Papers by Keyword: Dimensional Accuracy

Abstract: This study investigates an adaptive die concept for cold extrusion that actively modulates radial preload during the main forming and ejection phases. A Gaussian process regression (GPR) surrogate, trained on fewer than 400 finite-element simulations, provides a highly data-efficient model capable of accurately predicting geometric tolerances, residual stresses, and process forces. Experimental spot measurements validate the physical trends captured by the surrogate, demonstrating reliable reproduction of the underlying mechanical interactions. The results show that increased preload during forming enables micrometer-level calibration of final diameters, while higher preload during ejection promotes beneficial compressive residual stresses at the cost of elevated ejector forces. A part-to-part control strategy effectively improves accuracy by independently steering two target properties through separate preload adjustments. Furthermore, a reinforcement learning-based controller, enhanced by flow stress estimates derived from hardness measurements, reduces variance and compensates for stochastic fluctuations in material and friction conditions. Overall, the adaptive die system, combined with surrogate-and RL-based control provides a robust foundation for achieving high dimensional precision and stable product properties under future variability scenarios, such as green steel and sustainable lubrication systems.

Abstract: Fused Deposition Modeling (FDM) is used primarily to fabricate parts with complex geometries, but dimensional inaccuracies can often result in inefficiencies and limits to its use in high-precision applications. This problem increases in metal–polymer composites, such as this PLA–copper study, because of the combination due to the incorrect dimensional reactions of the heterogeneous materials. Thus, enhancing dimensional accuracy is critical in this application, not only to disprove the need for post-processing but also to support industrial applications. This investigation evaluates the impact of layer thickness, print speed, infill density, and wall thickness on the dimensional accuracy of PLA–copper parts. The experimental design using Taguchi’s L9 orthogonal array created 9 unique parts to evaluate and measure deviations in geometrical properties. Analysis of the results indicated that wall thickness exhibited the greatest influence on length accuracy, while layer thickness predominated breadth accuracy. For square side length and diameter accuracy, layer thickness and infill density appeared to have the most influence, respectively.

Abstract: The demand for coronary artery stents has risen due to global healthcare advancements. However, conventional fabrication methods often fail to meet clinical standards for dimensional accuracy and efficiency. This study aims to determine optimal 3D printing parameters for high precision polylactic acid (PLA) stents using fused deposition modeling (FDM). Twenty-six parameter combinations were designed via response surface methodology (RSM), varying printing speed (4–8 mm/s), nozzle temperature (190–220°C), orientation (XY, ZY), and layer thickness (0.05–0.2 mm). Optical microscopy was used to assess dimensional accuracy against computer-aided design (CAD) models. Only six combinations successfully printed stents, and four were further optimized. The best-performing sample showed a length deviation of 1.21% and a width deviation of 33%. Results confirm that printing speed critically affects dimensional precision. The study concludes that optimal FDM settings are material-specific; for PLA, the best range was 3–4 mm/s speed, 190–220°C nozzle temperature, ZY orientation, and 0.1–0.2 mm layer thickness. These findings support the feasibility of using FDM to fabricate dimensionally accurate PLA stents for coronary applications.

Abstract: Most of FDM 3D technique use filaments made of plastic as the feeder or raw material. Therefore, its application limited to prototyping purpose. Recently, some filaments made of metal and plastic available in the market, which makes it possible to print functional components. However, there is a very limited number of published papers on mechanical properties and their accuracy. This research aims to find the optimal parameters of tensile strength and dimensional accuracy on 3D printing specimens made of steel-PLA. Some of the combined parameters are infill pattern, raster angle, print speed and bed temperature. This study used a delta-type 3D printer to print out specimens with dimensions according to ASTM D638 Type I. The results of this study are a combination that has optimal tensile strength values infill pattern honeycomb, raster angle 90°, print speed 80 mm/s and bed temperature 45°C. As for the combination with optimal dimensional accuracy, the parameters for infill pattern triangle, raster angle 90°, print speed 80 mm/s and bed temperature 60° are obtained.

Abstract: This study delves into the nuanced challenges of additive manufacturing, specifically focusing on the application of sinter-based processes for reactive materials, with Titanium as the focal point. The thermal debinding and sintering processes, crucial steps in shaping, are analyzed with an emphasis on the intricate control required for the removal of polymeric binders, especially concerning the reactivity of metals during these processes. Historically, the emphasis has been on materials like 316L and 17-4-PH due to their straightforward thermal debinding and sintering processes. However, the shift to Titanium and its alloys introduces complexities, requiring special debinding and meticulous control of interstitial elements such as C and O to adhere to stringent material standards such as ASTM F2885-17. This research examines the various stages of shaping progressions, addressing specific requirements like green part strength, flexibility (filaments), flowability (Metal Injection Molding), and crosslinking (Stereolithography). The focus lies on achieving thermal removal with minimal residuals and reactivity, particularly in the context of reactive metals. Lithography-Based Metal Manufacturing (LMM) and Cold Metal Fusion (CMF) emerge as significant additive manufacturing processes for small to medium-sized batches of titanium parts, utilizing sinter-based production setups. Both processes not only serve as alternatives to Metal Injection Molding but also contribute to cost-effectiveness and sustainability through the efficient reuse of unused feedstock. The selection of the optimal shaping technology for individual parts becomes critical, considering mechanical properties, final density, acceptance of interstitials, complexity, wall thickness, overhangs, and internal structures. This presentation provides a detailed analysis of Lithography-Based Metal Manufacturing, comparing it with the Cold Metal Fusion process. Key considerations include mechanical properties, surface finishes, and cost, shedding light on the technical intricacies and trade-offs inherent in each technology.

Abstract: The fused deposition modeling (FDM) process is used increasingly in the manufacture of mechanical parts and more particularly in the automotive and aeronautical fields. The purpose of this work is to optimize build orientation for obtaining polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS) samples with the best mechanical properties, dimensional accuracy, surface quality, and minimal total cost. For achieving This, PLA and ABS specimens are fabricated by FDM technology with three build orientations (flat, on edge, upright) and three raster angles (0°, 45°, 90°).at first, the dimensions of the produced samples are measured .secondly, the tensile test, DETLAB equipment was used to obtain tensile stress. In addition, roughness testers were also used to measure surface quality. As a consequence, the findings indicate that the mechanical strength increases with decreasing raster angle and by aligning from upright to flat orientation for both materials due to the fracture mechanism and loading direction. Also, the manufacturing orientation and raster angles significantly affected the dimensional accuracy and total cost. Additionally, there was a big difference in the surface roughness depending on the manufacturing orientation and raster angle; perpendicular measurements increase surface roughness values. We aim to investigate the impact of flat, on-edge, and upright build orientations as well as raster angles on the total cost, tensile strength, dimensional accuracy, and surface roughness of PLA and ABS material through tensile experiments.

Abstract: The aim of this research work is identification of optimum drilling parameters to increase material removal rate, dimensional and profile accuracy during drilling. ASTM A516 (Grade70) which is a boiler quality plate of 12 mm thickness was considered as the specimen for conducting the experiments. The experiment was done based on full factorial design using 18 experiments generated using Minitab Software. Two levels for tool material and three levels for feed-speed combination and cutting environment were considered. Two runs were carried out for each trial. The metal removal rate was calculated for each hole drilled. The mean result of the two runs of a trial was taken as the result of the trial. The drilled holes were then tested for their dimensional, profile accuracies. With these results in hand the Artificial Neural Network software was trained to predict the optimized input parameters for drilling a hole of required dimensional and profile accuracies and with required metal removal rate.

Abstract: High dimensional accuracy is of crucial importance in digital manufacturing to guarantee production capability and product performance. For manufacturing of thin-walled complex extrusions, it is often challenging to meet the tight dimensional tolerance requirements for automated mass production, due to dimensional imperfections and variations accumulated from the thermo-mechanical processing history. Recently, a new calibration technique, called Transverse Stretch and Local Bending, was developed, enabling significant improvement of the dimensional accuracy of thin-walled open profiles at a low cost. However, the deformation mechanisms have not been well understood, which in turn affect the process design for achieving high-precision products. In this study, a through-process finite element model was established and experimentally verified, which is used as a tool to investigate the mechanisms in the calibration process. It is found that the gap opening is mainly reduced in the inserting stage, but the calibration stage plays a key role in achieving high-precision products after unloading. The critical factor to achieve high dimensional accuracy is reducing the through-thickness gradients on both the profile bottom and sidewall. By controlling the total vertical displacement in the transverse stretch and local bending, the stress gradients can be effectively reduced, and the dimensional deviation caused by springback after unloading can be well mitigated. This fundamental study will benefit the industry to obtain high-precision extrusions.

Abstract: The adoption of Additive Manufacturing (AM) is continuously growing due to its capability to produce complex shapes which leads to the dependence of manufacturers on AM to replace conventional manufacturing processes. One important focus of research now is on the accuracy of 3D printed products produced via the Fused Deposition Modeling (FDM). These products have great potential to be applied to tooling and other rapid prototyping applications. The aim of this study is to assess the accuracy of 3D printed Acrylonitrile Butadiene Styrene (ABS) through manual measurements of dimensions. Several sets of samples with cubic shapes were printed and measured using a digital micrometer to evaluate the dimensional accuracy of the 3d-printed parts. A 2² full factorial design was employed to investigate the effects of infill density and layer thickness on the dimensional accuracy of ABS parts.

Abstract: This paper highlights the detailed procedure for preparation of biocompatible sensors and transducers by CAD-CAM assisted investment casting (IC). Along with the properties such as biocompatibility and bioactivity, the presented materials possess good surface finish (required for aesthetic sense), acceptable dimensional accuracy (required for assembly purposes) and good surface hardness (required while chewing). In this paper efforts were made for improving surface hardness, finish, and dimensional accuracy of biocompatible materials by controlling composition/proportion of Ni and Cr in IC process. In this case study stir casting (SC) assisted Ni and Cr based metal matrix composites (MMC) has been prepared and composite prepared were poured in the investment mould. The result of study reveals that different material composition influenced the microstructure and the hardness of the MMC prepared. Further with change in weight percentage of Ni and Cr, different microstructures with particle clustering was observed. The employment of nickel and chromium composites for the fabrication of novel sensors and transducers is discussed.