Submit to Materials Review for Materials Propose a Special Issue

Journal Menu

Journal Browser

► Journal Browser

Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity

Print Special Issue Flyer
Special Issue Editors
Special Issue Information
Keywords
Benefits of Publishing in a Special Issue
Published Papers

A special issue of Materials (ISSN 1996-1944).

Deadline for manuscript submissions: closed (30 October 2019) | Viewed by 63110

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity book cover image

Share This Special Issue

Special Issue Editors

Prof. Dr. Grzegorz Królczyk

E-Mail Website
Guest Editor

Department of Manufacturing Engineering and Production Automation, Faculty of Mechanical Engineering, Opole University of Technology, 5 Mikolajczyka Street, 45-271 Opole, Poland
Interests: surface metrology; optimization of difficult-to-cut materials; sensor technology; metrology; measurement uncertainty; environmental measurement; optimization of geometrical and physical parameters of surface integrity
Special Issues, Collections and Topics in MDPI journals

Dr. Radosław W. Maruda

E-Mail
Guest Editor

Faculty of Mechanical Engineering, University of Zielona Gora, Prof. Z. Szafrana Street, 65-516 Zielona Gora, Poland
Interests: machining; powder metalurgy; MQL/MQCL; surface integrity

Prof. Dr. Szymon Wojciechowski

E-Mail Website
Guest Editor

Faculty of Mechanical Engineering, Poznan University of Technology, 60-965 Poznan, Poland
Interests: ultra-precision and micro-cutting; cutting mechanics; hard-to-cut materials; advances in manufacturing
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Hard-to-cut materials have excellent properties, such as a high hardness and abrasion resistance, high strength at room or elevated temperatures, increased thermal conductivity, as well as resistance to oxidation and corrosion. Therefore, these materials are being widely applied in many industries, including automotive, aerospace, medical and electronic. Nevertheless, the unique features of hard-to-cut materials significantly affect their machinability. The fundamental problems occurring during machining of hard-to-cut materials include the high values of cutting forces, high levels of vibrations in machining systems, the concentration of heat, the growth of cutting temperature, rapid tool wear and the risk of catastrophic tool failure, as well as frequent stability loss and a significant deterioration of surface finish. Thus, intensive studies are required for enhancing our knowledge regarding the properties of hard-to-cut materials, phenomena occurring during manufacturing processes, as well as the formation of surface finishes during machining. This knowledge will enable the efficient selection of machining conditions, strategies and types of tools, which allow the improvement of manufacturing performance and economics.

This Special Issue provides an excellent opportunity for researchers who are studying and working with hard-to-cut materials, such as hardened and stainless steels, titanium, cobalt and nickel alloys, composites, ceramics, hard clads fabricated by additive techniques, and others.

It is our pleasure to invite you to submit original research papers, short communications or state-of-the-art reviews which are within the scope of this Special Issue. Contributions can range from property characterization of hard-to-cut-materials, novel approaches in manufacturing, the analysis and modeling of process mechanics, to evaluation of surface integrity.

Prof. Grzegorz M. Królczyk
Prof. Radosław W. Maruda
Dr. Szymon Wojciechowski
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

hard-to-cut materials
machining
additive manufacturing
mechanics
surface integrity

Benefits of Publishing in a Special Issue

Ease of navigation: Grouping papers by topic helps scholars navigate broad scope journals more efficiently.
Greater discoverability: Special Issues support the reach and impact of scientific research. Articles in Special Issues are more discoverable and cited more frequently.
Expansion of research network: Special Issues facilitate connections among authors, fostering scientific collaborations.
External promotion: Articles in Special Issues are often promoted through the journal's social media, increasing their visibility.
e-Book format: Special Issues with more than 10 articles can be published as dedicated e-books, ensuring wide and rapid dissemination.

Further information on MDPI's Special Issue polices can be found here.

Published Papers (14 papers)

Download All Papers

Order results

Result details

Show export options Show export options

Select all

Export citation of selected articles as:

Editorial

Jump to: Research

5 pages, 372 KiB

Open AccessEditorial

Advances in Hard–to–Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity

by Szymon Wojciechowski, Grzegorz M. Królczyk and Radosław W. Maruda

Materials 2020, 13(3), 612; https://doi.org/10.3390/ma13030612 - 30 Jan 2020

Cited by 14 | Viewed by 2547

Abstract

The rapid growth of a modern industry results in a growing demand for construction materials with excellent operational properties. However, the improved features of these materials can significantly hinder their manufacturing, therefore they can be defined as hard–to–cut. The main difficulties during the manufacturing/processing of hard–to–cut materials are attributed to their high hardness and abrasion resistance, high strength at room or elevated temperatures, increased thermal conductivity, as well as their resistance to oxidation and corrosion. Nowadays the group of hard–to–cut materials includes the metallic materials, composites, as well as ceramics. This special issue, “Advances in Hard–to–Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity” provides a collection of research papers regarding the various problems correlated with hard–to–cut materials. The analysis of these studies reveals primary directions regarding the developments in manufacturing methods, and the characterization and optimization of hard–to–cut materials. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

Research

Jump to: Editorial

20 pages, 3897 KiB

Open AccessArticle

Optimization of Power Consumption Associated with Surface Roughness in Ultrasonic Assisted Turning of Nimonic-90 Using Hybrid Particle Swarm-Simplex Method

by Navneet Khanna, Jay Airao, Munish Kumar Gupta, Qinghua Song, Zhanqiang Liu, Mozammel Mia, Radoslaw Maruda and Grzegorz Krolczyk

Materials 2019, 12(20), 3418; https://doi.org/10.3390/ma12203418 - 18 Oct 2019

Cited by 39 | Viewed by 3363

Abstract

These days, power consumption and energy related issues are very hot topics of research especially for machine tooling process industries because of the strict environmental regulations and policies. Hence, the present paper discusses the application of such an advanced machining process i.e., ultrasonic assisted turning (UAT) process with the collaboration of nature inspired algorithms to determine the ideal solution. The cutting speed, feed rate, depth of cut and frequency of cutting tool were considered as input variables and the machining performance of Nimonic-90 alloy in terms of surface roughness and power consumption has been investigated. Then, the experimentation was conducted as per the Taguchi L9 orthogonal array and the mono as well as bi-objective optimizations were performed with standard particle swarm and hybrid particle swarm with simplex methods (PSO-SM). Further, the statistical analysis was performed with well-known analysis of variance (ANOVA) test. After that, the regression equation along with selected boundary conditions was used for creation of fitness function in the subjected algorithms. The results showed that the UAT process was more preferable for the Nimconic-90 alloy as compared with conventional turning process. In addition, the hybrid PSO-SM gave the best results for obtaining the minimized values of selected responses. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

15 pages, 3292 KiB

Open AccessArticle

Prediction of Tool Wear Using Artificial Neural Networks during Turning of Hardened Steel

by Paweł Twardowski and Martyna Wiciak-Pikuła

Materials 2019, 12(19), 3091; https://doi.org/10.3390/ma12193091 - 22 Sep 2019

Cited by 55 | Viewed by 4041

Abstract

The ability to effectively predict tool wear during machining is an extremely important part of diagnostics that results in changing the tool at the relevant time. Effective assessment of the rate of tool wear increases the efficiency of the process and makes it possible to replace the tool before catastrophic wear occurs. In this context, the value of the effectiveness of predicting tool wear during turning of hardened steel using artificial neural networks, multilayer perceptron (MLP), was checked. Cutting forces and acceleration of mechanical vibrations were used to monitor the tool wear process. As a result of the analysis using artificial neural networks, the suitability of individual physical phenomena to the monitoring process was assessed. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

15 pages, 5641 KiB

Open AccessArticle

Experimental Investigation on Micro-Groove Manufacturing of Ti-6Al-4V Alloy by Using Ultrasonic Elliptical Vibration Assisted Cutting

by Rongkai Tan, Xuesen Zhao, Tao Sun, Xicong Zou and Zhenjiang Hu

Materials 2019, 12(19), 3086; https://doi.org/10.3390/ma12193086 - 21 Sep 2019

Cited by 18 | Viewed by 3281

Abstract

The micro-groove structure on the planar surface has been widely used in the tribology field for improving the lubrication performance, thereby reducing the friction coefficient and wear. However, in the conventional cutting (CC) process, the high-quality, high-precision machining of the micro-groove on titanium alloy has always been a challenge, because considerable problems including poor surface integrity and a high level of the material swelling and springback remain unresolved. In this study, the ultrasonic elliptical vibration assisted cutting (UEVC) technology was employed, which aimed to minimize the level of the material swelling and springback and improve the machining quality. A series of comparative investigations on the surface defect, surface roughness, and material swelling and springback under the CC and UEVC processes were performed. The experimental results certified that the material swelling and springback significantly reduced and the surface integrity obviously improved in the UEVC process in comparison to that in the CC process. Furthermore, for all the predetermined depths of the cut, when the TSR (the ratio of the nominal cutting speed to the peak horizontal vibration speed) was equal to one of twenty four or one of forty eight, the accuracy of the machined micro-groove depth, width and the profile radius reached satisfactorily to 98%, and the roughness values were approximately 0.1 μm. The experimental results demonstrate that the UEVC technology is a feasible method for the high-quality and high-precision processing of the micro-groove on Ti-6Al-4V alloy. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

20 pages, 4159 KiB

Open AccessArticle

Performance Evaluation of Vegetable Oil-Based Nano-Cutting Fluids in Environmentally Friendly Machining of Inconel-800 Alloy

by Munish Kumar Gupta, Muhammad Jamil, Xiaojuan Wang, Qinghua Song, Zhanqiang Liu, Mozammel Mia, Hussein Hegab, Aqib Mashood Khan, Alberto Garcia Collado, Catalin Iulian Pruncu and G.M. Shah Imran

Materials 2019, 12(17), 2792; https://doi.org/10.3390/ma12172792 - 30 Aug 2019

Cited by 97 | Viewed by 5765

Abstract

Recently, the application of nano-cutting fluids has gained much attention in the machining of nickel-based super alloys due their good lubricating/cooling properties including thermal conductivity, viscosity, and tribological characteristics. In this study, a set of turning experiments on new nickel-based alloy i.e., Inconel-800 alloy, was performed to explore the characteristics of different nano-cutting fluids (aluminum oxide (Al₂O₃), molybdenum disulfide (MoS₂), and graphite) under minimum quantity lubrication (MQL) conditions. The performance of each nano-cutting fluid was deliberated in terms of machining characteristics such as surface roughness, cutting forces, and tool wear. Further, the data generated through experiments were statistically examined through Box Cox transformation, normal probability plots, and analysis of variance (ANOVA) tests. Then, an in-depth analysis of each process parameter was conducted through line plots and the results were compared with the existing literature. In the end, the composite desirability approach (CDA) was successfully implemented to determine the ideal machining parameters under different nano-cutting cooling conditions. The results demonstrate that the MoS₂ and graphite-based nanofluids give promising results at high cutting speed values, but the overall performance of graphite-based nanofluids is better in terms of good lubrication and cooling properties. It is worth mentioning that the presence of small quantities of graphite in vegetable oil significantly improves the machining characteristics of Inconel-800 alloy as compared with the two other nanofluids. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

15 pages, 2544 KiB

Open AccessArticle

Dimensionless Analysis for Investigating the Quality Characteristics of Aluminium Matrix Composites Prepared through Fused Deposition Modelling Assisted Investment Casting

by Sunpreet Singh, Chander Prakash, Parvesh Antil, Rupinder Singh, Grzegorz Królczyk and Catalin I. Pruncu

Materials 2019, 12(12), 1907; https://doi.org/10.3390/ma12121907 - 13 Jun 2019

Cited by 35 | Viewed by 3495

Abstract

The aluminium matrix composites (AMCs) have become a tough competitor for various categories of metallic alloys, especially ferrous materials, owing to their tremendous servicing in the diversified application. In this work, additional efforts have been made to formulate a mathematical model, by using dimensionless analysis, able to predict the mechanical characteristics of the AMCs that have already been optimized and characterized by the authors. Here, the experimental and statistical data obtained from the Taguchi L18 orthogonal array and analysis of variance (ANOVA) have been used. They permit collection of the output responses and allow the identification of significant process parameters, respectively, which thereafter were used to design the mathematical model. Second order polynomial equations have been obtained from the specific output response and the relevant input parameter were incorporated with the highest level of contribution. The obtained quadratic equations indicate the regression values (R²) equal to unity, hence, proving the performances of the fit. The results demonstrate that the developed mathematical models present very high accuracy for predicting the output responses. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

16 pages, 4993 KiB

Open AccessArticle

Surface Modification of Ti-6Al-4V Alloy by Electrical Discharge Coating Process Using Partially Sintered Ti-Nb Electrode

by Chander Prakash, Sunpreet Singh, Catalin Iulian Pruncu, Vinod Mishra, Grzegorz Królczyk, Danil Yurievich Pimenov and Alokesh Pramanik

Materials 2019, 12(7), 1006; https://doi.org/10.3390/ma12071006 - 27 Mar 2019

Cited by 112 | Viewed by 5602

Abstract

In the present research, a composite layer of TiO₂-TiC-NbO-NbC was coated on the Ti-64 alloy using two different methods (i.e., the electric discharge coating (EDC) and electric discharge machining processes) while the Nb powder were mixed in dielectric fluid. The effect produced on the machined surfaces by both processes was reported. The influence of Nb-concentration along with the EDC key parameters (Ip and Ton) on the coated surface integrity such as surface topography, micro-cracks, coating layer thickness, coating deposition, micro-hardness has been evaluated as well. It has been noticed that in the EDC process the high peak current and high Nb-powder concentration allow improvement in the material migration, and a crack-free thick layer (215 μm) on the workpiece surface is deposited. The presence of various oxides and carbides on the coated surface further enhanced the mechanical properties, especially, the wear resistance, corrosion resistance and bioactivity. The surface hardness of the coated layer is increased from 365 HV to 1465 HV. Furthermore, the coated layer reveals a higher adhesion strength (~118 N), which permits to enhance the wear resistance of the Ti-64 alloy. This proposed technology allows modification of the mechanical properties and surface characteristics according to an orthopedic implant’s requirements. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

12 pages, 1558 KiB

Open AccessArticle

Intelligent Optimization of Hard-Turning Parameters Using Evolutionary Algorithms for Smart Manufacturing

by Mozammel Mia, Grzegorz Królczyk, Radosław Maruda and Szymon Wojciechowski

Materials 2019, 12(6), 879; https://doi.org/10.3390/ma12060879 - 15 Mar 2019

Cited by 71 | Viewed by 4457

Abstract

Recently, the concept of smart manufacturing systems urges for intelligent optimization of process parameters to eliminate wastage of resources, especially materials and energy. In this context, the current study deals with optimization of hard-turning parameters using evolutionary algorithms. Though the complex programming, parameters selection, and ability to obtain the global optimal solution are major concerns of evolutionary based algorithms, in the present paper, the optimization was performed by using efficient algorithms i.e., teaching–learning-based optimization and bacterial foraging optimization. Furthermore, the weighted sum method was used to transform the diverse responses into a single response, and then multi-objective optimization was performed using the teaching–learning-based optimization method and the standard bacterial foraging optimization method. Finally, the optimum results reported by these methods are compared to choose the best method. In fact, owing to better convergence within shortest time, the teaching–learning-based optimization approach is recommended. It is expected that the outcome of this research would help to efficiently and intelligently perform the hard-turning process under automatic and optimized environment. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

14 pages, 3017 KiB

Open AccessArticle

Optimal Machining Strategy Selection in Ball-End Milling of Hardened Steels for Injection Molds

by Irene Buj-Corral, Jose-Antonio Ortiz-Marzo, Lluís Costa-Herrero, Joan Vivancos-Calvet and Carmelo Luis-Pérez

Materials 2019, 12(6), 860; https://doi.org/10.3390/ma12060860 - 14 Mar 2019

Cited by 10 | Viewed by 3326

Abstract

In the present study, the groups of cutting conditions that minimize surface roughness and its variability are determined, in ball-end milling operations. Design of experiments is used to define experimental tests performed. Semi-cylindrical specimens are employed in order to study surfaces with different slopes. Roughness was measured at different slopes, corresponding to inclination angles of 15°, 45°, 75°, 90°, 105°, 135° and 165° for both climb and conventional milling. By means of regression analysis, second order models are obtained for average roughness Ra and total height of profile Rt for both climb and conventional milling. Considered variables were axial depth of cut a_p, radial depth of cut a_e, feed per tooth f_z, cutting speed v_c, and inclination angle Ang. The parameter a_e was the most significant parameter for both Ra and Rt in regression models. Artificial neural networks (ANN) are used to obtain models for both Ra and Rt as a function of the same variables. ANN models provided high correlation values. Finally, the optimal machining strategy is selected from the experimental results of both average and standard deviation of roughness. As a general trend, climb milling is recommended in descendant trajectories and conventional milling is recommended in ascendant trajectories. This study will allow the selection of appropriate cutting conditions and machining strategies in the ball-end milling process. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

20 pages, 11038 KiB

Open AccessArticle

Multiscale 3D Curvature Analysis of Processed Surface Textures of Aluminum Alloy 6061 T6

by Tomasz Bartkowiak and Christopher A. Brown

Materials 2019, 12(2), 257; https://doi.org/10.3390/ma12020257 - 14 Jan 2019

Cited by 22 | Viewed by 4154

Abstract

The objectives of this paper are to demonstrate the viability, and to validate, in part, a multiscale method for calculating curvature tensors on measured surface topographies with two different methods of specifying the scale. The curvature tensors are calculated as functions of scale, i.e., size, and position from a regular, orthogonal array of measured heights. Multiscale characterization of curvature is important because, like slope and area, it changes with the scale of observation, or calculation, on irregular surfaces. Curvatures can be indicative of the topographically dependent behavior of a surface and, in turn, curvatures are influenced by the processing and use of the surface. Curvatures of surface topographies have not been well- characterized yet. Curvature has been used for calculations in contact mechanics and for the evaluation of cutting edges. Manufactured surfaces are studied for further validation of the calculation method because they provide certain expectations for curvatures, which depend on scale and the degree of curvature. To study a range of curvatures on manufactured surfaces, square edges are machined and honed, then rounded progressively by mass finishing; additionally, a set of surfaces was made by turning with different feeds. Topographic measurements are made with a scanning laser confocal microscope. The calculations use vectors, normal to the measured surface, which are calculated first, then the eigenvalue problem is solved for the curvature tensor. Plots of principal curvatures as a function of position and scale are presented. Statistical analyses show expected interactions between curvature and these manufacturing processes. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

11 pages, 2572 KiB

Open AccessArticle

An Experimental Study on the Precision Abrasive Machining Process of Hard and Brittle Materials with Ultraviolet-Resin Bond Diamond Abrasive Tools

by Lei Guo, Xinrong Zhang, Shibin Chen and Jizhuang Hui

Materials 2019, 12(1), 125; https://doi.org/10.3390/ma12010125 - 2 Jan 2019

Cited by 31 | Viewed by 4506

Abstract

Ultraviolet-curable resin was introduced as a bonding agent into the fabrication process of precision abrasive machining tools in this study, aiming to deliver a rapid, flexible, economical, and environment-friendly additive manufacturing process to replace the hot press and sintering process with thermal-curable resin. A laboratory manufacturing process was established to develop an ultraviolet-curable resin bond diamond lapping plate, the machining performance of which on the ceramic workpiece was examined through a series of comparative experiments with slurry-based iron plate lapping. The machined surface roughness and weight loss of the workpieces were periodically recorded to evaluate the surface finish quality and the material removal rate. The promising results in terms of a 12% improvement in surface roughness and 25% reduction in material removal rate were obtained from the ultraviolet-curable resin plate-involved lapping process. A summarized hypothesis was drawn to describe the dynamically-balanced state of the hybrid precision abrasive machining process integrated both the two-body and three-body abrasion mode. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

13 pages, 4432 KiB

Open AccessArticle

Evaluating Hole Quality in Drilling of Al 6061 Alloys

by Mohammad Uddin, Animesh Basak, Alokesh Pramanik, Sunpreet Singh, Grzegorz M. Krolczyk and Chander Prakash

Materials 2018, 11(12), 2443; https://doi.org/10.3390/ma11122443 - 2 Dec 2018

Cited by 86 | Viewed by 7410

Abstract

Hole quality in drilling is considered a precursor for reliable and secure component assembly, ensuring product integrity and functioning service life. This paper aims to evaluate the influence of the key process parameters on drilling performance. A series of drilling tests with new TiN-coated high speed steel (HSS) bits are performed, while thrust force and torque are measured with the aid of an in-house built force dynamometer. The effect of process mechanics on hole quality, e.g., dimensional accuracy, burr formation, surface finish, is evaluated in relation to drill-bit wear and chip formation mechanism. Experimental results indicate that the feedrate which dictates the uncut chip thickness and material removal rate is the most dominant factor, significantly impacting force and hole quality. For a given spindle speed range, maximum increase of axial force and torque is 44.94% and 47.65%, respectively, when feedrate increases from 0.04 mm/rev to 0.08 mm/rev. Stable, jerk-free cutting at feedrate of as low as 0.04 mm/rev is shown to result in hole dimensional error of less than 2%. A low feedrate along with high spindle speed may be preferred. The underlying tool wear mechanism and progression needs to be taken into account when drilling a large number of holes. The findings of the paper clearly signify the importance and choice of drilling parameters and provide guidelines for manufacturing industries to enhance a part’s dimensional integrity and productivity. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

10 pages, 5159 KiB

Open AccessArticle

The Influence of Exposure Energy Density on Porosity and Microhardness of the SLM Additive Manufactured Elements

by Janusz Kluczyński, Lucjan Śnieżek, Krzysztof Grzelak and Janusz Mierzyński

Materials 2018, 11(11), 2304; https://doi.org/10.3390/ma11112304 - 16 Nov 2018

Cited by 52 | Viewed by 4932

Abstract

Selective laser melting (SLM) is an additive manufacturing technique. It allows elements with very complex geometry to be produced using metallic powders. A geometry of manufacturing elements is based only on 3D computer-aided design (CAD) data. The metal powder is melted selectively layer by layer using an ytterbium laser. This paper contains the results of porosity and microhardness analysis made on specimens manufactured during a specially prepared process. Final analysis helped to discover connections between changing hatching distance, exposure speed and porosity. There were no significant differences in microhardness and porosity measurement results in the planes perpendicular and parallel to the machine building platform surface. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Figure 1

19 pages, 3978 KiB

Open AccessFeature PaperArticle

Synthesis, Characterization, Corrosion Resistance and In-Vitro Bioactivity Behavior of Biodegradable Mg–Zn–Mn–(Si–HA) Composite for Orthopaedic Applications

by Chander Prakash, Sunpreet Singh, Munish Kumar Gupta, Mozammel Mia, Grzegorz Królczyk and Navneet Khanna

Materials 2018, 11(9), 1602; https://doi.org/10.3390/ma11091602 - 3 Sep 2018

Cited by 69 | Viewed by 4794

Abstract

Recently, magnesium (Mg) has gained attention as a potential material for orthopedics devices, owing to the combination of its biodegradability and similar mechanical characteristics to those of bones. However, the rapid decay rate of Mg alloy is one of the critical barriers amongst its widespread applications that have provided numerous research scopes to the scientists. In this present, porous Mg-based biodegradable structures have been fabricated through the hybridization of elemental alloying and spark plasma sintering technology. As key alloying elements, the suitable proportions of silicon (Si) and hydroxyapatite (HA) are used to enhance the mechanical, chemical, and geometrical features. It has been found that the addition of HA and Si element results in higher degree of structural porosity with low elastic modulus and hardness of the Mg–Zn–Mn matrix, respectively. Further, addition of both HA and Si elements has refined the grain structure and improved the hardness of the as-fabricated structures. Moreover, the characterization results validate the formation of various biocompatible phases, which enhances the corrosion performance and biomechanical integrity. Moreover, the fabricated composites show an excellent bioactivity and offer a channel/interface to MG-63 cells for attachment, proliferation and differentiation. The overall results of the present study advocate the usefulness of developed structures for orthopedics applications. Full article

(This article belongs to the Special Issue Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity)

► Show Figures

Journal Menu

Journal Browser

Advances in Hard-to-Cut Materials: Manufacturing, Properties, Process Mechanics and Evaluation of Surface Integrity

Share This Special Issue

Special Issue Editors

Special Issue Information

Keywords

Benefits of Publishing in a Special Issue

Published Papers (14 papers)

Editorial

Research

Further Information

Guidelines

MDPI Initiatives

Follow MDPI