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 hole or rupture in the eardrum, a thin membrane that separates the ear canal and the middle ear, is called a perforated eardrum. The medical term for eardrum is tympanic membrane. The middle ear is connected to the nose by the eustachian tube, which equalizes pressure in the middle ear. A perforated eardrum is often accompanied by decreased hearing and occasional discharge. Pain is usually not persistent.