Shot Blasting Service & Advice

Shotblasting

There are many Powder Coating Companies (especially the ones without ISO 9001 Certification) who will coat components with scaly or rusty surfaces. Some of them believe that it is sufficient to give the parts a quick rub down with wire wool or abrasive paper to ‘’remove rust or corrosion’’! This method does not work and is a slap-dash way of Powder Coating parts that is guaranteed to create rejected parts in the future.

We always remove scale, rust and corrosion by shot blasting components with Chilled Iron G10 before Powder Coating them. Other types of media are available. Shot Blasting has become a much-used term to describe the method of cleaning a metal part with a stream of particles propelled by high pressure compressed air. In the Powder Coating industry, the process is used to remove rust and scale from steel parts or to clean residues that are present on the surface of other metals. Many steel components are made from Hot Rolled Steel, this type of steel has a layer of Mill Scale on the surface formed when the steel was shaped or rolled while hot. Rust marks or staining can also be present on the surface as very often steel stockholders store hot rolled sections in less than ideal locations.

The process of welding steel parts can also result in the welded area rusting because the area adjacent to the weld becomes hot during the welding process and any oils/grease on the surface is burnt off.

Shot Blasting is a very useful way to clean up welded areas removing any corrosion prior to Powder Coating the components.

The removal of Rust or Scale from the surface of steel parts to be Powder Coated is vital if the coating is to be corrosion resistant and retain a good cosmetic appearance during its life. Shot Blasting has the effect of roughening the surface of the metal and creating microscopic peaks and troughs on the surface, this not only cleans the surface, but it also increases the surface area of the component which results in a larger surface area for the Powder Coated surface to adhere to.

Shot Blasting is carried out in either a cabinet or in a specially prepared room. Smaller parts can be prepared using cabinet blasting. Usually, cabinets are rectangular enclosures with extraction and lights. Two holes are situated at the front of the cabinet so that the operator can hold the items to be shot blasted in protective gloved hands and using the blast hose control turn on the media stream and clean the components.

Larger Parts are Shot Blasted in a room or large walk in enclosure. Usually these have walls protected with heavy duty rubber and efficient extraction to remove dust from the air. The operator wears protective clothing and helmet and walks into the room to carry out the blasting process. The particles or media used in the blasting process vary enormously.

The most popular ones are;

• Chilled Iron, A very hard media, made from cast iron that is crushed and granulated to a variety of sizes. Usually designated by the symbol G. ranging in size from G07 (0.2mm) to G39 (1.6mm)
• Steel Grit. This is made from High Carbon Steel that is crushed and tempered to a particular hardness. Sizes range from 0.125mm to 2.35mm
• Aluminum Oxide. Made from crushed aluminium oxide, it is very abrasive and very good at quickly removing all manner of surface contaminants.

The above three types of media are only a very small selection of the wide range of substances that are used for shot blast cleaning of rusty,scaly or corroded parts.