Metamorphic Manufacturing - Return of the Blacksmith
The flow of technology is usually driven by the hope for the future but sometimes technology also takes
inspiration from the past and surprises us. Metamorphic Manufacturing is one of such novel idea. During
the industrial revolution, we moved away from versatile and tedious hand manufacturing methods to rigid
and efficient machines. This meant that the hardy blacksmith who could forge anything between an iron
nail to the hull of a ship was replaced with closed die forging methods that make a single part over and
over again. These new forging methods became exceedingly cheaper for mass production but this economics
of scale also made small-scale manufacturing very costly. There are already technologies in existence
that address this flaw by making our manufacturing methods more reconfigurable and agile. The most
widely used of them are numerically controlled subtractive manufacturing or CNCs and the latest additive
alternative of 3D printing. They have surely revolutionized the way we make things but they are not
without their own shortcomings.
CNC machining is a time-consuming process, adding considerable cost to components because only a
fraction of the original material is used in the part (the rest is turned into chips) and an expensive
machine is tied up for some time to make the part. Additive manufacturing is in its infancy, but often
components are created from powders. This also produces significant waste; secondary operations are
usually needed for high performance and the costs of raw materials and equipment used can be high. So in
order to make our manufacturing truly agile let’s get back to basics. Imagine if a machine can act like
a blacksmith does, squeezing and bending metal into shape, and doing this at temperatures and with
deformation that actually improves the properties of the material. This kind of process is referred to
as metamorphic manufacturing and is believed to take its place alongside existing additive and
subtractive manufacturing.
So why choose metamorphic manufacturing over CNCs and 3D printers? And how does it even works? To
understand these questions let’s take a look at iconic Japanese blades called Katanas. They are
traditionally made by folding multiple layers of steel with varying concentrations of carbon onto
themselves. This process is not only time-intensive, but it also takes an immense amount of skill to get
it right and tweak it ever so slightly for each blade in order to achieve perfect Katana. These blades
have very sharp edges and tough interiors which is next to impossible to recreate with either CNC or 3D
printing alone. Though a master of their art these blacksmiths cannot be relied upon to make parts with
high dimensional precision or highly reproducible properties. This is where automation comes in. It is
possible to mimic the attributes of a blacksmith, but with dramatically improved dimensional control,
reproducibility, and monitoring of the process path to assure quality and high performance. There can be
immense cost and time savings replacing closed-die forgings with robotically blacksmithed parts,
particularly if they are assured to have better properties and performance. This will come in
particularly handy for many industries as they can manufacture a plethora of replacement components
in-house at a cheap price and without a need to make a mold.
The full vision of metamorphic manufacturing integrates shaping, working, and heat treatment of the raw
material to optimize material properties and shape. Recording of local properties, shape, and
temperature is done to allow assured reproduction of critical process elements. This leverages recent
technical developments but requires significant integration and advanced control systems. There are many
machines that can be used including hammers, displacement-controlled presses, rollers, etc. Because
deformation is provided in small increments, only modest forces are needed. Optical monitoring and
Control systems are required to measure the current shape of the component and temperature field and
strains can be estimated by computation. Correction routines can adjust shape the way a blacksmith would
allowing for higher error tolerance and a robust manufacturing process. Significant integration and an
advanced closed-loop control system will be required to create advanced parts using this type of
incremental deformation. In order for this approach to truly thrive, it will need to be adopted to where
validation and verification protocols exist so that components made in this way can be certified for
safety-critical use, for example in aircraft. The rewards that can drive this are large. This approach
promises high-quality, rapidly produced parts that have a low environmental footprint, can have low
cost, and are produced locally.
