Perform Machining Operations Research Articles

Методика оценки брака: процесс контроля коренных шеек коленчатых валов в ремонтном производстве

Both the actual size of the part and measurement errors influence the results of tolerance control in repair production. For this purpose, the authors developed the mathematical model of reject estimation by probabilistic characteristics of parts sorting, taking into account the specifics of repair production and the shift of the distribution centre relative to the tolerance field. They tested and evaluated the mathematical model of rejects estimation at machining for repair size of crankshaft main journals of the YaMZ‑238 engines. In case of incorrect rejection and incorrect acceptance of main bearing journals, the character of reject losses will be different. Incorrectly rejected crankshafts with journals having irreparable rejects will be sent for recycling. New crankshafts will be purchased to replace them, and there will be reject losses to the left of the scatter zone. Incorrectly rejected crankshafts with journals that have reparable rejects will be sent for remanufacturing. In this case, the loss per crankshaft is determined by the cost of rework, which is the loss to the right of the scatter zone. Incorrect crankshafts with journals having defects to the left and right of the scatter zone will be sent for reassembly. If the largest size limit is exceeded, the liners may rotate and the engine must be rebuilt, which increases losses significantly. In case of violation of the lower size limit, the shaft life will be reduced and losses will occur only for the consumer. In contrast to the existing methodology for calculating the sorting parameters, where the scatter zone coincides with the middle of the tolerance field, the developed methodology for assessing rejects when the scatter zone is displaced relative to the tolerance allowed to form a more differentiated and refined methodological approach to the assessment of losses in disassembly of parts when performing machining operations in repair production.

Effect of Different Drill Bits on Delamination in Drilling Composite Materials

The most important problem of composite materials, which have been started to be used in every field of technology, is the ability to perform machining operations such as drilling and cutting. In this respect, in this experimental study, its performance in drilling different composite materials with different reinforcements and thicknesses with drills of different types and different diameters was investigated. Three different types of drills were used in drilling operations, namely HSS, TIN and Carbide. Reinforced composites of different types and properties were used as materials. As a result of the drilling processes, the surface roughness of the drilled surface, drilling performance, hole quality and different cutting parameters were examined depending on the rotation and feed rate. The same drilling conditions were applied for each composite material. All result values obtained were transferred to graphs and tables. In addition, photographs of all samples were taken under Scanning electron microscopy (SEM) and the surface roughness of these photographs was examined.

Development of Eco-Friendly Cutting Fluid for Machining of AISI 1010 Steel in Automotive Industry

In spite of better performance, the disposal of used petroleum-based cutting fluids threatens our environment. Thus, it is essential to develop eco-friendly cutting fluids for performing machining operations in industries. The main contribution of this paper is to develop an eco-friendly cutting fluid for the plain turning of AISI 1010 steel which is used in the automotive industry. In the present work, boric acid (H3BO3) was mixed with the neem seed. Neem seed oil is easily available in many countries including India. The effectiveness of the proposed cutting fluid was evaluated by conducting different tests as per the standards. The mean biodegradability value of the developed cutting fluid is 97% which is better than other cutting fluids. The average cutting force required by the proposed cutting fluid is only 127.2 N which is much less than the cutting force requirements of dry machining and conventional cutting fluids. The average surface roughness of the machined component using the proposed cutting fluid is 122.9 µm. The mean flank wear of the tool is only 289 µm. The flash point of the proposed cutting fluids is more than 250 °C which is better than the conventional cutting fluids. The fire point of the neem oil-based cutting fluids is 300 °C. The results of the stability test and the microhardness test revealed the effectiveness of the proposed cutting fluids. The results obtained in this work are superior to several other cutting fluids reported in the existing literature. Hence, it is suggested to replace the existing petroleum-based metal cutting fluid with this eco-friendly cutting fluid in the automotive industry in Hosur, India.

Comparison of laser beam, oxygen and plasma arc cutting methods in terms of their advantages and disadvantages in cutting structural steels

The laser beam, plasma arc, and oxygen cutting methods are widely used in metal cutting processes. These methods are quite different from each other in terms of initial setup cost and cutting success. A powered laser beam is used in laser beam cutting, plasma is used in plasma arc cutting, flammable gas - oxygen mixture is used in the oxygen cutting method. In this study, the cutting success of these methods was investigated on tensile specimens. Microstructure, hardness (HV 0.1), surface roughness, and strengths were investigated after the cutting process. The tensile test implemented with tensile samples cut from the same material by these three methods, it was observed that the strength values of the samples changed by about 8% in tensile strength depending on the cutting process. The hardness of the cut surfaces in plasma arc cutting increased from 150 HV to 230 HV for S235JR material. For this reason, it is difficult to perform machining operations after plasma cutting. The hardness value reached after laser beam cutting is 185 HV. Plasma arc cutting is more cost-effective than laser beam cutting. 1-3° vertical inclination (conicity) occurs on the cut surface in plasma arc cutting, while this inclination almost does not occur in laser cutting. In plasma cutting benches, cutting is done with oxygen, and in cutting with oxygen, the taper is seen in a small amount.

Tri-objective constrained optimization of pulsating DC sourced magnetic abrasive finishing process parameters using artificial neural network and genetic algorithm

ABSTRACT Owing to the exceptional mechanical properties of Ti-6Al-4V, it is widely utilized in numerous critical mechanical parts for the uncompromised factor of safety. However, performing machining operations on this alloy in close tolerance is a challenging task. Moreover, establishing a process for its efficient finishing has become the interest of researchers. In this research study, the magnetic abrasive finishing process (MAF) has been studied using the ANN-GA approach, where ANN has been used for modeling of input–output relations, and GA has been used to optimize the MAF process. The experiments were conducted on a pulsating DC sourced MAF set-up, and SiC-based loosely bonded magnetic abrasive media was used for material removal. During experimentation, the current, machining gap, speed of rotation, abrasive composition, and finishing time were taken as input parameters being arranged in an array of L16 orthogonal. In contrast, output parameters were changed in surface roughness, change in the microhardness, and change in the modulus of elastic indentation. ANN-GA approach provides a set of optimal solutions for obtaining suitable output values. Furthermore, loosely bound SiC-based magnetic abrasive media and its composition is found to be a very critical factor for the performance of the finishing quality on Ti-6Al-4 V.

The effect of the heat treatments on the tool wear of hybrid Additive Manufacturing of IN718

The application of the Direct Energy Deposition (DED) in the aerospace field offers the potential to manufacture and repair critical components. Nevertheless, the parts produced by DED require finishing operations such as machining. Consequently, the tool wear analysis is usually required to better understand the quality of the manufacturing process, especially when difficult-to-machine materials are involved. In this study, the tool wear analysis was carried out after performing machining operations on DED IN718, considering the material as “as-deposited” and “heat-treated” conditions. The microstructural investigation by electron microscopy analysis was performed to study tool wear depending on the variation of the process parameters. The study highlights the presence of different tool wear mechanisms during the machining of the DED IN718. The results demonstrate a correlation between cutting speed, feed rate, material conditions and tool wear. Indeed, although high values of the process parameters (high cutting speed, high feed rate) caused high wear rate, the material conditions affected the tool wear mechanisms involved. It was also found that the main wear mechanisms during the processing of IN718 were adhesive and abrasive. The tools used to machine the heat-treated materials were characterised by extreme wear as suggested by the crater formation, due to the superior mechanical properties exhibited by the material.

Simulation-dynamic model of working time costs calculation for performance of operations on CNC machines

This article presents a simulation-dynamic model for determining the time spent on machining operations on machines with a numerical control (CNC). The model is developed on the basis of the system dynamics method using Powersim Studio tools. In the shown model, the calculations of the probabilistic deviation of the actual time of technological operations on CNC machines from the technically sound time norm were carried out on the basis of the Gaussian normal distribution law. The model was used as a tool to study the probabilistic distribution of time for equipment retooling and to perform technological operations on HAAS SL-20 CNC machines. The study allows us to conclude that the constructed simulation dynamic model is quite universal and, on its basis, it is possible to carry out a variety of studies concerning various aspects of the technical substantiation of the time norms for performing machining operations on CNC machines.

Experimental investigation and optimization of process parameters during electric discharge machining of Inconel X-750

This article highlights the application of multiple criteria optimization using the Grey relation analysis (GRA) and Weightage principal component analysis (WPCA) method in EDM of Inconel X-750. Taguchi’s based design of experiment L9 orthogonal array (OA) was used to perform machining operations using a copper tool. When machining comes to accuracy, higher dimensional tolerances, extreme surface finish, cutting of hard materials, there is an extreme need for non-traditional techniques like EDM. The effects of process parameter namely, peak current ( $$I_{\text{p}}$$ ), pulse on time ( $$T_{\text{on}}$$ ), pulse off time ( $$T_{\text{off}}$$ ) and voltage (V) on Material removal rate (MRR) and Surface roughness (Ra) has been studied. The optimal parametric setting obtained from WPCA and GRA approach are found as 15 amp, 74 µs, 8 µs, 40 voltage, and 18 amp, 63 µs, 9 µs, 60 voltages, respectively. Outcomes of confirmatory tests show that WPCA gives better agreement with actual results which is highly desired for an efficient machining environment. Also, a comparative study of both the developed hybrid modules was performed to evaluate the feasibility. Outcomes reveal that WPCA improved the preferred solution value by 12.67%. The result of ANOVA confirms the most influencing parameter on machining performances.

A novel force and motion control strategy for robotic chamfering of gears

Accurate positioning of the workpiece in the robotic work cell is currently required to perform machining operations such as chamfering in order to obtain high quality products. However, registration and workpiece fixturing errors are inevitable and lead to uncertainty in the desired robot end-effector trajectory which will lead to poor quality of the finished product. This paper proposes a method for robotic gear chamfering that can compensate for the registration error of the workpiece while avoiding use of expensive and time-consuming metrology devices for accurately registering the gear in the robot workspace. We highlight the problems in chamfering with workpiece uncertainty when traditional contour following methods are employed. A novel chamfering trajectory based on a part identification procedure is proposed that can account for the gear registration uncertainty. A force control strategy is employed in identifying the gear center and gear root positions. Based on this identification, we employ a novel force/motion strategy that can simultaneously chamfer two edges of the adjacent gear teeth. We have conducted a number of real-time experiments with a six degree-of-freedom robot to evaluate the proposed strategy, and representative chamfering experimental results are presented and discussed.

Use of polymeric additive "Nanoterrasoil" produced by Germany for stabilization of soils of military-automotive (field, forest) roads and platforms

The article concerns the decision of the actual scientific and applied task of substantiation of the necessity of preparing troop movements in a short time with the corresponding requirements, for which it is proposed to use the technology of cold recaikeling to strengthen the soil. The basis of cold recycling technology is the principle of reinforcement and stabilization of milled mixtures, which leads to changes in the properties of materials from existing layers of road clothes of different composition and turning them into a monolithic strong frost-resistant constructive layer of road clothing. Soil reinforcement / stabilization with the use of inorganic abrasive materials has been used in road construction for a long time, both in our country and abroad. When using this technology, the stabilization and strengthening of soils are shared. Soil stabilization makes it possible to improve the conditions of consolidation of local soils. This method makes it possible to arrange frost protection layers, and to increase the bearing capacity of ground soils. When strengthening soils, there is a significant increase in the physical and mechanical characteristics of local soils. This is achieved by introducing abrasive materials and impurities into the soil, and successively performing machining operations using ground blending and sealing machines.This technology allows practically to avoid penetration of moisture everywhere the layer of reinforced base of road clothing to the materials of the earth's canvas, resulting in the humidity of the working layer of the earth's canvas being always less than when using traditional rubble foundations on the drainage sandy layer.To strengthen the milling material as astringent, mineral binders (cement, lime, active or high-grade slag), organic binders (bituminous emulsions, bitumen oil road liquids, bitumen petroleum road viscous) or complex binders (mineral and organic binders)are to be used. In this paper, the feasibility of using the Nanoterrasoil (NTS) polymer stabilizer as a component of a complex binder together with cement to strengthen the milled material with the use of cold recaikeling technology was substantiated.

Characterizing the effect of process variables on energy consumption in end milling

Manufacturing processes, such as machining, transform raw materials into finished goods, and these processes consume significant energy. There is an increasing concern about the energy required for such processes and the environmental consequences attributable to the generation of the energy. Reducing the energy required to perform machining operations will not only reduce the environmental footprint, but also provide economic benefits. To that end, the effects of cutting conditions (e.g., feed and speed) and tool geometry (diameter and number of teeth) on the power required for an end milling operation are investigated experimentally. Experimental results are presented from a cutting mechanism perspective with the goal of understanding the role of the process variables. The specific cutting energy (SCE) is found decreasing when material removal rate increases, but there is substantial variation about the general trend. In essence, the cutting parameters and the tool geometry influenced the changes of average chip thickness and cutting speed, which cause the shear deformation energy changes and eventually collectively influence the SCE’s change. Based on the experiments, suggestions on selecting process parameters are provided to improve milling energy efficiency.

Stiffness performance index based posture and feed orientation optimization in robotic milling process

Abstract Industrial robots are promising and competitive alternatives for performing machining operations. A relatively low stiffness is the major constraint for the widespread use of industrial robots in machining applications. In this study, the stiffness properties of an industrial robot are analyzed to improve the machining accuracy of robotic milling, and optimization methods for the robot posture and tool feed orientation are established. First, based on the relationship between the external force and deformation of the robot end effector (EE), the normal stiffness performance index (NSPI) of the surface, which is derived from the comprehensive stiffness performance index (CSPI), is proposed to evaluate the robot stiffness performance for a given posture. The NSPI is proven to be independent of the magnitudes of the external forces and dependent on the directions of these forces. A distribution rule is then proposed for the NSPI with respect to any direction in the Cartesian space for a given posture, which clearly reveals the anisotropic property of the robot stiffness. By maximizing the NSPI, an optimization model is established to optimize the posture of a six degree-of-freedom (DOF) industrial robot in a milling application. Using the NSPI, the optimized tool feed orientation for robot planar milling is obtained. Finally, the results of the robot milling experiments are discussed to illustrate the feasibility and effectiveness of the proposed optimization methods.

The Task of Machine Tool Operators in Small and Medium Enterprises in Indonesia

The needs of operators for each type of industry are different because the type and the complexity of the task is different. Small and medium-sized industries require machine operators with better capabilities than operators in large companies, thus it is necessary to identify what tasks are performed by these operators. This study aim at (1) identifying duties of machine tool operators in small and medium enterprises, and (2) identifying tasks carried out by machine tool operators in small and medium enterprises. This study used a descriptive research method. The participants were eight machine tool operators from five small and medium enterprises in Yogyakarta, Indonesia. The data collection used document review, observation, questionnaires and focus group discussions. The data were analysed using descriptive analysis. The results of the study were (1) five duties done by machine tool operators are identified (maintaining safe work environment, maintaining the machine tools, analyzing the blueprint, performing machining operations, cleaning the machines and the workplace), and (2) twenty seven tasks executed by machine tool operators are identified; twenty-two knowledge and skills, seventeen behaviors, and eighteen machines, tools and equipment required by machine operators.

An automatic method for the self-referencing and operation of portable machines

This article proposes a new method to perform the referencing procedure between the workpiece and small portable machines that can move along large parts to perform machining operations. The method is based on natural fiducials which are detected by a laser scanner and their identification in the computer-aided design file, without feature extraction. Once the usual requirements of the referencing of portable machines are studied, the method has been experimentally validated on a conventional three-axis milling machine to establish its accuracy, obtaining systematic and random errors and also its overall utility. The errors created by the experimental campaign have been studied and isolated, thus giving results that faithfully represent the proposed method. The results are compared with other state-of-the-art techniques to establish comparative accuracy values. Finally, the referencing method is expanded and integrated in an automatic working mode to operate portable machines and solve both local and distributed machining operations. To test this, the automatic method has been used to command machining operations in a conventional three-axis milling machine as it would be in portable machines to prove feasibility and overall validity.

A concept for actuating and controlling a leg of a novel walking parallel kinematic machine tool

The scope of this paper is to present a novel method of actuating the legs of a walking parallel kinematic machine tool (WalkingHex) such that the upper spherical joint can be actively driven while walking and remain a free, passive joint while performing machining operations. Different concepts for the number of Degrees of Freedom (DoF) and methods for actuating the chosen concept are presented, leading to a description of a three-wire actuated spherical joint arrangement. The inverse kinematics for the actuation mechanism is defined and a control methodology that accounts for the redundantly actuated nature of the mechanism is explored. It is demonstrated that a prototype of the system is capable of achieving a motion position accuracy within 5.64% RMS. Utilising the concept presented in this paper, it is possible to develop a walking robot that is capable of manoeuvring into location and performing precision machining or inspection operations.

Error budget and uncertainty analysis of portable machines by mixed experimental and virtual techniques

This paper analyzes the error sources of portable machines, which can move along large parts to perform machining operations and defines a mixed virtual-experimental model to quantify such errors. The method combines three different aspects of particular relevance in portable machines: a process force and machine stiffness model, a geometric error model and a machine and work piece inter-referencing error model. The combination of these models helps to control and define the effects of different errors in the virtual mobile machine, before a real prototype is built. An application to a particular portable machine is presented where error values are either simulated or experimentally obtained from a conventional three-axis milling machine where typical strategies of mobile machines are implemented and tested. The research shows that portable machines can be a solution for automatic and unattended machining operations with accuracy requirements below 0.1mm.

Overview of the State of Robotic Machining: Current Situation and Future Potential

Nowadays industrial robots are an appropriate technology for developing flexible and reconfigurable manufacturing systems which contribute to perform automatically operation such as milling, cutting, drilling, grinding, deburring and polishing. Machining robots symbolize a cost-saving and flexible alternative compared to conventional CNC machines which are the restricted working area and produced shape limitations. The improvement of individual elements and development of new devices has caused a perception change about the use of industrial robots to perform machining operations. The approach to this research was to analyze technical barriers of individual components that it was broken-down as well as full improving the system. This document is intended to provide technical constraints, current technology and future potential researches about robotic machining.

A Study on Machining Capability of a 2-DoF PKM-based Milling Machine

In the recent past, Parallel Kinematic Machines (PKM) with fixed-length legs have been claimed for their potential use as machine tools due to smaller moving masses leading to the high dynamic characteristics and accuracy. In this paper, the machining capability of a 2-Degrees-of-Freedom (DoF) PKM-based milling machine is explored. Stiffness of the PKM was estimated using finite element analysis approach. Extensive experimentation was carried out by varying machining conditions, i.e., cutting speed, feed rate and depth of cut to study the variation in performance measures, namely, surface roughness and material removal rate. Regression models were developed to predict the surface roughness. An attempt was made to find the optimum machining conditions for PKM using Genetic Algorithm. The experimental results confirm the capability of fixed- length leg PKM-based machine tool to perform machining operations upon metals like hard Aluminium alloys.

Computations for Simplification of Canned Cycles in CNC Programming for Turning Operations

Canned cycles are predefined machine instructions stored permanently in the machine controller. These are used while writing part program to perform machining operations that are of repetitive nature. Whenever G & M code for these canned cycles appeared in part program, the controller of the machine calls already stored instructions and executes. However all CNC machines may not have facility to run part programs with canned cycles due to lack of computational facilities. The developed utility in this program allows part programmers to write part program using canned cycles and later on convert them in simplified programs to run on the low cost CNC machines. Present work deals with computations required to convert a canned cycle into linear interpolation based on the machining parameters assigned in that canned cycles. Developed code reads the CNC part program and extracts the desired points from presented canned cycles and perform desired geometric computations to converts it into simple part programs with elimination of canned cycles and writes in another text file in the form of a part program. Developed system is user friendly and made available online for users at http://virtualcnc.iiitdmj.ac.in. It implies a web based online client-server architecture which facilitates user to send their own CNC part programs with canned cycles at server site via internet and get the simplified part program which contains only linear interpolation at their end. Therefore the developed utility in this work can also provide an interface/exchange program for part programs between various CNC machines of different make.

CALCULATION OF SPINDLE COMPLIANCE CONSIDERINGS IT ́S INTERACTION WITH MACHINE FRAME

The calculation of spindle dynamic compliance is usually performed taking into account only the mechanical system of the spindle and tool, while the influence of the machine tool frame is neglected. However, when performing machining operations characterized by high cutting forces – which typically arise e.g. during roughing – machine frame vibration may be induced. Under such conditions, a model of the spindle alone is not sufficient to predict the dynamic behaviour of the spindle; therefore, coupled models of the spindle and machine frame system need to be created. The paper presents two possible approaches that can be used for such tasks. The first approach consists in modelling the whole mechanical system in the Finite Element (FE) environment; the second one employs the technique of coupling modally reduced separate models of flexible bodies. The application of both approaches and their comparison is illustrated by an example of a real machine tool model. The influence of the machine tool frame on the spindle dynamic compliance is demonstrated using the machine tool coupled models.