Additive Manufacturing and 3D

lubricants on the insert surface, high speed filling of the mold at higher pressures and rapid cooling of the insert. Therefore, additives which bring along lubricating properties can be included in the polymer material. The stiffness requirements of the mold insert can be realized or compensated by designing the part for thicker sections, in case of fairly ductile/flexural materials, or filling the polymer with materials which have relatively high mechanical stiffness. The size of the molds to be produced using FFF 3D printing is limited by the fact that objects in the volume range of 200 mm x 200 mm x 200 mm can best be printed; above this size dimensional challenges increase. Although FFF 3D printers which have effective build volumes in the order of 1 m3 now exist, it still remains a challenge to control the tolerances of parts fabricated within such a space. Also, mold features below 0.5 mm in lateral thickness can be difficult to produce using an FFF 3D printer thus there might be a need to conduct post processing steps such as drilling and other material removal processes to meet design specification. Due to the compositional nature of polymers, the thermal cycling and mechanical loading during injection molding processing allows for only a limited use of the mold material. The thermo-mechanical fatigue resulting from these cyclic processes leads to structural failure of the material. This means that the number of injection shots derivable from the polymer mold is limited (50 to 100 shots) in comparison to metallic mold inserts where shots of up to 10,000 are achievable. Clearly mold inserts fabricated by FFF 3D printing technology is not for extended mass production purposes. The business strategy for FFF 3D printed mold inserts Given that the economics which presently accompanies mold manufacturing is poor. This is because most molds take a long time to be designed, machined out from metallic blocks, tested and then deployed to production lines. Some reports suggest that the time taken for the production of molds using traditional manufacturing methods such as machining can be reduced by up to 90% if done using 3D printing technology. Also, the overall manufacturing cost of the mold can be cut down by up to 70% using 3D printing technology. This is a huge form of savings in development and manufacturing cost. Therefore, based on this fact and even notwithstanding some of the constraints alluded to above regarding FFF 3D printed molds, it goes without saying that 3D printed mold inserts bring along key benefits to the economics of an injection molding business. It is typical that in the development cycle of most consumer products, several models of different designs are required before conclusive decision is made on which would be launched as a final product. Each of the models in review often requires a mold insert so that tangible sample pieces can be fabricated and assessed under real operating conditions. The cost of producing the mold inserts is simply high thus a technology like 3D printing which offers low cost mold insert fabrication and ease of implementing alterations in designs is attractive for industry. Conclusion FFF 3D printed mold inserts is currently the most affordable and quickest way of fabricating mold inserts for small batch production of parts. Materials for 3D printing the mold inserts is a critical factor. The development of polymeric based materials which exhibit mechanical stability up to 260 °C as well as thermal conductivity suitable for FFF 3D printing processing is imminent. Research efforts back this imminence where new knowledge on behaviour of advanced materials stable at extreme operating conditions and commercially accessible for industrial applications now makes entry into mold insert making by FFF 3D printing possible. This together with the fact that understanding of the different applications of 3D printing technologies in different industries is improving rapidly giving encouraging impulse that FFF 3D printed mold inserts for long production runs may well be underway. Figure 1 shows PEEK mold inserts fabricated using an Apium P 155 FFF technology 3D printer. The mold insert surface is untreated. Production time for the shown mold inserts, measuring 30 mm x 30 mm x 10 mm, added up to 6 hours per part. Raw material costs are 13 € for one mold insert. To generate the required pressure, the mold inserts have been cased in metal blocks and fixated with screws. Apium Additive Technologies GmbH is a German company specialised in the Fused Filament Fabrication 3D printing technology. As pioneers for 3D printing PEEK they develop new high performance polymers for this technology and the 3D printers to process them in the best possible quality. Authors: Philipp Renner, Julian Scholz, Brando Okolo, Uwe Popp