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.
Causes of a ruptured, or perforated, eardrum may include: 1  Middle ear infection (otitis media). 2  A middle ear infection often results in the accumulation of fluids in your middle ear.3  Pressure from these fluids can cause the eardrum to rupture. Foreign objects in your ear. 2  Small objects, such as a cotton swab or hairpin, can puncture or tear the eardrum. 3  Severe head trauma. 4  Severe injury, such as skull fracture, may cause the dislocation or damage to middle and inner ear structures, including your eardrum.