Comparative study of rapid and conventional tooling for plastics injection molding

Abstract

Purpose This study aims to evaluate the performance of injection molding inserts produced via rapid and conventional manufacturing techniques considering the mechanical and thermal performance of the tools as well as the resulting molded part quality. Design/methodology/approach Three insert materials and manufacturing techniques were evaluated, jetted photopolymer (PolyJet) 3D printing using digital ABS, direct metal laser sintering (DMLS) using bronze and machining using stainless steel. Molding trials were performed, and the insert surface temperature, longevity and part properties were evaluated. Complementary information was acquired using computer simulation. Findings Similar behavior and part quality were observed in machined and DMLS inserts. The latter were used for 500 cycles without any signs of failure. PolyJet inserts had increased cycle time and slower rate of cooling which increased shrinkage and crystallinity in the molded parts. PolyJet inserts could be produced quickly at a lower cost than machined or DMLS inserts. Research limitations/implications Cooling within the insert was not studied; inserts were cooled indirectly by the mold plates behind them. Subsequent studies will incorporate cooling lines directly into the inserts. Originality/value Little research has been done to understand the thermal behavior of inserts manufactured via rapid tooling techniques. This study provides a direct comparison between rapid tooling techniques, which is supported by simulation results and analysis of the actual molding properties.

Nanostructured Free‐Form Objects via a Synergy of 3D Printing and Thermal Nanoimprinting

“…Two types of materials were used in this study: VeroClear ( T g : 52–54 °C) and Digital‐ABS ( T g : 47–53 °C). In particular, Digital ABS has been widely used for 3D printing of mold inserts due to its long tool life (80 or more shots with elastomeric plastics) and suitability for molding complex geometries or molding with higher temperature thermoplastics . In nanoimprinting process, the surface to be imprinted is referred to as the substrate.…”

“…In particular, Digital ABS has been widely used for 3D printing of mold inserts due to its long tool life (80 or more shots with elastomeric plastics) and suitability for molding complex geometries or molding with higher temperature thermoplastics. [37,38] In nanoimprinting process, the surface to be imprinted is referred to as the substrate. Here, the 3D-printed curved objects are referred to as curved substrates.…”

Injection molding with an additive manufactured tool

“…The increased surface roughness can increase the ejection forces needed to remove the molded part, and that could lead to needing to change processing parameters to prevent damage to the molded part or AM tooling [3,4]. Current research suggests tooling made from AM can be used for a production run of between 10 and 500 parts, depending on the tooling and mold part materials used, for either analysis or short run distributions [2,5].…”

“…One of the key differences in metal and AM produced plastic tooling that affects both processing parameters and molded part properties is that the AM plastic tooling retains a greater amount of heat when compared to that of metal tooling. This is due to the differences in thermal conductivity of the various polymers that can be used in AM compared that of traditional metal tooling, some of which are shown in Table 1 [5][6][7][8][9][10].…”

“…To compensate for the differences in the thermal conductivity of the various tooling materials, the cycle time, tool temperature, and injection pressure need to be modified to allow the part to solidify and eject properly [5]. While the changes in the processing can help to improve tool longevity, it also affects the physical and mechanical properties of the final part [11][12][13].…”