engineering

Robocasting

Robocasting is a engineering topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Robocasting rather than just read about it. In short: Robocasting (also known as robotic material extrusion) is an additive manufacturing technique analogous to Direct Ink Writing and other extrusion-based 3D-printing techniques in which a filament of a paste-like material is extruded from a small nozzle while the nozzle is moved across a platform. The object is thus built by printing the required shape layer by layer.

Key takeaways

Robocasting belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Robocasting to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Robocasting from memory before moving on to harder problems.

Reference excerpt

Robocasting (also known as robotic material extrusion) is an additive manufacturing technique analogous to Direct Ink Writing and other extrusion-based 3D-printing techniques in which a filament of a paste-like material is extruded from a small nozzle while the nozzle is moved across a platform. The object is thus built by printing the required shape layer by layer. The technique was first developed in the United States in 1996 as a method to allow geometrically complex ceramic green bodies to be produced by additive manufacturing. In robocasting, a 3D CAD model is divided up into layers in a similar manner to other additive manufacturing techniques. The material (typically a ceramic slurry) is then extruded through a small nozzle as the nozzle's position is controlled, drawing out the shape of each layer of the CAD model. The material exits the nozzle in a liquid-like state but retains its shape immediately, exploiting the rheological property of shear thinning. It is distinct from fused deposition modelling as it does not rely on the solidification or drying to retain its shape after extrusion.

Process Robocasting begins with a software process. One method is importing an STL file and slicing that shape into layers of similar thickness to the nozzle diameter. The part is produced by extruding a continuous filament of material in the shape required to fill the first layer. Next, either the stage is moved down or the nozzle is moved up and the next layer is deposited in the required pattern. This is repeated until the 3D part is complete. Numerically controlled mechanisms are typically used to move the nozzle in a calculated tool-path generated by a computer-aided manufacturing (CAM) software package. Stepper motors or servo motors are usually employed to move the nozzle with precision as fine as nanometers. The part is typically very fragile and soft at this point. Drying, debinding and sintering usually follow to give the part the desired mechanical properties. Depending on the material composition, printing speed and printing environment, robocasting can typically deal with moderate overhangs and large spanning regions many times the filament diameter in length, where the structure is unsupported from below. This allows intricate periodic 3D scaffolds to be printed with ease, a capability which is not possessed by other additive manufacturing techniques. These parts have shown extensive promise in fields of photonic crystals, bone transplants, catalyst supports, and filters. Furthermore, supporting structures can also be printed from a "fugitive material" which is easily removed. This allows almost any shape to be printed in any orientation.

Mechanical behavior One key advantage of the robocasting additive manufacturing technique is its ability to utilize a wide range of feedstock "inks," as shear-thinning ability is the only inherently required material property. As such, robocasting has seen diverse application among many disparate materials classes such as metallic foams, pre-ceramic polymers, and biological tissues. This allows for a wide range of mechanical characteristics to be accessible through this technique, with additional tailoring possible through the use of ink fillers and varying extrusion parameters.

Filler effects Micro- and nano-scale filler materials are commonly used to create composite feedstocks for robocasting and are available in a wide range of compositions, with morphologies typically falling into the broad categories of spheres, platelets, and filaments/tubes. Both composition and morphology play significant roles in the mechanical characteristics imparted by the filler. For example, the inclusion of stiff boron nitride nanobarbs within epoxy feedstock has been demonstrated to anisotropically increase overall composite strength and stiffness along the direction of fiber orientation due to their shape asymmetry, while the inclusion of hollow glass microspheres within the same epoxy feedstock has been demonstrated to isotropically improve specific strength by significantly reducing total density of the composite. In addition to shape, differing size regimes within fillers of the same morphology have been demonstrated to yield significant changes in mechanical properties. For epoxy-carbon fiber composite systems of identical composition, flexural strength has been shown to generally decrease with decreasing fiber length. However, shorter fibers have also been demonstrated to produce better overall printing behavior during the robocasting process as increasing length also increases the likelihood of jamming within the extruder; higher print fidelity as seen for the shorter fibers generally results in greater reproducibility of mechanical behavior. In addition, very long fibers have exhibited a tendency to break during extrusion, essentially imparting a de facto size cap on filament-type fillers used in robocasting.

… excerpt ends here. Continue reading the full article.

Worked examples

Example 1 — a first encounter with Robocasting

Start with the simplest possible case. Write down what Robocasting claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In engineering, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Robocasting before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Robocasting ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Robocasting

In research: Robocasting appears in engineering research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Robocasting in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Robocasting is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1996 establishments in the United States, 1996 introductions, 3D printing processes, so understanding it makes those chapters shorter.
In everyday life: Look for Robocasting outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Robocasting in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Robocasting means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Robocasting out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Robocasting in simple terms?

Why does Robocasting matter?

Because it connects several engineering ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Robocasting?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Robocasting.