Q: What is chemical milling?
Chemical milling, sometimes called chemical
machining, is a process used to reduce the
weight of aircraft parts by selectively removing
precise amounts of material with chemical
solutions versus mechanical operations like CNC.
What kind of
metals are, or can be, chemically milled?
The most common metals that can be chemically
milled are aluminum, stainless steel and
titanium with each requiring a different milling
chemical solution. TAM specializes in milling
How does the
chemical milling process work?
Parts to be chemically milled are
first covered with a special coating which after
curing is cut and removed from specific areas to
expose the part surface. The part is then
immersed into a solution that dissolves the
exposed areas on a carefully timed basis which
depends upon the material type, solution
temperature and chemistry used. Milling
is highly controllable and can provide
tolerances of plus or minus 0.002”.
Are there any
advantages to using chemical milling?
There are several advantages to
using chemical milling not the least of which
is that many parts can be processed
simultaneously instead of individually.
Another advantage comes from the fact that many
aircraft parts are formed with complex contours
that would make it difficult, or even
impossible, to mill by another means.
Also, exterior skin parts can be milled to very
dimensions (.020”) without heat warping that can
be caused by conventional machining.
Are there any
special requirements needed for chemical
Chemical milling does require
that a reusable hard tool (or template) be
available in order to accurately transfer the
blueprint layout of the milled areas to the
material. These durable tools can be used for
many years without needing replacement and are
usually available through the original aircraft
manufacturer. Tooling can be fabricated and
provided by TAM if needed. You are welcome to
contact TAM if you have any questions. It’s
time and money saved for everyone if tools are
correctly set up the first time.