Since 12L14 is an extraordinary machining steel it has become the favorite carbon metal for machining-especially on light weight lathes. It offers inherent ductility combined with finer surface quality. 12L14 has a smooth cold finish (rolled) surface.
1 An infection in the middle ear. When the middle ear is infected, pressure builds up and pushes against the eardrum and can cause the eardrum to perforate. When that happens, you may suddenly notice that the pain and pressure you've felt from the infection stops and pus drains from the ear.  An injury to the eardrum.
If you think you have a perforated eardrum, see a doctor. A tear in the eardrum can allow bacteria and other things to get into the middle ear and inner ear. If that happens, an infection could develop that can cause more hearing loss. Most perforated eardrums heal in a few weeks. Sometimes, though, doctors need to do surgery to repair the tear.