Personalized Mass Production by Hybridization of Additive Manufacturing and Injection Molding

Abstract

The new trend in the composites industry, as dictated by Industry 4.0, is the personalization of mass production to match every customer’s individual needs. Such synergy can be achieved when several traditional manufacturing techniques are combined within the production of a single part. One of the most promising combinations is additive manufacturing (AM) with injection molding. AM offers higher production freedom in comparison with traditional techniques. As a result, even very sophisticated geometries can be manufactured by AM at a reasonable price. The bottleneck of AM is the production rate, which is several orders of magnitude slower than that of traditional plastic mass production technologies. On the other hand, injection molding is a manufacturing technique for high-volume production with little possibility of customization. The customization of injection-molded parts is usually very expensive and time-consuming. In this research, we offered a solution for the individualization of mass production, which includes 3D printing a baseplate with the subsequent overmolding of a rib element on it. We examined the bonding between the additive-manufactured component and the injection-molded component. As bonding strength between the coupled elements is significantly lower than the strength of the material, we proposed five strategies to improve bonding strength. The strategies are optimizing the printing parameters to obtain high surface roughness, creating an infill density in fused filament fabrication (FFF) parts, creating local infill density, creating microstructures, and incorporating fibers into the bonding area. We observed that the two most effective methods to increase bonding strength are the creation of local infill density and the creation of a microstructure at the contact area of FFF-printed and injection-molded elements. This increase was attributed to the porous structures that both methods created. The melt during injection molding flowed into these pores and formed micro-mechanical interlocking.

Hybrid Manufacturing of Oral Solid Dosage Forms via Overprinting of Injection-Molded Tablet Substrates

“…However, the injection pressure did not have a significant influence on drug release. The injection-molded tablets did not release the entire amount of the drug in 72 h, since it is difficult for the dissolution media to penetrate the dense inner area of the tablet [ 20 ]. Additionally, the presence of the PCL in a formulation can slow the dissolution rate, as it is a hydrophobic polymer that does not disintegrate during testing [ 47 ].…”

“…Overmolding is one of the processes in which a 3D-printed substrate can be combined with injection molding [ 19 ]. Overmolding has been used by researchers in pharmaceutical solid dosage forms [ 17 ], polymer mechanical properties [ 19 , 20 , 21 , 22 ], lightweight composites [ 23 ], fiber composites [ 24 ], hand splints [ 25 ], and aerocomposites [ 26 , 27 ]. We previously demonstrated the potential of this approach by combining FFF and injection molding to produce bilayer tablets that released two drugs [ 17 ].…”

Metal Additive Manufacturing of Plastic Injection Molds with Conformal Cooling Channels

“…Differently from the traditional machining tools, the recent developments in additive manufacturing (AM) technology make the fabrication of complex but effective channels in affordable ways. Hereby, AM can be effectively used in the plastic injection mold processes [ 8 ]. By means of the design and manufacturing flexibilities of AM tools [ 9 , 10 ], cooling channels can follow the complex contours of the plastic product in the mold geometry; hereby, they are named conformal cooling channels (CCCs).…”

Hybrid Manufacturing of Acrylonitrile Butadiene Styrene (ABS) via the Combination of Material Extrusion Additive Manufacturing and Injection Molding

“…Dr. Fuenmayor et al [ 36 ] used this HM technology in a pharmaceutical setting, showing that this method reduces production time and improves customization. Mr. Rajamani examined the bonding between the FDM preforms and IM components and investigated several ideas to improve the bonding [ 37 ]. In the current investigation, overmolding of tensile specimens happened over the whole length of the FDM substrates for all samples produced by HM.…”