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3D-printed products

The rise of additive manufacturing offers previously unknown freedom to the redesign of products or the development of new ones. Although 3D printing is often written off as too expensive, companies should consider the technology as an opportunity to add value. In 99% of cases, moving the manufacturing of a product directly from conventional production to 3D printing does indeed result in a more expensive product. But, if the speed of design, the freedom of form, material, etc. can be exploited, these can result in incredible business cases.

3D printing undeniably influences the corresponding material properties, quality  and feasibility of the product. For example, 3D printed products can combine material properties that were not previously possible within a single piece. The material treatment can also be adapted to make the most of the potential of 3D printing. This applies tothe additive manufacturing of both metals and plastics. Knowledge and experience with 3D printing are essential for companies, hence Sirris’ contribution in this field.

A multi-hardness concept for multi-purpose 3D-printed parts

Selective Laser Sintering (SLS) is constantly developing and used more and more in the production of finished parts. An SLS machine with adaptable control parameters ensures Sirris can apply not only conventional polyamide, but also other materials such as polyurethane, polypropylene and other additives using additive manufacturing.

Thermoplastic polyurethane (TPU) offers interesting prospects based on its flexibility at room temperature. The material is relatively easy to process, and most service providers offer it to their customers. TPU part functionalities can also be improved by applying the multi-hardness concept. One single part can include several areas with varying hardness, to perform a range of functions. Two approaches are possible: working on energy density during powder sintering, or integrating lattice structures within the parts.

By combining machine parameter control and the integration of lattice structures in parts, Sirris can innovate in terms of part design, specifically by implementing hardness gradients. One of the multi-purpose multi-hardness parts produced by Sirris is a scooter wheel, produced as a single part consisting of different zones: the wheel rim has a hardness value of 90 ShAm, and the tyre, with its internal lattice structure and external skin, has a hardness of 80 ShA.

This work was done as part of the IAWATHA ERDF project.

Knowledge and expertise in 3D printing with steel: now available to companies

As part of the INSIDE Metal AM project, Sirris, CRM and BIL have conducted research into the technical and economic viability of 3D printing with steel. Aside from understanding the opportunities for re-design and added value, issues of economic and technical viability increase the complexity of the application of additive manufacturing (AM). It is not simply a matter of selecting the right application; the most appropriate technologies must also be selected and implemented in the next phase. The INSIDE Metal AM project – completed in late 2020 – was aimed at providing support to Belgian companies considering 3D printing using steel. These projects ensure companies are not required to build up all the knowledge they require themselves. The experience gained within these subsidised projects – and the support provided by experts – can provide assistance in the successful selection of the appropriate applications for AM, and in the selection and implementation of suitable technologies at the next stage.

The INSIDE Metal AM project addressed several major issues and activities of relevance to both current and future 3D metal printing companies. The full process was discussed, from material selection and printing to the most optimal heat treatments and surface post-treatments. AM results in the use of non-conventional materials, meaning that the conventional processing procedures must also be adapted to optimise the material and product properties. Three concrete use cases were explored as part of the project: a generalised rotor, aluminium extrusion moulds and pump housing. The major findings from the project have been put together in a white paper, which can be viewed by clicking on the linkon the project page.

This project was supported by VLAIO (Flemish Agency for Innovation and Entrepreneurship) and the Strategic Initiative Materials (SIM). 

3D printing of steel extrusion and injection moulds

A specific application where the use of 3D printing can be of considerable benefit is the production of moulds for the extrusion and injection moulding of plastics. The freedom of form offered by 3D printing means that cooling channels close to the surface can be included in the mould. This significantly increases the efficiency of the cooling process. In turn, this provides for speedier production, and simultaneously reduces the number of failed products.

Many challenges still remain. These are researched in conjunction with industrial partners and KU Leuven as part of the METAMOULD project , launched in late 2020. Some of these challenges deal with the field of surface quality and material properties. Research has been conducted into methods to improve surface quality, without losing freedom of form or production speed, as well as into the use of new materials for 3D printing and heat treatment. The production process itself also causes considerable tensile stress within the material. Sirris is investigating this phenomenon with a device unique in Belgium for its measurement of residual tension.

Finally, research is due to be conducted into how conventional mould production can be combined with powder bed printing. The dimensions of moulds are frequently more solid than typical 3D-printed products. The solid part of the mould is of little interest to printing. Printing these parts with fine cooling channels on top of a conventionally produced base can result in the best of both worlds. The METAMOULD project addresses the technical implementation and the corresponding research questions on material quality and optimal post-treatment.

This project is supported by VLAIO (Flemish Agency for Innovation and Entrepreneurship) and the Strategic Initiative Materials (SIM).