Rough Machining Research Articles

Study on Residual Stress of Blasting Erosion Arc Machined Ti6Al4V and TiAl Alloys

In this paper, Blasting Erosion Arc Machining (BEAM) was applied to perform high efficiency rough machining of difficult-to-cut materials such as Ti6Al4V and TiAl alloys. In order to investigate the influence of BEAM on workpiece surface quality and material properties, the formation mechanism of residual stress was studied based on simulations and experiments. First of all, a thermo-elastoplastic simulation model was established to predict the residual stress after discharging. Then, a single arc discharge experiment was carried out under different discharge parameters. The results showed that after discharging, a high tensile residual stress existed on the surface, and the peak value increases with the increasing of discharge energy. The highest tensile residual stress of Ti6Al4V could reach up to 679 MPa when the peak current was 500 A and the pulse duration was 8 ms. The residual stress of Ti6Al4V decreases rapidly beneath the machined surface and is close to the material matrix at the depth of 700 μm. But for TiAl, the residual stress increased first and then decreased with increasing depth. A probable reason for the difference is that longer and wider cracks existed on the surface of TiAl and they can release residual stress partially. The simulation predicted the large tensile residual stress and the trend of residual stress distribution, which agrees well with the experiment results.

The Characteristics of Cutting Force in the Rough Machining Process of 5-Axis Milling on PEEK Material Based on Cutting Speed Parameters

The Characteristics of Cutting Force in the Rough Machining Process of 5-Axis Milling on PEEK Material Based on Cutting Speed Parameters

A Critical Review on Optimization of WEDM Process Using Taguchi Array

Abstract: Wire electrical release machining (WEDM) innovation has developed at special case rate since it was first applied over long term prior.WEDM is a widely recognized unconventional material cutting process used to manufacture components with complex shapes and profiles of hard materials. In this thermal erosion process, there is no physical contact between the wire tool and work materials. Wire Electrical Discharge Machining (WEDM) is getting more tasks in fields like dies, punches, aero and many more. It is the very difficult task to get optimum process parameters for higher cutting efficiency. In WEDM process rough machining gives lesser accuracy and finish machining gives fine surface finish, but it reduces the machining speed. This review involves process, principle, literature and applications of WEDM using Taguchi array. Keywords: WEDM; Materials; Machine; Cutting efficiency; Optimization process.

Study on face-milling roughing method for line gears–Design, manufacture, and measurement

Line gear (LG) is a recently proposed gear, which can realize transmissions between the parallel-axis, crossing-axis, and skewing-axis. To extend LG from basic research to practical application, efficient machining methods and measuring methods are necessary. In this paper, based on the LG meshing theory, driving contact curves and driven contact curves were solved. And the LG generated by the face-milling method was proposed, which was abbreviated as FMLG. The virtual simulations for machining the FMLGs were studied, and the models obtained by simulations were used for finite element analysis (FEA). From FEA results, the feasibilities of the design of contact curves and the models obtained by simulations were verified. Afterwards, three pairs of FMLGs were processed by using of special machine tool, and the measuring methods and accuracy evaluations of FMLGs were studied. Finally, performance experiments of FMLG boxes were carried out. From the measurement and experiment results, it can be concluded that the face-milling method is feasible for the rough machining of LG. Furthermore, the measuring method and accuracy evaluation are helpful for the subsequent optimization of processing parameters.

Effect of bleaching materials and whitening mouth wash on surface roughness of two types of composite resin materials nanohybrid and nanofill: an In‐vitro Study.

Background and objective: Bleaching teeth is one of the effective, comparatively safe, aesthetic treatments in dentistry. Many systems are available now in clinical practice that has a peroxide mechanism. The purpose of this study was to evaluate the effect of three different bleaching system on the surface roughness of two different composite resin materials (nanohybride and nanofilled). Methods: A total of 60 samples of two types of composite resin were used (nanohybrid and nanofill), 30 samples for each material were prepared. The total samples then divided into six groups, ten samples for each group. Each group were analyzed and tested before exposing to bleaching system that considered as control, by using surface roughness (Ra) machine using atomic force microscopy. Three bleaching system then used, hydrogen peroxide 35% with laser and carbamide peroxide 10% three times each time for 15 min‐ utes while whitening mouth wash for 1 minute/ day for one month. After bleaching ended, the surface roughness of all the samples were re‐evaluated. Results:Whiting mouth wash thtcontaing peroxide bleaching agents showed a significant differences for the two composite materials(nano hybrid and nano filled). While for the another bleaching systems(hydrogen peroxide and carbamide peroxide) there is no significant differences Conclusion:Whiting mouth wash showed more surface roughness for the two materials when compared with the another bleaching materials and Increased surface roughness of composites as a result of bleaching appears to be dependent on the bleaching agent used as well as the composite material types.

Fusing attribute reduction accelerators

In the fields of rough set and machine learning, attribute reduction has been demonstrated to be effective in removing redundant attributes with clear explanations. Therefore, not only the generalization performances of the derived reducts, but also the efficiencies of searching reducts have drawn much attention. Immediately, various accelerators for quickly deriving reducts have been designed. However, most of the existing solutions merely speed up the procedure of searching reduct from one and only one perspective, it follows that the efficiencies of those accelerators may be further improved with a fusion view. For such a reason, a framework called Fusing Attribute Reduction Accelerators (FARA) is developed. Our framework is specifically characterized by the following three aspects: (1) sample based accelerator, which is realized by gradually reducing the volume of samples based on the mechanism of positive approximation; (2) attribute based accelerator, which is realized by adding multiple qualified attributes into the potential reduct for each iteration; (3) granularity based accelerator, which is realized by ignoring the candidate attributes within coarser granularity. By examining both the efficiencies of the searchings and the effectiveness of the searched reducts, comprehensive experiments over 20 public datasets fairly validated the superiorities of our framework against 5 popular accelerators.

Obtaining Ti–Cu–C system composite materials by SHS process

The aim of the research is to obtain wear-resistant products from composite materials of a new type using the SHS technology. The Ti–Cu–C system was selected taking into account the data available in the scientific and technical literature. Various SHS charge compositions consisting of titanium powder, copper powder, and carbon black were experimentally burned to determine compositions that can burn during the SHS process and provide a melt containing titanium carbide and titanium cuprides as a binder featuring higher mechanical properties and lower melting points than pure copper. Model samples of products in the form of bushings with an outer diameter of 70 and 110 mm were produced by burning the SHS charge with selected compositions in a reactor followed by the compaction of the resulting melt with a force of 50–60 t. After the rough workpiece electrical discharge machining, samples were cut out for phase analysis, X-ray spectral analysis, and wear tests. With an optimal ratio of SHS charge components, titanium carbide and a binder in the form of titanium cuprides of different compositions were revealed in the model sample material. Using the method of testing for wear when sliding on a fixed abrasive under a specific pressure of 1 MPa, it was determined that the relative abrasive resistance of the new material at a hardness of 50–52 HRC is 1.8–2.0 units in comparison with the hardened tool and die steel Kh12MFL. In order to implement the technology in practice, an algorithm was developed for calculating the compositions of the newly formulated SHS charge, while its principle is such a ratio of components where the introduced carbon forms titanium carbide with titanium, and the added excess titanium forms titanium cuprides with copper. The developed material can be considered as promising for use as elements of equipment operating under abrasive wear conditions. This development is patented, Patent No. 2691656 (Russian Federation).

Optimization of end milling parameters for rough and finish machining of Al-4032/3%SiC metal matrix composite

Aluminum-based composites are known for better mechanical properties, superior corrosion performance, and light weight. Gradual increase in the reinforcement (SiC particles) produces improvement in several mechanical properties of Aluminum base alloy but adversely affects ductility. The present work depicts the end milling of the Al-4032/3%SiC composite. The investigation on the impact of end milling parameters has been attempted for rough and finish machining conditions. Two case studies (a) rough machining i.e., 100% weightage to material removal rate (MRR) (b) finish machining i.e., 80% weightage to surface roughness, and only 20% weightage to MRR have been investigated. Full factorial design with 3-factors at 3-level each has been used as the design matrix for conducting the milling experiments. Taguchi-based grey relational analysis (TGRA) has been adopted for the bi-objective optimization for finish machining. The significance of process parameters has been checked with analysis of variance (ANOVA).

Machining parameters in WEDM of EN31 steel using Taguchi technique optimization

Wire electrical discharge machining (WEDM) is often used in the machining of conductive materials when precision is important. The current study looked at wire-cut electric discharge machining of EN31 steel. Taguchi's L27 orthogonal array was used to finish the investigation using various amounts of input parameters. This method was used to determine the optimal parameter combination. The experimental findings show that the machining model is correct, and Taguchi's approach meets the practical requirements. Surfaces having micro cracks and porosity, as well as poor surface quality, are produced by rough machining with WEDM. Finish machining yields a better surface finish (Ra) but at a slower rate (MRR). As a result, the Taguchi approach's purpose is to improve MRR while lowering Ra. To check the performance measures in terms of Surface Roughness, control parameters such as voltage applied, pulse width, pulse interval, and speed were used.

Rapid stability analysis of serrated end mills using graphical-frequency domain methods

Serrated tools result in an irregular distribution of chip thickness and varying time delays along their flutes that disturb the regenerative chatter mechanism and maximize productivity in rough machining operations. The chatter stability simulation with such tools is complex due to the delay differential equations with multiple and distributed delays. Although the time domain numerical integration methods and the semi-discretization method are accurate, they are computationally expensive and hence inhibit the optimal design of serrated cutters. Despite the advantages that serrated tools offer, there has been little attention paid to rapidly predict stability lobes diagram for these tools to help instruct their optimal designs. To address this need, new graphical-frequency methods are presented to solve for stability of serrated tools with arbitrary geometry. The graphical method averages the number of teeth in cut to make the system time-invariant and results in a closed-form analytical solution. It reduces the simulation time by up to ∼99% compared to the semi-discretization method. Generalized solutions to the classical zero-order approximation and the multi-frequency methods are also presented by using the Nyquist stability criterion. The use of the zero-order approximation method and the multi-frequency method reduces simulation times by up to ∼97% and ∼79% respectively compared to the semi-discretization method. These are significant improvements over reports in the previous literature. Stability predictions are validated experimentally and benchmarked with high-fidelity time domain methods. The presented methods are general and can be applied to any end mill with non-uniform pitch and helix angles as well.

Fracture Analysis of Case Hardening in Kingpins Parts

Kingpin parts are the critical product for heavy vehicles and are generally made of 20MnCr5 steel. A kingpin is a heavy metal cylindrical pin that is located underneath the front end of the trailer. The kingpin is the mechanism on the trailer that locks it to a road tractor. The parts in this study have undergone to case hardening heat treatment after the rough machining operation. During the operation in the assembly line, cracks have been shown on the parts surface. In this study, kingpin parts are examined with Scanning Electron Microscopy (SEM) analysis, hardness and %C potential analysis in order to determine the potential causes of crack formations. It is shown that, heat treatment of the parts is not homogeneously distributed and therefore fractures occur. The exact outcome of the fracture could not be determined. Under the scanning electron microscope, it becomes clear that it is a crack. There are no signs of hydrogen embrittlement. With the present structure, it is to be expected that even a low dynamic load can lead to breakage. As a result, investigations suggest that the parts have exposed to incorrect heat treatment parameters.

High efficiency orientated milling parameter optimization with tool wear monitoring in roughing operation

High efficiency milling is one of the main goals of CNC machining. Although roughing operation has low requirement for machining accuracy, the milling parameter selection usually need to consider the cutting force, milling stability, spindle torque and power. Besides, the tool wear in difficult-to-cut material machining is another very prominent problem. Therefore, how to achieve the high efficient milling parameters under the multi-constraint condition has been a severe challenge in the field of CNC machining. In this paper, a milling parameter optimization method for efficient rough machining is proposed by combining the off-line optimization and real-time monitoring. Firstly, a mathematical model of the optimization problem is established, which takes the machining efficiency as the objective, the spindle speed, radial and axial depth of cuts as the variables, and considers the multi-constraint, such as the basic parameter feasible region, cutting force, stability, spindle torque and power. Secondly, the quantitative relationship between the spindle three-phase current and milling force is established to realize the real-time estimation of cutting force coefficients. Furthermore, a numerical optimization method based on the random vector search is proposed, and the overall optimization procedure is given. Finally, a series of experimental verifications on the titanium alloy Ti5Al5Mo5VCrFe machining has been carried out, and the case study results show that the proposed parameter optimization method can greatly improve the machining efficiency, which proves the validity of the method.

Pengaruh Parameter Proses Milling pada Austempered Ductile Iron (ADI) Terhadap Kekasaran Permukaan Benda Kerja dan Chip Thickness Ratio

<p><em>Austempered ductile iron (ADI) is a difficult material for machining, </em><em>even though ADI is believed to have several advantages such as strength, ductility, high toughness, fatigue resistance, good dynamic wear resistance, has a good strength-to-weight ratio, easy to manufacture and easy to cast that causes it to be widely used in various applications. </em><em>This study investigates the effect of milling parameters on surface rougness and chip thickness ratio on milling of ADI. To produce ADI, ductile irons were first austenitized in furnace at 900<sup>o</sup>C for 1 hour and then they were quenched in salt bath at 375<sup>o</sup>C for 1 hour. The work material was machined with uncoated carbide tool. The tool was 20 mm in diameter. The cutting experiments were carried out in the dry mode. The feed was varied from 0.05 to 0.1 mm/tooth for cutting speed ranging from 15 m/min to 25 mm/min and depth of cut ranging from 0.1 mm to 0.3 mm. The surface roughness was measured using the Mitutoyo SJ-201, surface roughness machine. The chip thickness was measured using software Image J from the photograph produced by digital microscope endoscope. The results show that connected and loose chips were produced. Long and continuous chips were not found in this study. The effects of cutting speeds, feeds and depth of cut on surface roughness and chip thickness ratio are reported in this paper</em><em></em></p>

On-Machine Measurement and Error Compensation for 6061 Aluminum Alloy Hexagonal Punch Using a Turn-Milling Machine

For machining parts with complex shapes, consisting of computer numerical control (CNC) machine tools, different CNC machine tools will be used according to the machining method. If the workpiece is removed for off-machine measurement after machining, when the size is incorrect, it will need to be returned to the CNC machine tool for secondary machining. In this case, the workpiece surface quality and machining accuracy will be affected, which is very time-consuming. On-machine measurement and complex machine center is a key to solve this problem. In the recent researches that the touch probe was integrated on three or five axis machine for error compensation and shape construction based on on-machine measurement, but turning-milling machine was rare. In addition, the most types of parts were thin-walled parts or thin web parts. In this study, a contact measurement system is integrated into a CNC combined turning-milling machine for on-machine measuring. Macro-programming is used to design the machining path of A6061-T6 aluminum alloy hexagonal punch, and the action of probe measurement is added to the machining path. As the measured data exceed the tolerance range, the calculated data are fed back to the controller for machining improvement by compensation. The finished hexagonal punch is measured in a 3D coordinate measuring machine and the error is compared. The experimental results show that the contact probe needs to be corrected before machining, and the size of the corrected workpiece can reach the tolerance range of ±0.01 mm. The size error of rough machining is larger than that of fined machining, and the size error of rough machining will increase with the length of the workpiece.

An online visual measurement method for workpiece dimension based on deep learning

Image preprocessing and edge detection are the two most critical steps when applying machine vision to measure workpiece dimension in industrial field. The surface of the workpiece is usually covered with interference regions, which makes edge detection difficult. Aiming at the problem, the Full Convolutional Network (FCN) model is used to detect interference regions of workpiece images, and then interference regions are processed by the directional texture repair method. To avoid the influence of workpiece surface texture after rough machining, a method based on Holistically-nested Edge Detection (HED) model for rough edge detection of workpiece images is proposed. The edge is obtained by HED, and then it is post-processed based on the non-maximum value suppression and double threshold segmentation methods in the Canny operator to obtain a refined edge image. In order to further improve the accuracy of the dimension measurement, sub-pixel level edge detection accuracy is achieved by cubic spline interpolation. Finally, the method is validated by a shaft workpiece. The measuring accuracy of the outer diameter of the workpiece can reach 0.02 mm, which can effectively meet the requirements of fast semi-finishing inspection. This research provides a common workpiece dimension measurement method in industrial field and methodological guidance for the application of deep learning in industrial inspection.

Evaluation of WEDM performance characteristics and prediction of machining speed during taper square profiling on Hastelloy-X

ABSTRACT Hastelloy-X is one of the wrought nickel-base superalloy comprising of oxidation resistance and high-temperature strength. Wire electric discharge machining process is the favoured technique for precise component fabrication of such materials. Apart from precision the most essential aspect with surface integrity and cutting velocity in manufacturing. This investigation deals with the effects of cutting speed override, corner dwell time, wire guide distance and wire offset on taper profile response characteristics. The variation of these parameters is studied by machining a simple square profile at 0°, 15° and 30° taper angles. It is observed that as the taper angle gets increased, both the machined errors at corners and machined roughness increased although the machining speed gets reduced. The recast layer and micro-hardness are explored for the taper square profile components. It is observed that the recast layer thickness was least for 30° taper profiles indicating least thermal degradation which was validated by micro-hardness. It was established that in a machined profile, that corners possessed lower hardness than the edges. The micro-hardness of inner profile corners was found to be lower than outer profile corners. Adaptive neuro-fuzzy interference system is better prediction computing method having least error ranging from 0–4.89%. In conclusion, the machining speed and taper angle also contribute to the output characteristics in wire electric discharge taper profiling.

Investigation of ultrasonic-assisted CNC cutting of honeycomb cores

As compared to traditional milling, ultrasonic-assisted cutting of honeycomb core materials has the advantages of small cutting force and superior surface quality. Currently, ultrasonic straight blade V-shaped machining is one of the most efficient roughing processes. The requirement of a processing path to be post-processed based on the processing characteristics of the straight blade cutter is one of the key issues faced while meeting the technological requirements of CNC machine tools for V-shaped machining. A post-processing method of NC code for V-shaped machining of straight blade cutter is proposed in this article. Initially, the V-shaped rough machining process planning is done, followed by the usage of Unigraphics (UG) to output the initial CNC code. Next, the CNC code is executed through the three key technologies of the second arrangement of cutter locations. Later, research is done on information planning of lifting and lowering cutter, along with research on planning of chip breaking toolpath. Eventually, the simulation cutting experiment is carried out through VERICUT. The results demonstrate that the post-processing method can meet the processing requirements.

A rough margin-based multi-task [formula omitted]-twin support vector machine for pattern classification

Twin support vector machine (TSVM) has attracted significant attention in recent years, but it is suitable for solving the single-task learning (STL) problems. It trains each task independently and neglects the relationships among all tasks. Conversely, multi-task learning (MTL) explores the shared information between multiple correlated tasks, which obtains a better classifier than STL. Nevertheless, the existing multi-task twin support vector machines give the same penalties to the misclassified samples. In fact, the misclassified samples play a different role in generating separating hyperplane. Motivated by above studies, we put forward a rough margin-based multi-task ν-twin support vector machine (rough MT-ν-TSVM) in this paper. The proposed rough MT-ν-TSVM gives different penalties to the misclassified samples depending on their positions. It not only takes full advantage of rough ν-TSVM, but also discovers the commonality among tasks and maintains the individuality of each task. Therefore, compared with the state-of-the-art algorithms, our method yields better classification performance. In addition, we apply it to Chinese wine dataset to verify the effectiveness. Finally, the related extensions are further discussed, especially a fast SMO-type decomposition method (SDM) is introduced to handle relatively large-scale problems for acceleration. Comprehensive experiments are conducted on eleven benchmark datasets and an image dataset. The results demonstrate that our proposed algorithm can avoid over-fitting and achieve better classification accuracy, meanwhile it does not increase computational time compared with DMTSVM and MT-ν-TSVM.

Study of residual casting stresses in cast iron rolling rolls

The metal magnetic memory method (MMM) is a fundamentally new direction in technical diagnostics. It is the passive method that uses information emitted by a product or structure. In addition to early detection of a developing defect, the MMM provides information about the actual stress-strain state of the test object. When diagnosing equipment using the metal magnetic memory, the main criterion for stress concentration zones is the presence in this zone of lines characterized by a change in the sign of the normal component of the intrinsic stray field. Studies have shown that storing the rolls during 22 days significantly reduces the residual stress level. An increase in the duration of the roll storing contributes to a greater reduction in stresses in castings. The studies have shown that the MMM method application made it possible to assess the unevenness of the stress-strain state of the rolls and to identify the stress concentration zones - the sources of cracking. Storing the rolls after casting leads to a significant reduction in the level of residual stresses. Rough machining results in the appearance of zones with an increased level of residual stresses, which can initiate the formation of cracks in rolls during their operation. The use of the MMM method will enable to develop a technology for accelerated stress relief in castings of rolls after their machining, eliminating aging.

THE EFFECT OF THE CIRCULAR FEED ON THE SURFACE ROUGHNESS AND THE MACHINING TIME

The surface roughness is analysed in different feeds and turning procedures (rotational and conventional) in this paper. Cutting experiments were made on different cutting speeds and feed rates with 2 cutting tool with helical edge geometry and 1 traditional turning tool. The measured 2D surface roughness values were compared between the different cutting tools. The benefit of the circular feed application is showed by the decrease of roughness parameters and machining time.