3D PRINTED COMPOSITES
#OneWordFromAnisoprintingWorld
This is the series of terms through which you can learn anisoprinting basics. Anisoprinting is all about the composites. You can learn more about these materials from the previous word. And now we’ll go deeper in 3D printed composites.
Most of the existing continuous fiber 3D printing technologies can be divided into 2 types depending on the stage on which composite material is created: before the printing or during this process. When it’s happening beforehand such technologies are called prepreg-based, in the other case — co-extrusion-based.
In the first case, dry fibers are preliminarily impregnated with polymer using special equipment to get so-called prepreg. Prepregs can be in the shape of filament like plastics in the spools you may buy for FFF printers. Or in the form of a tape.
Later the prepreg is heated to form the part. In the case of filament, it is extruded through the nozzle device like in usual FFF printing technologies. In case of tapes, it is applied using the compaction roller similar to classic composites manufacturing technologies — AFP (Automated Fiber Placement) or ATL (Automated Tape Laying).
Co-extrusion means two components of the future composite — reinforcing material with the matrix (plastic) — are combined during the printing to get composite material. That means the material is born right at the same moment the parts is forming. Many companies put in the nozzle dry fibers together with heated plastic. Anisoprint embodies co-extrusion in another way though.
Both approaches have their pros and cons. Since preparing prepreg is a separate process made with special equipment it’s more likely possible to provide good impregnation of fiber to the matrix material and good adhesion between them that eventually leads to a better quality of the final material.
However, prepreg technologies, in turn, bring many limitations: since composite material is prepared beforehand, fiber-plastic ratio is constant and determined by the manufacturer, not the user. It makes complex shapes and internal structures are not realizable. The plastic itself is also determined beforehand by the manufacturer, so you can’t choose the one with the properties you need at each moment of time. Co-extrusion, on the contrary, allows managing fiber-plastic ratio and use a wide range of plastics as a matrix.
Thus, prepreg placement can give better material properties due to better impregnation and higher fiber content, while co-extrusion allows to easily change matrix materials and fiber volume content. Prepreg placement gives better quality, while co-extrusion is more flexible.
3D printed composites can have both the good quality and freedom in shape and material at the same time if using the advantages of both approaches like in Composite Fiber Co-extrusion technology.
However, not only the technology is important for getting composite parts with superior mechanical properties but how we work with the composite materials. Often their best properties are eliminated due to so-called metal thinking. It will be the next word we talk about.
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