Innovative tool coatings for increasing tool life in milling Nickel-coated Nickel-Silver alloy

In the automotive market, there is a strong interest for the production of sidewinder keys made of Nickel-coated Nickel-Silver alloy. The Nickel coating improves wear resistance and brightness of the key, nevertheless it reduces the machinability and the tool life when milling the key groove is short. In this work, several innovative tool coatings were applied on conventional mills to enhance the machinability of Nickel-coated Nickel-Silver alloy. Tool life and burr formation obtained with the tested tools were investigated and discussed. Some of the coatings proved to be very promising for this application thank to their excellent tool life. Specifically, the PCD tool was the most interesting since the tool life was significantly longer than conventional carbide tool. \ua9 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

Analysis of the Integration of DFM Techniques and Effective Machining Parameter Selection in Metal Parts Manufacturing

This dissertation investigates the minimization of part design with self-locating features. The research focuses primarily on self-fastening characteristics, standardization of parts, and minimal use of fasteners. Further, the present research studies the design for base parts in the construction of a moving joint system, in order to locate potential part and system design improvements. This process may then be extended to industrial applications in the manufacturing industry. Relatively little work to date has examined the significance of Design for Manufacturing Techniques (DFMT), with their inherent machine element systems and machining parameters to investigate which DFMT has the most influence on cost reduction and increasing throughput, and under which circumstances. As such, this dissertation analyzes the inter-operational and synergistic elements of the DFMT, machine element systems, and machining parameters. The parametric specifications for the DFMT are examined and integrated with the cost and productivity-related information. In sum, this research applies DFMT to product design. The trade-off between cost of manufacturing and productivity in terms of DFM alternatives was subject to preliminary model development and sensitivity analysis. For each DFMT and associated machine element systems and Machining parameters, process planning was used effectively with computer-aided tools to enhance the evaluation impact of the dialogue between the design and manufacturing functions. Expert systems and systematic algorithms are inherently incorporated into the software tools used herein. Generative process planning software is used to measure and analyze sensitivity in plan effectiveness, particularly where material property attributes are changed. The shift that occurs according to process plan attributes is explored. These attributes are presented by manufacturing cost and production rate with respect to variations in specific material properties. The research analyzes four DFMT: Modifying the selection of raw material Modifying quality Modifying geometry Modifying the selection of process/es In terms of organizing and evaluating the work, a systematic algorithm was developed, discussed, and tested in this dissertation. This algorithm has sequenced elements to investigate and analyze each DFMT. This analysis identifies several potential process plans, from which the plan with the lowest projected cost and highest production rate is selected and constructed. The developed process plans illustrate the importance of alternative DFMT, without impacting product functionality. Each process plan attempts to decrease production cost, maintain quality, and increase throughput. The results of these plans show their respective effectiveness in relation to part utilization, process, and system-level parameters (such as surface finish, tolerance, heat treated condition of the material, geometry, material hardness, melting point, production quantity, cutting tools, cutting fluids, cutting conditions, and machine tools). The criteria for effectiveness include machining cost, tool cost, and throughput. From this data, the current study determines the most appropriate DFMT and examines underlying alternate machine element systems and machining parameters for each process plan. The effects of DFMT and inherent use of varying machine element systems and machining parameters on cost and productivity-based objectives are also examined. This enables exploration of the selected DFMT choice, according to effective cost reduction and production rate improvement for varying product design. The modified process plan is then compared to the original process plan to highlight areas of improvement. In this comparison, the results of DFMT analysis show significant influence on cost reduction and production rates. These findings suggest that further beneficial outcomes and variety might be obtained by applying this algorithm

Effect of Thermal and Chemical Treatment on the Microstructural, Mechanical and Machining Performance of W319 Al-Si-Cu Cast Alloy Engine Blocks and Directionally Solidified Machinability Test Blocks

The research presented in this work is focused on making a link between casting microstructural, mechanical and machining properties for 319 Al-Si sand cast components. In order to achieve this, a unique Machinability Test Block (MTB) is designed to simulate the Nemak V6 Al-Si engine block solidification behavior. This MTB is then utilized to cast structures with in-situ nano-alumina particle master alloy additions that are Mg based, as well as independent in-situ Mg additions, and Sr additions to the MTB. The Universal Metallurgical Simulator and Analyzer (UMSA) Technology Platform is utilized for characterization of each cast structure at different Secondary Dendrite Arm Spacing (SDAS) levels. The rapid quench method and Jominy testing is used to assess the capability of the nano-alumina master alloy to modify the microstructure at different SDAS levels. Mechanical property assessment of the MTB is done at different SDAS levels on cast structures with master alloy additions described above. Weibull and Quality Index statistical analysis tools are then utilized to assess the mechanical properties. The MTB is also used to study single pass high speed face milling and bi-metallic cutting operations where the Al-Si hypoeutectic structure is combined with hypereutectoid Al-Si liners and cast iron cylinder liners. These studies are utilized to aid the implementation of Al-Si liners into the Nemak V6 engine block and bi-metallic cutting of the head decks. Machining behavior is also quantified for the investigated microstructures, and the Silicon Modification Level (SiML) is utilized for microstructural analysis as it relates to the machining behavior

A review on conventional and nonconventional machining of SiC particle-reinforced aluminium matrix composites

AbstractAmong the various types of metal matrix composites, SiC particle-reinforced aluminum matrix composites (SiCp/Al) are finding increasing applications in many industrial fields such as aerospace, automotive, and electronics. However, SiCp/Al composites are considered as difficult-to-cut materials due to the hard ceramic reinforcement, which causes severe machinability degradation by increasing cutting tool wear, cutting force, etc. To improve the machinability of SiCp/Al composites, many techniques including conventional and nonconventional machining processes have been employed. The purpose of this study is to evaluate the machining performance of SiCp/Al composites using conventional machining, i.e., turning, milling, drilling, and grinding, and using nonconventional machining, namely electrical discharge machining (EDM), powder mixed EDM, wire EDM, electrochemical machining, and newly developed high-efficiency machining technologies, e.g., blasting erosion arc machining. This research not only presents an overview of the machining aspects of SiCp/Al composites using various processing technologies but also establishes optimization parameters as reference of industry applications

High Speed Machining for Enhancing the AZ91 Magnesium Alloy Surface Characteristics Influence and Optimisation of Machining Parameters

In this study, optimum machining parameters are evaluated for enhancing the surface roughness and hardness of AZ91 alloy using Taguchi design of experiments with Grey Relational Analysis. Dry face milling is performed using cutting conditions determined using Taguchi L9 design and Grey Relational Analysis has been used for the optimization of multiple objectives. Taguchi’s signal-to-noise ratio analysis is also performed individually for both characteristics and grey relational grade to identify the most influential machining parameter affecting them. Further, Analysis of Variance is carried to see the contribution of factors on both surface roughness and hardness. Finally, the predicted trends obtained from the signal-to-noise ratio are validated using confirmation experiments. The study showed the effectiveness of Taguchi design combined with Grey Relational Analysis for the multi-objective problems such as surface characteristics studies

Investigation into micro machinability of Mg based metal matrix compostites (MMCs) reinforced with nanoparticles

PhD ThesisAs composite materials with combination of low weight and high engineering strength, traditional metal matrix composites (MMCs) with micro-sized reinforcement (micro-MMCs) have been utilized in numerous area such as aerospace, automobile, medical and advanced weapon systems in the past two decades. With the development of composite materials, metal matrix composites reinforced with small volume fraction of nano-sized reinforcements (nanoMMCs) exhibits an equivalent and even better properties than that reinforced with large volume of micro-sized reinforcement and thus receive increasing attention from academia and industries. MMCs components are typically fabricated in near net shape process such as casting. But micro machining processes are indispensable in order to meet the increasing demands on the component with high dimensional accuracy and complex shapes. However, the enhanced mechanical properties of MMCs and tool-like hardness of reinforced particles bring challenges to machining process. The deteriorative machined surface finish and excessive tool wear have been recognised as the main obstacles during machining of MMCs due to their heterogeneous and abrasive nature. In this research, the detailed material removal mechanism of nano-MMCs in terms of micro machinability, micro tool wear and simulated material removal process with finite element analysis (FEA) is investigated. The systematic experimental studies on micro machining mechanism of magnesium-based MMCs reinforced with nanoparticles (Ti, TiB2, BN, ZnO) are conducted. The cutting force, burr formation, surface roughness and morphology are characterised to investigate the micro machinability under the effect of various machining parameters, particle volume fraction and matrix/reinforcement materials using design of experiment (DoE) and analysis of variance (ANVOA) methods. The micro structure changes of Mg-MMCs by addition of nanoparticles were taken into account. In addition, surface morphology and the minimum chip thickness is obtained and characterised with the aim of examining the specific cutting energy. A comprehensive investigation of tool wear mechanisms in the micro milling of Mg-MMCs is conducted. The tool wear is characterised both quantitatively and qualitatively by observing tool wear patterns and analysing the effect of cutting parameters and tool coating on average flank wear, reduction in tool diameter, cutting forces, surface roughness, and burr formation. The main wear mechanisms at different machining conditions are determined. Finally, the tool wear phenomenon observed from experiments is explained by simulating the tool-particles interaction using finite element modelling, and hence new wear mechanisms are proposed for machining nano-MMCs. iv The two dimensional micromechanical finite element (FE) models are established to study the material removal mechanism of MMCs reinforced with micro-sized and nanoparticles in micro machining process with consideration of size effect. Two phases, namely particle and matrix are modelled in FE cutting models. Particle fracture properties are involved in micro-sized particles to study the fracture behaviours. The cutting force, tool-particles interaction, particle fracture behaviours, stress/strain distribution, chip formation process and surface morphology are investigated in the FE models. The surface defect generation mechanism is studied in details by developing the additional three dimensional (3D) FE models in machining micro-MMCs. Moreover, the cutting mechanism comparison between machining nano-MMCs and microMMCs is conducted to investigate the effect of significant particle size reduction from micro to nano-scale. The model validation is carried out by studying the chip morphology, cutting force, surface morphology obtained from machining experiments and good agreements are found with the simulation results

Machining of titanium alloys for medical application: a review

Titanium alloys for their characteristics have acquired a prominent position in numerous industrial applications. Due to its properties, such as high resistance to corrosion, reduced density, high specific strength and low Young's modulus, titanium alloys became indispensable as a biomaterial with high use in medical devices, with special emphasis in the area of orthopaedics. Problems associated with its manufacturing by conventional machining processes, such as milling, turning and drilling are well known and studied. Its low thermal conductivity, high chemical reactivity, high hardness at high temperatures make it classified as difficult to machine material. Despite the already extensive knowledge about machining titanium alloys problems, and the constant technological development to overcome them, it is not yet possible to machine this material like other metals. This work is based on research and review papers from Scopus and Scholar from 2010 to 2020 and addresses the main issues related to the machining of titanium alloys used in medical devices manufacturing and current solutions adopted to solve them. From the research consulted it was possible to conclude that it is consensual that for milling, turning and helical milling cutting speed can reach up to 100m/min and up to 40m/min in drilling. As for feed rate, up to 0.1mm/tooth for milling and helical milling and up to 0.3mm/tooth for turning and 0.1mm/rev for drilling. Also, that Minimum Quantity Lubrication is a valid and efficient solution to mitigate titanium alloys machining problems.publishe

Engineered Surface Properties of Porous Tungsten from Cryogenic Machining

Porous tungsten is used to manufacture dispenser cathodes due to it refractory properties. Surface porosity is critical to functional performance of dispenser cathodes because it allows for an impregnated ceramic compound to migrate to the emitting surface, lowering its work function. Likewise, surface roughness is important because it is necessary to ensure uniform wetting of the molten impregnate during high temperature service. Current industry practice to achieve surface roughness and surface porosity requirements involves the use of a plastic infiltrant during machining. After machining, the infiltrant is baked and the cathode pellet is impregnated. In this context, cryogenic machining is investigated as a substitutionary process for the current plastic infiltration process. Along with significant reductions in cycle time and resource use, surface quality of cryogenically machined un-infiltrated (as-sintered) porous tungsten has been shown to significantly outperform dry machining. The present study is focused on examining the relationship between machining parameters and cooling condition on the as-machined surface integrity of porous tungsten. The effects of cryogenic pre-cooling, rake angle, cutting speed, depth of cut and feed are all taken into consideration with respect to machining-induced surface morphology. Cermet and Polycrystalline diamond (PCD) cutting tools are used to develop high performance cryogenic machining of porous tungsten. Dry and pre-heated machining were investigated as a means to allow for ductile mode machining, yet severe tool-wear and undesirable smearing limited the feasibility of these approaches. By using modified PCD cutting tools, high speed machining of porous tungsten at cutting speeds up to 400 m/min is achieved for the first time. Beyond a critical speed, brittle fracture and built-up edge are eliminated as the result of a brittle to ductile transition. A model of critical chip thickness (hc) effects based on cutting force, temperature and surface roughness data is developed and used to study the deformation mechanisms of porous tungsten under different machining conditions. It is found that when hmax = hc, ductile mode machining of otherwise highly brittle porous tungsten is possible. The value of hc is approximately the same as the average ligament size of the 80% density porous tungsten workpiece

Recent Advances on Coated Milling Tool Technology—A Comprehensive Review

The milling process is one of the most used processes in the manufacturing industry. Milling, as a process, as evolved, with new machines and methods being employed, in order to obtain the best results consistently. Milling tools have also seen quite an evolution, from the uncoated high-speed steel tool, to the now vastly used, coated tools. Information on the use of these coated tools in recent scientific researches was collected. The coatings that are currently being researched are going to be presented, highlighting some novel advances in the nanocomposite and diamond coatings area, as these coatings are seeing a growing use in the industry, with very satisfactory results, with performance and tool-life increase. Wear mechanism of various types of coatings are also a popular topic on recent research, as the cutting behavior of these coated tools provides valuable information on the tool’s-life. Furthermore, analysis of these mechanisms enables for the selection of the best coating type for the correct application. Recently, the employment of coated tools paired with sustainable lubrication methods as seen some use. As this presents the opportunity to enhance the coated tool’s and the process’s performance, obtaining better results, in terms of better tool-life and better surface finish quality, in a more sustainable fashionThis research was funded by ON-SURF Project, grant number NUP POCI-01-0247-FEDER-024521.info:eu-repo/semantics/publishedVersio