A rounded bolt is a bolt that has had its head or nut rounded off, making it difficult to grip with a wrench or socket. This can happen due to over-tightening, rust, or damage. There are several methods that can be used to loosen a rounded bolt, depending on the severity of the rounding.
One method is to use a bolt extractor. This is a tool that is specifically designed to grip and remove rounded bolts. Bolt extractors come in a variety of sizes and shapes, so it is important to choose one that is the right size for the bolt. To use a bolt extractor, simply insert the extractor into the bolt and turn it counterclockwise. The extractor will bite into the bolt and loosen it.