Joining our extensive offering of plastics materials is mineral-filled PA6. Though many, particularly in the automotive industry, are familiar with using PA6 with conventional technologies, we’re pleased to be one of the first to offer 3D-printed PA6 parts. Through extensive testing, we’ve seen that it comes with excellent tensile strength, stiffness, thermal properties, and chemical resistance.
Research engineer Giovanni Vleminckx is responsible for testing and onboarding new materials into our portfolio, and has been leading a pilot program with select customers over the past few months. We caught up with Giovanni to bring you everything you need to know about this new material.
What are the biggest benefits of Ultrasint PA6 MF (mineral-filled), and which industries would you say it’s most suitable for?
Giovanni: “PA6 has been on our radar for a very long time. It's quite well known in manufacturing, not as a 3D-printed material per se, but a great engineering plastic because it can withstand high temperatures for long periods of time, has high chemical resistance, and is very strong. This makes it ideal for the automotive industry, for example, in functional prototyping where pieces need to go from design to validation quickly to speed up time-to-market.
“We chose a mineral-filled version to add to our offering because we’ve seen it has significantly better mechanical properties, such as higher stiffness, more chemical resistance and can withstand higher temperatures.”
How does PA6 compare to other materials, whether in laser sintering or other technologies?
“If you're looking for something that can withstand a bit more in terms of heat and strength than PA12, but you don’t need the manufacturing-ready durability or mechanical performance of materials at a higher price point, such as Ultem, then this is the perfect fit. Aluminum-filled PA12 can of course handle short peaks of temperature increases. However, PA6, particularly our mineral-filled offering, is better to handle higher temperatures for longer periods of time.
“Plus, PA6 is even more rigid compared to PA12. This gives it a stiffness that makes it suitable for milling after, should that be necessary, for example to add threading.”
You’ve mentioned the automotive industry and functional prototyping. Could you tell me a little bit more about which applications PA6 is best suited for?
“PA6 MF is ideal for applications where you need durable components, under higher temperatures. Think of all kinds of industrial equipment and machinery that would have this need.
“We ran a pilot program with a few customers to test the applications where this material works best. So far, we've been testing a lot of under the hood applications. I mentioned automotive as being a key industry for this material. PA6 is one of the most used plastics in that sector. It is used a lot for everything that connects to the engine, but is not the engine itself.
“3D printing for PA6 can be used in functional prototyping for design cycles to test specific components. It can be used to have auxiliary components ready while testing out a new motor design, for instance. To do this with conventional technologies, individually designing and manufacturing each part to connect to fuel injection devices, air intake, and other parts, becomes time consuming and costly. Rapid prototyping these additional components eases the pain and helps the automotive industry speed up their time-to-market.
“Plus, PA6 MF is even strong enough to be used for field tests. One of our pilot customers, has 3D printed an oil cap and gauge for the dipstick for a motorcycle model that they were testing. They used the 3D-printed parts in ten of their prototypes that were being road-tested. This is an important component, you don't want the oil splattering out, of course. And they liked the fact that they could easily manufacture this by using 3D printing.
“Chemical resistance is one more strength of this material. Another example from a customer in our pilot program 3D printed a cap that seals off the brake fluid container as it gets pressurized. They did functional testing in-house to confirm this material’s suitability for prototyping — and it passed the requirements. So again, here is an application where the part might come into contact with oils and fuels, or fumes of those liquids, and higher temperatures.”
How does 3D printing PA6 differ from conventional technologies?
“One of the main benefits of 3D printing is always freedom of design. Some of the issues that you might run into with conventional design — for example, the fact that latticed interiors are impossible to mold and expensive to mill — are not a problem with design for 3D printing.
“For example, BASF has redesigned a bracket for Daimler as a functional prototype to suspend the motor block. This is a highly demanding part from a mechanical engineering point of view. But using freedom of design with 3D printing, they could take the components surrounding the part into account and they ended up with a more viable product. BASF also benefited from the easy mechanical post-processing and insertion of metal components. The material proved strong enough to hold the whole engine assembly and handle all heat, vibration, and static loads. It even fulfills the same Noise-Vibration-Harshness parameters as the original injection molded part geometry.
“It's usually too expensive to make a mold or to mill for prototypes or small series. So, you tend to take a material with higher mechanical properties so that you can get away with more of these simpler designs, but with 3D printing, you don't have to compromise. So many times, you could have a better part at a lower cost.
“One challenge that comes up with both 3D printing and conventional technologies is that the material tends to warp. However, we have seen less warpage when 3D printing compared to injection molding, for example, so the 3D-printed part will look closer to the nominal design than if you have a mold in the shape of the final part.
“Other than warpage during production, PA6 parts can change over time as well. BASF has done quite extensive testing, not only on the 3D-printed variants, but also on conventionally manufactured ones. They found that over a period of six months the properties of these parts tend to change owing to moisture absorption, and after six months they reach a final state. Interestingly, the effect is reversible by drying out these parts. Therefore, included in our standard PA6 offering is a conditioning process, which is basically an accelerated way to get to this final set of properties. By the time that you get your part, it will have its properties that should be stable over time.”
Why did you start looking into PA6?
“Back when we predicted the trends in 3D printing for 2019, I mentioned that materials would get developed that are fit for purpose or application. And PA6 is a material that's right up that street.
“We first saw a need in the market from our customers looking for a durable functional prototyping material at a competitive price point. Our partnership with BASF helped make it possible for us to launch it at this time. We have built a close-knit collaboration with them, in which we can provide them with solid feedback on what we experienced during the research stage. We can also go to them when we’re stuck, or we can put suggestions on the table and BASF is able to counter that with feedback from their side including additional material developments and grades. So, it usually takes away some of the hurdles with respect to information flowing both ways. We can share our experiences, we can learn, and we can significantly boost the time-to-market.”