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.
Because it is so thin, the eardrum can be ruptured or perforated, exposing the ear to damage or infection. The main causes of perforated eardrum are infection of the middle ear or trauma to the ear or head. Symptoms and signs of perforated eardrum include. ear pain, vertigo or dizziness, hearing changes or hearing loss, ringing in your ears (tinnitus), or. fluid or blood draining from the ear.