engineering

Multi-material 3D printing

Multi-material 3D printing 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 Multi-material 3D printing rather than just read about it. In short: Multi-material 3D printing is the additive manufacturing procedure of using multiple materials at the same time to fabricate a workpiece. Similar to single material additive manufacturing it can be realised through various 3D printing methods such as fused filament fabrication (FFF), selective laser sintering (SLS), stereolithography (SLA) and inkjet (material jetting).

Key takeaways

Multi-material 3D printing belongs to engineering; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Multi-material 3D printing to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Multi-material 3D printing from memory before moving on to harder problems.

Reference excerpt

Multi-material 3D printing is the additive manufacturing procedure of using multiple materials at the same time to fabricate a workpiece. Similar to single material additive manufacturing it can be realised through various 3D printing methods such as fused filament fabrication (FFF), selective laser sintering (SLS), stereolithography (SLA) and inkjet (material jetting). By expanding the design space to different materials, it establishes the possibilities of creating 3D printed objects of different colours, that is multi-colour printing, or with different material properties like elasticity or solubility.

History One of the first multi-material 3D printers for consumers, Fab@Home, became publicly available in 2006. The concept was quickly adopted by the industry followed by many consumer-ready multi-material 3D printers.

Multi-material 3D printing technologies

Fused filament fabrication (FFF)

Fused filament fabrication describes the process of continuously extruding a line of thermoplastic material to form a three dimensional model. The FFF process supports a variety of materials reaching from biodegradable ones like PLA to PETG, ABS and engineering-grade materials like PEEK. This technology additionally allows for the use of flexible materials like TPU. Some possible solutions to realise a multi-material filament printer are:

Single-nozzle: Filament changer: For using different materials or filaments in the same nozzle. Some well-known commercial examples are Prusa Multi-Material Upgrade 3 (MMU3) and Bambu Lab's Automatic Material System (AMS), and some open-source alternatives are Enraged Rabbit Carrot Feeder (ERCF) and BoxTurtle for Voron Design. Multi-nozzle: Tool changer: One dedicated printhead per material or filament, with a mechanism for switching between the multiple printheads. Each printhead (also called toolhead) has its own hotend, as well as an extruder in the case it is a direct-drive extruder. Commercial examples include Bambu Lab Vortek, Prusa XL and Snapmaker U1, while open-source alternatives include for example Stealtchanger and Tapchanger. Nozzle-changer: A single printhead can swap between different nozzles, thereby using the same hotend and multiple materials or filaments. A commercial examples includes Bondtech INDX. Separate gantries: Multiple printheads can run independently, like for example independent dual extruder (IDEX) in the case of two printheads, or independent quad extruder (IQEX) in the case of four printheads. Combinations of the methods above can allow for even more combinations of filaments, at an additional complexity

Single-nozzle design The single nozzle design combines the different materials before or in the melting zone of the print head such that the materials are extruded through the same nozzle. For example: The different filaments can be cut and rejoined to a single strand of a mixed filament before being fed into the melting chamber. Such a technique is implemented in the Mosaic Palette. Another example is the Multi-Material Upgrade by Prusa Research, which is mounted on top of a single material printer to add multi-material capabilities. It uses a bowden style extrusion system with an additional axis to cut and select the material. To prevent impurities inside of the object, a combined melting chamber has to be cleared from the previous material before a new one can be used. Depending on the implementation, the amount of waste material (often referred to as "poop") produced during the printing process may be significant. In some implementations, the previous material may be used as in-fill to prevent waste, or to simultaneously print a different object in which the colour does not matter.

Multi-nozzle design

The multi-nozzle design features a separate nozzle for each material. The nozzle can either be mounted on the same print head or on independent print heads. For this approach to work the different nozzles have to be calibrated to the exact same height relative to the print surface to circumvent the interference of an inactive nozzle with the printed object. Such a design reduces the amount of waste material during the printing process significantly compared to a single-nozzle design which does not use the previous material as infill or to print another object.

Stereolithography (SLA) Stereolithography is the process of solidifying a photopolymer with a laser layer by layer to form a three-dimensional object. To realize multi-material prints with this technology, one can use multiple reservoirs for different photopolymers. A major problem with this approach is the removal of the not yet polymerised material as the print may contain cavities filled with the old material, which should be emptied before the next material can be used. The photopolymer resins used for SLA can have highly different physical properties, generally being more brittle and having a lower heat deflection temperature. The SLA standard resins come in different colours and opacities. Besides the engineering grade materials like ABS-like or PP-like resin, there exists bio-compatible resins used for medical applications and flexible resins.

Material jetting

The process of material jetting, often also called inkjet 3D printing, is similar to the 2D inkjet printing procedure. The print head consists of multiple small nozzles which jet droplets of photopolymers on demand. Each nozzle can extrude different materials, which allows for the creation of multi-material parts. The droplets of material are then immediately cured using an ultraviolet light (UV) source mounted to the printhead. In contrast to the filament FFF printing process, a layer is not formed by moving the printhead along a pre-calculated path, but by scanning the layer line by line. For example, the Stratasys J750 allows for full colour prints. The materials supported by the material jetting printing process are similar to the ones of the SLA process, and hence share similar properties. Additionally there have been advances in the field of material jetting metals by suspending nano metal particles in a fluid. After the removal of the support material the printed object has to be sintered to create a final metal part.

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Multi-material 3D printing

Start with the simplest possible case. Write down what Multi-material 3D printing 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 Multi-material 3D printing 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 Multi-material 3D printing 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 Multi-material 3D printing

In research: Multi-material 3D printing 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 Multi-material 3D printing 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: Multi-material 3D printing is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3D printing, Computer printers, DIY culture, so understanding it makes those chapters shorter.
In everyday life: Look for Multi-material 3D printing 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 Multi-material 3D printing in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Multi-material 3D printing 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 Multi-material 3D printing out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Multi-material 3D printing in simple terms?

Why does Multi-material 3D printing 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 Multi-material 3D printing?

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 Multi-material 3D printing.