Blast Cleaning Machines Blast Cleaning Machines About In the various industries the Blast Cleaning Machines are called Shot Blasting Machines or Airless Shot Blasting Machines. They all are build the same and have the same purpose - to clean surfaces of metals by means of throwing abrasive (small metallic ball or particles) at high velocity on the surfaces of cleaned objects. Blast Cleaning is used for finishing, surface texturing, roughening, deburring, deflashing, descaling, stripping coatings, and surface preparation of products made of metals. Blast Cleaning Machines are used for metal surface preparation, prior to paint or coating, automotive parts manufacturing and shot peening for metal fatigue life and stress relief. Throughout the manufacturing industries using steel or other metals the materials require Blast Cleaning. Steel billets are cleaned before they become wire or structural shapes and these along with steel plates and sheets are cleaned prior to production to remove mill scale and rust. Fabricated components are Blast Cleaned to remove welding residue to prepare them for painting. Because of the nature and complicity of products (raw metals or prefabricated parts) there are many types of Blast Machines and each of them can be designed to suit the size and quantity of products manufactured by given company. The main components of Blast Machine are: Blast wheel, powered by electric motor a set of 4 to 12 blades (depending on the manufacturer) propels shot at high velocity on the surface of processed product. Cabinet, housing made of manganese steel where mounted blast wheel(s) cleans parts. Liners in line, a set of manganese plates or manganese castings mounted in the cabinet in line with the stream of thrown shot (abrasive) to protect the cabinet. Vestibule, housing with sets of seals on either side of the cabinet to prevent abrasive escaping from the machine. Spill hopper, often mounted at exit end of a machine to capture abrasive accumulated on parts during blasting. Screw conveyor (auger), transfers abrasive from the bottom of spill hopper, vestibules and cabinet to bucket elevator. Bucket elevator, transports abrasive to separator. Separator, it is where abrasive is cleaned through a screen to remove trash and high velocity air to separate from it the dust and small particles of broken abrasive (to small to be able to be used in blast cleaning). Storage hopper is situated under a separator and holds enough of abrasive to supply the blast wheels for uninterrupted blasting through the process. Feed pipes are hoses connecting the storage hopper and blast wheels. Slide gates located under storage hopper can close them for maintenance. In line with feed pipes are abrasive control valves, they are just above the blast wheels to open and close abrasive flow and adjust the volume of shot supplied. Roll Conveyor Machines To blast clean raw steel are used roll conveyor machines with the blast wheels oriented perpendicularly to blasted material to utilize the full power and energy but for manufactured components even such as beams with gussets the orientation of blast wheels have to be such to allow the abrasive to clean the entire surfaces of the beam, gussets and all the welding. To clean the entire parts these machine require the use of at least four blast wheels but with the increase of part size and when desired finish and rate of production is greater more blast wheels are employed. There are machines with 16 and more blast wheels. Roll Conveyor Machines are blast cleaning all surfaces of parts in one pass and are build for: only for plates or sheets of steel, they can be horizontal or where the products are processed at an angle at 45 to 70 degrees. The Horizontal type does require expensive shot (abrasive) and dust removal after blasting process. The wider the plate the more expensive is to remove the shot carried on the plates after blast cleaning. The machines where plates are processed at an angle may require only a blow-off for removing of dust. only for raw structural steel, these can be build for single pass of a product or multiple pieces can be blasted at the same time. for plates and raw structural steel, usually purchased by larger manufacturing companies for large volumes of steel to be processed. for weldments, prefabricated parts are conveyed through the machine on rolls or carried by a crane on chains. If parts are irregular a crane must be employed and the entire roof of the machine has to have a slot with multiple seals to prevent the abrasive from escaping. If crane can't be used the irregular parts could be carried on sleds and roll through on the roll conveyor but the sled can prevent some areas to be sufficiently cleaned. Table Machines The elements which can not be transported on a roll conveyor, heavy and not very long and heavy castings are blast cleaned in Table Machines. They can not be cleaned in one cycle, the blast can not reach the entire surface of the parts, they must be turned over or relocated at least once. To speed up the production are designed machines with two tables attached to the doors of the machine. Depending on the size of product and quantities desired to be cleaned at once, one, two or more blast wheels are installed. The main two types of Table Machines are: single table located inside the machine, will allow blast cleaning of lager and heavier pieces but loading parts and turning them over for multiple cycles could be cumbersome. single or two table machines, where the tables are mounted on the door(s) of the machine. Because they are on the doors the loads are limited but as the door with a table opens the loading is much simpler. And if the machine is featured with tables on two doors this allows for increased production. Spinner Hanger Machines These are used for blast cleaning irregular parts of various sizes just as the Table Machines but for much higher production rates. There are three main types of Spinner Hanger Machines: drive through, where the product(s) are carried by a crane or a monorail and as the parts enter the blast cabinet they do spin as they are blasted. In this fashion are blasted single large parts or multiple smaller parts hanged on a fixture. Drive through machines can be equipped with doors on both ends of the machine or if there is enough space in the building at both ends of the machine are vestibule with sets of seals. cabinet type with single door, where parts enter on a single monorail or "v" shape track to blast one batch of parts as the second is unloaded/loaded. The parts are rotating in front of the blast wheels during process of blasting. It is possible for larger or more complex parts to introduce linear movement of the parts as they do rotate to achieve all surfaces to be blast cleaned. cabinet type with single or two doors , where the door(s) are featured with hook and spinning mechanism. These are built for smaller parts and the double door allows for increased production.