The surface finish of your machined products is very crucial. That’s why bead blasting has become such an important process in CNC machining. Bead blasting involves shooting small ceramic or glass beads onto the surface of a part at a high velocity thus creating a uniform and smooth finish.
Basically, this process is effective when it comes to improving your products surface appearance and performance. The process removes imperfections from the surface of CNC machined products and also creates an exceptional finish that cannot be achieved by using other surface finishing methods.
Additionally, bead blasting reduces friction and improves wear resistance thus making it ideal for components used in harsh conditions. It is also cost-effective and eco-friendly as it does not require any toxic chemicals or materials. This makes the process safe and efficient thus it is one of the most famous strategies of surface finishing CNC machined parts in the manufacturing sector.
In this article, we will look into everything you need to know about bead blasting. Let’s get started!
Bead Blast Finishing (Image Source: Pinterest)
Introduction to Bead Blasting
Bead blasting is a vital process in the manufacturing industry and it can refer to abrasive blasting. However, it simply is a process that entails casting beads against parts such as aluminum, stainless steel or any other material that necessitates smooth and uniformly blasted surfaces.
Ultimately, bead blasting is used to make components that require a smooth uniform finish with a dull ‘satin’ finish.
Some of the various materials used for bead blasting include:
- Glass Beads: Ideal for precision work, polishing, and finishing delicate surfaces without significant material removal.
- Aluminum Oxide: Versatile abrasive suitable for general-purpose blasting, effective in removing rust, paint, and scale.
- Silicon Carbide: Aggressive abrasive with sharp edges, used for substantial material removal, such as removing coatings and addressing corrosion.
- Steel Shot: Robust abrasive with rounded steel particles, used for heavy material removal, surface strengthening, and inducing compressive stresses.
- Steel Grit: Angular steel particles suitable for aggressive material removal, commonly used for tasks such as removing heavy rust or scale from metal surfaces.
- Plastic Media: Soft abrasive made from materials like acrylic or urea, used for gentle cleaning and surface preparation, particularly on sensitive materials.
- Ceramic Beads: Spherical beads made from zirconia or alumina, providing a durable and consistent abrasive option for cleaning and peening applications.
- Garnet: Natural mineral abrasive suitable for precision work and achieving a smooth finish on various surfaces.
While the above materials are used to achieve a bead blast finish, the materials are use-case specific. For instance, for parts that require a dull and satin finish, fine glass beads are used to achieve this. Coarser glass beads are used to give a rough finish while also covering up imperfections on the part surface.
Materials like aluminum oxide, garnet and silica carbide, leave the part with a dark gray finish even in their finest grits. Nonetheless, this is usually not the case with glass bead blasting as this material does not make the change appear differently but maintains its base color which results in a whitish and brighter finish.
Bead Blasting vs. Other Blasting Techniques
In CNC machining, there are various blasting techniques available. Among these techniques is sand blasting. This technique, just like bead blasting, is also widely used for stripping, surface preparation, removing contaminants, as well as improving the cosmetic appearance of a part.
So, how do these two techniques compare? First off, the two techniques share a similarity in the way they operate. They involve imparting an abrasive material (beads) at a high velocity on the surface of the part being prepared or cleaned.
The abrasive material is blasted using compressed air or other mechanical pressurizing means. However, the operator can adjust the intensity and duration of the blast based on the application.
When it comes to differences, the main difference between bead blasting and sand blasting is in the type of abrasive utilized in each process. Sandblasting, just like the name suggests, uses sand or other hard abrasive materials like aluminum oxide, silicon carbide, or steel grit.
Bead blasting on the other hand, makes use of small glass beads usually made of soda-lime glass to clean and polish part surfaces without damaging them. This method is typically gentle and ensures precise surface preparation to create a smooth, polished surface finish.
Advantages of Glass Bead Blasting vs Sandblasting
- Cleaning effectiveness: Glass bead blasting is better suited for cleaning and polishing relatively smooth surfaces, such as stainless steel or aluminum.
- A gentler process: Glass bead blasting leaves a smoother surface finish as compared to sandblasting which leaves a rougher surface finish.
- Less material removal: Glass bead blasting is a more precise method of surface preparation and only removes the top layer of the material, leaving the base material unaffected.
Disadvantages of Glass Bead Blasting vs Sandblasting
- Environmental friendliness: Glass bead blasting is less environmentally friendly as compared to sandblasting.
- Safety: While the two methods can cause harm to the operator, sandblasting is a safer method as compared to glass beads blasting.
- Cost-effectiveness: Sandblasting is less expensive than glass bead blasting, as the abrasive materials used in sandblasting are less expensive than glass beads.
Equipment and Materials for Bead Blasting
You can choose either steel beads or glass beads for your bead blast finishing. Due to their toughness, steel beads are used to clean contaminants and reduce rough texture from hard metals surfaces.
On the other hand glass beads are used for bead blasting due to their gentleness. Some of the equipment and materials used for glass bead blasting include:
Bead Blaster Cabinets
A bead blaster cabinet 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.
The most 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 hold several health risks. Inhaling those dust or having some slippery media on the floor can cause some serious injuries.
- View window protection: A bead blasting cabinet must have a large window to adequately observe parts during the process. Additionally, the view window might develop frosting overtime due to the glass beads.Including replaceable protective sheets on the view window can help to keep the window clear.
- Bead blaster gloves: The bead blasting gloves come in handy to ensure safety and comfort for the specialist performing the bead blasting process. These gloves usually come connected to the cabinet and help to have a solid grip on bead blaster guns.
- Bead blaster gun: A bead blaster gun is another important component of the bead blaster cabinet. In fact, you cannot have bead blasting without the blast gun. There are various gun designs, and some can be quite complex and the choice of gun is up to the specialist.
- Glass beads: The most important bead blasting material is the media itself – the glass beads. Glass bead blasting is environmentally friendly because you can recycle them up to 30 times.
Properties and Applications of Bead Blast Finishes
Bead blasting helps to achieve uniform surface finishes without affecting the part’s dimensions. This finishing process is flexible, and it fits into an extensive array of manufacturing processes.
Bead blasting is used for:
- Peening – used in firearms to prevent the metal from cracking
- Polishing materials like aluminum, stainless steel, and cast iron
- Removing paint, rust, calcium deposits, and scale
- Preparing metal surfaces for painting and powder-coating
- Cosmetic finishing
- Deburring
Glass Beads (Image Source: Pinterest)
Applications of Bead Blast Finish
- Automotive industry – It is used when there is a need to add a brand-new paint
- Aircraft components – Used to make the surface smooth before painting
- Military Sector – On military components to create a smooth finish
- Electrical materials – For power poles used for various uses
Pros and Cons of Bead Blast Finishing
Bead blast finishing has various advantages and disadvantages. Let’s explore them below!
Pros of Bead Blast Finishing
The pros of bead blast finishing include:
- Surface Cleaning: Bead Blasting effectively removes rust, scale, old paint, dirt, and other contaminants from the surface of the material, restoring it to its original condition.
- Surface Preparation: It creates a clean and roughened surface, enhancing the adhesion of coatings, paints, or other finishes applied afterward.
- Deburring and Descaling: Bead blasting can remove burrs, sharp edges, and scale from metal components, improving their safety and functionality.
- Surface Finishing: By adjusting the type and size of abrasive beads, bead blasting can produce various surface finishes, from a smooth matte look to a textured or matte appearance.
- Non-Destructive: Bead blasting is a non-destructive method, as it removes only surface contaminants and does not damage the material itself.
- Versatility: It can be applied to various materials, including iron, steel, aluminum, brass, and even non-metallic materials like glass or plastics.
- Affordability: Bead blast finishing utilizes glass beads thus making it a very cost-friendly finishing technique.
Cons of Bead Blast Finishing
The cons of bead blast finishing include:
- Health and Safety: Bead blasting generates dust and airborne particles that can be hazardous if inhaled. Proper safety measures, such as wearing protective clothing, and masks, and ensuring adequate ventilation, must be followed.
- Surface Damage: If not performed carefully or with improper equipment, bead blasting can cause damage to delicate or thin materials. It’s important to choose the appropriate pressure, abrasive type, and technique for each specific application.
- Surface Contamination: If the blasting process is not properly controlled or cleaned afterward, residual abrasive particles can remain on the surface, leading to potential contamination issues.
- Cost and Equipment: Bead blasting equipment can be expensive, especially for large-scale applications. Additionally, the cost of abrasive materials and the maintenance of the equipment should be considered.
Maximizing the Benefits of Bead Blast Finishing
The art of bead blasting is nuanced, demanding a keen understanding of materials, techniques, and machines. Here are some essential tips for achieving the ideal bead blast finish:
- Correct Use of Pressure: Contrary to popular belief, more pressure does not equate to a better finish. Rather, using lower pressures can yield superior results. High pressures risk embedding the glass beads into the surface, which can affect the material’s properties.
- Choosing the Right Glass Bead Size: The size of the glass bead blasting media you use is pivotal to the outcome. For more delicate parts, smaller bead sizes are ideal. For robust materials, larger bead sizes can be more effective.
- Proper Surface Preparation: Before bead blasting, the workpiece should be clean and free from contaminants. Any oil, dirt, or previous coatings can impact the efficacy of the bead blasting and the quality of the finish.
- Optimal Machine Settings: Understanding the best settings for your bead blasting machine can drastically affect the results. The right balance of air pressure, distance from the workpiece, and the angle of attack can make all the difference.
- Use of Sharp Cutting Abrasives for Rust and Oxide Removal: Before bead blasting, it might be necessary to remove any rust or oxide layer. For this, sharp cutting abrasives, such as aluminum oxide, are more effective than glass bead blasting.
- Regular Maintenance of Bead Blaster Cabinets: To ensure a consistent bead blast finish, maintenance of your bead blaster cabinets is essential. Regular cleaning, inspection, and replacement of worn-out parts can keep your machine in top condition.
- Safety Precautions: Always prioritize safety when performing bead blasting. Use the right personal protective equipment, and follow the correct procedures to protect yourself and those around you.
Whether you’re a DIY enthusiast or a seasoned professional, these bead blasting tips can help you achieve the perfect bead blast finish on your projects. However, remember that practice is the key to perfection. Over time, as you gain experience with different materials and equipment, your bead blasting skills will naturally improve.
Bead Blasting Surface Finish (Image Source: Pinterest)
Conclusion
Bead blast finishing is a versatile and powerful surface preparation technique that will give you various benefits across a wide range of industries. Its ability to remove contaminants, rust, old coatings, and imperfections while achieving precise and uniform surface finishes makes it an invaluable process for achieving flawless surfaces.
Understanding the various types of abrasive media and their applications allows you to choose the right media for your specific project, ensuring optimal results and efficiency. Proper surface preparation, equipment setup, and safety precautions are essential prerequisites for a successful bead blasting operation.
With bead blast finishing, you can make various parts for use in industries such as automotive, aerospace, and healthcare, among others. Its adaptability and effectiveness make it a go-to method for achieving surface perfection and meeting industry standards.
