3D Printing - Teamwork for Future Ideas
The companies AKRO-PLASTIC GmbH, Plasmatreat GmbH and Yizumi Germany GmbH presented a combination of ideas on the subject of 3D printing at Fakuma 2021. The basic idea behind the project of the three innovative companies is 3D printing a high-strength sustainable plastic onto a stainless steel sheet coated with a plasma-polymerised bonding agent.
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"3D printing of highly stressed, large-volume components is becoming increasingly important," knows Michael Rieck, Business Development Manager, AKRO-PLASTIC GmbH. According to the compounder, the SEAM process (Screw Extrusion Additive Manufacturing) is proving to be particularly favourable for highly productive and cost-effective additive manufacturing due to the use of standard granulate and high throughputs of more than 5 kg/h.
When printing fibre-reinforced plastics, a very high orientation of the fibres can be achieved. Under optimal conditions, strengths above those of injection-moulded geometries can be realised.
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"The achievable throughputs and material properties, combined with a component-specific design, also make quantities beyond 10,000 units in additive manufacturing possible and offer an alternative to injection moulding. Depending on the geometry and system, this limit can also be set significantly higher," explains Dr Nicolai Lammert, Head of Business Unit Additive Manufacturing, Yizumi Germany GmbH.
"Scaling via the number of systems or within a production cell via the number of extruders and nozzles multiplies the number of pieces per hour at low investment costs."
According to the three companies, the flexibility of the process allows new designs in 3D structures that cannot be manufactured in injection moulding. When using a 3D honeycomb structure, extreme pressure loads can be supported with low component weights. Amorphous plastics are often used in 3D printing because they shrink significantly less than semi-crystalline ones, and therefore warp less. Adhesion to the build platform is significantly improved due to less contraction.
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AKRO-PLASTIC develops fibre-reinforced compounds with semi-crystalline polymers suitable for additive manufacturing. These combine high chemical resistance, with high stiffness, strength and dimensional stability, which ensure high throughputs in additive manufacturing. The AKROMID® NEXT U3 ICF 40 1 black (8238) is a polymer-based on castor oil. The biomass content in the polymer is 97 %, and the compound is also reinforced with 40 % recycled carbon fibres (PIR).
According to the compounder, the shrinkage of the product is so low that even very large components with a layer length of almost 4 metres can be produced without any problems. The mechanical properties are very high, with a modulus of elasticity of 20 GPa and a strength of 190 MPa, and yet extremely ductile, with an elongation at break of 3.5 %.
The creation of a strong bond between normally incompatible materials, such as in this example a high-strength, sustainable plastic and a stainless steel sheet, was demonstrated at FAKUMA using the pen holder as an example. Plasmatreat's PlasmaPlus technology was used here. A nanolayer was deposited on the sheet metal using the special PlasmaPlus process PT-Bond, thus causing the melt to adhere to the metal. "PT-Bond is a special nanolayer created with our PlasmaPlus technology to create functionalised surfaces.
When using PT-Bond, a gaseous precursor is injected into the plasma jet generated under atmospheric pressure. The substrate is coated with an ultra-thin, transparent, plasma-polymer protective layer. This then acts as an adhesion promoter layer," Lukas Buske, Head of Plasma Applications, Plasmatreat GmbH, explains the process. "This allows us to bond materials together with long-term stability and flexibly expand the fields of application of 3D printed components for industrial production."
