The shot blasting machine is designed for cleaning metal products and metal structures, including large ones, from dirt and corroded areas by throwing shot and processing the surface of products. It is possible to process parts of a complex profile that are in hard-to-reach places.
Principles of operation of installations with shot throwing
Shot blasting provides cleaning or treatment of the metal surface using small particles like pellets. They are most often spherical. This is an abrasive blasting method for working with metal products and structures.
The main functions of shot blasting machines:
- Removal of scale after hot processing of metal products, including shaped ones.
- Mechanical cleaning from rust by removing a corroded layer of material both over the entire surface of the product, and in individual areas, especially affected by corrosion.
- Matting the surface, if it is necessary to make a smooth top layer matte. Different degrees of matt can be achieved: rough satin or soft velvety.
- Giving the surface the required level of roughness. You can achieve varying degrees of roughness, it depends on the material of manufacture of the shot and on the nature of the air flow.
The basic principle of operation: supply of “shot”, abrasive elements with a strong flow of air or liquid through nozzles, shot blasting machines.
Striking the surface of a metal product, the pellets act on the crystal lattice of the metal, compacting it, while the damaged areas are destroyed, and a strong, solid layer of surface material remains. Thanks to this principle, with the help of processing, it is possible to remove the load “fatigue” of the metal: parts and structures receive a “second” life, and the service life of new ones is extended.
The equipment can be adjusted to different processing modes, and different types of abrasive material are selected to achieve the desired result.
What are shot blasting machines
Shot blasting is carried out either with manual open-type installations, or in closed-type shot blasting chambers, either manually or automatically.
Varieties of closed installations according to the principle of operation:
- Pass-through installation with a conveyor for feeding structures into the chamber.
- Suspended shot blasting machine with a dead end chamber with shot blasting machines.
- Installations with feeding shot with special blades.
- Drum set with a horizontal drum-type container. The rotation of the container ensures that the abrasive elements hit the part or product.
- Installation for cleaning pipes with a complex structure.
Large shot blasting chambers are high-performance automated devices for in-line operation, with the help of which many similar objects and parts are processed. They achieve productivity up to 200 sq. meters per hour.
There are so-called “habitable” cameras, inside which the operator works.
In the most common belt-fed devices, the conveyor transports the products into the chamber. Possibility of feeding by means of a rail carriage, uniformly sending structures or parts for processing.
The camera is switched on manually or automatically, depending on the design.
Design features of chambers for processing shot
An abrasive blast chamber is a sophisticated piece of equipment assembled in housings of various sizes.
The camera is equipped with the following working units:
- Shot-blasting apparatus. It delivers the abrasive elements inside the chamber body to the processed structures in the required mode.
- A transport system that allows the delivery of products, structures, parts for processing.
- Loading and unloading devices.
- Shot cleaning and recovery system. Cleans abrasives from dust and returns to working mode.
- Filtration system to supply fresh air so that the system operator can breathe normally.
- Lighting equipment in shockproof version.
- Control panel in automatic blast machines.
The camera body is assembled from profiled panels with built-in swing gates.
A system for collecting abrasive material is mounted on the floor, consisting of conveyors on pneumatic cylinders with scrapers.
The bucket elevator picks up the used shot and transfers it to the cleaner.
The purifier works on the principle of a two-phase device with two stages of cleaning: first, larger impurities are separated, then fine particles are separated up to fine dust. The second stage is realized with the help of air flow.
Then the abrasive material passes into the hopper, from which it enters the shot thrower.
A chamber-type installation includes systems
- Electrical equipment with electrical cabinet, control units for individual components and wiring.
- Pneumatic equipment with a pneumatic cabinet, pneumatic control systems that perform production functions and provide the operator with fresh air.
Shot types for different metal surfaces
Abrasive elements differ in the material from which they are made and for their intended purpose. According to these criteria, the following types of fractions can be distinguished:
|Fraction type||Special purpose|
|Cast iron chipped. It is based on white cast iron and cementite.
|Surface treatment for painting or anodizing.
Creation of a high-quality type of matte surface, descaling and corrosion.
Peening is a surface treatment method that increases the strength and hardness properties of a material.
|Aluminum||Processing of aluminum parts and structures, including those made of soft aluminum alloys. You can get the desired roughness.|
|Ceramic||Finish products for a clean, smooth surface.|
|Glass||High-strength processing method.|
|Plastic, polyamide and polycarbonate||Processing of glossy extra smooth surfaces.|
|Electrocorundum||Treatment of particularly dirty and highly corroded surface layers|
Regulatory requirements for the operation of installations
The regulatory requirements for the operation of shot blasting devices relate to both technical characteristics and safety rules if the work is carried out by the operator.
Technical requirements are regulated by regulatory documents such as GOST and international ISO standards.
Safety requirements assume the presence of an alarm when working in cameras. This should be both light and sound alarms, which informs that a working cycle is taking place inside the equipment.
Security issues also concern the employee’s work within the system. They belong to personal protective equipment in the form of special protective suits and a helmet, a special air filter.
Shot blasting of metal structures and parts is considered the most modern and advanced way of processing metal material of complex configurations with various types of surface.