Subtractive Manufacturing Research Articles

Study on hybrid 3D printing and milling process for customized polyether-ether-ketone components.

Polyether-ether-ketone (PEEK) has been widely applied in various fields due to its excellent mechanical properties and biocompatibility. The efficient and high-quality customized manufacturing of PEEK components are investigated in this study by the hybrid 3D printing and milling process. At first, the alternating hybrid process is selected and verified by comparing two typical hybrid process categories and conducting experiments, respectively. Second, a set of procedures are designed to automate the engineering application of the hybrid process trying to avoid the disadvantages of manual programing. Then, considering the tool length and possible interferences during the hybrid process, a model segmentation algorithm, namely, the exchange principle of avoiding interference (EPAI) is proposed. Based on the introduced EPAI and the programing language Python, the additive and subtractive hybrid manufacturing (ASHM) data processing procedure is proposed and realized by post-processing of the conventional 3D printing codes. Finally, the feasibility experiments have been conducted. The experimental results verify the hybrid manufacturing process in the fabrication of parts with complex internal features. The surface roughness Ra and dimensional error L of the parts have been reduced by 75.5% and 85.2%, respectively, while the shear strength τ has been increased by 14.1%. Compared with conventional milling process, the material consumption is reduced by 48.7%.

Continuous Toolpath Optimization for Simultaneous Four‐Axis Subtractive Manufacturing

Continuous Toolpath Optimization for Simultaneous Four‐Axis Subtractive Manufacturing

Maxillary intaglio surface of CNC milled versus 3D printed complete denture bases – an in vitro investigation of the accuracy of seven systems.

The accuracy of the intaglio surface of maxillary complete dentures produced with a variety of digital manufacturing systems have been comprehensively investigated, however, not for multiple systems in the same study. This in vitro study endeavors to measure and compare the accuracy of the intaglio surface of maxillary complete denture bases constructed with different photopolymerization-based 3D printing and CNC milling systems. Two subtractive manufacturing machines and five additive manufacturing machines were used to manufacture a maxillary denture bases (n=10) for analysis. The samples were stored in artificial saliva at 37°C for 7 days to mimic intraoral use before they were air dried for 5 min, and then scanned with an E3 dental laboratory scanner to generate STL files. A 3D metrology software program was used to analyze the data against the original CAD design. Statistical differences were determined with 1-way analysis of variance (ANOVA) and the Kruskal Wallis test (α=.05). Color deviation heat maps were used to interpret areas of clinical significance. The results indicated that the subtractive manufacturing method delivers the truest and most precise intaglio surface of maxillary complete denture bases. The additive manufacturing technique delivers less true and less precise results with inconsistency observed between the different systems as opposed to the subtractive manufacturing groups which showed no significant differences. When manufacturing a complete maxillary denture base subtractive manufacturing will deliver the most consistent and true results.

The Effect of Gastric Acid and Material Type on the Surface Roughness of Additive and Subtractive Manufacturing Resins.

The aim of this study is to examine the effect of gastric acid on the surface roughness of additive and subtractive manufacturing resin. In this study, two subtractive manufacturing CAD-CAM resin nanoceramic (CerasmartTM270 (CS), LavaTM Ultimate (LU)) and two additive manufacturing 3D printing permanent resin (VarseoSmile Crownplus (VSP), Crowntec (CT)) was used. CS and LU samples were turned into 10 mm diameter cylinders with a scraper and cut into 2 mm slices on the cutting device. CT and VSP samples were produced on a 3D printer (2mm thickness-10mm diameter) (n:15). All samples were exposed to a cycle of 60 seconds of gastric acid, 5 seconds of distilled water, and 30 minutes of artificial saliva, 6 times a day for 10 days. Surface roughness mean (Ra) and depth (Rz) was measured with a contact profilometer at baseline and after gastric acid cycling. Data were analyzed using SPSS (22.0), One way ANOVA, post-hoc Tukey's and Independent-t test (p <.05). Ra-Rz values of CT and VSP were significantly higher than CS and LU at baseline and after the gastric acid cycle (p <.05). After the gastric acid cycle, the Ra-Rz values of all materials increased significantly compared to the baseline (p <.05) but the Ra values of all materials were at a clinically acceptable level (<0.2µm). Although additive manufacturing 3D printing permanent resins offered higher roughness values, they weren't at a clinically unacceptable level. Therefore, they can be an alternative to subtractive manufacturing CAD-CAM resin nanoceramics.

Toolpath and Tool Design Innovations in Deformation Machining for Superior AA-7075 T6 Fins

Abstract A hybrid manufacturing process, deformation machining (DM) combines subtractive manufacturing with incremental forming. Monolithic components with complex profiles are created through the hybridization of manufacturing technologies, which also reduces the wastage of raw materials. The properties of geometry and surface quality of the fin made from the aluminum alloy Al-7075 T6 using the DM process’s bending mode was examined in this research, as were the effects of various approaches, toolpath methods, and tool design. To achieve the desired shape for the machined fin, various combinations of arcuate and slanting fin toolpath techniques were explored utilizing both top-down and bottom-up methods. The bottom-up method and the arcuate toolpath strategy were used to investigate various tool profiles. Using the best combination of toolpath strategy and tool profile, named as the T3 tool profile, which has a 0.6 mm nose radius and a circular sector, bottom-to-top (BTT)technique, and arcuate toolpath method, components with better geometrical features and surface roughness (SR) were produced. The analysis of the forming force in the bending approach of the DM progression was further carried out using this optimal combination.

On morphology and roughness of upskin surfaces in laser powder-bed fusion additive manufacturing – Contouring strategy effects

The surface quality of inclined parts made by Laser powder-bed fusion (L-PBF) additive manufacturing is inferior to those made by conventional formative and subtractive manufacturing techniques. The inherited step edges formed during such layer-by-layer fabrications and partially melted or non-melted particles attached to the newly formed surface are the major causes of poor surface finish of L-PBF parts. This study is a part of a research framework, in which the effects of different contouring strategies and scan parameters on the surface morphology of inclined parts are investigated by both experimental and numerical methods. In particular, the effect of two different contour scan strategies, namely pre-contouring and post-contouring, on the upskin surface roughness of 30⁰ inclined parts is analyzed. The inclined specimens were fabricated with Ti6Al4V powder using an EOS M270 system and the upskin surfaces were measured by a white light interferometer. In addition, a multi-track multi-layer numerical approach using coupled discrete element method and thermo-fluid simulation was also performed to understand the inclined surface formation in L-PBF.The findings show that the pre-contouring strategy with high linear energy density (LED) (0.4 J/mm) results in average surface roughness (Sa) as low as 7.43 µm, whereas the lowest LED (0.05 J/mm) resulted in the highest Sa of 33.74 µm. Larger melt pool dimensions were obtained in the high LED pre-contouring simulations, which indicates a better material fusion resulting in a good surface finish. The numerical simulation showed that the upskin surface roughness is also affected by the raster scan, if the raster scanning LED is higher than that of pre-contour scans. For the post-contouring strategy studied, higher and lower LEDs were used in inner and outer contour scanning, respectively. It is indicated that the inner contour scanning with a high LED reduces the surface roughness because of a larger melt pool size, irrespective of outer contour scanning. The lowest Sa obtained was 8.24 µm for the highest LED inner contour (0.05 J/mm) case and the highest Sa was 19.95 µm, for the parts made with the lowest LED inner contour scan (0.075 J/mm) strategy. The coupled discrete-element and thermo-fluid-based simulations offer insights into the sloped surface formation and the results supported the experimental findings in qualitative manner.

Subtractive manufacturing of composite materials with robotic manipulators: a comprehensive review

AbstractRobotic manipulators play an innovative role as a new method for high-precision, large-scale manufacturing of composite components. However, machining composite materials with these systems presents unique challenges. Unlike traditional monolithic materials, composites exhibit complex behaviour and inconsistent results during machining. Additionally, robotic manipulator as a machine tool often associates with stiffness and vibration issues which adds another layer of complexity to this approach. By employing a comprehensive analysis and a combination of quantitative and qualitative review methodology, this review paper aims to survey diverse properties of composite materials by different categories and their interaction with machining processes. Subsequently, a survey of manufacturing techniques for composite machining following with a review in various modeling practices to capture material machining behaviour under a systematic framework is presented. Thereafter, the reviewed literature examines the errors inherent in robotic systems, alongside ongoing research efforts in modeling to characterise robot behaviour and enhance its performance. Afterward, the paper explores the application of data-driven modelling methods, with a primary focus on digital twins, in enabling real-time monitoring and process optimisation. Finally, this paper aims to identify the gap in this field and suggests the potential routes for future research and application as well as their challenges.

Robot path planning for metrology in hybrid manufacturing

The objective of the wire arc additive manufacturing (WAAM) hybrid cell is to significantly reduce lead time associated with large scale parts. The WAAM process utilizes a 6 degree-of-freedom (DOF) robot manipulator in addition to a 2 DOF part positioner. After printing, the part is translated into position for scanning to inform the subtractive manufacturing process. Scanning in a manual setting can be a long and arduous process to generate scans of sufficient quality for the basis of informed machining. Effective path planning for scanning with the intent to reduce scanning time, increase quality of scans, and move toward a full automation of the hybrid manufacturing cell is investigated in this paper. Simulation software is used to create and verify path plans prior to importing and implementing on a 6 DOF robotic manipulator to which a GOM ATOS Q 3D scanner is mounted. The quality, amount of time necessary to produce, and number of scans required to produce a sufficient representation for machining are compared using three methods. The first method is a manual scanning configuration, the second is using a generalized path plan, and the third is using a geometry-based path plan.

THE EFFECT OF DIFFERENT STAINING SOLUTIONS ON THE COLOR STABILITY OF PERMANENT INDIRECT COMPOSITE RESINS PRODUCED BY ADDITIVE AND SUBTRACTIVE TECHNIQUES

Objective: To investigate the effects of various beverages on the color stability of permanent composite resins produced by additive (AM) or subtractive manufacturing (SM) techniques comparatively. Materials and Methods: Six composite resin materials produced by SM (Vita Enamic-VE, Cerasmart-CE, Lava Ultimate-LU) and AM (Varseo Smile Crown plus-VSC, Saremco print Crowntech-SPC, Formlabs 3B Permanent Crown-FPC) techniques were selected and soaked in different solutions (artificial saliva, black tea, coffee) for different times (0, 1 and 7 days). L*, a*, b* values of the samples were recorded using a spectrophotometer. The color changes of the samples were determined using the CIELAB formula. In determining the color differences between the test materials, Kruskal-Wallis analysis was used when one-way analysis of variance wasn’t available. Results: Group VE was the least stained group on the 1st and 7th day of artificial saliva solution and the 7th day of coffee solution, while Group CE was the least stained group on the 1st day of coffee solution. In the tea solution, on the 1st and 7th days, there wasn’t difference in the materials' color change (p&amp;gt;0.05). Tea and coffee solutions caused statistically significantly more color change in all test materials than artificial saliva (except Group CE on the 7th day, Group VSC and FPC on the 1st day) (p&amp;lt;0.05). Conclusion: 3D permanent composite resins generally showed more staining than CAD/CAM milled composite resins. Tea and coffee staining solutions changed the color of the materials compared to artificial saliva. As the storage time increased, more color changes were observed.

Equal–Additive–Subtractive Remanufacturing Integrated Laser Directed Energy Deposition with Shot Peening and Machining Induced High Performance of Plunger Rod

The number of easily destroyed parts with high value is increasing in industry, and green remanufacture engineering is now mainstream in this new and expanding industrial field. Equal–additive–subtractive manufacturing, as a new technology that combines strengthening technology, additive manufacturing, and machining technology has great potential for development in the area of remanufacturing. Aiming at the damage characteristics of a plunger rod, this paper carries out a study about the repair technology by equal–additive–subtractive manufacturing of laser-directed energy deposition and shot peening. It was found that the microstructure of the materials repaired by equal–additive–subtractive technology is finer and the tensile strength can reach 100.4% of the base material. The surface residual stress of cladding materials changes from tensile stress to compressive stress, which reduces forming defects. Equal–additive–subtractive manufacturing has great significance in expanding the application of hybrid manufacturing and promoting green remanufacturing of parts with high value.

High-Q integrated lithium tantalate microring resonators for on-chip comb generation.

Lithium tantalate on insulator (LTOI), taking advantage of high cost-effectiveness, ultra-low optical loss, and prominent electro-optic (EO) coefficient, shows great potential as an integrated waveguide-based optical platform for commercialization. Further research on monolithic nonlinear source generators with tunable features is crucial in its early stages. Here, we fabricate low-loss microring resonators (intrinsic Q value above 4 × 106) via universal subtractive manufacturing. Both Kerr and EO combs are realized based on X-cut LTOI high-Q resonators. Specifically, we elucidate the complicated synergy caused by a photorefractive (PR) effect and thermo-optic modulation, observing the soliton step using the facile laser scanning technique. Furthermore, the preliminary experimental result of the static EO comb is also exploited in a 20 GHz free spectral range (FSR) LTOI microring resonator, verifying the versatility of this unique photonic platform for on-chip microcomb generation.

Additive and subtractive hybrid manufacturing assisted by femtosecond adaptive optics

Additive and subtractive hybrid manufacturing assisted by femtosecond adaptive optics

A model-adaptive compensation algorithm for additive-subtractive hybrid manufacturing

Abstract Additive-subtractive hybrid manufacturing (ASHM) is a manufacturing method that combines additive manufacturing (AM) with subtractive manufacturing (SM) techniques. Given that the surface accuracy of ASHM components primarily relies on numerical control (NC) machining, it is imperative to incorporate model compensation to preserve finishing allowances, thereby obtaining additive manufacturing (AM) models from design models. This paper proposes a model adaptive compensation algorithm capable of dynamically adjusting the design model based on both model characteristics and the AM process. This algorithm not only ensures the retention of suitable finishing allowances but also addresses part size errors arising from the AM process. Comparative analysis against traditional CAD reconstruction methods highlights the algorithm’s superior attributes in terms of accuracy, efficiency, and adaptability when confronted with intricate model compensation scenarios.

Influence of printing parameters on the mechanical behavior of 3D-printed SS316L parts manufactured using laser hot wire directed energy deposition

Hybrid manufacturing combines the simultaneous benefits of additive manufacturing (complex geometries, part consolidation, and mass customization) with the advantages of subtractive manufacturing (superior surface finish and enhanced dimensional accuracies) by integrating a suite of complementary traditional processes into a base platform of additive manufacturing. The use of hybrid technology has grown in recent years given its capabilities on repairing metallic structures, producing parts with conformal cooling features, and manufacturing functionally graded products. These kinds of capabilities are of great interest to the medical implant, energy, automotive, maritime, and aerospace industry sectors, among many other fields. This work investigated the mechanical properties of stainless steel (SS) 316L as a function of different tool paths strategies using an integrated 5-axis CNC hybrid Mazak system with a laser hot wire deposition system (LHWDS). This study includes the evaluation of different printing parameters and their impact on the quality of the printed bead as well as the incorporation of a structure–property material relationship based on the mechanical performance of the manufactured coupons.

Generation of Customized Bone Implants from CT Scans Using FEA and AM.

Additive manufacturing (AM) allows the creation of customized designs for various medical devices, such as implants, casts, and splints. Amongst other AM technologies, fused filament fabrication (FFF) facilitates the production of intricate geometries that are often unattainable through conventional methods like subtractive manufacturing. This study aimed to develop a methodology for substituting a pathological talus bone with a personalized one created using additive manufacturing. The process involved generating a numerical parametric solid model of the specific anatomical region using computed tomography (CT) scans of the corresponding healthy organ from the patient. The healthy talus served as a mirrored template to replace the defective one. Structural simulation of the model through finite element analysis (FEA) helped compare and select different materials to identify the most suitable one for the replacement bone. The implant was then produced using FFF technology. The developed procedure yielded commendable results. The models maintained high geometric accuracy, while significantly reducing the computational time. PEEK emerged as the optimal material for bone replacement among the considered options and several specimens of talus were successfully printed.

Comparison of Tensile Bond Strength of Soft Denture Liner Material on Denture Base Resins

Aim: This study aims to evaluate the tensile bond strength (TBS) of a silicone-based soft denture liner material on denture bases produced via conventional, subtractive, and additive manufacturing techniques and examine the effect of aluminum oxide particle abrasion (APA) on TBS. Material and Methods: A total of 48 cylindrical denture base resin samples were manufactured using three different techniques: conventional, subtractive, and additive manufacturing. The samples were divided into two groups: control and APA. All samples were separated at the center, and the soft liner was applied to the corresponding surfaces. The specimens then underwent TBS testing. Data were analyzed using Two-way ANOVA and Bonferroni post hoc tests. Results: Two-way ANOVA results indicated a significant difference among the denture base resins, while no significant difference was found between the control and APA groups. The highest TBS was observed in the subtractive-manufactured APA group, while the lowest TBS was in the additive-manufactured APA group. Significant differences were found between the subtractive and additive-manufactured groups (p=0.022). Conclusion: This study demonstrates that TBS varies with the DB's manufacturing technique. While APA increased TBS in subtractive manufacturing, it had no statistically significant effect. Further research should explore different soft lining materials and consider in vivo conditions for more comprehensive insights.

Evaluation of wear and friction properties of graphite modified Lubri polylactic acid with various infill fabricated by additive manufacturing techniques

AbstractThree‐dimension (3D) printing technology, also known as additive manufacturing, is a manufacturing technology that creates three‐dimensional objects by depositing material layer by layer, as opposed to subtractive manufacturing methods. However, the newness of the technology brings with it many unknowns. In particular, the raw materials used are constantly increasing. For this reason, testing each raw material used in many aspects and to determine the optimum production conditions is important for the wide use of 3D printing technology. These optimal conditions may be the parameters used to produce a material, and sometimes they can appear as a new material. In addition, the production of new materials with varying production parameters is fundamental research topic that requires comprehensive study. For all these purposes, in this study, a new material type known as Lubri PLA (LPLA) was selected and produced in different filling types and subjected to a series of friction and wear tests. Thus, it is aimed to determine the tribological properties of the material. Additionally, samples were produced in ten different infill types (grid, lines, triangels, hexagon, cubic, octal, zigzag, diagonal, diagonal 3D and gyroid) to show the effect of filler type on friction and wear behavior. These filler types were used for both PLA and Lubri PLA materials and a total of twenty samples were produced. Thereby, it is aimed to conduct a comprehensive study showing the effect of both material difference and filling type on friction‐wear behavior. Diameter deviations, hardness deviations, friction coefficient, temperature, specific wear rates (SWr), and vibration were selected as output parameters. According to the analysis of the test results, the best result in terms of material structure was given by Lubri PLA, while the best result in terms of filling type was obtained with Diagonal 3D filling type. In addition, the lowest vibration level was obtained in the LP‐Diagonal 3D sample with 0.041 mm/s2, while the highest vibration level was obtained in the P‐Grid sample with 1.756 mm/s2.Highlights LPLA closed to nominal value in diameter and hardness deviations Addition of graphite nanoparticle increased the dimensional accuracy Diagonal 3D infill type Lubri PLA composites showed the superior performance Graphite modified Lubri PLA composites demonstrated superior performance

Monomer Elution of Additive and Subtractive Manufactured Resins for Permanent Restorations.

Purpose: To evaluate the elution of residual monomers from resins used in additive and subtractive manufactured permanent restorations over a period of one month, using highperformance liquid chromatography (HPLC). Materials and Methods: Two additive manufacturing permanent crown resins (Crowntec, CT and VarseoSmile Crown Plus, VS) and a subtractive manufacturing resin nanoceramic (Cerasmart, CS) were used to fabricate 30 disc-shaped samples (10 × 2 mm) (n=10). The elution of bisphenol A ethoxylate dimethacrylate (BisEMA), urethane dimethacrylate (UDMA), and triethylene glycol dimethacrylate (TEGDMA) monomers was measured with HPLC at 1 day and 30 days after immersion. One-way analysis of variance (ANOVA) and post-hoc Tukey tests were used to evaluate differences in eluted monomer concentrations. Paired-sample t tests were used to test the differences in monomer concentration between storage times. Results: CS released BisEMA and UDMA residual monomers, while VS and CT released BisEMA and TEGDMA residual monomers. The residual monomer elution from CT was consistently lower than that from VS for both BisEMA (p <0.001) and TEGDMA (p <0.001). CS showed a decreasing release pattern in BisEMA (p =0.002) and UDMA (p <0.001) residuel monomers, whereas VS and CT showed an increasing release pattern in BisEMA (p <0.001) and TEGDMA (p <0.001) residuel monomers. Conclusions: The additive manufactured composite resins released higher amounts of residual monomers than the subtractive manufactured resin nanoceramic. Although the amounts of residual monomers released in the additive manufactured composite resins increased over time in contrast to subtractive manufactured resin nanoceramic, these values were below cytotoxic levels.

Measuring thermomechanical response of large-format printed polymer composite structures via digital image correlation

Large-format additive manufacturing (LFAM) is a branch of additive manufacturing (AM) research with the ability to create large structures typically measuring several meters in scale. LFAM is advantageous for tooling applications, not only because it offers the ability to create complex geometries not easily made using subtractive manufacturing processes, but the cost savings of pelletized feedstock used by these systems result in larger parts printed at faster speeds than traditional AM systems. Fiber reinforced polymer (FRP) is a commonly used feedstock material in LFAM structures because it reduces the distortion experienced during printing. However, FRP introduces highly anisotropic thermomechanical properties and contributes to a nonhomogeneous microstructure that can result in critical distortion of dimensions during tooling. Measuring the global thermomechanical response of LFAM structures requires a more representative method that accounts for not only anisotropic properties but also the nonhomogeneous nature of the final part. This is where traditional techniques to measure thermomechanical response, such as thermomechanical analysis (TMA), fall short as they assume homogeneity. This study evaluated the coefficient of thermal expansion (CTE) of LFAM structures as measured by TMA as compared to a novel digital image correlation oven (DIC Oven) system. The LFAM structures were made from 20 % by weight carbon fiber reinforced acrylonitrile butadiene styrene (CF-ABS). TMA measurements showed significant variations in CTE across a single LFAM bead, confirming the need for a global technique that captures overall thermomechanical response. The CTE values measured using the DIC Oven compared well to average TMA values obtained from localized measurements across the sample. The DIC Oven was also used to quantify the effects of different layer orientations on thermomechanical properties, which cannot be easily captured using TMA. A predictive model was also developed by using localized TMA values across an LFAM bead to predict the overall thermomechanical response of an LFAM structure.

Surface integrity improvement of the ground surface of Inconel 718 fabricated by forging and additive manufacturing using a robotic rotational burnishing method

Given that the surface acts as the primary interface with the surrounding environment, the surface integrity of a component significantly influences its operational effectiveness. In the aerospace industry, materials like Inconel 718 are often utilized for their high-temperature strength despite their poor thermal conductivity and machinability, resulting in inferior surface integrity during grinding procedures. This research proposes an innovative robotic rotational burnishing method that leverages self-generated heat to aid in the post-grinding burnishing process, eliminating the need for an external heat source. The surface integrity achieved through this method undergoes a comprehensive evaluation, encompassing surface topological features, microstructure, and mechanical properties, and is compared with surfaces treated by grinding and slide burnishing. The findings demonstrate that during the rotational burnishing process, the friction between the high-speed rotating burnishing tip and the workpiece surface induces circumferential flow of the surface material, thereby enhancing surface anisotropy. Additionally, this process generates significant heat, further encouraging plastic deformation of the material surface under high burnishing forces. As a result, the surface acquires a compressive residual stress exceeding 1000 MPa and develops a microhardness-strengthened layer with a thickness exceeding 500 μm. Both forging and additive manufacturing techniques for preparing Inconel 718 raw materials yield consistent outcomes. This study not only achieves a fusion of additive, subtractive, and equivalent manufacturing but also validates the applicability of the proposed robotic rotational burnishing method in enhancing surface integrity across materials manufactured by various techniques.