Bead blasting is an excellent surface treatment suitable for a variety of applications. It falls under the umbrella term “blasting,” one of the most popular surface treatments for custom parts. In addition to bead blasting, there are other blasting techniques, including blasting and sandblasting, with each method having its advantages and disadvantages.
This article is about bead blasting and everything that comes with it. We explain the principle of the process and the different tools used to obtain the best sandblasted surface finish. You will also learn the advantages and disadvantages of this surface finish so you can make the right decision for your project. Let's start!
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What is bead blasting?
During bead blasting, fine glass or steel beads are released under high pressure to refine the surface of a component. During the process, a high-pressure tool shoots bead-like media onto the surface.
This process takes place in a well-monitored blast cabinet and leaves a shiny, smooth and clean surface. Manufacturers often use sandblasting treatment on metals, plastics, rubber, and glass materials to improve their appearance and physical properties.
The principle of the glass bead blasting process: how does it work?
If you are familiar with other blasting processes, you will know the principles of shot blasting. In general, spherical or sphere-shaped blasting media are shot onto the surface of a workpiece. The impact of the serrated blast media leaves a smooth, even surface on the component. The depressions of the blasting agent result in the final blasted surface finish.
Glass bead blasting is also an excellent option if you want to achieve a rough but even surface. Fine glass particles can leave a “matte” or “satin” finish on the surfaces of your 3D printed or machined parts, making them the first choice for post-processing services. On the other hand, you can use coarse glass particles to get a uniform, “rough” surface blasted with glass beads.
In addition to providing a uniform surface finish, blasting also helps hide imperfections on the surface of the piece. Although surface treatment techniques for some parts may leave surfaces darker, sandblasting preserves the base color of the substrate. As a result, you get parts with lighter surfaces.
Bead blasting vs. sandblasting: what's the difference?
The main difference between glass bead blasting and sand blasting is the material used in the blasting process and the associated safety concerns. Although both work on similar principles, they are best used in different circumstances. Glass bead blasting uses spherical glass bodies under high pressure, while sand blasting uses quartz sand for the finishing process.
Sand blasting is a much faster technique than blasting. However, sandblasting surface treatment is much gentler on the material and effectively removes it without damaging the underlying material. This process does not affect the dimensions of the component and guarantees a more polished surface with excellent quality.
Sandblasting, on the other hand, is much more aggressive. Fine grains of sand are thrown at extreme speeds to clean or etch metal surfaces. This creates a lot of sand or quartz dust, which can be harmful to your health if inhaled. Prolonged inhalation can cause a disease called silicosis.
Additionally, if not properly controlled, sandblasting can reshape the underlying component and change the dimensions of the part. Therefore, it is important to carefully monitor the process and wear protective equipment during sandblasting.
Equipment and materials used for the ball blasting process
The key to a successful blasting process is efficient tools that serve the right purpose. Let's look at the different tools you need to get the best results.
Bead Blasting Medium
The blasting agent itself is an essential blasting agent. Machinists generally use two types of blasting balls for surface treatment of blasting balls. They are glass beads and steel beads.
Glass beads are made from lead-free soda lime glass and are available in spherical shape. These materials are more environmentally friendly as they can be recycled more than 30 times. They are also gentler on component surfaces.
Steel balls, on the other hand, are made of steel cast in the form of round objects with round shapes. They are an economical alternative because they are durable and allow for multiple rounds of recycling. Steel balls are best for polishing or removing unwanted textures on metal surfaces.
Bead blasting booth
The entire detonation process takes place here. You must choose a high-quality blasting booth that guarantees the safety of the personnel carrying out the blasting. At the same time, the cabin must not compromise the quality of the results.
A typical bead blasting machine must be made of a solid material. Steel is the perfect choice in this case as it is a strong and durable material. Steel casings typically last longer and can withstand the high pressure that comes with the process.
Likewise, you must prevent your stand from having weak legs and interfering with the finishing process. The legs of the glass bead blasting booth must be strong enough to support the weight of the booth, the bead blasting medium and the workpieces. Weak legs constantly wobble and are unstable, which can be dangerous for the operator. Additionally, it is discouraging if your tool breaks during sandblasting finishing.
So, what are the essential components of a good glass bead blasting booth?
●Consistent housing sealing
The seal inside the cabinet must be very good. Residues or deposits from blasting surfaces can be harmful to health. Therefore, seals must prevent dust or debris from escaping the case.
●Show window protection
Your glass bead blasting booth should have larger windows so you can clearly see the parts while working in the booth. However, more important than the size of the window is its protection. Some glass beads tend to cause ice on the glass after some time.
This can harm visibility, which in turn has a negative impact on the quality of results. Therefore, you should place replaceable protective films on your cabin's viewing window so that it can shine longer without any problems.
Bead Blaster Pistol
A bead blast finish cannot be achieved without the blast gun. Therefore, it is an important component that you should always keep an eye on. There are different designs of explosive weapons and the way they work is also different. While some work with a manual pedal, others work with a pedal.
The choice of explosive gun is up to you or the operator. However, if your project requires long blasting sessions, consider using pedal blasting guns. They are more comfortable and place less pressure on the operator.
Blasting Gloves
Safety and comfort are the top priorities in any sandblasting procedure. Blasting gloves are part of the protective equipment to ensure adequate operator protection. Gloves usually come with the case. Since you may be holding the explosive pistol in your hands, you want to protect it from subsequent damage. These gloves also help you maintain good control of the gun.
Sandblasted surface finish properties
Without changing the dimensions of the component, blasting allows the creation of uniform surfaces. Unlike other media, this method is not aggressive. Plus, it works great with a variety of materials, making it suitable for a variety of industries.
Bead blasting is a technique that manufacturers use to increase the life of components. This machining process is customizable and works with many other manufacturing processes. For example, smaller spheres are useful in lighter processes where fine details are required.
However, when blasting stainless steel or aluminum, medium-sized beads are the ideal choice. They are popular because they can hide surface defects in components. Finally, larger balls are preferred for cleaning and deburring rough surfaces on automotive parts and other metal castings.
Bead blasting applications
Functional applications
In general, bead blasting is a versatile process that covers a wide range of applications, including the following:
- Shot peening – to give metals greater resistance to fatigue and prevent cracking
- Deburring – Smoothing metal edges or burrs
- Cosmetic finish – components that improve aesthetics
- Preparation of metal surfaces for other secondary surface treatments such as powder coating and painting
- Polishing materials such as aluminum, stainless steel and cast iron
- Removal of paint deposits, rust, scale and limescale
Industrial applications
Bead blasting is also suitable for a variety of applications across a range of industries, including:
- Aircraft components preparing for painting
- Car parts before applying new paint
- Military components
- Aluminum Parts for Medical Applications
Advantages and Disadvantages of Bead Blast Finish
Shot peening surface treatment creates a non-directional, smooth and structured surface that is also aesthetically pleasing. This surface treatment technique is versatile and works on a variety of materials, including aluminum, stainless steel, titanium, copper, brass and plastic.
Despite its usefulness and versatility, you should also consider some disadvantages of sandblasting. This section highlights the advantages and disadvantages of shot peening for your project.
Benefits of bead blasting
- It is one of the most economical and least aggressive surface treatments on the market.
- Bead blasting is much safer than many other blasting methods.
- The blasting process does not alter the base color of the piece, providing a lighter finish.
- Abrasives like glass beads can be recycled and reused up to 30 times before needing to be replaced.
- Because glass beads are made from lead-free material, the environmentally friendly process leaves no harmful residue.
- If desired, you can use sandblasting to cover some areas of the component.
- It is an excellent option for surface finishing of complex components.
Disadvantages of shot peening
- May not be suitable for applications requiring tight and tight tolerances.
- Harder materials may take longer to explode.
- If glass beads are used, the paint may not adhere properly.
- As the operation is manual, it can require a lot of work.
Proven processes for high-quality surface treatments with glass beads
From the different blasting media available to the pressure used during the process, many variables can affect the final appearance of blasted parts. Therefore, you must provide adequate specifications to control these variables to obtain consistent and quality results.
Let's look at best practices and tips for better control of the blast finishing process and a superior finish.
Specify medium and grain
The type of media you use will determine the feel and appearance of the final glazing bead finish. For example, fine glass beads provide an even, satiny finish, while thick glass beads provide a rough finish. Steel balls, on the other hand, are better for polishing and removing unwanted textures from materials.
The smaller the grain size of the abrasive material, the coarser the particles will be. In contrast, larger grain sizes have finer particles. In general, media sizes can be very thin, thin, medium, or thick. Your choice depends on the desired result. You must include this information on part drawings or order notes when requesting a quote.
Avoid strict surface roughness specifications
The type of blasting process has a direct impact on the surface roughness of the component. It is sometimes difficult to meet strict surface roughness requirements during surface processing using shot blasting processes. Therefore, if you need a smooth part, it is preferable to keep the surface roughness no less than 32 µin Ra.
Add masking guidance for critical functions
Suppose your component has surfaces or features that should not be sandblasted. In this case, you must add masking notes for these resources. Examples of such features include O-ring grooves and sealing surfaces. You can also add masking requirements for small pitch thread features.
Use the lowest pressure possible when blasting the bead
You also want to keep the bead emitter pressure as low as possible. Glass beads generally provide the best results at low pressure. So you should start with around 50 PSI. This increases the lifespan of your pearls and ensures great pearl blasting results.
If the beads are struck into the component at extremely high pressure, the beads can be crushed and overall production costs increase. Additionally, this often creates excess debris and dust, which can be dangerous to the operator or settle on the surface of the component.
Remove any oxides or rust before applying the sandblasted finish
When sandblasting aluminum, you must first remove the oxide layer, otherwise it will be very difficult to polish. This layer cannot be removed with glass beads. Therefore, you need to use sharp cutting material to remove the oxide or rust layer.
Concluding
The sandblasting technique is ideal for giving your pieces a semi-gloss and satin finish. It is a versatile surface finishing technique that works well on a variety of materials and is suitable for a wide range of applications. It is also less aggressive and relatively affordable, making it a great option for your project.
Common questions
What is the purpose of glass bead blasting treatment?
Sandblasting is flexible and versatile. It can help clean the surface of your component to create a uniform, matte or satin surface texture and improve its overall appearance.
Is glass bead blasting safe?
Using glass beads is safer than most other blasting media. They do not produce silica dust or dirt that could harm the operator. They are also gentle on the surface of the part and do not alter its dimensions.
