In the past 10 years there has been a keen interest by industry towards the application of rapid prototyping methods in product development. By extending this interest to new fabrication methods such as 3D printing technologies, industry is intent on adopting new pathways in order to redefine its future. To chart these pathways, practice based testing of 3D printing technologies is becoming a strategic activity in a growing number of industrial establishments. Some of the tests reveal data which has given industry the confidence to engage 3D printing technology as a rapid manufacturing tool. The ability to stably process metals, composites as well as high performance polymer materials using additive manufacturing tools opens a unique opportunity for industry to do new things in the field of manufacturing. Particularly within the past 5 years fiber reinforced polymers as well as high to extreme temperature polymers such as PEEK (Figure A) have received special attention in a range of industries for different kinds of reasons. Some of these reasons border on energy conservation, light-weight construction, thermo-mechanical performance, biocompatibility, chemical inertness or on electrical properties. Therefore materials are at the core of the situation pulling industry towards additive manufacturing. Polymers are without doubt the only class of materials that can be easily processed at relatively low energy cost, composited using different kinds of other materials and used to meet different kinds of requirements in engineering and technological applications. For this reason there is a need to intensively explore the processibility of polymeric materials using additive manufacturing tools.
Rapid manufacturing is guided by the philosophy of manufacturing functional parts at the shortest possible time. Together with the freedom to fabricate parts which have complex geometries rapid manufacturing also allows for mass customization within industry. Whilst processing time/unit-part remains a challenging aspect of rapid manufacturing when compared to conventional manufacturing methods like injection molding processing (Figure B), it goes without saying that 3D printing technologies are inherently designed for small series production and parts which have highly complex forms.
In other words there now exists a market for enterprise based 3D printing or additive manufacturing. In the materials market producers are expanding their portfolio to include additive manufacturing-designed materials in order to meet requirements in tool development, molds, die and support structures used for practical engineering activities. These materials are relatively more expensive than those (such as ABS, PLA, photopolymers) historically used in rapid prototyping 3D printing processing. The performance value of these materials is high and the 3D printers capable of delivering these materials to industry are also relatively more expensive than those used for hobby or purely prototyping purposes.
The processing requirements for high performance materials can be very stringent. For example industry-established thermoplastic materials such as PEEK are not easy to process. Amongst the current selection of 3D printing technologies, only Fused Filament Fabrication (FFF) and selective laser sintering (SLS) methods are technically capable of processing PEEK. These processing methods are markedly different hence producing different effects on the processed material in such a way that the printed parts from each of the methods are structurally different especially at the microscopic level thus lending parts produced from each method different mechanical properties (Figure C). The technical or scientific explanation for this property difference is not trivial but can be traced to the thermal load imposed on PEEK during laser processing as against mere melting and solidification for the FFF method. This kind of discrepancy especially in terms of part property can significantly drive market preferences.
Figure C. (a) FFF 3D printed PEEK part (b) Tensile test PEEK sample in test machine (c) Tensile strength and Strain plotted for SLS produced PEEK and FFF produced PEEK.
We now have about 30 years of evidence indicating that 3D printing technologies work. Building on this fact, the authors see a very bright future for rapid manufacturing. It fits well within a landscape where lean production lines, short supply chains, logistics and warehousing operations are changing. Rapid manufacturing as well as the tools that support it fit quite well with the school-of-thought Production-on-demand making a case for its positioning within an Industry 4.0 sector.
We appreciate Technical University Delft and University of Applied Sciences Merseburg for the mechanical tests data.
Brando Okolo (PhD)
Indmatec GmbH – Karlsruhe – Germany / firstname.lastname@example.org