Welcome to our first lesson in our introduction to material processing ansys innovation course.
In this lesson, we'll be going over the general stages involved in processing a material from its
raw state to a final product. If we're talking about material processing, we can split it into
three different stages. We have the preparation of our raw material, stage one. Stage two
is our processing operations and stage three is the post-processing, if needed. Now
this might seem quite simple--there's only three steps; but there are multiple elements
that go into each of these stages, which we'll expand on a little bit right now.
So let's start with stage one, prepping our raw material. As I said in the course introduction,
often our raw material isn't in a usable state. We actually have to process the raw material
in order to get it to what's called starting material and this is what
we can use in our processes to get to our final parts. Let's take aluminum for example,
the material that makes up our soda pop cans, our baking dishes, airplane wings. This lightweight
yet strong metal is used in a wide variety of industries. Aluminum is also one of the most
common elements found in the Earth's crust yet we never find aluminum ore on its own.
Instead, aluminum is always mixed with other elements. Bauxite is one of the aluminum ores that
we commonly use to get pure aluminum out of. It exists in a mostly hydrated aluminum oxide state.
To get from our bauxite to aluminum, we use what's called the Bayer process. First we grind
and calcine our bauxite. Then it's treated with sodium hydroxide at high temperatures to convert
our aluminum hydroxide to sodium aluminate. After removing impurities and other undesirable
byproducts of this reaction, we slowly cool our solution to precipitate out aluminum hydroxide.
We then wash this, heat it up to 1100 degrees celsius, and finally get aluminum oxide.
We can now take this much more pure aluminum oxide and dissolve it in a bath of molten cryolite.
Now we use an electrochemical process to deposit
almost pure aluminum. The purity we get is from 99.5 to 99.9%.
This is a very energy and time-consuming process to go from our bauxite ore to pure aluminum.
It's actually less energy intensive to recycle aluminum and get our pure aluminum back --we'll
learn more about these things in lesson three, but it's all the more reason to keep recycling.
So now we've completed stage one; we have a usable starting materia,l whether it's our pure aluminum
our polymer monomer we got from crude oil or a carbon fiber. Now we can move on to stage two, our
processing operations. Once again there are going to be multiple steps in our processing operations,
but in this stage we're generally using one of three approaches. We're forming our material,
we're adding material, or we're subtracting material. Regardless of which approach you're
picking, you're somehow altering the shape of your material. Let's start with forming.
If we're forming our material we're somehow defining the shape our material should be.
An example of this is injection molding, used to make a variety of polymer parts. In this
schematic we see that our starting material is some type of polymer powder. This is pushed
through our screw nozzle and melted and this melt is then pushed into our mold or injected.
This mold will define our product shape. As the part cools within the mold, the shape
is maintained. The next approach is addition. You may be familiar with this already-- this
is additive manufacturing. If a printhead is used it can be called 3D printing. Additive processing
involves starting with no material and adding our starting material through various techniques to
finally end up with our part or product. We can see an example here of selective laser sintering,
which can be used with both metal and ceramic powders. We start with a substrate submerged in
a bath of our starting material-- in this case a metallic powder. A laser will sweep over the
material, solidifying a layer of our powder. The substrate will then move down a specific distance,
allowing for new fresh powder to flow over the top of our part and then the laser will
pass over again. This allows us to build up our material layer by layer. Additive manufacturing is
highly sought after for its rapid prototyping capabilities and minimal material waste. Finally,
we have the subtraction approach. To me, this is a classic way of doing things.
Think of carving a piece of wood--maybe for a bowl, a decorative item, or a chair leg. You
start with a larger piece of material than what the final part needs then you subtract or remove
material to get to the final piece. Maybe you're turning a piece on a lathe, cutting with a saw, or
chipping away with a chisel. However the method, we subtract material to get where we need to be.
We've now completed stages one and two. We can move on to stage three:
the post-processing. Some materials might need a significant amount of post-processing, others
not so much. If i'm thinking of additive manufacturing, often we have small supports,
just to keep our pace piece stable as we're adding our different layers. These supports
can then be removed and we're pretty much good to go. In the case of our injection molding,
perhaps we overfilled the mold just to make sure we fit into all the noocks and crannies.
We'll want to cut off the excess material from the edges of our mold. Perhaps I need to drill a
hole in my part because it's going to be joined with something else. Perhaps i need some type
of surface treatment or finish. I might need to polish the piece or apply a coating or paint it.
Whatever the post-processing treatment, it's always chosen with the final way that
the material needs to behave once service in the product in mind. And with that, we've covered all
of our three stages of our processing operations and gotten from raw material to a final product.
Now this is a simplified version due to the introductory nature of this course but we've
seen how many different steps can go into getting from our raw material to the various products
in our homes. For lesson two we're going to be talking about four key elements of processing:
time, temperature, environment, and pressure and seeing how these impact our material processes.
For ease of understanding, we split this into four shorter videos
so join us as we see the impact that these four little elements can have.