Part of the PA 12 production complex in Marl Chemical Park in Germany

Part of the PA 12 production complex in Marl Chemical Park in Germany

New Evonik line for powders

As it expands its portfolio of high-performance materials for powder-based 3D printing technologies, Evonik is driving forward its commitment in the attractive 3D printing market, writes ABDULAZIZ KHATTAK

March 2019

Leading the race in the 3D printing industry, Evonik, a world leader in specialty chemicals, has developed a new polymer powder for applications in higher temperature range as part of its polyamide 6 series further expanding its portfolio of high-performance materials for powder-based 3D printing technologies.

This comes after the company’s announcement to build new production lines for polymer polyamide 12 (PA 12) powder including a new production complex worth €400 million ($453.6 million) for Vestosint, a modified high-performance PA 12 powder that is manufactured from a polyamide granulate using a proprietary Evonik process.

Evonik’s Line 4 came on stream early 2018, and Line 5 will come together with the new PA12 complex, which includes the whole lines for C12-Chain starting from monomers up to PA12 compounds and powders.

Evonik’s produces specialty powder materials such as PA 12, PEBA and PEEK for various 3D printing technologies.

“Evonik is driving forward its commitment in the attractive 3D printing market,” said Prof Dr Stefan Buchholz, general manager, Evonik Creavis.

The new line at its largest site, Marl Chemical Park in North Rhine-Westphalia, Germany, will increase the group’s existing annual capacity for PA 12 powders by 50 per cent. It is set to become operational in early 2021.

According to Buchholz, the Vestosint plant can produce various powder grades with defined particle size distribution from fine powders as additives for lacquer and paints to coloured powders for coating applications.

Evonik has developed a plastic filament based on PEEK in implant quality for use in 3D printing

Evonik has developed a plastic filament based on PEEK in implant quality for use in 3D printing

In addition to 3D printing, PA 12 is required in attractive growth markets such as the automotive industry, oil and gas pipelines.

“Vestosint powders are used, for example, to coat metals for household appliances such as dishwasher baskets, but also in automotive and medical technology production and as matting and structural agents in coatings,” said Buchholz.

The 3D printing industry is another area that is expected to drive demand for these powders, since PA 12 provides an excellent balance of mechanical, thermal and chemical resistant properties.

Meanwhile Evonik’s new polyamide 6 series powder features high mechanical strength as well as excellent chemical and temperature resistance.

“Its heat deflection temperature (HDT B) is around 195 deg C. Moreover, the powder material stands out for its low water absorption (below 3 per cent) which has a positive effect on processability in 3D printing and the dimensional stability of printed 3D components,” he said.

Additionally, the polyamide 6 series with its nearly round grain shape stands out for excellent flowability and application properties, making it suitable for all powder-based 3D printing technologies. A proprietary procedure of Evonik is employed to produce the high-temperature material at the company’s Marl site, Buchholz said.

Evonik recently also acquired Texas-based startup Structured Polymers, giving it access to a new patented technology that will allow it to expand its portfolio of specialty polymer powders in the additive manufacturing market.

“Structured Polymers’ innovative technology starts with a polymer granulate, which is converted to a fine powder through various process steps. This makes it possible to produce polymer powders with controlled particle sizes ranging in diameter between 0.1 and 400 µm, while achieving excellent material properties,” said Buchholz.

He added the new technology allows Evonik to take virtually any semi-crystalline thermoplastic, such as polybutylene terephthalate, polyether ketone, or polyamide 6, or polymer powders with specialised properties like colour, conductivity, or flame protection, and produce them for common powder-based 3D printing processes, such as selective laser sintering, high-speed sintering, or multi-jet fusion.

Evonik is a world leader in the production of PA 12 powders, the demand for which has shown steady growth. In fact, the PA 12 global market is posting annual growth rates of over 5 per cent.

Last year, the company also became the world’s first to develop a polymer filament based on PEEK (polyether ether ketone) in implant-grade quality for use as a 3D printing material for implants.

This high-performance material can be used in fused filament fabrication (FFF) technology and is expected to enable additive production of three-dimensional plastic parts for medical implants in the human body.

Another world’s first was the development of flexible plastic material based on PEBA (polyether block amide) for use in 3D printing. The new high-performance powder stands out for its high elasticity and strength and is suitable for a variety of powder-based 3D printing technologies.

3D printed parts made from the new PEBA powder show a high degree of flexibility, excellent resistance to chemicals and outstanding durability over a wide temperature range from -40 to 90 deg C.

The company also produces a full range of additives such as dispersion agents, flow improvers or reactive modifiers.

All this development shows Evonik’s confidence in the 3D printing market, which is posting double-digit growth rates. The main drivers in the 3D printing industry are the aircraft/aerospace, automotive, healthcare and consumer goods industries.

However, Buchholz said, the industry like any other has its challenges and opportunities to offer.

The opportunities, he said, include customised and personalised part production down to lot size, production of complex parts which are not feasible with conventional production methods, elimination of assembly steps, design changes overnight, reduction of logistics and warehouse costs (printer can be placed close to the point of use), just in time production, and no or less inventories necessary.

The challenges include design and simulation capabilities with 3D printing materials; printing speed, which although has improved significantly over the last years; limited material portfolio; missing norms and standards for 3D printed parts; lack of knowledge at OEMs and part suppliers; reproducibility, and costs per part.

Regarding cost, Buchholz said it depends on the requirements, lot size, part design, etc.

“The break-even on ‘costs per part’ for 3D-printed parts compared to conventional production methods like injection molding is somehow between a few hundred up to 50,000 parts,” he said.

When it comes to production speed, it’s perceived that 3D printing is slow. Buchholz said: “As most of the 3D-printing technologies are based on a layer-by-layer process, the main drivers for speed are: how fast you can melt/cure the material, move the print head, apply the next layer etc and control it all.”

However, the continuous development of materials, advanced print heads and new printing technologies has led to significant improvements over the last years. The industry has seen the development of high speed printing technologies like multi jet fusion (hp), new laser technology at EOS or the CLIP technology from Carbon 3D.

Allaying concerns regarding the strength of 3D printed parts, Buchholz said by using Vestosint, in many cases the performance, for example, of mechanical properties of the 3D printed part is comparable to conventional produced parts. For higher mechanical requirements, glass bead reinforced Vestosint powders are available.

After printing, a post processing step is necessary to remove the remaining powder particles and/or to provide a certain surface finish (matting, colouring, etc). From all available powders, Vestosint provides a perfect balance between processing, printing and performance and is therefore the material of choice in all powder based printing technologies.

Normally all industrial 3D technologies use closed equipment to avoid any impact on the environment. However, there are some examples, such as concrete 3D-printing for building a house where printing is done on site.

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