Bead Blasting Overview

How does Bead Blasting Work?

Bead blasting is a type of abrasive blasting that involves the use of tiny beads to clean or etch a surface. The beads are accelerated by the gas and hit the surface at high speed, removing any dirt or debris. So, how does bead blasting work?

Firstly, you should put the surface to be bead blasted in a chamber. After that, the compartment is sealed and pressured with air. The abrasive material enters the chamber from the nozzle, and the blast of abrasive particles impacts the workpiece’s surface. The impact of the blast eliminates particles or impurities from the workpiece’s surface and smooths or polishes it.

Bead blasting can provide various finishes, ranging from matte to highly polished finish. The finish obtained relies on the size and type of the abrasive particles employed and the air stream pressure.

What Metals Can be Bead Blasted?

The bead blasting process gives metal a matte finish, removes rust from metal, and prepares it for painting. Many metals can be bead blasted, including aluminum and titanium.

Bead Blasting Aluminum

Aluminum that has been bead-blasted is an excellent material for many purposes. It is robust, long-lasting, and lightweight, making it ideal for usage in manufacturing, construction, and other sectors. Furthermore, bead-blasted aluminum is corrosion and weather-resistant, making it a perfect choice for outdoor applications.

Bead Blasting Titanium

There are many applications for titanium that have been bead blasted. Bead-blasted titanium has a clean and clear surface ideal for jewelry, high-performance sporting equipment, marine parts, and heavy-duty industrial parts.

Among the reasons titanium is bead-blasted are:

• Remove a thin layer of material from the titanium’s surface to smooth it.
• To remove a titanium layer from the part’s surface in preparation for coating.
• To give titanium a semi-permanent color or finish.

Tools Used for a Bead Blast Finish

Choosing the right tool can make your bead blasting process more productive with less effort. Let’s look at the equipment and materials needed for the best results.

Bead Blasting Media

The medium itself is an indispensable bead-blasting material. Two beads are commonly used for bead blast surface finish: glass and steel.

Glass Beads

Glass beads come from lead-free, soda-lime glass that is shaped into spheres. Glass beads are more eco-friendly and can be recycled up to 30 times. Glass bead blasting is gentler than other abrasive blasting methods.

Steel beads

Steel beads come from molten steel designed into a round object using a round die. They are less expensive alternatives since they are long-lasting and allow for several recycling cycles. Steel beads are more effective at eliminating unwanted textures from metal surfaces.

Bead Blaster Cabinet

Selecting a high-quality bead blaster cabinet can assure the safety of the operation’s people. A top-notch bead blaster cabinet must be made of solid material. Steel is an excellent choice in this situation since it is a strong and long-lasting material. Steel cabinets often have a longer lifespan and can resist the high pressure associated with the operation.

Similarly, the legs of the bead blaster cabinet must be capable of supporting the cabinet, the bead-blasting media, and the workpieces. Weak legs will frequently wobble and be unsteady, putting the operator at risk. Furthermore, it will be frightening if your tool malfunctions during the bead blast finish.

A quality bead blaster cabinet should include some essential features:

Seamless Cabinet Sealing

The interior of the bead blaster cabinet must have a tight seal. The most effective seals prevent debris and dust within the cabinet from escaping. Inhaling dust and debris from bead blasting can pose many health hazards for humans.

View Window Protection

The view glass is a part of the bead blasting cabinet that many people ignore. Large windows allow you to see parts and work inside the cabinet more clearly. Nonetheless, window protection is the most critical consideration. Some glass beads may develop frosting on the glass over time. As a result, they significantly reduce visibility. As a result, placing replaceable protective sheets on your view windows is an excellent practice, making a bead blast process for extended periods without trouble.

Bead Blaster Gun

A bead blast finish is impossible to achieve without a bead blasting gun. There are several gun designs, and some may be rather sophisticated.  You can operate a bead blaster gun with a foot or hand pedal. Blast guns with foot pedals are frequently more comfortable for extended bead blasting sessions. Prolonged bead blasting with a trigger blaster gun can tire your hands.

Bead Blaster Gloves

It would be best if you took care of safety and comfort when doing bead blasting. Bead blasting gloves can come in handy in this situation. They allow you to apply a bead blast finish in the cabinet securely and pleasantly. Typically, these gloves are attached to the cabinet. Bead blaster gloves would help protect your hands from blasts. They also help you get a good grip on the bead blaster gun.

The Advantages And Disadvantages of Bead Blasting

A bead blast finish provides a smooth, clean, and visually attractive surface to your CNC machined part. Bead blasting may be used on many materials, including strong metals such as aluminum, titanium, and stainless steel, soft metals such as brass or copper, and even plastic.

While bead blasting has utility and versatility, you should also consider some disadvantages of it. Below will describe the advantages and disadvantages of bead blast finish used in projects.

Advantages of Bead Blasting:

• Bead blasting is one of the more economical and less aggressive solutions for surface finishing.
• A part’s base color is not altered by bead blasting, resulting in a brighter surface finish.
• Bead media may be reused many times before replacement, and you can recycle glass beads up to 30 times.
• Bead blasting is environmentally friendly since the glass beads come from lead-free material and do not leave any harmful residues.
• You can mask some surfaces of the part from the bead blaster. Bead blasting is excellent for delicate parts.

Disadvantages of Bead Blasting:

• More rigid surfaces require more time to bead blast.
• Glass bead blasting doesn’t allow for paint adherence because it doesn’t leave a profile.
• The bead blasting process would remove a small quantity of material from the part. It may not be suitable for applications that require strict tolerances.
• The bead blasting process requires manual operation by a trained operator.  The skill of your operator will have a significant impact on the final bead blasting outcome.

Applications of Bead Blasting

Manufacturers use bead blast finishes to achieve a uniform surface finish and improve part durability. In addition, bead blasting can be perfectly matched with various materials for various applications.

Functional applications of bead blasting include:

• Peening: Peening is used to assist metals in withstanding fatigue and fracture.
• Deburring: Deburring is smoothing the rough edges or ridges of metals.
• Cosmetic Finishing: Cosmetic finishing refers to adding aesthetic features to parts.
• Preparing for Other Finish: Preparing metal surfaces for powder-coating and painting.
• Cleaning: Removing rust, paint, scale, and calcium deposits.
• Polishing: Can be used to polish materials like stainless steel, aluminum, and cast iron.
• Finishing: Can be used to create a matte finish on surfaces.

The industry’s applications of bead blasting include:

• Aircraft parts before painting.
• Guns and other military parts.
• Aluminum parts for medical applications.
• Automotive parts as preparation for adding brand-new paint.

What is the Difference between Bead Blasting and Sandblasting?

Many people may confuse bead blasting and sandblasting. Let’s take a look at their differences:

Using Different Blasting Media 

The primary distinction between bead blasting and sandblasting is the media utilized in the blasting process and also the safety considerations involved. Glass bead blasting uses spherical glass media to provide a uniform finish on part surfaces at high pressure. In contrast, sandblasting employs silica sand to give the material a smooth surface finish.

Sandblasting is Much Quicker

Sandblasting is significantly faster than bead blasting. However, a bead blast finish is far kinder to the material and will not damage the coating underneath. The bead blasting process does not impact the part’s size and produces a highly polished and high-quality surface.

Sandblasting is Harsher on Metal Material

Sandblasting is harsher on the metal material. It drives fine sand particles at high speeds to clean or etch metal surfaces. As a result, sandblasting generates a lot of sand or silica dust. Inhaling the resulting sand or silica dust might harm the operator’s health. Silicosis can result from prolonged exposure to silica dust.

Sandblasting Can Reshape the Underlying Part

Sandblasting can reshape and smoothen the underlying part, which would affect the part’s size. As a result, the operator needs close monitoring of the process and the use of protective equipment during sandblasting.

Best Tips for Quality Bead Blast Finish

Many variables can influence the final look of bead-blasted parts, ranging from the various bead-blasting media available to the pressure utilized throughout the operation. As a result, you must offer enough specifications to constrain these variables to obtain the expected results. Let’s see some bead-blasting tips to have the best bead-blast finish.

Avoid Tight Surface Roughness Callouts

The part’s surface roughness will be directly affected by the bead blasting. When applying a bead blast surface finish, it might be challenging to maintain tight surface roughness standards. Therefore, preserving the surface roughness at no less than 32 µin Ra is better if you need a smooth part.

Specify the Media and Grit Size

The feel and appearance of your final bead blast finish depends on the type of media that you choose. Fine glass beads produce a uniform and satin surface, whereas coarse glass beads produce a rough finish. On the other hand, steel shots are ideal for polishing and eliminating undesirable textures from materials.

Media sizes could typically be extremely fine, medium, or coarse. Your decision will be based on the outcome you want. Therefore, you should provide the media specification in your part drawings.

Add Masking Callouts for Critical Features

Assume your part has surfaces or features that should not be bead-blasted. In that situation, you should add masking callouts for these critical features. O-ring grooves and sealing surfaces are examples of such features. Additionally, don’t forget to include masking requirements for tiny pitch-threaded features.

Use Low Pressure for Bead Blasting

The recommendation is to use low pressure for bead blasting, with 50 PSI being a decent starting point. Glass beads often give the best results at low pressures.  Low-pressure blasting can extend the life of your beads and get considerably superior metal surface finishing.

On the other hand, beads begin to smash when they collide with parts under high pressure, which incurs higher processing costs. Additionally, the high-pressure smashing of glass beads into your parts generates excessive dust, dirt, and sharp particles. These particles would collect within the cabinet and affect the remaining clean beads. Contamination is unavoidable in this situation, resulting in degraded finishes.

Strip off Rusts or Oxides before Bead Blasting

You can achieve a nice bead blast finish on aluminum without first removing its oxide layer. Typically, the oxide layer is too difficult to polish or burnish. Note that glass beads will not assist in striping off or removing the oxide layer directly. This is because the round design of glass beads prevents them from cutting. A sharp cutting abrasive will more effectively remove the oxide or rust. For example, black beauty aluminum oxide, broken glass, etc., can assist in the removal of rust and oxides.

Blasting Media Selection Chart

Regarding bead blasting surface finish, the choice of media is critical to getting the desired results. The following blasting media selection chart compares the effectiveness and properties of different media types for various applications. This can help you determine which media type may be best for your project.

Conclusion

The bead blasting process is very flexible and suitable for various manufacturing processes. For example, smaller beads are helpful for light processes that need finely detailed work. Medium-sized beads are famous due to their ability to conceal surface flaws on parts. Larger beads are ideal for deburring and cleaning the rough surfaces of metal castings and automobile parts.

Bead blast finish is dependable, eco-friendly, and cost-effective, giving parts a beautiful and uniform surface. At LEADRP, we can assist you in determining when and where to apply a bead blast finish and selecting the appropriate type of bead blast for your parts. Contact us immediately for more information.

References

Sandblasting – From Wikipedia