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FRONTpage Don Nelson
Publisher
Hybrid processes raise the performance ceiling
4 | MAY/JUNE 2012 | MICROmanufacturing
first encountered hybridization in manufac-
I turing 25 years ago, shortly after being hired
as associate editor of MICROmanufacturing’s
sister publication, Cutting Tool Engineering.
One of my duties was to sift through the vast
number of press releases we received about
new products. A release crossed my desk one
day describing a tool I had never heard of—the
Dreamer, a hybrid tool for drilling and reaming.
“Wow,” I thought, “how clever!”
The number of clever hybrid tools, machines
and processes has grown exponentially in
the quarter-century since I was awed by the
Dreamer. And, given the increasing level of
research into hybridization, I expect many more
hybrid products and processes to come online in
the next few years.
The need to reduce manufacturing costs
by increasing production efficiency underlies
the hybridization trend. Many single-process
techniques, like milling, turning and other
subtractive methods, operate near the upper
limits of their performance capabilities.
Combining technologies can raise their respective
productivity ceilings.
Among today’s biggest productivity
squelchers are advanced materials developed
for aerospace and medical components.
They boast significantly higher mechanical
and thermal properties than earlier-generation
materials. These characteristics result
in stronger, lighter parts, but they are much
harder to machine.
One hybridization strategy for cutting
advanced materials is to use a laser to soften
the workpiece right before a tool cuts it.
Researchers at a Michigan university have
devised a novel system for machining ceramics,
wherein a laser beam passes through a
diamond turning insert and strikes the material
in front of the insert’s cutting edge. (See Tech
News, page 10.)
Another appeal of hybrid methods is their
ability, in certain situations, to produce morecomplex
part features, impart finer surface
finishes and/or achieve higher productivity
levels than a single process can. These
performance improvements occur when
the combined processes mutually enhance
one another, when one process mitigates an
inherent weakness of the second or when each
process cancels out the other’s shortcomings.
Many studies cite examples of a hybrid
technique dramatically outperforming its
constituent processes.
Additive manufacturing (AM) seems likely
to join the hybridization movement. Hybridizing
lets a manufacturer combine the best of
the subtractive and additive worlds.
An engineer I spoke to recently cited an
example from his experience. An aerospace
company had approached his firm, seeking ways
to shorten the time needed to produce a component
consisting of a tube with a crown-shaped
feature on top. Previously, the tube and crown
were machined from a single piece of metal.
The firm recommended forming the tubular
section instead of machining it; this saves
material as well as the time previously required
to program and cut the tube. The crown now is
fabricated via a powder-metal AM process that
meets specs while eliminating the occasional
scrapping of components that resulted from
machining the crown’s intricate features.
Because additive techniques are relatively
new compared to subtractive ones,
little research has been conducted into additive-subtractive
hybridization. An interesting
paper on the subject was published recently
by researchers at the Institut de Recherche en
Communications et Cybernétique de Nantes
(France). Titled “A new DFM (design for manufacturing)
approach to combine machining and
additive manufacturing,” the authors propose
a method by which a one-piece CAD model
of a part can be separated into modules—like
pieces of a 3-D puzzle. Users can then determine
which part features would be best to
produce by additive and subtractive methods.
Clever stuff that’s worth reading. You can find
the paper at www.micromanufacturing.com. µ
Publisher
MICROmanufacturing
(847) 714-0173, dnelson@jwr.com