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 a hole or tear in the eardrum. It can be uncomfortable, but usually heals within a few weeks or months provided your ear is kept dry and thereâs no infection. The eardrum, also known as the tympanic membrane, is a thin layer of tissue that separates the outer ear from the middle ear.A hole in the eardrum can be caused by: 1  a middle ear infection, if pus builds up inside your ear and puts pressure on your eardrum.2  an injury to the eardrum, such as a severe blow to the ear or poking an object such as a cotton bud deep into the ear. 3  a sudden loud noise, such as a loud explosion.our GP may prescribe antibiotics if your perforated eardrum was caused by an infection or if there is a risk that an infection will develop while your eardrum heals. You can reduce your risk of developing an infection by keeping your ear dry until it's healed.