Finish Machining Research Articles

Wear behavior of innovative niobium carbide cutting tools in ultrasonic-assisted finishing milling

The resources of niobium exceed the ones of tungsten by an order of magnitude. With 92%, Brazil is today the main global producer of niobium. Hence, niobium carbides (NbC) are a sustainable and economic alternative to conventionally used cutting materials, especially tungsten carbides (WC). Moreover, NbC can be used in Ni alloy matrix and thus offer significant advantages by substituting WC in Co matrix as cutting materials in terms of health risks and raw material price and supply risk. Based on recent studies which found an increased performance of NbC compared to WC cutting tools in machining higher strength steels, the composition NbC12Ni4Mo4VC was chosen for finish machining of a high-strength steel S960QL in this study. The experiments were carried out on an ultrasonic-assisted 5-axis milling machine using NbC tools specially made to benchmark them with commercially available coated WC cutting inserts. In addition, the influence of a coating system for the NbC inserts is tested and evaluated for its performance in the cutting process. Tool wear and cutting force analyses are implied to identify optimal parameter combinations as well as tool properties for the novel NbC tool. Together with the oscillation of ultrasonic-assisted milling, the loads on the component surface and the tool can be reduced and the wear behavior of the novel NbC tool can be refined. These milling tests are accompanied by standardized wear tests, i.e., pin-on-disc, between the aforementioned material combinations, and the results are correlated with each other. Finally, the behavior when using hard-to-cut materials such as Ni alloys, or innovative materials such as iron aluminide is also being tested, as these are constantly in the focus of machining optimization. With this strategy, comprehensive knowledge is achievable for future efficient application of NbC for milling tools, which have already been researched for decades using WC.

Effects of roughing, finishing, and aggressive machining conditions on the milling performance of AISI 1045 steel using TiAlN coated inserts

The objective of the present study is to develop a better understanding of machining performance of TiAlN coated tools during face milling of AISI 1045 medium carbon steel. The influences of three different cutting conditions (roughing, finishing, and aggressive conditions) were investigated on cutting forces, chip temperature, tool wear, surface roughness, and chip characteristics. The highest cutting forces were obtained under roughing condition, while, aggressive mode of machining (high values of cutting speed, feed, and depth of cuts) resulted in the highest chip temperature, crater, and flank wear. Material adhesion and coating delamination were predominant under roughing condition. On the other hand, aggressive condition exhibited diffusion wear causing large depth of crater and severe thermal cracks leading to fracture of the cutting edge. Attrition and abrasion wear were also evident. The results of cutting forces, chip temperature, surface roughness, and chip characteristics were correlated with those of tool wear. Results were found to be beneficial in recommending appropriate criteria for choosing different cutting conditions in face milling of AISI 1045 steel using TiAlN coated insert.

Potential and Challenges of Fused Granular Fabrication in Patternmaking

Efficient manufacturing of tooling and patterns is an essential part of a good foundry process. Traditional patternmaking methods have been honed to almost perfection during the years. Additive manufacturing has been growing as an industry and presents many new possibilities for the foundry industry. However, many additive manufacturing technologies do not currently provide usable sizes and scales for foundries to properly use. Fused granular fabrication (FGF) in conjunction with finish machining might provide an answer to this issue, with printing volumes and speeds many times of those compared to filament-based fused deposition modeling printing. In this work, some traditional patternmaking materials are compared to a FGF manufactured one based on polylactic acid and cellulose blend, and their characteristics are discussed. 3D scanning of as-printed geometry shows variations inherent to material extrusion methods, while the final machined state shows comparable results to traditional polyurethane model material. The combination of high-volume material extrusion with machining to final dimensions might allow more utilization of additive manufacturing in patternmaking, especially when combined with high-performance polymer materials.

Modeling of Rapid Response Characteristics of Piezoelectric Actuators for Ultra-Precision Machining

Piezoelectric actuators are characterized by high positioning accuracy, high stiffness and a fast response and are widely used in ultra-precision machining technologies such as fast tool servo technology and ultrasonic machining. The rapid response characteristics of piezoelectric actuators often determine the overall quality of machining. However, there has been little research on the fast response characteristics of piezoelectric actuators, and this knowledge gap will lead to low precision and poor quality of the final machining. The fast response characteristics of a piezoelectric actuator were studied in this work. Firstly, the piezoelectric actuator was divided into a no-load state and a load state according to the working state. A fast response analysis and output characteristic analysis were carried out, the corresponding dynamic model was established, and then the model was simulated. Finally, an experimental system was established to verify the dynamic model of the piezoelectric actuator's fast response by conducting an experiment in which the piezoelectric actuator bounces a steel ball. The experimental results verify the correctness of the model and show that the greater the cross-sectional area and height of the piezoelectric actuator, the higher the bouncing height of the ball, and the better the dynamic performance of the piezoelectric actuator. It is believed that this study has guiding significance for the application of the dynamic characteristics of piezoelectric actuators in the machining field.

Computer Aided Process Planning for Rough Machining Based on Machine Learning with Certainty Evaluation of Inferred Results

Process planning is well known as the key toward achieving highly efficient machining. However, it is difficult to standardize machining skills for process planning, which depend heavily on skilled operators. Hence, in a previous study, a computer aided process planning (CAPP) system using machine learning is developed to determine the operation parameters for finish machining of dies and molds. On the other hand, in rough machining, it is assumed that some machining operations are conducted sequentially using a respective tool according to the workpiece shape, which induces a much higher complexity in process planning. Therefore, in this study, machine learning is adopted to determine operation parameters for rough machining. The developed CAPP system converts the removal volume into a voxel model and infers a machining operation for each voxel. The inferred machining operation is visualized using different colors and identified corresponding to the voxel. Finally, the removal volume is classified using three different machining operations. However, machine learning is said to have a critical problem in that it is difficult to understand the reasons for the inferred results. Hence, it is necessary for the CAPP system to demonstrate the certainty level of the determined operation parameters. Thus, this study proposes a method for calculating the degree of certainty. If an artificial neural network is trained sufficiently, similar inferred results would always be obtained. Consequently, by using the Monte Carlo dropout to delete weights at random, the certainty level is defined as the variance of the inferred results. To verify the usefulness of the CAPP system, a case study is conducted by assuming rough machining of dies and molds. The results confirm that the machining operations are inferred with high accuracy, and the proposed method is effective for evaluating the certainty of the inferred results.

Process Development for Batch Production of Micro-Milling Tools Made of Silicon Carbide by Means of the Dry Etching Process

Downsized and complex micro-machining structures have to meet quality requirements concerning geometry and convince through increasing functionality. The development and use of cutting tools in the sub-millimeter range can meet these demands and contribute to the production of intelligent components in biomedical technology, optics or electronics. This article addresses the development of double-edged micro-cutters, which consist of a two-part system of cutter head and shaft. The cutting diameters are between 50 and 200 μm. The silicon carbide cutting heads are manufactured from the solid material using microsystem technology. The substrate used can be structured uniformly via photolithography, which means that 5200 homogeneous micro-milling heads can be produced simultaneously. This novel batch approach represents a contrast to conventionally manufactured micro-milling cutters. The imprint is taken by means of reactive ion etching using a mask made of electroplated nickel. Within this dry etching process, characteristic values such as the etch rate and flank angle of the structures are critical and will be compared in a parameter analysis. At optimal parameters, an anisotropy factor of 0.8 and an etching rate of 0.34 µm/min of the silicon carbide are generated. Finally, the milling heads are diced and joined. In the final machining tests, the functionality is investigated and any signs of wear are evaluated. A tool life of 1500 mm in various materials could be achieved. This and the milling quality achieved are in the range of conventional micro-milling cutters, which gives a positive outlook for further development.

The process planning for additive and subtractive hybrid manufacturing of powder bed fusion (PBF) process

Additive and subtractive hybrid manufacturing (ASHM) technology has attracted extensive attention in industry and academia because of its vast design freedom and surface accuracy. The powder bed fusion (PBF) process has high forming accuracy, the ASHM of PBF process is more suitable for integrated precision manufacturing of components with complex internal structures. However, existing process planning for ASHM are not suitable for the ASHM of PBF process because of the limitation by the powder bed. This research work focused on planning the process for the ASHM of the PBF process, while dividing it into three stages. Firstly, a model adaptive compensation algorithm is proposed to retain the finish machining allowance. Then, considering tool accessibility and constraint of the powder bed, the compensation model is decomposed into several sub-models and the hybrid manufacturing of sub-models in the sequence of construction. Finally, some unprocessed parts of the internal structure could be re-process after removing the parts from the powder bed. Combined with experiments and examples, this hybrid manufacturing process planning can provide technical support for the integrated precision manufacturing of components with a complex internal structure based on the ASHM of the PBF process.

Multi-response optimization of magnetic abrasive finishing process parameters on AISI H13 hot die steel using grey relational analysis

This paper presents a new approach for the optimization of machining parameters on magnetic abrasive finishing (MAF) of AISI H13 hot die steel with multiple responses based on the orthogonal array with grey relational analysis. The process has been explored widely for the finishing of plane surfaces on pillar drilling machine. Taguchi orthogonal arrays L27 Designs of experiment method was used for planning of experiments. Total of 27 Experiments were conducted on AISI H13 hot die steel to check the best factor level combination. Five process parameters such as abrasive size, cutting speed, finishing time, machining gap, and magnetic flux density are optimized using multiple responses such as surface roughness (Ra) and metal removal rate (MRR). The Grey Relational Analysis (GRA) was utilized to analyze the results to find the optimum condition and identify the significant parameters affecting the surface roughness and the metal removal rate on H13 hot die steel. Magnetic abrasive finishing machining parameters combination of experiment no. 14 has the highest grey relation grade (GRG) of 0.922. The ideal parameter combination to achieve optimum output are cutting speed of 118.24 m/min, abrasive mesh size of 600, finishing time of 10 min, Machining gap of 1 mm, and Magnetic flux density of 485 gauss. The surface roughness (Ra) value was improved from 0.753 µm to 0.452 µm.

Hardware and software system for monitoring the modes of the finishing operation on automatic machine

The prerequisites of the market and competition requires the efficiency of production of industrial enterprises. This requirement can be met by the tools of Industry 4.0. But many enterprises have unique technological equipment without the ability to connect digital solutions such as IIoT and Supervisory Control and Data Acquisition (SCADA). IIoT and SCADA enables monitoring of the equipment condition, which makes it possible to monitor technological process compliance with required modes, as well as the technical state of the equipment. The paper presents the development of software and hardware systems to eliminate this gap. The paper presents the scheme of the hardware and software system for monitoring the finishing machine, which contains sensors for monitoring the technical and technological characteristics of the machine and recording, analysing and visualizing data using the Winnum Platform. The double-acting finishing machine is a special class of equipment that allows to obtain a surface with precision quality. The presented hardware and software system can be used for other finishing machines with a similar design.

Surface integrity and superelastic response of additively manufactured Nitinol after heat treatment and finish machining

This paper explores the feasibility of adopting additive manufacturing followed by heat treatment and finish machining to fabricate Nitinol components with enhanced surface integrity and more favourable superelastic characteristics. The most suitable manufacturing approach is demonstrated to achieve these characteristics by establishing appropriate bulk and surface conditioning. New insights are presented on the correlation of process chain parameters and Nitinol superelastic response focusing on the role of the microstructural constituents and surface integrity generated from finish machining with different cooling conditions. The wear behaviour of Nitinol components fabricated by the proposed manufacturing approach is also evaluated to demonstrate bearing applications.

Machining characteristics of additively manufactured titanium, cutting mechanics and chip morphology

Application of additively manufacturing (AM) metals is growing rapidly; however, post-process finish machining is still required to improve dimensional accuracy and surface quality. Determining the high-strain high-temperature behavior of AM metals is critical in simulating finish machining, designing appropriate cutting tools, and predicting surface integrity. This paper investigated the machining characteristics of AM Ti-6Al-4V produced using powder bed fusion. High-strain high-temperature behavior of AM Ti-6Al-4V was determined numerically and used in simulating the process. Machining tests were performed in different directions with respect to the build orientation and chips were collected to examine the mechanic of chip formation.

Processing Method of Rectangular Unequal Distance Thread

With the improvement of the social demand for our daily life, the products needed in our life are getting higher and higher, and the requirements for the mechanical structure and functions need to be constantly improved, which leads to an increase in the demand for unequal distance threads. This will further improve the processing technology and processing efficiency of unequal distance threads. In the following, we will talk about the processing method of rectangular unequal distance threads, focusing on the basic idea of NC processing of unequal distance threads Programming skills, rough and finish machining methods in CNC machining, tool application.

Rotary ultrasonic machining of advance materials: A review

With its superior machining quality, rotary ultrasonic machining (RUSM) is the best alternative to machine complex, brittle materials like ceramics, glass, composites, and quartz. These materials are complex to machine with the conventional process. Other advanced materials during ultrasonic machining also result in poor machining characteristics. To achieve fine machining, hole accuracy was primarily focused on hard-to-cut materials like ceramics regarding deep drilling of holes. Hybrid machining is one of the best methods for RUSM to experience these challenges. The main objective of this review paper was to identify the different machining variables of rotary ultrasonic machining and their influence on the output response variables such as material removal rate (MRR), tool wear rate (TWR), and surface roughness (S.F.), etc., considered especially for different glass composites. In rotary ultrasonic machining, a review of the material removal methods, a description of the operation, the rate of material removal, and problems with tool wear are discussed. Based on the literature studied, the experimental results obtained for machining of advanced materials such as composites, silicon, advanced glass, CFRP, titanium, and carbides, etc., on RUSM, the various input parameters were analyzed to figure out the effect on output responses critically. Future research in rotary ultrasonic machining should optimize output responses such as cutting force, chipping size, hole cylindricity, and tool wear using advanced optimization techniques.

Grinding of composite materials

Grinding plays an important role in ensuring the final machining quality in the manufacturing process of composite parts. Problems such as grinding damage, grinding wheel wear and loading undermine the grinding efficiency and quality. This review presents relevant research progress in the field of composites grinding in recent years from the aspects of material removal mechanisms, surface integrity, and advanced grinding technologies. It further discusses the common problems of composites grinding and summarizes grinding process strategies to suppress damage. It can provide an in-depth understanding of the fundamental mechanisms involved in composites grinding and solutions to the composites grinding problems.

К. Б. Поварова, А. А. Дроздов, А. В. Самохин, О. А. Скачков, А. А. Фадеев, А. А. Дорофеев, В. П. Сиротинкин, А. А. Ашмарин, М. А. Булахтина, А. В. Антонова, А. Е. Морозов

The article discusses the possibilities of preparing high-quality powder materials from heat-resistant light alloys based on refractory monoaluminides of nickel β-NiAl and ruthenium β-RuAl for the manufacture of compact samples/products of complex shape using additive technologies with minimal final machining. Additive technologies are based on the use of spherical precursor micro-powders with a regulated granulometric composition, good fluidity and an oxide-free surface. The possibilities of obtaining precursors from RuAl-based alloys by plasma spheroidization of powders obtained by crushing mixtures from scrap samples of alloys based on RuAl with various additives are considered.

A Study on Improving the Machining Performance of Scrolls

To improve machining efficiency and product precision in scroll manufacturing, we studied three adaptive milling processes: adaptive feed rate planning, chatter suppression measures, and optimization of milling parameters during the rough, semi-fine, and fine machining of scrolls. In the rough machining of scrolls, adaptive feed rate planning was used to compute the cutting area per cutter tooth in real time in order to adjust the feed rate and optimize the material removal rate (MRR) under a given maximum acceptable cutting load. To suppress the possibility of chatter in the semi-fine and fine machining processes, the chatter frequencies were detected with a microphone and the spindle speeds were promptly modified using a developed program in combination with the controller of the milling machine. Based on the Taguchi method and analysis of variance (ANOVA), we determined the optimum milling parameters for the fine machining processes to improve contour characteristics, such as the profile errors and surface roughness of scrolls. Experimental tests were implemented to demonstrate and verify the feasibility of the adaptive milling processes proposed in this study.

Metallurgical Quality of Cast Iron Made from Steel Scrap and Possibilities of Its Improvement

In the field of metallurgy, there are many factors that influence the final quality of cast iron. These are mainly charge materials, chemical composition and metallurgical preparation up to the final casting process. Even small deviations from metallurgical processing lead to fluctuations in melt quality and the occurrence of casting defects. Charge materials have a significant impact on the quality of cast iron, especially steel scrap, which is increasingly used from an economic and ecological point of view, especially when melting cast iron in electric furnaces. Cast iron produced from a higher proportion of steel scrap in the charge has a higher hardness and tensile strength. On the other side, these cast irons have a higher tendency of chillout, brittleness, shrinkage, pearlitic microstructure, stresses and higher purity due to the difference in hardness at different wall thicknesses of the castings. It is the high hardness that is the problem in the final machining of castings. These negative properties are recorded mainly in heavy thick-walled castings with a higher tensile strength and hardness. This negative effect is mainly due to the nitrogen content in the steel scrap. Based on this knowledge, operating melts were realized in the foundry’s operating conditions. The influence of steel scrap in the charge and the possibility of eliminating its negative effects on the properties of cast iron were investigated.

Effects of Machining Parameters on Electrochemical Multi-Field Coupling

Electrochemical machining involves three couplings between electric field, flow field and thermal field. The precipitation of hydrogen on the surface of the cathode will affect the entire electrochemical machining process and the final machining quality of the workpiece. Finite element software is used to analyze the effects of different voltages, electrolyte inlet pressure and interelectrode gap on current density, hydrogen volume fraction, conductivity and temperature distribution in this article. The research results show that the increase of processing voltage will increase the current density, hydrogen volume fraction and temperature, and decrease the conductivity of the solution. As the pressure of the electrolyte increases, the current density and conductivity increase, but the hydrogen volume fraction and temperature decrease. The current density, hydrogen volume fraction and temperature decrease, and the conductivity increases when the gap between electrodes increases. At the inlet, the current density and conductivity are relatively large, and gradually decrease along the electrolyte flow direction, while the hydrogen volume fraction and temperature are the smallest at the inlet, and gradually accumulate along the electrolyte flow direction, and reach the maximum at the outlet. Through multi-physics coupling simulation, the current density, temperature, conductivity and bubble distribution in electrochemical machining can be predicted, which can provide a theoretical basis for actual electrochemical machining process parameter selection.

Overview of finish machining methods for the internal surfaces of rectangular pipe parts

The article deals with the proble of finish machining the internal surfaces of straight and curved pipe parts of rectangular cross-section. There is carried out analysis of technological capabilities of special finish machining technologies of internal surfaces in the Russian Federation. General information, disadvantages and advantages of these methods are presented. The selection criterion is the uniformity of machining on straight and curved parts of the pipe part. There are proved the main advantages of choosing an abrasive flow machining method as a fairly inexpensive method of finish machining. A scheme for finish machining the internal surfaces of rectangular parts is proposed. The composition of the working medium has been chosen, which allows for uniform machining, including in the corners of a rectangular cross-section.

Assessment of surface quality in extrusion honing process using dimensional analysis approach

It is critical to obtain the desired surface quality on machined parts’ internal and external portions. The estimated level of surface texture can be induced on the outer regions using traditional finish machining processes such as grinding, honing, and so on. While the problem emerges when processing miniature core components such as micro bores and inlet/outlet valves. The EH approach overcomes this limitation of the conventional finishing method. It is a novel micromachining process that extrudes pressured flow of carrier media combined with abrasives into the confined passage to generate the desired level of surface texture. Due to the abrasion process, micromachining occurs by taking away negligible stock material. The present study focus on the impact of the number of passes at the specimen’s entry and exit sides of the carrier media. The improvements in the surface finish (Ra) on both sides, i.e. entry and exit, are also evaluated. A dimensionless expression for Ra is also developed. The relation is implemented using Buckingham’s π theorem, and the developed model is compared with experimental results. SEM analysis is made to portray surface texture produced by selected