Sand Blasting VS. Glass Bead Blasting Difference

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Sand Blasting VS. Glass Bead Blasting Difference

There are many types of abrasive blasting services, including: glass bead, sand, water, and wheel are a few others. Abrasive blasting is used to remove rust, dirt, old paint, and any other residue from the metal's surface to prepare it for finishing.

The type of abrasive that you use will depend on how dirty the metal is and how much blasting it can withstand. Delicate materials require a gentler blasting technique to avoid scratching the surface. Two of the most common blasting materials are glass beads and sand. Sand blasting and bead blasting are both abrasive blasting techniques used for cleaning, finishing, or surface preparation. Here’s a detailed comparison of the two methods:

Sand Blasting

Overview: Sand blasting involves propelling sand or another abrasive material at high velocity onto a surface to remove contaminants, rust, or old paint and to prepare the surface for further treatments.

Materials Used

· Abrasives: Typically includes silica sand, but other materials like aluminum oxide or garnet can also be used depending on the application.

Applications

· Metal Cleaning: Removing rust and scale from metal surfaces.

· Surface Preparation: Preparing surfaces for painting or coating.

· Etching: Creating patterns or textures on glass or stone.

Benefits

· Effective Removal: Efficient at removing thick layers of material and contaminants.

· Versatile: Can be used on a variety of surfaces, including metals, concrete, and stone.

· Cost-Effective: Sand is generally inexpensive and widely available.

Limitations

· Dust and Health Risks: Silica sand can create hazardous dust, posing respiratory risks. Proper safety measures and dust extraction are required.

· Surface Damage: Can be too aggressive for delicate surfaces, potentially causing damage.

· Environmental Concerns: Sand blasting can be messy and create significant waste.

Bead Blasting

Overview: Bead blasting, also known as glass bead blasting, uses glass beads or other spherical abrasives to clean or polish surfaces. It provides a more controlled and gentle abrasive action compared to sand blasting.

Materials Used

· Abrasives: Typically glass beads, but other materials like ceramic beads or plastic media can be used depending on the required finish.

Applications

· Surface Finishing: Achieving a smooth, matte finish on metals and other surfaces.

· Cleaning: Removing surface contaminants or residues from delicate parts.

· Texturing: Creating a uniform texture on various materials.

Benefits

· Surface Integrity: Less aggressive than sand blasting, reducing the risk of surface damage.

· Consistent Finish: Produces a smoother, more uniform surface finish.

· Less Dust: Glass beads create less dust compared to silica sand, making for a cleaner operation.

Limitations

· Cost: Glass beads and other spherical abrasives can be more expensive than sand.

· Limited Aggressiveness: May not be effective for removing heavy coatings or deep rust.

· Wear and Tear: Glass beads can wear out faster and require frequent replacement.

Choosing Between Sand Blasting and Bead Blasting

Considerations

· Surface Type: Sand blasting is suitable for heavy-duty cleaning and surface preparation, while bead blasting is better for fine finishing and polishing.

· Desired Finish: For a rough, aggressive clean, sand blasting is effective; for a smoother, more polished finish, bead blasting is preferable.

· Material Sensitivity: Bead blasting is ideal for more delicate or precision surfaces to avoid damage.

· Environmental and Safety Concerns: Bead blasting generally produces less dust and is safer for operators, but it can be more expensive.

Each method has its strengths and is suited to different applications. Your choice will depend on the material, the required finish, and operational considerations such as cost and safety.

Comparing the Two Methods

When to Choose Sand Blasting?

Heavy Rust or Paint Removal: Sandblasting is ideal for removing thick layers of rust or paint on tough metal surfaces or concrete.

Surface Preparation for Coatings: When you need a surface with some “tooth” for paint, powder coating, or other coatings to adhere well.

Durable Surfaces: For materials like steel, cast iron, or concrete that can withstand the rough impact of sand.

When to Choose Bead Blasting?

Cosmetic Finishing: Bead blasting provides a uniform, satin-like finish, making it a good choice for aesthetic purposes, especially for decorative or visible metal surfaces.

Cleaning Without Damage: Ideal for parts that need cleaning without significant material removal, such as engine components or softer metals like aluminum and brass.

Delicate Materials: For softer or more delicate materials, bead blasting is less likely to cause damage, making it the preferred choice for detailed or intricate parts.

Best Practices for Specifying Media Blast Finishes

From the wide selection of available media to the applied pressure and technique, many variables can influence the appearance of your bead blast finished parts. Suppose you are looking to achieve a particular finish. In that case, it is essential to provide specifications to control some of these variables to guide the intended result. When striving for consistent results across production runs or multiple batches, specifications are critical.

When ordering bead blasted parts from IDEAL, if no further instructions are provided, we will defer to using glass bead media and sufficient pressure to remove tool marks and smooth the surface without damaging the part. The sections below go over tips and best practices you can incorporate to achieve greater control of the process and more predictable and consistent bead blast finishes.

Media Specification

The type of media or abrasive used will significantly influence the look and feel of your finish. For instance, fine glass beads will produce a consistent, satin-like finish, whereas aluminum oxide will yield a uniform but duller appearance. It may take some experimentation to determine what media works best for your project, but you will want to include that information in your order or part drawings notes section once you do. In addition to the type of media, be sure to specify its shape if there are multiple options to choose from.

Abrasive Grade / Grit Size

Another variable that plays a role in how your finish comes out is the particle size of your chosen media. Suppliers often refer to the abrasion grade or grit. The grit is very similar to what you would find when shopping for sandpaper at your local hardware store. The lower the grit, the larger and more coarse the particles are. On the other hand, higher grits will be of finer particles. Mesh size is often referred to as well. The easiest way to understand mesh size is if you were to observe a 1"x1" screen made up of equally sized holes. With a mesh size of 20, there would be 20 holes in the screen, and particles smaller than those holes will pass through, while larger ones will be blocked. With a mesh size of 200, there would be 200 holes in the same 1"x1" area, and thus would be much smaller and only allow finer particles to pass through.

Media size is typically broken down into coarse, medium, fine, and very fine grades. Calling out a grade will simplify your notes and prevent being overly specific, which can limit a manufacturer's options.

Avoid Tight Surface Roughness Callouts

By the nature of the blasting process, the part's surface roughness will be directly impacted. It can be challenging for shops to maintain tight surface roughness requirements while also applying a media blasted finish. When these requirements mix, it is often the case that a shop will want to pause the project and get clarification on what the expectations are.

We recommend limiting surface roughness to no lower than 32 µin Ra when you need a smooth bead blasted part. We do not recommend blasting surfaces that must be lower than 32 µin Ra and instead call out for masking on just those surfaces. Take note that masking requirements can significantly increase labor time and thus cost.

Provide a Boundary Sample

A boundary sample can be invaluable for manufacturers when producing a finish that meets expectations. If your project has strict finishing criteria or detailed notes, a boundary sample can help resolve concerns and provide clarity. Manufacturers can use their knowledge and expertise to produce an output that matches provided examples, reducing the need for detailed notes. If a physical sample is not available, the next best thing would be high-resolution photos taken at various angles. Xometry's engineers and case managers can help you make such arrangements with our manufacturers after placing your order.

Masking Callouts for Critical Features

Lastly, we recommend including masking notes if your part has any critical features or surfaces that should be guarded against abrasion. Examples of these features are sealing surfaces and o-ring grooves. Although most shops already do this per shop practice, we recommend adding masking requirements for threaded features, especially for small or fine pitch threads.

Example drawing notes for bead blasted finishes:

"Bead blast all surfaces using fine grade glass bead media."

"Media blast with #70-100 glass bead at 50-60psi."

"Mask indicated surfaces and tapped holes prior to media blasting. Media blast un-masked surfaces with medium grade aluminum oxide."

Conclusion

At IDEAL, we excel in providing top-quality custom machining services tailored to meet your project needs. Our advanced technology and skilled team ensure your specifications are met with exceptional accuracy and efficiency.

Contact IDEAL today to see how we can assist with your next project!