When you purchase a tool with movable or disposable parts, you will eventually have to replace part of it. Electric grinders are tools like that. Eventually the part that actually comes in contact with your materials will wear out, like sandpaper on a sander. When that happens, you want to replace it with products from Walter Abrasives. They have Enduro-Flex flap discs, zip wheels for steel cutting as well as cleaners and lubricants.