Bead Blasting Finish: The Ultimate Guide
Bead blasting is one of the types of mechanical metal processing. The method involves the impact of a gas jet with small particle shots. Bead blasting cleans the metal and improves its properties. The surface of any material needs to be processed before the intermediate and final operations for the manufacture of parts and structures. Bead blasting allows effective cleaning and enhances strength.
To maintain the technical and operational properties of any metal product in the norm, it is necessary to periodically clean it. Irregularities, roughness, rust, scale, dust, dirt, greasy stains, and so on are formed on it. To eliminate these problems, bead blasting is suitable.
What is Bead Blasting?
Bead blasting is a process that uses small beads to remove material from a surface. The beads are projected at high speed from a nozzle, and they impact the surface of the object being blasted.
This process can be used to clean or strip surfaces, or to create a textured finish.The power of the supplied air-abrasive jet allows you to remove various dirt and coatings, rust, as well as scale, bumps, and much more.
Bead blasting produces a rough, clean surface that provides good adhesion to the overlay materials. Basically, bead blasting machines are used for processing concrete and metal surfaces.
The equipment is of two types:
- Closed – for processing parts, and objects in a confined space;
- Open – for external processing of external surfaces.
The design of the machines can be different – it depends on what surface the equipment is designed to work with (steel, polymer, concrete, and so on).
The shot is used as an abrasive, the material, shape, and size of which, as well as the mode of operation of the bead blasting machine, are also selected based on the type of surface to be treated.
From a physical point of view, bead blasting of surfaces looks like this:
- Small pellets are inserted into a special sprayer; at the initial stage, their kinetic energy is zero.
- When the apparatus is started, the pellet particles fall under a stream of compressed air, which imparts large kinetic energy to the pellets – this leads to a serious acceleration of the particles.
- Under the action of a jet of compressed air, particles fly out of the atomizer at high speed and hit the metal surface.If there are any foreign particles on the surface of a metal object (dirt, dust, debris, rust, scale, and so on), then the pellets impart a large amount of kinetic energy to such particles. Therefore, always prefer for best bead for finishing technique.
- This leads to the fact that, due to an excess of kinetic energy, foreign particles fly off the surface, which leads to metal cleaning (the metal itself, subject to all the rules, does not deform since it has increased strength).
- It should be borne in mind that during processing, pellet particles can both retain their shape and deform or collapse (in whole or in part) – it all depends on the physical properties of the pellets.
How Does Bead Blasting Work?
There are two models of bead blasting process – manual and automatic. In the first case, all work is done manually using special sprayers. In the second case, a special shot-blasting chamber is used, where everything is automated – the workers only clean up problematic fragments (with strong corrosion, with a lot of soot). We’ll look at these bead blasting process methods in more detail below.
Manual Processing Of Metals
This method is great for processing small batches of metal that have a complex shape). A special bead blasting machine is used, which is connected to an electric compressor. It generates air under pressure, which pushes the pellet particles out of the sprayer. The procedure itself looks quite simple:
- A few workers wear special protective suits that help filter the air or contain their own oxygen supply (which produces a large number of puncture pellets that can be inhaled). Work should be carried out in a workshop where favorable conditions for cleaning are created (low humidity, good ventilation).
- After that, they connect the shot blasters to the compressor, place the metal objects on props and carry out the processing. The term of the work depends on the nature of the damage to the metal, the type of alloy, and so on.
- After processing, workers leave the workshop so that metal particles and dust can settle. After that, with the help of special liquids, dust particles that have settled on the metal during storage are washed off.
Also, the bead blasting process chamber, which operates in automatic mode, has become widespread. On sale, there are large fixed installations that operate on the principle of a conveyor. You can also buy small compact platform installations that can be transported if necessary. Bead blasting chambers are a great option for quickly cleaning large batches of simple-shaped metal (sheets, beams).
Works like bellow:
- A worker places a metal object into a bead blasting machine. Please note that almost all installations are isolated. No need to wear a special protective suit, which greatly simplifies his work.
- After placing the part, a person starts a shot-blasting chamber, to which devices are connected from the inside that sprays an abrasive shot. The principle of operation here is standard – all spray units are connected to an industrial compressor, which accelerates pellet particles with the help of compressed air.
- During operation, the participation of an operator may be required, which will control the parameters of the procedure. He will also monitor the state of technical parameters – the state of ventilation, and the quality of cleaning. Please note that in some cases the participation of the installation works in a completely offline mode.
- Upon completion of cleaning, the worker must check the external condition of the part. In case of poor quality cleaning, the operator can place a metal object in the apparatus for another cycle.
- It happens that the cleaning went well except for some hard-to-reach places. Then the worker can complete the work in manual mode.
The Materials of Bead Blasting
1. Glass Beads
Glass bead blasting. In the form of heavy-duty balls that do not break and deform with frequent use, which makes the material very economical. Suitable for cleaning medium hard metal alloys, fine glass beads can also be used for cleaning iron-based alloys. The main advantage of the material is the absence of pollution.
Glass bead blasting of the surface is carried out according to the same principle as sand or shot blasting technology. During the treatment process, the surface is bombarded with fine abrasive blasting process particles driven by a high-pressure air jet.
The peculiarity of the method is the material used. Microscopic glass beads made of tempered soda glass are used as an abrasive in glass blasting.
The characteristics of glass bead blasting create a unique combination that no other abrasive material can boast of. Yes, they are:
have a smooth surface;
have a rounded shape;
chemically inert (they do not contain free oxides);
have a fixed size.
Glass bead blasting with glass bead (glass bead) allows you to process parts and clean surfaces.
Processing with coarse glass beads avoids the occurrence of various damages on the treated surface, which is the main advantage of their use.
Thanks to this, glass shot can be used quite calmly for cleaning even fragile surfaces.
An equally important advantage of the material is that glass cannot contaminate the treated surface with metal oxides, which cause corrosion.
2. Steel beads
Shot based on cast steel. It is produced in several varieties depending on the carbon content in the steel (due to this, the hardness of the shots can be controlled). Cast steel is suitable for processing massive metal structures based on cast iron and steel (rolled products, beams, metal structures).
Bead Blasting Surface Roughness
An important factor to consider when using a bead blasting machine is the surface roughness of the material being blasted. The size and shape of the beads will have an impact on how rough or smooth the finished surface looks. Different materials may require different-sized and shaped beads to achieve the desired degree of polish.
Cleaning of old coatings, and rust in a short time. Each particle of the shot deforms the surface when it hits the metal. The metal tries to return to its original shape, and as a response, high compressive stress arises in the upper layer.
Protection of metal from corrosion and fatigue damage. Damage to the metal appears on its surface. The cold-deformed layer obtained after shot-blasting has high compressive stress, and increases the strength of the metal, protecting the surface from defects.
Giving the surface of the metal a rough surfaces or matte appearance due to the purification of small irregularities – chips or scale. Even old, almost completely rusted metal can be cleaned and improved in appearance.
Pros and Cons of Bead Blast Finish
Using a bead blasting machine to finish a surface has many advantages. It is fast, efficient, and cost-effective. It also produces an attractive, uniform finish that is resistant to corrosion. However, the process can damage softer metals such as aluminum or copper, so it may not be suitable for all materials.
- The metal surface after exposure to shot becomes stronger;
- Clean the parts surface;
- After processing, the surface becomes matte and rough;
- Shot removes rust, scale, paint, and plaque from metal;
Improve labor productivity.
- loss of time for filling the abrasive into the pressure unit;
- high operating costs;
- danger to the health of the operator and people nearby
- when using a better abrasive, an increase in operating costs;
Bead Blasting VS Sand Blasting, What iIs The Difference?
Bead blasting and sandblasting are two similar techniques used for cleaning surfaces. The main difference between the two is that bead blasting uses tiny spherical beads while sandblasting uses a much finer abrasive material.
Bead blasting is typically gentler on surfaces than sandblasting, so it may be better suited for delicate surfaces or materials. It is also less likely to leave a rough finish. However, sandblasting can produce smoother and more polished results than bead blasting in some cases.
Q: What fraction can you use when processing?
A: Steel, chipped, rounded, according to your technical specifications, with a fraction of not more than 3.5 mm.
Q: What is the cost of Bead blasting?
The cost of shot blasting will depend on several factors such as the size and type of material being blasted, the type of equipment used, and the labor involved.
Generally speaking, the larger and more complex a job is, the more expensive it will be. However, with advances in technology, many companies are now able to offer much lower rates than ever before.
Q: How long does it take you to carry out the bead blasting after the parts finished?
According to our internal rules, the processing is carried out from two to five days, as a rule, parts are ready the very next day after they are received. Regardless of the quantity, our production facilities allow us to process orders quickly.
Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.