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.
A perforated eardrum is when the thin membrane, called the tympanic membrane or eardrum, that separates the middle ear from the outer ear has a hole or tear in it. 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.