Abrasive blasting for preparation of metal surfaces
Abrasive blasting is most often used for preparation of metal surfaces of heavy structural parts, particularly HRS weldments. It is a very good way of removing the encrustations and carbonized oils that are characteristic of this type of product.
Blasting operations can be manual or automated and they can be installed as part of a conveyorized powder coating system or as a batch process.The blasting device may be a nozzle type or a centrifugal wheel type. As previously stated, nozzle blast systems require compressed air for delivery of the media while a wheel system uses centrifugal force. Even though the compressed air is an added cost, it may be necessary to direct nozzles into hard to reach areas of a part.
The blast area must be enclosed to contain the blast media and dust.In addition to cleaning, a blasted surface can create a very good anchor pattern for a coating.
Different blast media can be used to vary the profile created on the metal surface.Less aggressive media will remove most soils without cutting too deeply in the metal and leaving a visible texture on the metal surface.more aggressive media can be used to cut stubborn encrustations, such as red oxides, but it will leave more texture on the surface.
A blast system does not require as much space as a spray washer that uses chemical cleaning and it does not generate any wastewater. For these reasons, mechanical cleaning may be the only treatment required for finishes where initial paint adhesion is required.
However, mechanical cleaning alone will not provide undercoat corrosion resistance or extend the life of the finished product.Blast cleaning standards depend on the quality requirements of the surface.