CNC Machined Metal Parts Cleaning

A Basic Guide to Manufactured Parts Cleaning: Importance And Methods

The manufacturing process is dirty and involves numerous pollutants. Cleaning parts can remove all types of remaining surface dirt, including casting sand, iron filings, rust, abrasives, oil, dust, etc. Because the cleanliness of parts after cleaning will directly impact the assembly quality and service life of construction machinery, parts cleaning is a vital part of the manufacturing process.

This article will explore a basic guide to manufactured parts cleaning, including its importance, cleaning methods, features, considerations, and more.

A Brief Introduction to Parts Cleaning

Part cleaning is crucial in numerous industrial processes as a prelude for surface finishing or protecting sensitive components. Electroplating is very sensitive to the cleanliness of the part, as molecular layers of oil might prevent the coating from adhering.

In terms of cleaning processes, there are solvent cleaning, hot alkaline detergent cleaning, electro-cleaning, and acid etch. The most typical industrial test for cleanliness is the water-break test, where the surface is thoroughly cleaned and held vertically.

Why Are Manufactured Parts Cleaning So Important?

Parts cleaning is a critical part of manufacturing, particularly preparation for finishing operations. We must maintain industrial parts clean in any industrial setting and for any industrial process.

Why is manufactured parts cleaning so important? Here we give some reasons:

  1. Parts cleaning helps to mitigate any process flaws or errors.
  2. Cleaning the parts help keep the machinery running smoothly.
  3. Keep the manufacturing process working efficiently and increase tooling life.
  4. Avoid damaging, corroding, or contaminating sensitive industrial parts and components.
  5. Promote quality in nearly every facet of an industrial operation.

Manufactured Parts Cleaning Method

The appropriate cleaning method must be chosen to effectively clean the parts based on their material, structural characteristics, pollution level, and cleanliness standards. The following is the common cleaning method for manufactured parts.

Hand Washing

As the name implies, hand washing means someone physically cleans the part with their hands. Having someone in charge of hand washing is beneficial for cleaning parts.


  • Hand washing is labor intensive because it taxes shop employees responsible for manually cleaning parts.
  • It is time intensive, requiring time that belongs to other process tasks.
  • It is costly; while the equipment costs are low, the personnel costs involved with manual cleaning quickly build up.
  • Some manufactured parts may be exceedingly unclean, and hand washing alone is insufficient to clean them adequately.

Aqueous Cleaning

Aqueous cleaning’s principal solvent is water. We can add surfactants and detergents, emulsifiers, inhibitors, anti-foaming agents, PH buffers, builders, and chelating agents. It is possible to remove different substances more effectively by adjusting the PH of the aqueous solution.

Alkaline aqueous solutions remove salts, oxides, organic soils, metal chips, and grease. In contrast, acidic aqueous solutions remove scale, rust, and oxides from metals. Alkaline solutions are the most prevalent sort of aqueous solutions and are effective within a range of temperatures.


  • Aqueous cleaning is much healthier for the environment and those who have to operate the parts cleaners.
  • Aqueous cleaning offers a safer working environment.
  • The cost of aqueous cleaning is lower.

Solvent Degreasing

In solvent degreasing, a cleaning chemical is used on a part’s surface by spraying, brushing, or wiping. This method removes any oil, grease, dirt, loose particles, or other contaminants that may be present on the surface.

Solvent degreasing is a good choice for cleaning most electronic assemblies, electrical components, and metals. Parts are often dried at a high temperature. It is possible to clean almost any size or shape of a part.


  • A small degreasing operation is relatively simple to set up.
  • Minimal ventilation is required.
  • Emissions are lower, and liquid solvents are safer to handle than vapor degreasing.
  • Solvent disposal is complicated and expensive.
  • Using petroleum and mineral solvents may exist a significant risk of fire.
  • Emissions remain relatively high, with negative environmental consequences.

Vapor Degreasing

In vapor degreasing, we can use solvents to dissolve contaminants on a part and then remove them by dripping off the part. Vapor degreasing can remove excess oil, grease, wax, and other non-water soluble particles of industrial parts. It is a practical choice for cleaning parts to finish procedures like painting, welding, soldering, and bonding.

Vapor degreasing uses a basin of solvent with a heating coil to bring the solvent to a boil. As this solvent evaporates during the operation, it rises to the chamber’s fill line. And following vaporized solvent will condense on the colder industrial part. At this stage, the liquid solvent dissolves the grease on the industrial part. The liquid solvent beads and whatever contaminants they contain then flow off the part.   


  • N-propyl bromide (nPB)-based solvents are environmentally friendly, non-flammable, non-chlorinated, and non-hazardous.
  • Some vapor degreasing systems may recover the solvent, making this method reasonably cost-effective.
  • Vapor degreasing is expensive and inefficient when compared to other cleaning methods.

Ultrasonic Cleaning

Ultrasonic cleaning employs cavitation bubbles created by high-frequency pressure (sound) waves to agitate a liquid. The agitation exerts strong forces on impurities clinging to metals, plastics, glass, rubber, and ceramic substrates. This process can also penetrate blind holes, fissures, and recesses. The result is to eliminate any remnants of contaminants that are firmly adhered or ingrained onto solid surfaces.

Ultrasonic cleaning may remove contaminants like grease, algae, fungi, bacteria, lime scale, dust, dirt, oil, pigments, rust, polishing compounds, flux agents, fingerprints, soot wax, mold release agents, and biological soil. It is a perfect choice for medical, pharmaceutical, aerospace, automotive,  and engineering industries, etc.


  • It can be used for various workpiece sizes, shapes, and materials.
  • Ultrasonic cleaning can reduce hazardous cleaning solvents.
  • Short cycle times save time and money and boost plant productivity.
  • Industrial parts are less likely to be damaged because the ultrasonic cleaning process cleans the parts gently.
  • It may not be necessary to disassemble the part before cleaning. And reduced labor costs equate to improved profits.
  • Ultrasonic cleaning’s high-intensity vibrations may damage electronic components like gyroscopes, accelerometers, and microphones.

Acoustic Cleaning

Acoustic cleaning is most commonly used in storage systems, material handling systems, and huge pieces of equipment. The method removes material accumulation on surfaces by producing intense sound waves that shake particulates away from surfaces.


  • Acoustic cleaning is easy to operate.
  • Repetitive use during operations typically results in fewer unplanned shutdowns.
  • Reducing buildup on heat exchange surfaces nets lower energy usage.
  • Minimizes cross-contamination by ensuring that the cleansed environment is completely emptied.
  • Acoustic cleaning is more suitable for storage systems, large material handling systems, boilers, and spaces. 

Parts Washer Cleaning

A parts washer is typically a cabinet-type machine. It can remove impurities or debris from industrial parts such as metal chips, fluids, dirt, filth, carbon, oil, grease, mold-releasing agents, ink, paint, and corrosion.  It is designed to clean, degrease, and dry bulk loads of small or big parts.

Parts washers for industrial parts can be solvent-based or aqueous-based. Solvent-based type uses chemical solvents to remove contaminants or debris. And in the aqueous-based type, water and detergent combine with heat and mechanical energy to clean parts.


  • You may not need to disassemble the part before cleaning. 
  • Short cycle times save time and money and increase plant efficiency.
  • Parts washer cleaning can be used for various workpiece shapes, sizes, and materials.

How to Clean the CNC Machined Parts?

It is vital to clean precision CNC machined parts in the manufacturing industry properly. We should know five typical cleaning methods: scrub, boil, spray washing, vibration cleaning, and ultrasonic cleaning.


Scrubbing is easy to operate but is inefficient. Scrub the parts with cotton yarn or a brush in a container filled with diesel, kerosene, or other cleaning solvents. Generally speaking, gasoline is unfit for use in this method because its fat-soluble qualities can be harmful to human health. The scrub method is only suited for prototypes or small batches of small parts.


You must place the parts that require cleaning in the container and heat them up. Please note that: 

1. The container’s frame must be made of steel.  

2. The final temperature should range from 85 to 90℃. 

3. Use the stove to boil for at least three minutes.

Spray Washing

Spray washing has a good cleaning effect and high production efficiency. To remove oil stains, you need to spray a cleaning fluid at a specific pressure and temperature onto the part’s surface. This method is appropriate for cleaning parts with simple shapes and minimal surface grease spots.

Vibration Cleaning

Just place the parts you want to clean on the cleaning rack or cleaning basket of the vibration cleaning machine, and then immerse them in the cleaning liquid. The cleaning machine’s vibration simulates the manual rinsing action and the chemical action of the cleaning fluid to eliminate oil stains.

Ultrasonic Cleaning

The ultrasonic cleaning machine uses the principle of ultrasonic vibration to remove oil, radioactive substances, dirt, and other substances from the surface of various mechanical parts. This method usually cleans the parts with complex shapes and stringent cleanliness standards, such as medical equipment, optical parts, automobile parts, electronic parts, etc.

7 Things to Consider When Cleaning the CNC Machined Parts

I believe that everyone has a deeper understanding of manufactured parts cleaning through the above. Next, I will continue introducing the considerations of CNC machined parts cleaning to help your project run more smoothly.

When we clean parts, we should pay attention to the following Considerations:

  1. Easy first and then the complex one. That is to say, we should remove the soil on the surface of the parts first and then clean the interior of the parts; Similarly, clean the lightly soiled parts first, then clean the heavily soiled parts.
  2. The aqueous-based detergents can be diluted, rinsed, and shaken for cleaning; the solvent-based detergents should not be in contact with the flame and should not be diluted with water.
  3. We should use different cleaning methods for different kinds of stains (oil, scale, rust).
  4. Thoroughly clean the surface of the parts, and at the same time, protect the parts from damage.
  5. When using solvent-based cleaning detergents, keep the workplace well-ventilated.
  6. The cleaned workpiece can’t be assembled immediately. We should cover the cleaned workpiece with moisture-proof paper to make it dry faster and prevent dust from it.
  7. The detergents should be non-corrosive to metal workpieces, non-flammable, safe and light to pollute, and has a remarkable degreasing effect.


With the rapid development of industrialization, people have higher and higher requirements for the quality and surface of metal workpieces. After the metal workpiece is produced, it will inevitably be stained with oil, stains, or mixed adhesions. Parts Cleaning can keep equipment running efficiently and ensure high-quality machining of mechanical parts.

At LEADRP, we strive to provide the best CNC machining service for different materials to meet the most advanced applications. We believe that sharing design and manufacturing tips can help our customers make the right choices for your product. You can reach us by email or online chat tool, we are happy to help with your project.


Parts cleaning – From Wikipedia.

PARTS CLEANING – From Products Finishing.

The Importance of Cleaning Manufactured Parts – From Alliance.

Industrial Parts Cleaning 101: Understanding Methods, Costs, Pros and Cons – From UltraSonic LLC.

What Is Aqueous Cleaning? – From AEC Systems, LLC.


Benefits of vapor degreasing:


  1. Vapor degreasing is a viable option in cases where water-based systems are impractical.
  2. Some vapor degreasing systems can capture and reclaim the solvent, which makes the process relatively economical.
  3. N-propyl bromide (nPB)-based solvents are environmentally friendly compared to some other solvents. Additionally, nPB-based solvents are non-flammable, non-chlorinated, U.S. EPA SNAP approved, non-hazardous waste, and non-ozone depleting.

Both can be effective cleaning methods, depending on the specific context. To choose the proper cleaning solution, you must first understand how these two approaches differ in their work.


In aqueous cleaning, water-based detergents emulsify and encapsulate contaminants so they can be washed away.


Solvent-based detergents enable the cleaning solution's chemical dissolution of oils and greases.

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