Machining Of Gray Cast Iron Research Articles

Plasticity Resource of Cast Iron at Deforming Broaching

The contact interaction mechanics of deformation broaching in low-plasticity materials is studied. Particular attention is paid to the study of the stress–strain state parameters and the plasticity margin in the deformation zone during the machining of gray cast iron EN-GJL-200. The stress–strain state was analyzed using a finite-element model of the deforming broaching process for each area of the deformation zone. The model parameters of the machined material were determined experimentally by compressing specimens of gray cast iron EN-GJL-200. The changes in the parameters of accumulated strain, stress tensor components, stress triaxiality ratio, hydrostatic stress, and plasticity margin at different deformation zones along the machined specimen depth are analyzed. It is shown that there is a zone of local plastic deformation in conditions of critical contact stresses. This leads to the appearance of tensile stresses that reduce the plasticity margin in the surface layer. The impact of tool geometry on the stress–strain state of the surface layer is also discussed, and recommendations for the optimal working angle of the deforming element are provided based on plasticity margin minimization.

Studying and Improving the Hardness Properties of Gray Cast Iron

This research focuses on the hardness of gray cast iron. Hardness is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. The machinability cannot set a specific definition. However, several indicators and directories give a clear image, the most important of which is the factors that affect the machinability of gray cast iron according to the metallurgies and the metal cutting and cutting conditions. The main goal of this research is to improve the hardness of gray cast iron. Many experiments on several samples to get different results and then compare these results to get the best which is the goal of the research. The conclusions through the practical side of this research are the different values of hardness through the different hardening processes. As the hardening processes gave a sample of grey cast iron a hardness value that differs in each type of hardening. The notes through the graph that the hardness reaches its peak in the traditional hardening, where its value is (370.6), followed by the laser hardening process, which reaches (321.6) The amount of increase between the hardness of the laser and the traditional hardness takes the value of (15.24 %) The work on samples in the form of aggregates, and each group will be treated in a specific way and then subject to tests.

Coated CBN cutting tool performance in green turning of gray cast iron EN-GJL-250: modeling and optimization

The present research investigates the performance of a TiN/PVD-coated CBN7050 tool when turning the gray cast iron EN-GJL-250. This is performed through carrying out two series of tests. The first are parametric tests aiming at evaluating the effect of each cutting parameter, i.e., the cutting speed, the feed rate and the depth of cut on the cutting forces, the cutting pressure, the surface roughness, and the cutting power. The second series of tests concern the modeling that would lead to predicting the output parameters. Both the analysis of variance and the response surface methodology are selected to develop the relationship between the input factors (Vc, f, and Doc) and the output parameters. The tests are carried out according to the Taguchi design (L27). The derived models are used to perform a multi-objective optimization of the cutting parameters through the application of the desirability function approach (DFA) for four objectives. Furthermore, the CBN7050 tool wear behavior was investigated during the machining of gray cast iron EN-GJL-250. Tool lives reached 7, 18, and 41.5 min when Vc was varied from 450, 600, to 750 m/min, respectively. Finally, a topographical analysis of the machined surface 3D roughness was carried out for different cutting parameters and led to displaying the texture of the surfaces.

Chatter Investigation on Machining of Gray Cast Iron Considering the Damping Effect

In recent years, the study of chatter vibrations has been intensifying in the machining of materials. In this paper an investigation of this phenomena was conducted for gray cast iron (CGI). The chatter vibrations in machining process can considerably compromise the workpiece surface finish, tool wear and in some cases provide severe damage to the machine-tool. Thus there is an imminent need to expand the theory of chatter vibrations for the class of brittle materials. To analyze the vibrations of the process of machining and zones where the process is stable, and where it is unstable, the stability lobes diagram was used. This diagram is constructed at low speed cutting, where the phenomenon of damping arises. The damping is a crucial factor in the process, it increases system stability. This effect was considered in the formulation of chatter vibrations using the indentation model of Wu. For experimental validations the signals of cutting force were acquired and analysis was conducted in frequency domain to identify where the vibrations emerged allied with a roughness analysis of the workpiece. The results demonstrated perfectly the consequences of chatter vibrations in surface finish of grey cast iron and proved that the stability lobes diagram provides good results to detect these vibrations, determining the areas where the material removal should be avoid.

Tool Wear Mechanisms of pcBN tooling during High-Speed Machining of Gray Cast Iron

The presence of graphite particles in gray cast iron commonly implies a good machinability, especially if compared to common steels. However, increasing industrial demands have resulted in a new interest for high-speed machining of these materials with higher performing tool materials than the traditionally used. Thus, the research presented in this paper focuses on evaluating the active tool wear mechanisms while high-speed machining EN-GJL-250 gray cast iron with pcBN tools with different composition, geometries and edge preparations. In addition to the expected flank and notch wear, formation of MnS, SiO2, and Al2O3 tool protection layers was found on the worn surfaces. Non-chamfered tools exhibited higher tendency towards notching. In general, the tools were found to have a rather small wear land but large edged radius indicating edge rounding being a more accurate wear criterion.

Surface feature formation mechanism during finish milling of gray cast iron

Gray cast iron (GCI) is highly anisotropic at the microscale consisting of stochastically distributed and orientated graphite flakes within a ferric matrix. The anisotropy of the microstructure endows gray cast iron with favorable damping characteristics which makes it a common material for machine tool structural components. However, the microstructure inhibits the formation of a finished surface of sufficient quality for use as a slideway when milled with a defined cutting edge. The mechanisms of irregular surface formation during the machining of GCI were investigated using both a 3-D finite element cutting simulation and milling experiments. Investigation of simulation and machining tests indicates that the interaction of the primary shear zone in front of the cutting edge and graphite flakes is the cause of microcavity formation on the machined surface.

Surface Formation Study Using a 3-D Explicit Finite Element Model of Machining of Gray Cast Iron

Gray cast iron is the material of choice for machine tool structural components. However, since cast iron is a multiphase, anisotropic material it is difficult to machine to a high quality surface finish. To gain insight into the surface formation mechanisms during the machining of gray cast iron an explicit 3-D finite element cutting simulation was developed. To capture the anisotropic nature of gray cast iron flakes were modelled using zero thickness cohesive elements embedded in a pearlite matrix modelled using solid elements. The simulated cutting forces, surface formation, and finished surfaces were examined.

Continuous and varied depth-of-cut turning of gray cast iron by using uncoated and TiN/Al2O3 coated silicon nitride-based ceramic tools

Silicon nitride-based (Si3N4) ceramic cutting tools are particularly good for high speed machining of gray cast iron due to their high red hardness, wear resistance and chemical stability with gray cast iron. However, the intrinsic brittleness of Si3N4 ceramics makes the cutting tools easy to be damaged when subjected to impact force. In the present work, turning tests on gray cast iron were carried out by using uncoated and CVD TiN/Al2O3 coated Si3N4 cutting tools under continuous turning and varied depth-of-cut turning. Tool wear, tool life, chemical composition on worn flank faces and failure mechanism of the cutting tools after turning tests were studied. The results show that the improved cutting performance of the coated cutting tools can be attributed to the increasing wear resistance and toughness of the cutting tools with the covering of TiN/Al2O3 coatings, both in continuous and varied depth-of-cut turning. The dominant failure mechanism of the cutting tools was abrasive wear in continuous turning and a combination of abrasive wear and chipping in varied depth-of-cut turning. In addition, adhesive wear also found to play a role in the tools failure to some extent for both uncoated and coated Si3N4 cutting tools in continuous and varied depth-of cut turning.

Effects of Seasoning and Stress Relief Annealing on Machinability of Gray Cast Iron

Effects of Seasoning and Stress Relief Annealing on Machinability of Gray Cast Iron

Applying an Improving Measurement of Cutting Force to Study Machinability of Gray Cast Iron

In order to study the machinability of gray cast iron, the cutting force must be precision measure. An improving measurement based on strain gauge dynamometer has been proposed in this paper, the measurement changed the traditional calibration method of strain gauge dynamometer. A set of new calibration device have been designed. Use the device, the process of calibration could be made after the strain-gauge dynamometer for cutting force measuring fixed on lathe, in this way, the states of calibration and measuring in experiment achieved same, and the error of measuring which had been begot by the differ states of calibration and measuring could be eliminated. The results of experiment show that the method presented in this paper achieved high precision and low cost cutting force measuring, and the results of cutting force measuring could be used for estimating machinability of gray cast iron.

Control of parameters of the cutting process on the basis of diagnostics of the machine tool and workpiece

A method of control of cutting parameters without direct measurement of these parameters on a machine tool in the course of machining based on diagnostics of the tool and the workpiece is considered. Implementation of the method is demonstrated in machining of gray cast iron. The method may be used, for example, in real-time cutting control systems.

Dimensional Tolerance and Machinability of Gray Cast Iron

Dimensional Tolerance and Machinability of Gray Cast Iron

The Improvement of Machinability of Gray Cast Iron Using Nonmetallic Inclusions in High Speed Cutting (2nd Report)

This paper deals with machinability in high-speed face milling of gray cast iron to which small quantities of Al and Mg were added. The machinability of Al-Mg-added gray cast iron was evaluated in face milling with cermet inserts at cutting speed from 100 to 1000 m/min in comparison with conventional gray cast iron and Al-added gray cast iron. In the face milling of conventional gray cast iron and Al-added gray cast iron, the wear increased significantly as the cutting speed increased. The wear pattern of tools in the milling of these irons were almost the same, and the thermal cracks similarly occurred in both cases. On the other hand, the addition of both Al and Mg has drastically decreased the wear rate and the wear hardly progressed even in prolonged cutting length after initial wear. The amount of the adhesion on tool faces increased as the cutting speed increased. The adhered layer mainly consisted of the elements added to the work material. As this result, the increase cutting speed resulted in the thick adhered layer and the reduction of tool wear. Furthermore, the small addition of Al and Mg prevented the thermal cracks in the face milling of the gray cast iron.

Effect of inoculating addition on machinability of gray cast iron

Gray cast irons were inoculated with FeSi75+RE and FeSi75+Sr inoculants. The changes of apex angle of the drills before and after being used were used to evaluate machinability of gray cast irons. Effect of FeSi75+RE and FeSi75+Sr inoculants on mechanical properties, machinability and sensibility of gray cast iron used in cylinder block were investigated. Experimental results showed that gray cast iron treated with 60%FeSi75+40% RE inoculants exhibited tensile strength consistently at about 295 MPa along with good hardness and improved metallurgical quality. While gray cast iron inoculated with 20%FeSi75+80% Sr inoculants exhibited the best machinability, the lowest cross-section sensibility and the least microhardness difference. The tool flank wear of the drill increased correspondingly with the increase of the microhardness difference of the matrix, indicating the great effect of homogeneity of the matrix on the machinability of gray cast iron.

The Improvement of Machinability of Gray Cast Iron Using Nonmetallic Inclusions in High Speed Cutting

Al, Mgを機械的性質や鋳造性に影響のない範囲で微量添加した片状黒鉛鋳鉄を製作しサーメット工具で高速乾式旋削した結果, 微量添加した元素を主成分とする保護皮膜が工具表面に生成され一般的な片状黒鉛鋳鉄の切削時に比べ工具摩耗は大幅に抑制された. 特に切削速度700m/minで切削した際の工具摩耗抑制効果は顕著であった.

Possibility of High Speed Machining of Gray Cast Iron

Possibility of High Speed Machining of Gray Cast Iron

Wear properties of coated ceramic tools in high speed machining of gray cast iron

The toughness of ceramic cutting tools made of silicon nitride (Si 3 N 4 ) is improving in recent years. The nose of tool, however, wears out when cutting is performed at high speed condition, and consequently the life of the tool comes to an end. In order to reduce nose wear, the effects of coating with hard materials on the resistance of the Si 3 N 4 ceramic tool to wear were investigated. Coating the Si 3 N 4 tool with TiN+TiC+Al (ON) using the chemical vapor deposition (CVD) method proved effective for reducing nose wear as compared to when it was not coated and coated with Al 2 O 3 . The nose wear of the TiN+TiC+Al (ON) -coated Si 3 N 4 tool was reduced most effectively when applied with 6-layer coating. The nose wear in the coated Si 3 N 4 tool was found to be determined by the coating in the tool land and wear end of tool. Based on the obtained knowledge described above, a novel coating method was developed in which 3-layer coating was applied to the land part of the tool, and 6-layer coating to the other part.

ＳｉＣホイスカ強化セラミック工具の切削特性

Cutting performance of SiC-whisker (SiCw) reinforced ceramic tools on the machining of gray cast iron was investigated. In continuous dry cutting, the toughened Al2O3 + SiCw tool exhibited a stable and prolonged tool life compared to the Al2O3 + TiC tool. The life of the Al2O3 + SiCw tool was about twice as long as the Al2O3 +TiC tool at the optimum cutting condition. Since groove wear was inhibited by the whiskers incorporation, the surface roughness of the workpiece after cutting was improved, resulting in the possibility of using the tool for finishing operation. Nevertheless, SiCw reinforced ceramic tool can not be applicable for cutting of the cast iron containing a large amount of ferrite phase. In the interrupted cutting, a significant improvement of the tool life due to whisker reinforcement was observed in the alumina based tools compared to silicon nitride based tools. However, the SiC-whisker incorporation was effective for inhibiting the groove wear for both alumina and silicon nitride based tools.

Process-controlled machining of gray cast iron

Prior research (ref. 1) reported a model to predict surface roughness for specified values of cutting tool nose radius, feed rate, cutting speed and tool wear. The model is based on experimental data from finish turning of gray cast iron using uncoated tungsten carbide inserts. The results suggest that feed rate and cutting speed can be modified to produce a specified surface roughness in the presence of increasing levels tool wear. The method used in the paper to calculate values of feed rate and cutting speed is based on a multiple objective goal programming optimization scheme. The method predicts optimal machining conditions under the conflicting objectives of maximal production rate and minimal cost, subject to realistic constraints imposed by the capability of the machine tool and restrictions on the process parameters. Further adjustment of the cutting parameters is then made based on specified values of surface roughness and levels of tool wear.

Effect of copper on the thermal conductivity, wear resistance, and machinability of gray cast iron

1. Copper markedly increases the thermal conductivity of acast iron as a result of which there is an increase in its wear resistance and machinability. 2. Under thermal cycling conditions copper separates in the form of a thin film at the cast iron surface and also preferentially at other interphase surfaces of the metal which gives it a positive role. 3. To a greater extent than for nickel, copper reduces the tendency of cast iron towards cementite formation at the surface, which makes it possible to alloy it with increased amounts of carbide-forming elements (Cr, Mn, V). 4. As a result of additional alloying with copper it is possible to exclude entirely scarce and expensive nickel from wear-resistant highly alloyed cast irons.