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Jeremy Spencer, Product Engineer III, Saint-Gobain Abrasives
A few years ago, many of the major fast-food chain restaurants started advertising supersize options for a few cents more to their customers. This may be a good value option in fast-food but can the same be said when talking about coated abrasive products?
Norton offers coated abrasive products with a supersize layer on top of the grain surface. Other abrasives companies offer a similar option and have their own unique name for this layer; however, it is all applied to prevent the same issue - heat. Supersize is a grinding aid used to prevent the metal being ground from getting hot during the grinding process. Why is this needed? The simple answer is heat.
Heat is one of the worst enemies of coated abrasives. When grinding harder to grind metal, such as stainless steel, the metal will heat up and can create a capping effect on the abrasive grain. Capping happens when the extremely soft metal covers the grain causing it to be encapsulated by a metal coating. Coated abrasives work best when the grain starts to wear which causes the grain to fracture allowing the rounded edges to become sharp again, and therefore allowing the product to continue to cut. If metal capping occurs, the grain is not allowed to fracture, thus causing metal on metal rubbing and the generation of additional heat. Metal, such as carbon steel, which is easier to grind does not become tacky while grinding, so the need for supersize is not necessary like it is for harder to grind metals such as stainless and aluminum. A supersize product can still be used for carbon steel; however, the addition of the supersize aid will increase the overall cost of the abrasives. Supersize products cost more to manufacture than non-supersize products; therefore, the added cost means a higher overall price to the end-user.
Depending on the brand, size, and type of product, the cost can be a great deal higher. Using fiber discs as an example, Supersize discs can be up to 16% higher in price than non-supersize fiber discs. Listed below are the results of internal tests comparing supersize vs. non-supersize discs on A36 carbon steel and 301 stainless steel.
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As shown in the charts, the supersize product removed more material from both metals, but for carbon steel, the improvement was not as significant. On carbon steel, the Supersize product removed 6% more material, but factoring in the 16% higher price, the only value would be time saved performing the task.
When used to grind stainless steel, the supersize product was much more effective, removing 56% more material. Even with the 16% higher price, the customer would still save $500 in abrasive costs along with $4000 in overhead and labor, due to the higher rate of cut, for every 1000 discs used. Therefore, spending more on supersize abrasive products for harder to grind metals is well worth the investment, but maybe pass on the supersize combo meal next time you are in the mood for fast food.