Many developers of ceramic additive manufacturing (AM) have adapted the feedstock materials by incorporating ceramic particles, to suit existing AM processing hardware. However, this creates certain challenges within ceramic production, especially when you consider the complexity of ceramic processing. The researchers behind Hydra’s CHAMP technology took a different approach; instead adapting the manufacturing process and hardware to suit existing ceramic materials. This allows CHAMP to integrate into existing ceramic manufacturing workflows and accelerate product development.
So what is CHAMP?
The acronym stands for Ceramic Hybrid Additive Manufacturing Platform, obviously. It is a platform technology, designed for shaping ceramic1 components that uses a hybrid version of an additive manufacturing process. Keep reading to find out what that actually means.
What is Additive Manufacturing?
Additive manufacturing (AM), otherwise known as 3D printing, has been predicted to revolutionise the manufacturing industry2. It is a shaping method whereby the desired geometry is created by sequential addition of material to create the desired geometry, directly from digital data, in a layer-by-layer method. This is opposed to formative manufacturing, where the geometry is obtained by changing the shape of a starting block of material, or subtractive manufacturing (SM), where the shape is achieved by removal of material from the starting block.
AM has certain key advantages over these methods. The digitally-driven nature removes the need for templates or tooling, meaning that every single unit can be different. This accelerates the prototyping phase and paves the way for single-unit customisation, enabling the production of patient-specific medical devices, for example. The other major advantage is the sequential addition of material enables higher levels of complexity. The geometry of the component is no longer limited by the constraints of mould release or tool accessibility. It also facilitates designed heterogeneity for the first time. This is the ability to spatially control the material composition, creating multi-material, or functionally-graded components, enabling flexible production of truly functional devices.
However, additive methods also have their limitations: equipment is expensive and can often be slow, the build time scales disproportionately with part size; the resolution is directly linked to the smallest built element2; and the range of compatible materials is often limited. This is especially true for ceramics where the presence of ceramic particles significantly increases the processing difficulty. For these reasons, advanced manufacturing research has increasingly turned towards hybrid methods.
And what is hybrid?
Hybrid manufacturing processes combine (usually distinct) manufacturing operations to improve either component quality or process efficiency by leveraging the advantages of each operation to overcome their individual limitations.
In the case of CHAMP, the process combines the AM technology of material extrusion, hybridised with the SM technology of CNC milling, in a build-then-refine strategy. The platform also includes polymer printing and ceramic drying as assistive technologies, and in-situ monitoring for intelligent process control. More information on the specifics of these processes will be given in future posts.
The rationale for this process combination becomes apparent considering the advantages and disadvantages of the constituent processes:
| Material Extrusion | CNC Milling | |
|---|---|---|
| Description | Selective deposition of material3 by extrusion through a fine nozzle. | Selective removal of material from billet or preform by cutting with a rotating tool. |
| Advantages |
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| Disadvantages |
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Implementing these two technologies in a single platform enables them to overcome the other’s limitations, key relationships in this regard are highlighted in different colours. In short, the paste extruder rapidly deposits material (or materials!) into the designed geometry (roughly) and the milling tool refines this geometry, creates finer features, and improves the surface finish and dimensional accuracy. What’s more, the ability to both add and remove material enables a re-manufacturing paradigm - preventing fabrication defects by intelligent process control.
Critically, this is all completed in a single machine with digitally driven control. Hydra’s software toolkit streamlines the CAD/CAM process, enabling rapid design iteration and accelerating the concept-product pipeline.
Further implications of this method and the opportunities it unlocks will be discussed throughout this series. Keep reading to find out more!
--------- Science Corner ---------
Footnotes for those curious about the science. Be warned: the complexity of ceramic materials often demands caveats in caveats!
[1] CHAMP is not strictly limited to ceramic materials. It has previously been proven on ceramics and cemented carbides (metal matrix composites) but the material scope is broad, as explained in [specifics of material extrusion].
[2] This isn’t science but it’s worthy to note that while AM is an important tool, accelerating product development and low volume manufacture, it will never replace all manufacturing, especially high volume production of simple products. For example, one would not be sensible to 3D print plastic bottles for soft drink manufacturing…
[3] Refers to the smallest volume of material that can be built with the specific AM process. In all cases the layer height constrains the resolution in the Z direction. In the XY direction it depends on the method. In an extrusion process, the bead width. In a jetting process, the droplet size. In a polymerisation process, the pixel size of the projector or the laser spot size.
[4] This process was initially designed for thermoplastic polymers, where they were heated to soften, enabling extrusion, then cooled to resolidify, retaining geometry post deposition. Adaption to suit ceramic materials has used various approaches. Hydra’s method uses paste extrusion, where the ceramic particles are suspended in an aqueous paste which is partially dried to cause resolidification post deposition. This process is also known as direct-ink-write (DIW) and robocasting (robotically controlled casting).
