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The application of additive manufacturing (AM) for tooling in the mould and die industry brings a disruptive potential in process performance, design flexibility and product enhancements. Maturing of existing AM technologies and emerging technologies such as metal-fused filament fabrication (metal FFF) can further support the applicability of AM tooling in polymer profile extrusion. This study provides a complete characterization of metal FFF 17–4 PH stainless-steel die inserts and evaluates their applicability in a polymer extrusion process chain. The presented experimental assessment pivots on the metrological characterization of the produced inserts and the impact of the insert characteristics on the final extrudates' product. Considering a conventionally manufactured benchmark insert, produced via subtractive methods (CNC machining and electrical discharge machining), comparable results for AM tools in terms of extrudates' quality and process repeatability are presented. It was found that despite significant higher average surface parameters for AM insert tools (Sa = 2–9 µm vs. Sa = 0.3–0.9 µm for dies manufactured by machining), a much smaller difference was observed in the resulting quality of polymer extrudates' product. The roughness generation effect of polymer profile extrusion based on the different dies' internal surface roughness topography and the effect on extrudates product was evaluated. Three-dimensional average roughness Sa on acrylonitrile butadiene styrene extrudate surfaces obtained from conventionally machined dies was in the range of 0.3 µm. For extrudates obtained from additively manufactured dies, their Sa was in the rage of 0.5 µm (despite the much higher surface roughness of FFF dies compared to machined dies). The results confirm that with suitable extrudates' product requirement, it is feasible to apply metal FFF as the selected manufacturing method for tooling in polymer profile extrusion. [ABSTRACT FROM AUTHOR]

Powder injection molding is like the process of plastics injection molding capable of the mass production of highly functional complex 3D parts, just in ceramics and metals. The market for products made by powder injection molding is constantly growing. With this growth, the need for reliable process simulations arises. Simulation tools are widely used in the development of new products and are applied in powder and polymer injection molding to support the product design, shorten the development time, avoid errors, and help to optimize the mold and process design. However, material data for feedstocks and thus simulations of the powder injection molding process are hardly available yet. The present work introduces the necessary material data for establishing a material model for simulations. An extensive material characterization of ceramic feedstocks was conducted. The material investigations comprised the determination of basic, thermal, and rheological material properties to collect a comprehensive data set. The necessary measurements and tools are outlined and their results are discussed in detail with regard to powder content and in comparison to pure plastics. The gained data enabled to successfully create a material model for mold filling simulations. Powder injection molding experiments were carried out with a spiral test geometry. The mold was equipped with a sensor array for the process monitoring during injection. Furthermore, a simulation model of the test geometry was established. Finally, the results of the experiments and simulations are discussed and are compared to validate the performance of the simulations. The results showed the potential and limitations of process simulations and standard software applied in conventional and micro powder injection molding. [ABSTRACT FROM AUTHOR]

There is a growing interest for integrating additive manufacturing (AM) technology in different manufacturing processes such as injection moulding (IM) due to the possibility of achieving shorter manufacturing times and increased cost effectiveness. This paper evaluates IM inserts fabricated by the AM vat photopolymerisation method. The inserts are directly manufactured with a photopolymer material, integrated on an injection moulding tool and subsequently used for IM. Therefore, particular attention has to be paid in order to develop the soft tooling process chain and the IM experimental procedure as detailed in this study. Different combinations of IM parameters are investigated in this work in order to determine the influence of the various process settings on the inserts' performance (lifetime, crack propagation, consistency of the mould surface features). The mould inserts were analysed by three-dimensional optical metrology and evaluated with regard to the different surface features that were affected by the IM process. A three-dimensional thermo-mechanical with phase change model for the analysis of the effects of the IM process on the additive manufactured tools was accomplished in the FE software COMSOL Multiphysics. The potential causes for the insert failure are identified both by means of the IM experiments and the numerical model. The developed model could also predict the thermally induced deformations produced in the mould and identify where this phenomenon would eventually lead to defects in the shape of the parts. The influence of three different temperatures of the insert at 25 °C, 50 °C and 100 °C on the failure of the insert was investigated. Also a detailed discussion about the solidification and temperature changes is given. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) can create considerable value when integrated into conventional manufacturing process chains. Tooling for new molded product development as pilot case of integration of AM in the injection molding process chain is investigated. The study shows that injection molding based on AM for fabrication of polymer tool inserts is economically advantageous allowing 80-90% production costs reduction as compared with a conventional tooling process chain based on machining. Fabrication of soft tools with AM results in a production lead time reduction in the range of 60-70% compared to the time required to machine mold inserts in brass or aluminum. [ABSTRACT FROM AUTHOR]

The number of industrial applications of computed tomography (CT) for dimensional metrology in 100-103 mm range has been continuously increasing, especially in the last years. Due to its specific characteristics, CT has the potential to be employed as a viable solution for measuring 3D complex micro-geometries as well (i.e., in the sub-mm dimensional range). However, there are different factors that may influence the CT process performance, being one of them the surface extraction technique used. In this paper, two different extraction techniques are applied to measure a complex miniaturized dental file by CT in order to analyze its contribution to the final measurement uncertainty in complex geometries at the mm to sub-mm scales. The first method is based on a similarity analysis: the threshold determination; while the second one is based on a gradient or discontinuity analysis: the 3D Canny algorithm. This algorithm has proven to provide accurate results in parts with simple geometries, but its suitability for 3D complex geometries has not been proven so far. To verify the measurement results and compare both techniques, reference measurements are performed on an optical coordinate measuring machine (OCMM). The systematic errors and uncertainty results obtained show that the 3D Canny adapted method slightly lower systematic deviations and a more robust edge definition than the local threshold method for 3D complex micro-geometry dimensional measurements. [ABSTRACT FROM AUTHOR]

Micro milling process has been utilized for several decades due to the flexibility of the process in producing complex components. The small size of the process makes the comprehension of cutting phenomenon details more difficult. This study presents a 3D finite element modeling (3D FEM) approach for the micro end-milling process of Aluminum material (Al6082-T6). 3D FEM simulations are carried out in full slot micro end-milling and contour up milling. The model first implements the actual tool geometry and then the effect of typical built-up edge (BUE) on the milling tool. The influence of BUE on the process performance is investigated by comparing the predicted 3d chip flow shape, burr formation and cutting forces with experiments conducted on an ultra-high precision micro milling center. Simulations indicate that BUE has significant impact on the chip shape and chip load for different teeth engagements. Results prove that also burr height is negatively affected by the presence of BUE. The predicted micro milling cutting forces resulted affected by BUE with different teeth engagements. Analysis of experimental measured forces indicates comparable results in respect to simulated profiles confirming the usefulness of the develop 3D FE modelling approach. [ABSTRACT FROM AUTHOR]

Using elevated mold temperature is known to have a positive influence of final injection molded parts. Induction heating is a method that allow obtaining a rapid thermal cycle, so the overall molding cycle time is not increased. In the present research work, an integrated multi-turn induction heating coil has been developed and assembled into an injection molding tool provided with a glass window, so the effect of induction heating can directly be captured by a high speed camera. In addition, thermocouples and pressure sensors are also installed, and together with the high speed videos, comparison of the induction heating and filling of the cavity is compared and validated with simulations. Two polymer materials ABS and HVPC were utilized during the injection molding experiments carried out in this work. A nonlinear electromagnetic model was employed to establish an effective linear magnetic permeability. The three-dimensional transient thermal field of the mold cavity was then calculated and compared with the experiments. This thermal field was transferred to an injection molding flow solver to compare simulations and experimental results from the high speed video, both with and without the effect of induction heating. A rapid thermal cycle was proved to be feasible in a mold with an integrated induction coil. Furthermore, it was shown that the process can be modeled with good accuracy, both in terms of the thermal field and of the flow pattern. [ABSTRACT FROM AUTHOR]

The challenge of fabricating geometries with critical dimensions ranging from few microns down to 10 nm with high production rate is delaying the development of nanotechnology based products. Diverse research works have shown the capability of technologies such as UV lithography, nano imprint lithography and e-beam lithography to produce micro and nano features. However, their application for tooling purposes is relatively new and the potential to produce nanometer features with high volume and low cost is enormous. Considering possible implementation in a mass production environment the precision of measuring results and the accuracy of measurement relocation are very relevant. In this paper, the capability of producing with high volume Lab-on-chip devices through injection molding is evaluated. Preparation of master geometries was made in a Si wafer using e-beam lithography and reactive ion etching. Subsequent nickel electroplating was employed to replicate the obtained geometries on the tool, which was used to mold on transparent polymer substrates the functional structures. To assess the critical factors affecting the replication quality throughout the different steps of the proposed process chain, test geometries were designed and produced on the side of the functional features. The so-called 'Finger Print' of the lithography and molding processes was qualitatively and quantitatively evaluated through scanning electron microscopy and atomic force microscopy respectively. The entire process chain is therefore characterized and the degree of replication among the different replication steps quantified with precise measurements using a high accuracy relocation technique on the produced key test geometries. Influence of injection molding process parameters, feature dimensions and orientation relative to the polymer flow direction have been assessed in respect of the replication fidelity of the produced micro/sub-μm channels. Finally the paper addresses product compliance with specifications, focusing on tolerances of vertical dimensions using a metrological approach: sub-μm features on silicon, nickel stampers and injection molded substrates are measured. Results of measurement uncertainty calculation, quantitative replication fidelity assessment, and dimensional tolerances at the nanometer scale verification are reported. [ABSTRACT FROM AUTHOR]