Multi-Material Additive Manufacturing
Posted on November 4th, 2022
We are all familiar with single material 3D printing but what about multi-material printing? Multi-material printing, while less common than single material, has huge impact potential. From medical applications to being able to manipulate the microstructure of a material. It’s not just researchers and commercial vendors that are taking notice of the benefits of these multi-material AM machines. In 2021 the US Air Force acquired 3 multi-material AM systems from Inkbit Vista with the first to be deployed by the Texas National Guard.
Fused Filament Fabrication (FFF), Stereolithography (SLA), material jetting and binder jetting Additive Manufacturing processes can all perform multi-material manufacturing. For FFF, single and dual extruders can be used for multi-material AM. A single extruder multi-material AM machine combines different materials before or in the melting zone of the print head so that the materials are extruded through the same nozzle. A dual extruder multi-material AM machine has two extruders/nozzles and move independently of each other. They can be used to print with two different colors or different materials simultaneously. Multi-material printing creates possibilities for unique parts that cannot be manufactured by other methods. It also allows for more functionality for a printed part and therefore a part with mechanical properties tailored for a unique purpose. However, the mechanical performance of multi-material printed objects, especially the interface zone generated between the different materials at their geometrical boundaries can be a weakness. Simply put, sometimes the two materials don’t stick together sufficiently.
For dual extruders, two independent print heads that are controlled and moved separately means that more commands are executed by the AM machine than for a single extruder machine. Maliciously altering G-code commands remains relatively easy. An attacker could target a multi-material AM machine with the intention of changing the intended part material in such a way that critically alters a part. With multi-material parts, soluble support material can be extruded by one print head while the other print head extrudes the part material. Imagine a situation where a malicious actor alters the G-code to change a section of the part material to the soluble support material. If this change is made on an internal feature it may be very difficult to detect. The resulting part will not be fit for its purpose. In another scenario a malicious actor could alter the percentages of each material used and in doing so alter the microstructure and give the final part different mechanical properties than were intended. As these multi-material printers start to be utilized for military and secure applications it is imperative that we ensure the integrity of the parts produced. BISON monitors the G-code executed by an AM machine and compares it to the intended G-code. In doing so, every command is verified. If an unusual or unintended command is executed an alert is sent to the machine operator.
If you are interested in learning more about securing Additive Manufacturing or a demonstration of BreakPoint Lab’s BISON AM solution capability, please contact us at email@example.com