SURGICAL

Cold-forged blanks are made out of sheet metal or bar stock. Instead of
being shaped under heat, they are shaped using the force of heavy
hammers. Still other blanks are made using laser cutters or milling
machines, which cut out or mill the desired shape.
6.5 Milling and Turning
Once the instrument maker has verified the quality of the blanks to be
used, the next process is milling and/or turning. In the case of forceps,
this process is used to create the basic shape of the box lock, jaws and
ratchets.
6.6 Assembly
On a two-part instrument there is a male and a female part, which
depending on the type of hinge used, are then assembled. A typical
forceps has a box lock, which is created by widening the female part
under heat and inserting the male part. They are then secured with a
pin. Upon close inspection you can see the pin in a finished instrument.
6.7 Filing and Grinding
The shape of the metal is still quite rough at this point, so it is necessary
to file and grind the instrument into its final shape. This is a process done
entirely by hand and takes great skill.
6.8 Heat Treatment
Instruments requiring it undergo a process called heat treatment,
tempering or hardening. This is necessary to make the instruments hard
enough to withstand the rigors of their usage. The process differs
somewhat according to the stainless steel chosen, but in all cases the
stainless steel is brought to a very high temperature and then cooled
until it has reached the proper hardness.
Achieving the right hardness is extremely important. If the steel is too
soft, it will wear out or bend prematurely; if the steel is too hard, it will be
brittle and break too easily.
The proper hardness is measured in units called Rockwell Hardness
(HRC). A typical hardness range for a needle holder without tungsten
carbide inserts is HRC 40–48. For scissors, the hardness ranges
between HRC 50–58.
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