Recirculation and cleaning the abrasive shot is required to maintain a consistent cleaning operation. In conventional shot blasting equipment after the shot hits the part the abrasive falls into the collection hopper under the machine.
The shot is then carried by gravity or screw conveyor to a bucket elevator. The elevator carries the shot, removed oxides and other contaminates to an air wash separator located in the upper portion of the machine. A combination of baffles, strainers and plates separate these contaminates which are ineffective during the shot blast operation. The cleaned abrasive is contained in an upper hopper (feeding-box) and is subsequently fed into the shot turbine by gravity.
The recirculating and cleaning capacity of the abrasive in each machine is related to the shot blasting power used for the turbines. An incorrectly sized system will cause premature wear to the machine and decrease overall shot blasting effectiveness and shot consumption.
The machine cabinet contains dust and abrasive. A machine mounted dust collector, reduces air pressure inside the machine thereby preventing dust from escaping into the shop environment. Material access openings in the entrance and exit of the shot blaster must be designed and protected to prevent abrasive spillage.
Cabinets are built from low carbon steel with an inner shell made of abrasive resistant materials including high strength alloy plates and thick rubber compounds. In the areas that are subject to direct high velocity shot, alloy steel plates (64 RC hardness) are used which have much more abrasion resistance than other more commonly used materials like manganese steel.
Dust collector system
Dust produced during shot blasting is withdrawn from the machinery cabinet and continuously recirculating abrasive by a dust collector. Typical dust collector design uses baffle filters or cartridges.
The dust collector not only evacuates dust within the machine but also keeps the surrounding area clean and dust free. Changes in airflow will reduce collector efficiency and therefore result in lower dust extraction, loss of the cleaning power, and contribute to dust in the immediate production area. A properly designed and sized dust collector is therefore critical to the ongoing performance of the shot blasting System.