In addition to the use of hand tools, the processing of metal workpieces is mainly achieved by the machine tools, such as lathes, planers, milling machines, grinders, boring machines, drilling machines, etc. These machines have different performances to match the job requirements. In recent years, various industrial advanced countries have used machines to replace manpower, making the application of machine tools more extensive and important. Although the processing precision of milling machines and grinding machines is superior to that of planers, the price is more expensive than that of planers. Generally, planers are still used for many initial processing jobs in small and medium-sized factories. So, what exactly is a planer?