Are the guide rails of ordinary lathes and milling machines scraped?

Generally, the guide rails of machine tools produced by regular manufacturers are scraped after grinding, because the hardness and hardness of cast iron used for guide rails are often uneven. When the grinding wheel is grinding, the hard part will be less resistant to knife grinding, and the soft part will be ground more, resulting in unevenness, which needs to be scraped by hand. When scraping manually, draw red lead on the guide rail, scrape the position where the red lead is erased, and then polish it until it is flat.