IDENTIFYING and using the correct abrasive product, whether for cutting, grinding or blending, is core to the successful completion of any job. Besides the safety risk involved when using incorrect products and the potential harm this may cause, the effect on production lead times and final finish of parts or items being manufactured should also be considered.
Material contamination like oxidation and rust, is a major cause of component and weld failure and occur either through – direct contamination when using the incorrect abrasive products, cross contamination when using the same abrasives on multiple materials; or general contamination due to improper processing of the materials in the work environment.
A common misconception is that stainless steels steel cannot rust. The same is often true for aluminium. While the actual oxidation process is different to “normal” steels, these metals can still oxidise (rust) if not handled and processed correctly. With stainless steels, normal oxidation creates a thin barrier or film like layer on the surface, called chromium oxide. Unlike mild steel rusting, the chromium oxide layer sticks to the metal, thereby protecting it. If this layer is stripped off, the metal will rust. High quality grade stainless steels steel, with higher chromium content will have better protection from this unwanted oxidation.
Direct contamination occurs when conventional cutting and grinding discs for steel are used for applications on stainless steels or aluminium. Abrasive cutting and grinding discs, as well as coated abrasive flap discs, are designed and manufactured with various components that make up the final product. Some of these components like fiber reinforcing, are added to provide structure and support to the final product for strength and support to avoid breakage and damages when in use. Together with these components, other additives are also added into the mix to provide better results, usually by increasing the oxidative and corrosive effect in mild or carbon steels. However, such oxidative and corrosive compounds (iron, sulphur and chlorine) can cause major issues down the production line when used on stainless steels Steel or aluminium applications. If the work piece is not thoroughly cleaned of these compounds, should it become contaminated, subsequent welding processes will also be influenced and might cause welds not penetrating well, or porosity that will lead to weak welds that can cause catastrophic failures if not resolved
To avoid cross contamination, care should be taken to avoid using abrasive products on mild or carbon steel, and then on Stainless steels Steel or Aluminium. Even though abrasive products are manufactured to be free of contaminants, unwanted iron, sulphur and chlorine compounds will be introduced when used on mild or carbon steel, which will be transferred to stainless steels or aluminium upon contact.
Grinding Techniques locally manufactures specialised abrasive products free of contaminants which are perfectly suited to applications on Stainless steels Steel, like the Superflex INOX Ultra and the Premium Aluminium range, specifically manufactured for use on aluminium.
With its Superflex range, easy selection of a dedicated product suitable for various materials avoids cross contamination. Where this is not possible and only a limited product range is used, care should be taken to keep the products quarantined from the other materials. If a disc or wheel has been used on one material, it should be marked as such or stored in a manner that operators will know not to transfer it to another material.
It needs to be noted that general workspace contamination can also contribute to contamination of various materials. Ideally, a floor layout should be planned in such a way that different material types are processed at opposite ends of a factory. This will ensure (to an extent) that swarf created during cutting, blending or grinding operations will not come into contact with stainless steels or aluminium materials in the vicinity, thereby eliminating the possibility of contaminating materials.
Grinding Techniques provides a solution driven service through its national network of branches, with a technical sales force geared to provide the best possible product solutions to optimize your production.
- For more information, +27 11 271 6400 | info@grindtech.com | www.grindtech.com
