Profitability in Composite Extrusion Modeling (CEM) with PA6GF30 Polyamide

Quality Specialist

Profitability in Composite Extrusion Modeling (CEM) with PA6GF30 Polyamide

3D printing material offers high tensile strengths

Posted: Thursday, July 21, 2022 – 12:01 PM

(AIM3D: Rostock, Germany) — The composite extrusion 3D modeling process has great potential for profitability compared to alternative 3D printing processes. In cooperation with the University of Rostock, the start-up AIM3D conducted a series of tests with the material PA6GF30 (BASF Ultramid B3WG6). Specimens were printed on the AIM3D ExAM 255 and ExAM 510 machines, and the tensile strength of the specimens was compared to alternative processes such as injection molding and conventional 3D printing. The material test ratings were surprising: the printed PA6GF30 is significantly superior to other 3D printing processes and almost achieves the tensile strength of conventional injection molding.

3D printed glass fiber reinforced polyamide has high tensile strength

Today, PA6GF30 is an indispensable material in industrial mass production applications, almost ideally combining high mechanical properties with temperature and fluid resistance. PA6GF30 is therefore a well-established material for applications in automotive, special machine construction or equipment technology. PA6GF30 components are ideal for metal or aluminum replacement applications where operating temperatures permit (PA6GF30: 130°C continuous use; 150°C for short periods).

Regarding mechanical properties, such as tensile strength, very high values ​​were obtained by 3D printing on the AIM3D ExAM 255 and ExAM 510 systems (see graph below). Compared to powder bed processes or 3D printing processes that use filamentary materials, CEM process systems achieve tensile strengths close to conventional thermoplastic injection molding processes.

Material testing and analysis in detail

First, pull up bars were printed on an ExAM 255 machine with PA6GF30 and the larger ExAM 510 (to be launched at Formnext 2022). The orientation of the 3D printed webs was also varied: 0° for a layup in the tensile direction (the orientation of the fibers was also in the tensile direction) and +/- 45° for a pattern with a alternating direction of +/- 45° to the direction of traction.

In addition, the Rostock-based company compared this with the data sheet values ​​for injection molding with the original material, as well as the filament usage for comparable PA6GF30 filaments. A comparison was also made with a PA12 material used for powder bed 3D printing, as this material is often used as a reference in 3D printing.

The graph shows that CEM technology is very close to injection molding but has a significant advantage over filaments. This phenomenon is due, among other things, to the fact that the original pellets used from BASF’s injection molding technology actually contain glass fibers as long as 3 mm which can withstand tensile forces for a longer period. .

In comparison, the fiber length in filaments is significantly shorter for technological reasons. Generally, a distinction is made between fiber reinforced (GF) and fiber filled (if only short fibers are used). If other data sheet characteristics of BASF’s Ultramid B3WG6 material used in the test are also taken into account, it is clear that the combination of high resistance during 3D printing and high continuous operating temperature from 130°C to 150°C means that it is a universally applicable material. Combined with excellent printability on CEM systems, versatile applications such as grippers or handling tools can be printed in the future.

Today, these components are typically machined from aluminum, which is material intensive. In contrast to this, 3D printing has great potential in terms of material costs, resource conservation, component weight, rapid component production, and ultimately greater energy efficiency. A general approach when printing these components should not be forgotten: the application of bionic design approaches can increase the performance of 3D printed components with respect to their mechanical properties.

In summary, there are many positive cost aspects (unit costs) as well as the improved performance parameters of a 3D printed component. The results of the investigations at the University of Rostock will form part of a scientific publication.

Cost benefits through functional integration in 3D printing

Compared to conventionally manufactured components, the particular appeal of 3D printing lies in the so-called functional integration through design approaches compatible with 3D printing. Functional integration means that assemblies can be manufactured in a single printing process, which is just one of the strategic advantages of 3D printing.

AIM3D produced an extruder housing fitted with a PA6GF30 motor mount as a demonstration of the process. The motor mount, two air ducts routed through the walls, a ventilation outlet and a sensor mount have all been integrated into the case as a single component. In the case of a conventional production strategy with milled aluminum parts, three or four parts would have had to be milled from a block, resulting in a waste of raw materials.

Also, it would take time during the design phase to devise a workaround to avoid the use of special tools (such as slotted drills) and to implement a connection adapted to the shape of the components. . Time spent writing CAM milling programs is also eliminated, especially for small batch production. Manual assembly work is significantly reduced, which also has a positive effect on the cost calculation of parts.

Convincing cost savings in EMC

PA6GF30 is generally difficult to use for 3D printing. It is difficult to obtain and, when available, it costs 20 to 30 times the price of other materials (500 g of Owens Corning XSTRAND PA6GF30 three-dimensional filament costs 86 euros).

When processing with filaments, additives must also be used, which can have an adverse influence on price and certification. The original aggregates, as used in classic injection applications, constitute the reference for costs of the order of 5 euros for 6 kg. The CEM process is unique in that it allows the use of commercially available pellets without filaments where the material supply costs are the same as for injection molding but without the tooling costs. However, as a 3D printing process, it is more likely to be found in the small to mid-run production segment. In addition, 3D printing has advantages in terms of geometric freedom (such as undercuts), bionic designs or selective densities (different strengths, material saving, selective elasticity, etc.).

“A price comparable to that of injection molding for raw materials that do not contain filaments is a huge advantage for our CEM 3D printing systems technology,” said Vincent Morrison, CEO of AIM3D. “Thanks to the PA6GF30, our ExAM 255 machine is able to produce both complex and delicate parts with fine print resolution as well as large structural components with greater layer thicknesses, resulting in maximum profitability. with state-of-the-art 3D printing.

PA6GF30 as a substitute for aluminum in 3D printing

Of course, a state-of-the-art 3D printing process can’t match the cost savings of injection molding for medium to large sized production runs. Its advantages lie more in smaller batch production and bionic design approaches.

However, 3D printing has the upper hand in the case of small and medium series and rapid prototyping, since tooling costs here represent a disproportionate share of price calculations.

Above all, the substitution of the CEM process for milled aluminum production solutions has great potential, as Morrison explains: “Aluminium as a material is relatively expensive due to its energy-intensive production. “

“Aluminum parts are often machined from a solid block. This puts strong pressure on prices. Added to this are the current shortages of raw materials. The PA6GF30 material printed with our CEM technology as an alternative production solution creates completely new dimensions in terms of cost efficiency. This applies all the more when bionic design approaches come into play to increase component performance.

Examples of 3D printed parts in PA6GF30. On the right, an extruder housing has been produced with functionally integrated 3D printing.

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