In the aerospace and medical fields the surface finish of machined components is of utmost importance.

1. The Importance of Surface Finish in
Components for The Aerospace and
Medical Industries
Introduction
In the aerospace and medical fields the surface finish of
machined components is of
utmost importance. High
pressure hydraulic systems
and fuel injections systems in
particular require high quality
surfaces and precisely defined
features, such as o-ring
grooves, if system integrity is
to be maintained. In the
medical field, equipment
manufacturers and
pharmaceutical producers demand stringent specifications
with respect to surface finish. Literally, lives can be on the
line if these systems fail, so it is critical that the quality of
the machined components is maintained.
Nuclead Inc. has over 30 years of experience producing
components for the Aerospace and medical fields. This
article describes the capabilities and expertise available
that has made that possible. First though we begin with an
explanation of surface roughness measurement and
definition.

2. Surface Finish
Surface finish is defined in terms of 4 factors:
Roughness – closely spaced surface irregularities,
resulting from the manufacturing process or tools
Lay – the overall direction of the roughness pattern
which can be affected by the machine and setup.
Waviness – longer spaced irregularities caused by
machine vibration and material warping among other
factors.
Flaws – unique surface imperfections in the material
or processing
Surface finish is measured in terms of RMS (root mean
square), this is the square root of the sum of individual
surface readings over a particular sampling distance.
Another way of looking at this is that the higher the RMS
value that is observed, then the greater the depth of any
irregularities on the piece and as a result the greater the
likelihood of poor functionality of the component.
The surface finish requirements depend on the
application. Low pressure applications may allow a RMS
value as high as 64 or 128 microinches, a typical static seal
may require a finish with a RMS of 32 microinches, but
many applications in the aerospace and medical fields,
particularly in high pressure systems, will require finishes

3. with a RMS of 8 to 10 microinches. This is well within
Nuclead’s capabilities.
In addition to RMS, surface roughness can also be
measured using the value Ra (roughness average) this is
typically measured using a profilometer.
Capabilities
From the definition of the factors affecting surface
roughness as noted above, it is clear that achieving the
best in surface finish requires the manufacturer to have
several capabilities. These include the highest quality CNC
machines; experience, skilled and talented operators; QC
measurement capabilities and modern CAD-CAM systems.
Nuclead has all of
these capabilities.
The rest of this
article will provide
more details on the
capabilities
necessary to
produce
components of a quality to satisfy the Aerospace and
medical industries.
CAD/CAM
CAD/CAM refers to software tools that allow the design
and drafting of prints (CAD), the electronic transfer of

4. those prints and the subsequent manufacture of the
component using computer contolled tools (CAM)
Computer-aided design (CAD), software allows the
operator to use a computer to streamline the process of
designing and documenting components to be
manufactured at a subsequent operation. The output can
be for either print or machine code, and can display both
vector graphics as in traditional drafting or raster graphics
that display the physical appearance of the finished object.
Computer-aided manufacturing (CAM) takes the output of
the CAD process, transfers it to a computer controlled
machine, like a CNC machine, and then uses the code to
control the machining of the component.
CAD/CAM increasing efficiency in terms of both time and
material comsumption and also improves surface finish
capabilities.
CNC Machining
CNC stands for computer
numerical controller that
reads computer generated
instructions that are
extracted from electronic
drawings. This allows
complex 3 dimensional shapes to be created within
accurate and repeatable precision. Thus allowing for the

5. custom fabrication of many components in quantities from
single parts to long production runs for both aerospace
and medical applications.
As well as CNC machines, Nuclead also uses saws, mills and
to produce these sophisticated components.
Surface Grinding
Nuclead has surface
grinding capabilities up to
52" x 20" x 20" (LxWxH),
and can hold tolerances of
+/- .0001” and surface
finishes of 6 rms. Nuclead
can OD and ID grind any
material to .0001”
tolerance with .0001” roundness.
Surface grinding is a common grinding operation used in
the finishing process it uses a rotating abrasive wheel to
smooth the flat surface of the workpiece. The workpiece is
held in place on a chuck, either by using a magnet or
vacuum and is then moved under the rotating grinding
wheel to allow the piece to be abraded.
Nuclead offers Blanchard grinding services up to 60”
diameter. Blanchard grinding, also know as Rotary Surface
Grinding, removes large amounts of stock quickly and

6. efficiently and is ideal for large parts such as rotary tables,
mold plates, and vacuum chambers.
QC measurement
In addition to a full supply of qualified gages, digital height
sets, granite plates, comparators, profilometers, and
inspection equipment, Nuclead also uses CMM's to check
surface profile can component specification.
A coordinate measuring
machine (CMM) is a device
used in manufacturing and
assembly processes to test
a part or assembly against
the design drawings. The
CMM measures the X, Y,
and Z coordinates position
of preprogrammed positions on the workpiece and then
uses regression analysis to determine to prove that the
part meet specification.
Nuclead is an ISO9001:2008 certified company.
Experience and Conclusion
Nuclead’s production machining and custom machining
capabilities includes all materials used in aerospace and
medical industries, including beryllium, tungsten, nickel,
titanium, stainless steel and invar.

7. For over 30 years, Nuclead’s experienced personal have
been manufacturing components to high tolerances and
surface finishes that exceed the requirements of both the
aerospace and medical industries.