This study establishes a systematic and reproducible workflow for topology optimization (TO) of indexable face milling cutter bodies with integrated internal coolant channels, designed for Additive Manufacturing (AM) of metallic parts. Grounded in Design for Additive Manufacturing (DfAM) principles, the workflow combines displacement-based TO and computational fluid dynamics analysis to generate simulation-driven tool geometries tailored to the constraints of AM. By leveraging iterative design knowledge, the proposed methodology enhances the scalability and repeatability of the design process, reducing development time and supporting rapid adaptation across various tool geometries. AM is explicitly exploited to integrate support-free internal coolant channels directed toward the insert cutting edge, thereby achieving a 20% mass reduction relative to the initial milling tool designs, and improving material usage efficiency at the design stage. The workflow yields numerically optimized geometries that maintain simulated global stiffness under the considered loading conditions and exhibit coolant flow distributions that effectively target the exposed cutting edges. These simulation results demonstrate the feasibility of an AM oriented, workflow-based approach for the numerical design of milling tools with internal cooling, mass reduction and provide a focused basis for subsequent experimental validation and comparison with conventionally manufactured counterparts.

Sintered ceramics are recognized as promising materials for high-precision and advanced applications, such as orthopedic grafts implants, owing to their superior mechanical performance and biocompatibility. The fabrication of complex or intricate geometries often necessitates post-processing, for which micro-milling is frequently utilized. This paper focuses on the micro-milling of zirconia-toughened alumina (ZTA), a high-performance ceramic widely used in the medical industry for joint implants and rehabilitation components. The study investigates the surface formation mechanisms, size effects, and chip thickness characteristics associated with the process. In addition, the performance of cemented carbide micro-milling tools coated with a multi-layer HF-CVD diamond film is evaluated to assess their suitability for precision machining of ZTA ceramics. The tool wear mechanisms were systematically investigated, with particular attention given to the main failure modes occurring during the micro-milling process, including coating deterioration of the cutting tool. The surface formation and damage behaviour of ZTA under various cutting conditions were analysed in detail. Experimental results demonstrate that ZTA can be efficiently machined by micro-milling under controlled cutting parameters, achieving high surface quality and an industrially relevant tool life. The micro-milling of sintered ceramics remains challenging due to their inherent high strength and brittleness. Attaining the desired surface integrity and dimensional accuracy requires further optimization of machining parameters and strategies. Key aspects include the control of ductile-regime machining and the reduction of cutting near the tool center, both of which are critical to achieving improved performance.

Tribological testing is essential for evaluating the performance and reliability of advanced ceramic multilayer-coated tools. Unlike conventional materials, coated inserts are designed to enhance hardness, thermal stability, and resistance to wear and friction. Owing to these properties, accurate specific wear rate determination becomes challenging, primarily due to the very small depth of the resulting wear tracks. In this study, a new wear evaluation method based on Material Ratio Curve Integration (MCI) is proposed. Reciprocating ball-on-flat tribological tests were performed on cemented tungsten carbide (WC-Co) samples coated with multilayer ceramic films produced using both physical and chemical vapor-based deposition techniques. Wear behavior was analyzed using high-resolution optical profilometry, and wear volumes were quantified using three approaches: the Averaging Cross-Section (ACS) method, following the procedure outlined in ASTM G133-05; Direct Volume Calculation (DVC), based on the integration of cross-sectional profiles along the wear track length; and the newly proposed MCI method. The accuracy, limitations, and reliability of each method were systematically evaluated. The MCI method was validated for sufficiently large wear track depths, showing very good agreement with results obtained using the DVC method implemented using dedicated functions in SensoMAP (R). The main advantages of MCI-method are its applicability when other methods fail (e.g., very shallow wear tracks) and the reduced operator dependence.

The manufacturing sector faces significant challenges in efficiency, adaptability, and sustainability, with cutting tool performance being critical for both production processes and final product quality. The development of new multilayer coatings for cutting tools has become a constant concern in today's industrial landscape, driven by the need for enhanced tool life and improved machining efficiency in increasingly demanding applications. In this study, multilayer structures were designed with TiN (<0.3 mu m)/TiCN (4 mu m)/Al2O3 (3 mu m)/TiN (1 mu m) base layers deposited via CVD, followed by AlCrN (4 mu m) or AlCrN (3 mu m) + ZrN (1 mu m) applied via PVD-HiPIMS. The textured Al2O3 intermediate layer exhibited a preferred (006) crystallographic orientation, typically associated with enhanced hardness of the CVD layer. Energy Dispersive X-ray Spectroscopy (EDS) and tribological tests demonstrated lower adhesion of workpiece materials and improved wear resistance for the hybrid coatings compared to conventional CVD coatings. Machining tests on AISI 316 stainless steel during a turning operation revealed that the hybrid-coated tools exhibited significantly better tool life compared to the CVD-coated tools (by 69.20 %), considering a flank wear of VB = 0.134 mm as the end-of-life criterion. These results provide strong evidence that the hybrid CVD/PVD multilayer coating strategy significantly enhances cutting tool performance and longevity in demanding machining applications.

Inconel is a nickel-based superalloy whose high strength, low thermal conductivity, and strong work-hardening behavior make machining particularly demanding, leading to high temperatures, severe friction, and rapid tool wear. Enhancing cutting tool wear resistance and thermal stability is therefore essential. In this study, HiPIMS-deposited multilayer PVD coatings were applied to polished and ground SiAlON ceramic cutting tools to evaluate the influence of substrate preparation and coating composition on performance. Three systems were investigated: AlTiN+TiSiN+TiN (TiN1), AlTiN+TiSiN+ZrN (ZrN1), and AlCrN+ZrN (ZrN2). Coatings were characterized by SEM/EDS, digital microscopy, adhesion testing, and tribological evaluation. Results show that polished substrates promote smoother, more uniform coatings with improved adhesion and tribological stability. Coating composition also plays a key role: TiN top layers form finer crystallites than ZrN, leading to lower roughness and superior wear performance. These factors directly affect coating integrity and tool life during Inconel machining.

Physical vapor deposition (PVD) with High Power Impulse Magnetron Sputtering (HiPIMS) presents a highly promising surface modification approach for the performance enhancement of SiAlON cutting tools in the machining of Nickel-based superalloys alloys, which are renowned for their challenging machinability. This study systematically investigates the coating roughness, microstructural characteristics, and cutting performance of HiPIMS-coated SiAlON tools in Inconel 718 milling. The deposited multilayer coatings were comprehensively analysed using advanced characterisation techniques, including scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Cutting tests were carried out with different tool geometries and machining conditions, as well as coated and uncoated tools-factors that highly influence tool's performance. The HiPIMS coating demonstrated improved thermal stability and reduced susceptibility to diffusion-related deterioration-factors that are critical in managing the high temperatures encountered in superalloy machining. These results underscore the potential of HiPIMS technology to significantly extend tool longevity and enhance machining efficiency, establishing it as a viable solution for high-performance manufacturing sectors.

Additive manufacturing of hard metals is gaining attention for its ability to create complex parts and innovative designs. Binder Jetting (BJ) is particularly promising due to its low cost, fast production, and ability to produce stress- and crack-free parts with isotropic properties. The correct binder selection plays a significant role in determining both the green part properties and, especially, the depowdering performance. This study investigates the influence of two different binders (AQUAFUSE and CLEANFUSE-commercial designations) on the properties of hard metal parts manufactured by BJ using commercially available WC-12%Co powder (WOKA 3111FC). The green part properties (green density, green strength), as well as sintered part properties (density, shrinkage, and microstructure), obtained using each binder type, were evaluated and compared. The results suggest that binder selection is a critical factor in optimizing the performance of BJ-manufactured hard metal parts and highlight the potential of CLEANFUSE for applications requiring higher mechanical integrity.

Micro-milling of hard materials can be an efficient processing technique to attain high-precision parts in difficult- to-machine metal matrix composites, such as cemented carbide. Despite their brittle mechanical behavior, within specific operational conditions plastic-flow (ductile) cutting occurs, enabling significant technological advances on ultra-precision machines and components. This brittle-to-ductile threshold (which has been defined based on grinding operations) depends on material properties, such as the elastic modulus, material hardness and fracture toughness of the tool-workpiece materials pair. Despite the similar process size scale, grinding and micro-milling significantly differ on how well defined the cutting edges are, and the control of micro-milling operations towards stable ductile cutting is still rather unexplored. In the present work, micro-milling of WC-15wt.%Co sintered samples was performed with diamond coated end mills, confirming the influence of a ductile-to-brittle threshold on the cutting regime. Critical scale effects and structure-related behavior were also confirmed, as well as the impact of edge radius optimization with laser sharpened coating. A positive effect on machined surface quality was observed when ductile cutting regime mode was applied, likewise the effect of edge radius control with laser sharpness technology. Scanning electron microscopy and micro 3D topography were used to evaluate the machined surface microstructure features after different machining conditions, The experimental study confirmed the ability to control the cutting regime during micro milling of cemented carbide, the great impact of the edge radius on the ploughing effect and the ability to apply laser edge treatment as a solution to control this scale effect, however, the sharp edges promoted a reduction in the quality of the machined surfaces.

The rapid growth of the machining market and advancements in additive manufacturing (AM) present new opportunities for innovative tool designs. This preliminary study proposes a design for additive manufacturing (DfAM) approach to redesign a milling cutter head in 17-4 PH stainless steel by integrating topology optimization (TO) and internal coolant channel optimization, enabled by laser powder bed fusion (LPBF). An industrial eight-insert milling cutting tool was reimagined with conformal cooling channels and a lightweight topology-optimized structure. The design process considered LPBF constraints and was iteratively refined using computational fluid dynamics (CFD) and finite element analysis (FEA) to validate fluid flow and structural performance. The optimized milling head achieved approximately 10% weight reduction while improving stiffness (reducing maximum deformation under load from 160 μm to 151 μm) and providing enhanced coolant distribution to the cutting inserts. The results demonstrate that combining TO with internal channel design can yield a high-performance and lightweight milling tool that leverages the freedom of additive manufacturing. As proof of concept, this integrated CFD–FEA validation approach under DfAM guidelines highlights a promising pathway toward superior cutting tool designs for industrial applications.

Laser-Directed Energy Deposition (L-DED) is an additive manufacturing technique used for producing and repairing components, mainly for coating applications, depositing metal matrix composites such as cemented carbides, composed of hard metal carbides and a metallic binder. In this sense, this study evaluated the preparation of a ready-to-press WC-25Co powder as a reliable feedstock for L-DED process. This powder required pre-heat treatment studies to prevent fragmentation during powder feeding, due to the absence of metallurgical bonding between WC and Co particles. In the current study, the Taguchi methodology was used, varying laser power, powder feed rate, and scanning speed to reach an optimised deposition window. The best bead morphology resulted from 2400 W laser power, 11 mm/s scanning speed, and 9 g/min feed rate. Moreover, defects such as porosity and cracking were mitigated by applying a remelting strategy of 2400 W and 9 mm/s. Therefore, a perfect deposition is obtained using the optimised processing parameters. Microstructural analysis of the optimised deposited line revealed a fine structure, comprising columnar and equiaxed dendrites of complex carbides. The average hardness of the deposited WC-25Co powder on a AISI 1045 steel was 854 ± 37 HV0.2. These results demonstrate the potential of L-DED for processing high-performance cemented carbide coatings.

Multi-materials have aeronautical, automotive or industrial machine components applications due to combining high specific stiffness and low weight from the composite with the ductility, impact resistance, and damage tolerance of the metal. In this work, 25.5 mm-thick multi-materials with carbon fibre reinforced polymer and aluminium were drilled using four conventional twist drills with two different geometries, N-type and W-type, being the first two just polished (uncoated) and the latter two coated with physical vapour deposition tantalum carbide. Five different feed-rate values and four cutting speeds were used in a full factorial design to evaluate each parameter’s influence in the results, with emphasis on the cutting loads. Furthermore, the chip geometry, hole quality (dimensional analysis, internal roughness and presence of defects) and tool wear were also analysed resorting to an analysis of variance. From the combination of results, a feed of 0.15 mm/rev and a cutting speed of 180 m/min were the optimal parameters, leading a compromise between low thrust force and high material removal rates. The N-type and W-type coated drills had similar responses, with the first having 20.98

During machining processes, cutting tools suffer severe tool wear, due to the friction generated at the tool-chip and tool-workpiece interfaces that produce a considerable amount of abrasion and heat in the cutting zone. Surface texturing has the ability to improve the cutting performance of cutting tools by providing enhanced lubricant availability to the inaccessible area of the tool-chip interface, increasing load carrying capacity, enhancing wetting properties and heat transfer coefficient and reducing the tool-chip contact area and chip on tool contact length, thus reducing friction, tool wear and cutting temperature and forces. This study presents a novel surface modification approach for fabricating cross-hatched micropatterns on the rake face of WC–Co cutting inserts, consisting in performing the laser surface texturing process in the green body of the inserts. The addition of micropatterns to WC–Co cutting tools decreased tool wear by 33

The use of carbon fibre reinforced polymers (CFRP) has transitioned towards applications with large-scale manufacturing with specific desired material characteristics, such as in the aerospace and automotive industries. Despite being manufactured in a near-net shape, machining of CFRP is often necessary to meet dimensional tolerances. The requirement to improve both the processing capability and production cost is heightening given the challenging cutting operations of CFRP, with common issues arising such as machining-induced delamination, poor surface finish and increased tool wear. Sharp polycrystalline diamond (PCD) tools are often employed during CFRP milling, however these are not economically practical due to their high cost, geometric construction limitation and inherent weakening of their geometry (due to relative low toughness and very sharp edges), leading to decreased tool longevity. Sharp diamond-coated carbide tools represent a cost-effective alternative to PCD tools. A novel approach is presented utilizing a high-thickness HF-CVD (Hot-Filament Chemical Vapor Deposition) diamond coated carbide milling tool, with laser sharpened edges, which was used for investigating the effect of coating on cutting force and surface quality of fibre reinforced composites. This paper is an introductory exploration of laser sharpened tools, focusing on their durability and performance. Instrumented experimental tests in contour milling operations demonstrated the increased cutting performance for achieving well-finished surfaces, with negligible rounding of the coated cutting edge. Future studies will compare these tools with standard PCD coated tools without laser sharpened edges to evaluate their relative advantages in machining applications during extensive tool wear tests, when machining abrasive materials, such as CFRP.

Inconel 718 is used in many industry sectors, particularly, in the aerospace, automotive and energy industries. This alloy is selected due to its excellent mechanical properties and stability at high temperatures. However, this material is considered difficult to machine. Its high-strength, low thermal conductivity, and tendency to work-hardening, makes the machining of this material quite challenging, generally causing high amounts of tool-wear. To surpass these processing problems, usually, coated tungsten carbide tools are used for machining Inconel 718, due to their high-hardness and wear resistance. In the present work, finishing turning experiments were conducted on Inconel 718 alloy, using TiAlSiN coated WC-Co tools at different cutting parameters. Different values of feed and cutting speed were used. Tool-wear was assessed and characterized, as well as the machined surface quality. Additionally, cutting forces were measured and evaluated, trying to establish relations between the cutting forces and observed tool-wear. It was found that for lower cutting speeds the registered force values were higher, particularly for worn tools. Tool-wear also seemed to increase these cutting force values. Furthermore, numerical simulations of the cutting process, using finite element method, was performed. These simulations were conducted aiming for the prediction of tool-wear and to compare the developed cutting forces with the obtained through this method. A low error value was obtained for the comparison of the force values, and an accurate tool wear distribution was obtained.

Machining in ductile mode is usually applied for finishing precision parts of hard materials, such as cemented carbide parts, medical ceramic components or glass material applications. Thus, the study of ductile mode cutting of brittle materials has been attracting more and more efforts. The possibility of applying predominant plastic-flow cutting (ductile mode), using ultra-precision machines, in hard/brittle materials has been previously linked to the careful selection of operational conditions, regarding the brittle-to-ductile threshold. This threshold, also known as the critical depth of cut, relates with material specific properties (i.e., elastic modulus, material hardness and fracture toughness) as is widely employed in grinding processes control. In the present work, micro-milling of WC-15wt.%Co sintered samples was performed with diamond coated end mills, confirming the influence of a ductile-to-brittle threshold on the cutting regime. Critical scale effects and structure-related behaviour were also confirmed. A positive impact on machined surface quality was observed when ductile mode was applied. Scanning electron microscopy was used to evaluate the microstructure features after different machining conditions.

The automotive industry encounters daily challenges as it navigates through new design trends and technological developments, which drive companies to rapidly develop new models. This scenario paves the way for new manufacturing approaches such as additive manufacturing (AM) which is transforming the manufacturing industry by enabling the production of complex geometries while minimizing material usage. Regarding the cutting tools sector, AM enables the resource-efficient generation of shapes and features that are not possible with conventional subtractive processes. This work explores the feasibility of AM, specifically Laser Powder Bed Fusion (LPBF), in the creation of a complex milling tool geometry with enhanced machining efficiency and increased durability in cutting applications. The final developed tool incorporates internal conformal channels, high teeth number (relatively to tool size) within a hollow interchangeable body. The combination of (post-AM) brazed PCD (PolyCrystalline Diamond) inserts, which is the hardest cutting tool material available, with enhanced tribological conditions at the cutting zone (improved cooling and lubrication of the cutting edge) and increased number of teeth is expected to promote ideal cutting conditions, therefore extending tool lifespan, which is particularly relevant in the automotive industry, where lightweight design dictates the usage of metals such as aluminium. The remarkable durability of PCD in aluminium machining makes them an ideal choice as the active cutting zone for AM produced milling tool bodies. The typical relative small series of tooling (as compared to parts produced) supports the usage of AM, which in turn boosts efficiency and cost effectiveness of these cutting tools. The demand for aluminium parts is rapidly increasing as the automotive industry accelerates towards light weighting and electrification, creating a favorable opportunity for the implementation of the developed tool within the automotive industry.

Achieving a mirror-like finish surface quality in plastic injection molds and dies is necessary for the manufacture of optical components in the automotive industry. Any defects present on the mold surface will be evidenced on the injected part, compromising the functionality of the final product. Moreover, the typically employed finishing techniques (milling and polishing) in mould steels can be excessively time-consuming. The identification of machining and polishing combinations that meet the demanding surface requirements while minimizing time and material resources is therefore essential for ensuring the efficiency and cost-effectiveness of the mould-making process. In this work, an experimental study was conducted on the milling of hardened tool steel using a 6 mm two flute ball nose end mill. Distinct configurations of axial and radial depths of cut as well as feed per tooth were considered and their impact on the pre-polishing surface roughness was analysed. A methodology for the parametrization of polishing conditions was developed, ensuring consistency of speed and pressure. Further tests were conducted to evaluate the relation between post-polishing surface quality and the total duration of the combined finishing approach. The polishing stage consisted on submitting the milled samples to SiC paper (800 and 1000 grit) and diamond cloth (6 and 3 µm) polishing. The method provided enhanced control of the polishing operation and revealed milling/polishing improved sequences for attaining surface roughness technical requisites.

A maquinagem de superligas termorresistentes promove a elevada geração de calor, o rápido desgaste das ferramentas de corte e alterações superficiais nas superfícies geradas, mesmo com taxas de remoção de material conservadoras. O principal objetivo deste estudo é avaliar, através de uma metodologia experimental e numérica, a maquinabilidade da liga IN718 utilizando ferramentas de fresagem em SiAlON. O trabalho centra-se em operações de fresagem, com foco específico na evolução do desgaste e sua correlação com dados do processo, como as forças e binários de corte, temperatura e o movimento relativo entre rotação e avanço (concordante vs. discordante). A rugosidade superficial e alterações microestruturais das superfícies maquinadas, foram também objeto de estudo. Adicionalmente, foram construídas simulações numéricas do processo para evidenciar o mecanismo de corte, com o objetivo de identificar as condições de funcionamento ideais para aplicações industriais. As ferramentas de corte cerâmicas constituem uma alternativa viável a soluções convencionais compósitas de carbonetos cementados (i.e., WC-Co) especialmente porque permitem alcançar taxas de remoção muito elevadas.

Com o intuito de minimizar o peso dos veículos, cada vez mais são utlizadas peças em ligas de alumínio produzidas por fundição injetada. Contudo, devido às elevadas velocidades de injeção durante o processo de HPDC, ar fica aprisionado no metal líquido, originando porosidades nos componentes. Estas porosidades gasosas impossibilitam a realização de tratamentos térmicos devido ao fenómeno de “blistering”. Assim, o trabalho realizado centra-se no desenvolvimento de tratamentos térmicos (T5 e T6 relâmpago) em peças obtidas pelo processo de HPDC assistido por vácuo, recorrendo às ligas AlSi10MnMg e AlSi10Mg(Fe). As peças foram caracterizadas tendo em consideração a ocorrência de “blistering”, microestrutura e propriedades mecânicas alcançadas. Adicionalmente, foi avaliada a maquinabilidade da liga primária AlSi10MnMg, recorrendo a uma ferramenta com PCD produzida por fabrico aditivo, sendo esta comparada com a da liga convencional AlSi9Cu3(Fe). Para todas as combinações de parâmetros usadas no tratamento térmico de solubilização verificaram-se “blisters” nos componentes. Com o tratamento térmico T5 não houve formação de “blisters” e a resistência mecânica aumentou. Em termos de maquinabilidade da liga primária AlSi10MnMg, esta apresenta uma rugosidade superficial ligeiramente superior e forças de corte inferiores, comparativamente à liga de injeção convencional AlSi9Cu3(Fe).