone may not be sufficient for:

• Strongly adhered contamination
• Deep holes
• Blind holes
• Internal oil passages
• Narrow grooves
• Other difficult-to-access areas

These areas may require targeted cleaning.

2. Targeted Cleaning: Focused Jet Cleaning for Critical Areas

Targeted cleaning directs a cleaning nozzle toward a specific location on the workpiece, such as:

• Port openings
• Blind holes
• Grooves
• Weld seams
• Threaded holes
• Oil passages
• Other critical internal features

Because the cleaning jet is concentrated on a defined location, it can provide a stronger local cleaning effect than a general turbulent flow.

Targeted Cleaning and Positioning

Targeted cleaning is often combined with positioning technology and can therefore be referred to as targeted positioning cleaning.

The process typically involves:

1. Identifying the target position through mechanical positioning or vision-based positioning.
2. Determining the required nozzle coordinates.
3. Moving the nozzle or robot to the target location.
4. Applying a focused cleaning jet to the specified area.

For example, a robotic cylinder head cleaning system for a six-cylinder diesel engine can use a targeted cleaning unit to process hundreds of individual holes on the cylinder head.

The Main Limitation: Cycle Time

Targeted cleaning provides concentrated cleaning action, but each target requires the nozzle to reach a specific position.

Therefore, as the number of cleaning points increases, the required cycle time generally increases as well.

For this reason, targeted cleaning is normally applied to critical areas rather than the entire workpiece surface.

3. How Turbulent and Targeted Cleaning Work Together

The relationship between the two processes can be summarized as:

Turbulent cleaning provides overall coverage; targeted cleaning addresses critical areas.

A typical process sequence is:

Turbulent cleaning → Targeted cleaning → Rinsing → Drying

Turbulent cleaning is usually performed first to remove the majority of contamination from the overall workpiece surface. Targeted cleaning then focuses on areas where the required cleanliness level cannot be achieved through general cleaning alone.

This sequence also helps prevent contamination removed during targeted cleaning from being redistributed onto surfaces that have not yet received overall cleaning.

For high-cleanliness applications, rinsing is often added after the targeted cleaning stage to remove residual cleaning fluid and suspended particles.

Application Examples

For a new energy vehicle transmission housing, a robotic high-pressure cleaning system may combine turbulent cleaning, targeted cleaning, and high-pressure cleaning to address both external surfaces and critical internal areas.

For a battery housing, the process may be configured as:

Spray Cleaning → Robotic Targeted Cleaning → Rinsing → Air Blow-Off → Vacuum Drying

The exact process configuration depends on the workpiece geometry, contamination type, cleanliness requirements, and production takt.

4. Two Specialized Forms of Targeted Cleaning

Targeted cleaning can be adapted to different internal structures. Two common approaches are insertion cleaning and plug-sealing cleaning.

4.1 Insertion Cleaning

Insertion cleaning moves the cleaning nozzle into an internal passage or hole to establish a direct cleaning flow.

It is particularly suitable for:

• Deep holes
• Long oil passages
• Internal channels
• Angled oil passages

For example, commercial vehicle engine block cleaning systems can use insertion cleaning for main oil passages, while crankshaft cleaning systems can use high-pressure insertion cleaning for angled oil holes.

The key characteristic is that the nozzle physically enters the passage so that the cleaning jet can reach areas that cannot be effectively treated from the outside.

4.2 Plug-Sealing Cleaning

Plug-sealing cleaning uses a sealing mechanism to close an opening and force cleaning fluid through an internal cavity or passage.

This approach is suitable for:

• Water jackets
• Internal cavities
• Oil passages
• Large enclosed internal volumes

For example:

• Heavy-duty axle housing cleaning systems may use plug-sealing cleaning for internal oil passages.
• Cylinder head cleaning systems may use dual-station plug-sealing cleaning for water jackets.
• Motor housing cleaning equipment may incorporate plug-sealing cleaning for internal oil passages.

Both approaches are extensions of targeted cleaning for specific workpiece geometries.

Insertion cleaning is generally suited to long and narrow passages, while plug-sealing cleaning is suited to larger enclosed cavities where controlled fluid circulation is required.

5. How to Select the Right Cleaning Process

The appropriate combination of turbulent and targeted cleaning should be determined by the workpiece structure, cleanliness requirements, contamination characteristics, and production takt.

5.1 Workpiece Geometry

For components with relatively simple geometry and mainly external contamination, turbulent or spray cleaning may be sufficient.

For components with deep holes, blind holes, internal cavities, or complex passages, targeted cleaning should normally be considered.

5.2 Cleanliness and Particle Requirements

As cleanliness and particle-size requirements become more demanding, more attention may need to be given to difficult-to-reach areas.

Targeted cleaning, insertion cleaning, or plug-sealing cleaning may be required to achieve the specified acceptance criteria.

5.3 Production Takt

The number of targeted cleaning points has a direct influence on cycle time.

When a component contains a large number of cleaning points and the required takt is short, the system may need:

• Multiple robots
• Parallel cleaning stations
• Optimized nozzle paths
• Automated positioning
• Simultaneous processing of multiple features

5.4 Contamination Characteristics

Loose dust and general surface contamination can often be addressed primarily through turbulent or spray cleaning.

More strongly adhered contamination, machining chips, core sand, oxide scale, and other difficult residues may require concentrated high-pressure cleaning at specific locations.

Frequently Asked Questions

Q: Is turbulent cleaning the same as ultrasonic cleaning?

No.

Turbulent cleaning primarily relies on the mechanical flushing and impact of moving cleaning fluid to remove contamination.

Ultrasonic cleaning relies on cavitation, where microscopic bubbles form and collapse in the cleaning liquid, generating localized mechanical effects.

The two technologies therefore use different cleaning mechanisms and may be suitable for different applications. Turbulent cleaning is commonly used for broad-area industrial cleaning, while ultrasonic cleaning is often considered for precision components, small parts, and applications with many closely spaced features.

Q: Does more targeted cleaning always mean better cleaning?

No.

Increasing the number of targeted cleaning points also increases nozzle travel and processing time. This can increase cycle time and system complexity.

A more practical approach is to first use turbulent cleaning to provide broad coverage, then apply targeted cleaning only to the areas that require additional cleaning performance.

The final number and location of targeted cleaning points should be determined through process validation.

Q: What is the difference between insertion cleaning and plug-sealing cleaning?

Insertion cleaning places the nozzle inside a hole or passage and directs the cleaning flow along the internal channel. It is suitable for long and deep passages.

Plug-sealing cleaning seals an opening and forces cleaning fluid through an internal cavity or passage. It is more suitable for larger enclosed spaces.

In simple terms:

• Insertion cleaning: long and narrow internal passages
• Plug-sealing cleaning: larger and enclosed internal cavities

Q: Why does the cleaning process need to follow a specific sequence?

Process sequence affects how contamination moves through the cleaning system.

A commonly used principle is:

Coarse cleaning before fine cleaning → Overall cleaning before localized cleaning → Cleaning before rinsing → Deburring before cleaning

The exact sequence should still be determined according to the workpiece, contamination characteristics, equipment configuration, and process validation.

If localized cleaning is performed before overall cleaning, loosened contamination may be redistributed onto other surfaces. A properly designed sequence helps prevent recontamination and improves overall process consistency.

Conclusion

Turbulent cleaning and targeted cleaning should not be viewed as competing processes.

Turbulent cleaning provides broad coverage, while targeted cleaning delivers concentrated cleaning action to critical areas.

For complex automotive and industrial components, the most effective solution is often a combination of both processes, followed by rinsing and drying.

The final process design should consider:

• Workpiece geometry
• Internal passages and cavities
• Contamination type
• Cleanliness and particle-size requirements
• Production takt
• Number of targeted cleaning points
• Required drying performance
• Future production flexibility

For applications involving deep oil passages, blind holes, water jackets, or complex internal cavities, insertion cleaning and plug-sealing cleaning can further extend the cleaning capability of an automated system.

Big Bird Industrial develops customized industrial cleaning systems for automotive powertrain components, new energy vehicle components, and other precision industrial parts, with process configurations tailored to specific workpiece and cleanliness requirements.