Shot blasting sounds as though it should be a fun activity similar to paintball. But it isn’t! It’s actually an industrial process used to remove residue and impurities from metal prior to powder coating. The method used, however, is not all that different – you’re just aiming at metal, not people!
Essentially, as its name implies, shot blasting involves blasting steel shot or steel grit onto a (usually) metal surface in order to remove dirt, oil, metal oxides, welding scale and lubrication greases, among others. Different finishes can be obtained using different-sized shot - smaller shot particles create a smoother, more polished finish, while larger shots are great for removing flash (excess forged material), so there’s no need for filing.
Shot blasting is an essential part of the surface preparation prior to powder coating, as if any impurities are left behind on the metal, they can cause the coating to be uneven. More importantly, a badly prepared surface significantly affects the longevity of the paint, powder or other coating being used.
It’s essential to coat over a clean, bare, white metal surface. Anything else leads to premature failing of the coating, which will then have to be removed, the surface properly treated, and then recoated. This is both time-consuming and costly.
Shot blasting is a highly effective and environmentally-friendly way of cleaning and preparing metal surfaces. It is used in a wide range of industries, including automotive, aerospace, shipbuilding, foundry and construction, among others. It is often done in a blast room, which is typically made up of three parts: the containment structure, the abrasive blasting system and the dust collector. Most blast rooms also have some kind of recycling system, as shot can be successfully reclaimed and cleaned before being reused.
Types Of Shot Blasting
There are two main shot blasting methods – air blasting and wheel blasting. Air blasting usually takes place in the aforementioned blast room. Compressed air is used to pneumatically accelerate the blast media, which are then projected onto the surface through nozzles. These nozzles can either be installed in fixed positions or manipulated manually or automatically.
With wheel blasting, a turbine wheel is rotated to convert electric motor energy into kinetic energy. The wheel then “throws” shots at the metal. The speed of the wheel can be adjusted to create different surface results. Wheel blasting is usually used when large parts with extensive surface areas have to be prepared, as large amounts of accelerated abrasive – up to 1200kg/minute – can be blasted using this method.
Steelmor is one of the leading stockists and manufacturers of stainless steel products in the country and has been for over 40 years. We boast the most comprehensive stainless steel stockholding and manufacturing facilities in Southern Africa and are more than able to handle any project you may have – including shot blasting.
Visit us at www.steelmor.co.za for more information.