There are several finishing techniques available, offering various options to choose from. Media blasting ranks among the top choices, with methods such as sandblasting, plastic abrasive blasting, and bead blasting. Each approach has its pros and cons. In this article, we will focus on bead blasting and its finish.
Understanding how bead blasted finish works, the materials involved, and how to use them effectively can help you achieve an excellent surface finish. We will provide a detailed guide on this finishing technique, including its benefits and drawbacks, helping you decide if it’s the right option for your needs. Additionally, you’ll find tips to get the most out of this process.
What is Bead Blasting?
Blasting is a finishing process used to treat the surface of various objects. Bead blasting, a type of shot blasting, involves using fine glass beads at high pressure to clean or finish a surface.
In this process, a bead blaster directs bead-shaped media toward the material’s surface using a high-pressure tool. The goal is to achieve a smooth, shiny, and clean surface. Manufacturers commonly use this technique on metals, plastic, glass, and rubber to create an excellent surface finish.
When to Choose Bead Blast Finish
Bead blasting is a versatile surface treatment process that serves multiple purposes in manufacturing. It removes coatings or corrosion, prepares surfaces for coatings, cleans cosmetic defects, modifies surface finishes, and deburrs surfaces. It also helps to improve surface uniformity for mechanical and cosmetic needs.
You should choose a bead blast finish when:
- Machining marks from tools like end-mills leave unsightly swirl marks, scratches, and nicks on the surface, and a uniform finish is required.
- Surfaces require a consistent texture and finish for aesthetic purposes, such as in automotive or consumer product applications.
- Corrosion or existing coatings need to be removed quickly and efficiently without damaging the underlying material.
- Deburring is necessary to smooth out rough edges and surfaces to ensure safe handling and assembly.
- A surface must be prepared for additional coatings or treatments, like painting, powder coating, or plating.
- Machined parts require a satin-like finish to cover imperfections and achieve a clean, professional look, such as in medical devices or precision instruments.
- Surfaces need to be cleaned and prepared for welding or bonding operations.
- A uniform surface roughness is required for non-slip or wear-resistant applications.
How Bead Blasting Works
The bead blasting process is similar to other abrasive blasting techniques but involves projecting sphere- or bead-shaped media against a substrate. Unlike other methods, jagged media are used to leave a coarser surface finish. The impact of glass beads on the material creates a more uniform texture. Abrasive blast cabinets, powered by compressed air, are typically used for this high-velocity process.
This results in a bead blasted finish, where spherical media create a smooth, uniform surface, often leaving a “dull” or “satin” appearance. In some cases, the process also provides tensile conditioning for the component.
If you’re seeking a finish that’s rough yet consistent, the bead blasting technique is an excellent choice. Glass bead blasting is a popular 3D printing surface finishing solution, as fine glass beads create dull or satin finishes, while coarser beads provide a rougher texture. This method effectively masks imperfections, and unlike other materials like garnet or aluminum oxide, bead blasting preserves the component’s base color, leaving a brighter finish.
Tools Used for a Bead Blast Finish
To achieve the best result from your bead blasting process, you need to ensure that you use the most effective tooling. This section will give you a run-down on the various equipment and materials for the process.
Bead Blaster Media
The choice of bead blasting media is a crucial first step in the finishing process. Machinists can select from various options, such as glass, steel shots, aluminum oxide, and plastic media, depending on the desired surface finish. Unlike angular-shaped alternatives, bead blasting utilizes spherical media to achieve a smoother finish.
Glass beads are suitable for delicate surfaces and provide a gentle, matte finish. Steel beads are used for more aggressive surface preparation and to remove corrosion and burrs. Aluminum oxide media offers a balance between gentleness and abrasiveness. It is ideal for surface roughening and coating preparation. Plastic media is used for sensitive surfaces to provide a soft, non-abrasive finish. We will discuss each of them further in this article.
Bead Blaster Cabinets
From the name, you’d have noticed that this equipment is where the bead blasting process takes place. This cabinet must be of the highest quality to ensure the overall success of the process and to prevent whoever carries out the process. There are some essential aspects of top-notch cabinets.
First, their construction must be in solid materials. The sturdiness of steel makes it a great choice. It lasts longer and confers incredible durability on the tool. Furthermore, you don’t want to have a cabinet constructed with weak legs. Therefore, good, strong, and durable legs should be welded to the cabinet.
The legs must be able to support the cabinet’s weight, the parts to be blasted, and the bead media. Thus, unsteady legs will eventually wobble. This often proves dangerous to the worker. It can also be frustrating when the tool breaks down during work.
What do you look for in a glass bead blasting cabinet?
Some other important features of a quality cabinet include the following:
Seamless cabinet sealing
The cabinet must have a good seal inside it. The best seals ensure that debris and dust from inside the cabinet do not leave the cabinet. Abrasive blasting dust and debris can pose several health risks. Inhaling that dust or having some slippery media on the floor can cause some serious injuries.
View window protection
One aspect of the bead blasting cabinet most people overlook is the view window. Large windows will help you adequately observe parts and works inside the cabinet. However, the most important thing to keep in mind is the protection of the window. Some glass beads may cause frosting over time on the glass. Thus, they impair the visibility, making it very poor. So, including replaceable protective sheets on your view windows is a good practice to allow you to blast longer without issues.
Bead Blaster Gloves
You want to prioritize safety and comfort while carrying out the bead blasting process. This is where gloves come into play. These gloves, typically attached to the cabinet, protect your hands from the abrasive blasts while allowing you to work comfortably. Additionally, they provide a strong grip on bead blaster guns, ensuring both precision and safety.
Bead Blaster Gun
Another critical component is the bead blaster gun. There is no blasting without the blast gun. There are various gun designs, and some can be quite complex. Operating a bead blaster gun may be through a foot pedal or with a pedal. The choice of gun is up to the user. However, guns enabling foot pedal use are often more comfortable for long blasting sessions. Holding a trigger blast gun for a long time can be tiring.
Types of Bead Blasting Media
Machinists employ a range of bead blasting media types to achieve specific surface finishes, each with unique characteristics and applications. We will help you understand the different media options and select the most effective one for your desired outcome.
Glass Bead
Glass beads are versatile and widely used due to their ability to produce a clean, bright, and uniform surface finish. Made from lead-free soda-lime glass, they are environmentally friendly, chemically inert, and can be reused up to 30 times. As a result, they are cost-effective options.
The spherical shape of these beads contributes to a peening effect, strengthening the material’s surface being blasted. This makes them an excellent choice for applications where the part must maintain its original dimensions. They are suitable for surface cleaning, peening, and semi-polishing applications. However, they may not be effective for extremely tough materials or paint preparation.
Various glass bead sizes are available, ranging from fine (40-60) for a smoother finish to coarser (170-325) for more texture. Thus, you can adapt them to different finishing needs.
Steel Shot
This durable media option for the bead blasting process is available in various sizes (S-70 to S930) and hardness ranges (40 to 62 Rc). Its high density and hardness make it suitable for heavy-duty applications. These applications include cleaning, de-rusting, and shot peening.
The rounded steel particles produce a smoother surface than glass or sandblasting media, and the varying sizes allow for adjustable finish textures. Steel shot also creates a better peening effect to induce compressive stresses and stress-relieving metal surfaces. Additionally, due to its durability and the peening effect, it generates less dust, which removes less substrate material.
However, shot blasting is a more aggressive form of blasting method. Therefore, it is reserved for harder metal surfaces requiring significant material removal or etching. it is not recommended for plastics or softer metals.
Aluminum Oxide
This media is robust and abrasive and characterized by its angular shape. So, it is usually an effective substitute for sandblasting. Its hardness and angularity enable it to cut into and etch even the hardest materials quickly. As a result, it is suitable for surface preparation, edge rounding, and achieving a consistent finish. The roughness correlates with the used grit size. Larger grits produce faster etching and rougher finishes. On the other hand, finer grits yield smoother finishes with extended processing times.
Aluminum oxide blasting produces a uniform matte finish. It’s often used before anodizing to achieve anodized bead blasted parts with uniform finishes. However, it gives a dull appearance, and the media’s brown color may lead to discoloration. It is also not a suitable choice for plastic parts finishing.
Plastic Media
Urea is the most commonly used plastic blasting media due to its gentle and lightweight properties. Made from angular-shaped plastic grains, it is ideal for delicate parts or materials that require a non-abrasive cleaning process. The lightweight plastic particles can be accelerated to high velocities, so they are effective for stripping light coatings more efficiently. Additionally, plastic media like Urea is suitable for deburring and de-flashing operations on molded parts.
It is an excellent choice for stripping and gentle cleaning applications. Thus, manufacturers often choose this media for delicate or sensitive surfaces that require a non-damaging cleaning process. However, plastic media is not suitable for cosmetic finishes. It doesn’t create the same dimpling effect as other media types.
Best Bead Blasting Tips to Have the Best Finish
Most bead blasting projects result in dull finishes with a slight satin shine, as shown on the bead blast surface finish chart. However, these finishes are often not optimal. Glass bead blasting has gained popularity in recent years, primarily due to its advantages in manufacturing.
Many people view glass beads as tools for restoring parts, often using them to remove rust, dirt, and scale. While they do serve this purpose, they are also expected to produce high-quality finishes. Now, let’s explore some tips to help you achieve the best bead blasted finish.
Use low pressure for bead blasting
The first tip is to turn down the pressure of your bead blaster, with 50 PSI (3.5 Bar) usually a good point to start. You must note that glass beads work best at low pressures. Therefore, the pressure should be as low as possible. This way, you can increase how long your beads stay and get a much better metal surface finish.
50 PSI pressure with a siphon blaster will help get the optimum result. The design of the beads does not allow them to be cut. Instead, they are made to polish or burnish a part. However, they do this at higher rates than other tumbling media. When you turn their pressure up, the beads begin to smash on impact with the component. This way, you crush the beads and incur higher processing costs.
Furthermore, smashing glass beads into your parts at high pressure produces excess dust, debris, and sharp particles. These particles trap inside the cabinet and affect the remaining clean beads. Contamination is bound to happen this way, leading to degraded finishes. With higher pressures on beads at impact, a lot of the smashed particles embed on the component’s surface. Therefore, you don’t want to use a high-pressure process on internal engine parts or other critical components.
Strip off any rusts or oxides before bead blasting
There is no way to get a great aluminum bead blasting without first stripping off its oxide layer. The oxide layer is usually too hard to polish or burnish. Also, it may make it hard for stains to be removed. Although there may be some shine to it, it will look like some shine stains. Note that glass bids will not help you strip off or get rid of the oxide layer. This is because their design does not allow them to cut.
Instead, it will help to use a sharp cutting abrasive to strip off the oxide or rust. Black beauty aluminum oxide, crushed glass, etc., will help you strip off rust and oxides. The crushed glass is a preferred option because it is a fast process, similar to silicon carbide or aluminum oxide. It is also very clean, leaving a nice brighter finish on metals. Regardless of your choice of abrasive for stripping off oxides, a material with consistency is perfect. Some coarse braces with an abrasive will easily help you take off heavier scales.
Pros and Cons of Bead Blast Finish
While bead blasting offers several advantages to the manufacturing space, there are a few downsides to consider. Here, we will be going through the different benefits and drawbacks of the process.
Pros
Some of the advantages include the following:
Smooth Surface Finish
It achieves a remarkably uniform surface finish, particularly when using delicate glass beads. This uniformity is crucial for applications requiring precise surface roughness. An example is aerospace engineering, where bead-blasted titanium components require a smooth finish to ensure minimal drag and maximum performance.
Non-Abrasive Process
This blasting method is a non-abrasive process that preserves surface integrity and reduces the risk of damage. Unlike abrasive methods, it doesn’t remove material or alter the surface structure, making it ideal for delicate or sensitive components. This non-abrasive nature minimizes the risk of surface damage, scratches, or cracks, ensuring the material remains intact.
Versatility
Bead blasting’s versatility makes it applicable to a wide range of materials, including metals, plastics, ceramics, and composites. The availability of various blasting media allows it to cater to different surface finish requirements.
Rust and Corrosion Removal
This process removes rust and corrosion from metal surfaces to ensure a clean and smooth finish. It also helps prepare them for further processing or coating. This is important for applications where surface integrity is critical, such as in aerospace engineering and medical device manufacturing.
Preparation for Coating
Bead-blasted surfaces provide an ideal foundation for paint and coatings, leading to better paint adherence and improved coating durability. The clean, smooth surface finish achieved through the process ensures a strong bond between the surface and the coating.
Environmentally Friendly
Most bead blast media are non-toxic and recyclable. A good example is the lead-free soda lime glass beads. They help reduce waste and minimize environmental impact, making the process a preferable choice to other abrasive methods that may use more harmful materials.
Precision Cleaning
It also allows for precision cleaning without damaging delicate surfaces. It is suitable for restoration and sensitive applications, such as medical device manufacturing and aerospace engineering.
Cons
Despite its many benefits, you should take note of the following cons of bead blast finish:
Limited Material Removal
The relatively slow material removal rate of this process can be a challenge when dealing with thick coatings or heavy rust. It may take multiple passes to achieve the desired level of cleanliness. More aggressive methods like sand bead blasting or grit blasting may be more suitable in such cases.
Surface Contamination
Residual abrasive particles can remain on the surface if the process is not adequately controlled or cleaned afterward. They can be challenging to remove completely, potentially leading to contamination issues if not appropriately managed.
Surface Finish Variability
While the process can produce a smooth finish, additional processes may be needed for precise surface finishing. This can add complexity and time to the overall process.
Media Breakdown
Bead blaster media can break down over time, become less effective, and require more frequent replacement. This can potentially affect the overall quality of the finish. Media breakdown can also lead to increased costs, as more media may be required to achieve the desired result.
Applications of Bead Blast Finish
Bead blasting helps to achieve uniform surface finishes without affecting the part’s dimensions. This process is not an aggressive one, as you would see with other media. Also, it works perfectly with a wide range of materials, making it suitable for various industries. This finish enhances the durability of components.
This finishing process is flexible, and it fits into an extensive array of manufacturing processes. For instance, smaller beads help with lighter processes that require finely detailed work. On the other hand, medium-size beads are the best choice when dealing with metal materials like stainless steel and aluminum. They are popular for their ability to hide defects on component surfaces. Larger beads are perfect for deburring and cleaning rough surfaces on metal castings and automotive parts.
The bead blasting surface finish helps for a range of purposes, including:
- Peening. This is often used in firearms to prevent the metal from cracking and resisting fatigue. A study found that peening can increase fatigue strength by up to 17.14%. It also allows the component to take paint a lot smoother.
- Deburring
- Cosmetic finishing
- Removing paint, calcium deposits, rust, and scale
- Polishing materials like stainless steel, aluminum, and cast iron
- Preparing metal surfaces for powder-coating and painting
Some of the things that may require a bead blasted finish are:
- Automotive components, when there is a need to add a brand-new paint
- Aircraft components before painting
- Firearms and other military components
- Aluminum materials for medical components
- Light poles for a variety of uses
Bead Blasting vs Sand Blasting: Key Differences
Bead blast and sand blast finishes are among the most commonly used surface finishing processes in custom manufacturing. While both techniques share similarities, they differ significantly in some parameters.
Material Used
Sandblasting uses sharp-edged sand particles, silicon carbide, or aluminum oxide to aggressively clean and etch surfaces. As a result, it is suitable for heavy-duty tasks. In contrast, the bead blast uses spherical glass or ceramic beads. Thus, it provides a softer abrasive action that is ideal for delicate and intricate components.
Techniques and Equipment
The equipment for bead blast vs sand blast varies, reflecting differences in pressure, nozzle design, and media size. The bead blast process uses a wide nozzle, moderate pressure (40-150 PSI), and small media size (50-300 microns). On the other hand, sandblasting employs a narrow nozzle, high pressure (50-180 PSI), and varied media size (16-220 grit).
Environmental Impact and Safety
Both methods have environmental impacts that need consideration. Bead blasting finish requires proper protocols to ensure environmentally responsible practices while sandblasting demands careful handling of environmental concerns, including proper disposal of spent media, adequate ventilation, and dust control.
Cost and Efficiency
Sandblasting is generally more cost-effective due to the lower cost of abrasive materials. However, it can be more aggressive and potentially damage certain surfaces. This may increase the overall cost in the long run. On the other hand, bead blasting comes at a higher cost due to the more expensive media. However, it provides a smoother surface finish, which is desired by many applications.
Applications
Sandblasting excels in heavy-duty applications, removing thick coatings and surface contaminants. In contrast, bead blasting is better suited for achieving a smoother, polished surface finish without damaging delicate surfaces.
RapidDirect’s High-Quality Finishing Services
Bead blasting finish is one of the best finishing choices for your applications. However, having your project in the wrong hands may prove harmful. Therefore, you should search for experience and expertise. The best company that offers a perfect mix of both is RapidDirect.
RapidDirect has 15 years of experience in offering cost-effective sand blasting solutions and more surface finish options for a wide variety of industries. We offer an extensive array of materials and finishes, including metal plating. Our team of experts works with you to create a custom metal finishing procedure. This way, you can be sure of high-quality services that meet all of your unique needs.
We prioritize customer satisfaction at RapidDirect. All our services come at competitive rates. All you have to do is contact us or upload your design file today. You will receive an instant quote, and we are ready to get to work.
Conclusion
Bead blasting uses specialized acrylic beads to give semi-polished, peened, satin finishes to your metal parts. This surface finishing technique is suitable for a wide range of purposes, and it works well on several materials. A great advantage of bead blasting is that it does not affect the dimension of your product.
Suppose you’re looking for the best bead blast finish on your parts. In that case, you should contact the experts at RapidDirect or request a quote today. Let’s help get your project to the next level!
FAQs
The glass bead is often safer to use than other blasting media. It is less associated with the dust and debris that comes with silica sandblasting. Thus, users can be sure of a safe and comfortable blasting process with adequate protection.
Bead blasting offers several advantages, providing soft, smooth, and even finishes. A bead blasted surface also enhances mechanical strength and aesthetics. This versatile process is compatible with metals such as stainless steel, aluminum, and cast iron, making it popular across various industries, including military, automotive, aerospace, and medical applications.
Bead blasting can potentially cause damage to parts if not done properly. For instance, using too much pressure or the wrong media can cause pitting or scratching of the surface, warping or bending of thin materials, damage to threads or small features, or embedment of media into the surface. To minimize the risk of damage, machinists need to choose the right type of media for the material being blasted and adjust the pressure and nozzle distance accordingly. A good practice is to ensure proper fixturing and support of the part and monitor the blasting process closely.
Yes. It’s a common method for cleaning and finishing stainless steel parts. It helps remove contaminants and residue, smooth surfaces, prepare surfaces for coating or painting, and deburr and remove sharp edges. Various media, including glass beads, ceramic beads, and stainless steel shot can help achieve a bead blasted stainless steel surface.
While this process is highly versatile, it may not suit all materials. Some materials are prone to damage or may not be suitable for blasting. For example, abrasive action can harm soft materials like copper, bronze, or brass, while brittle materials such as glass or ceramics may shatter or crack. The blasting process can also damage materials with complex geometries or thin walls. Likewise, materials with sensitive surfaces, such as mirrors or optics, can be scratched or damaged.