How to chose your abrasive blasting system
An abrasive blasting cabinet is a machine into which the object to be processed is placed. Blasting then occurs either automatically or manually. If you chose a manually opreating cabinet, the operator performs the work by placing his hands through the glove holes in the cabinet, grasping the blast gun or nozzle, and directing it toward the object, while viewing the operation through a window. An automatic machine only requires the operator to load and unload the object from the machine. All abrasive, dust, and dirt will be contained within the machine and its associated equipment.
When selecting an abrasive blasting cabinet, it is best that you should follow the information below:
- Size of cabinet you desire
- Amount of area on the object that requires blasting
- Type of abrasive you would like to use
- How much production you require
- Amount of compressed air available
With this information, you will then be prepared to talk to one of our abrasive blast equipment salespersons. Talking to a knowledgeable salesperson will save you money and lost production time.
Blast cabinets can be divided into manual and automatic machines. Manual machines can be further divided into the classes of standard duty, and heavy-duty machines.
Manual Air Blast Cabinets
Manual machines require a source of compressed air to propel the abrasive toward the surface of the object. There are 2 basic methods of blast: suction blast (low production) and pressure blast (high production).
Low production incorporates the use of a hand-held gun with an air jet and nozzle. This gun is usually referred to as a suction, or induction gun.
High production pressure blast incorporates a pressurized tank of abrasive, a single hose, and a nozzle. The pressure blast method offers 3-4 times the production and impact of the suction/induction blast method. The high production method should be considered when there is a large area to be blasted, or where heavy rust, multiple layers of paint, or heavy oxides and scale must be removed.
The cleaning speed varies with the amount of compressed air used. When you double the amount of compressed air, you triple the production capacity by two-thirds.
Never choose a blasting cabinet based on part size alone. Better operator visibility and room for moving the part within the cabinet result in faster blasting. Larger cabinets produce better vi- sibility by allowing the abrasive to expand to a lower particle density inside the cabinet. A larger cabinet size also increases part mobility, allowing for movement and rotation when blasting 100% of the part surface. Visualize painting the part: if you need to flip or turn the part to paint it, you will need to do the same inside the cabinet when blasting. The more three-dimensional the part, the more rotation required.
Automatic or Manual Blasting Equipment
This type of equipment may be of various styles, including tumble blast, through conveyors, powered rolls, powered turntable, indexing turntable, satellite turntable.
The operator does not manually blast clean each item, but loads the items to be blasted into the machine, either individually or by batch; turns on the machine for desired time cycle; then unloads processed items at the end of the cycle.
This type of machine should be considered when there is a large volume of a particular configuration of workpiece, and when consistency of finish is mandatory.
The most important decision before chosing an automatic shotblasting machine is to achieve the desired result with the surface treatment. To make your project a success, we at Clemco Denmark, work closely with our customers so that we can find a solution tailored perfectly to yóur needs. It doesn't matter if it is a modified standard system or a brand new development of new blasting cabinets tailored to specific topics to be shot blasted.
You should also be familiar with abrasives and compressed air consumption. If you are using the correct type of abrasive, or do not use the right amount of air pressure, your shot blasting equipment could not reach its full potential. If you use harsh abrasives like corundum you should expect that an automatic sandblasting cabinet requires a lot of maintenance, as hard abrasives is rouhgly wearing out the cabinet's surfaces.
It is not wise to use sand in an enclosed blast cabinet unless the machine is designed for it because the breakdown rate of sand is approximately 50 percent to 80 percent on impact, producing a large volume of dust.
Special abrasives have been mined and manufactured specifically for use in blasting cabinets. These abrasives are recyclable or reusable, and are available in many types and sizes. They include, but are not limited to, glass beads, glass grit, aluminum oxide, silicon carbide, garnet, corn cob, walnut shell, metal grit, metal shot and plastic abrasives.
When you select a size of abrasive to use, you should realize that the finer the abrasive is, the more aggressive it becomes, creating more wear on your machine’s components. But do not let this stop you in using fine abrasives; just be certain that it is considered when chosing your equipment.
One exception to this rule is glass beads. Glass beads are round, and they do not create a high degree of component wear. Abrasives that will create a high degree of wear are sand, aluminum oxide, silicon carbide, garnet, and iron or hardened metal grit.
Air pressure is not as important as volume of air when it comes to selecting and using blasting cabinets. Most blasting is performed between 5 and 125 psi pressure. Only the necessary amount of pressure should be used; too high a setting may cause rapid breakdown of abrasive, without any significant increase in production.
The volume of compressed air a machine will consume is based on the size of the air jet in a suction/induction blast gun, or the nozzle in a pressure blast system. The amount of compressed air, measured in CBM3/min. at a specific pressure, is what you need to know to select a compressor. The larger the size of airjet/nozzle combination in a suction/induction blast gun, or the larger the nozzle in a pressure blast system, the more production you will achieve, and the larger the size of the air compressor you will need.
Again, as in abrasive blasting cabinet purchases, it is wise to speak with a knowledgeable salesperson before buying. So please call us at +45 7013 1030