On the Light Cutting of the Hardened Steel SAKAMOTO, Masafumi; MATSUNO, Jun'ichi
Journal of the Japan Society of Precision Engineering,
1980/08/05, Letnik:
46, Številka:
8
Journal Article
Odprti dostop
In order to clarify the basic characteristics of the cutting of the hardened steel, an experimental study was carried out on various workpieces with different hardnesses, cutting velocities and tool ...rake angles. It is observed from the work that the form of chip can be classified into three types and their forms are influenced by the cutting velocity and the workpiece hardness. The thin chip thickness is obtained in the range of high hardness and relatively higher cutting velocity. On the condition that the thin chip is found, the cutting force is small and shear zone temperature rise is low for its hardness. There is close relation between the increase of hardness and velocity on cutting results. It is tried to consider hardness and velocity collectively, and a conception of equivalent cutting velocity was proposed.
Nicks engraved on the cutting edges of a twist drill split the chips into narrow bands which can easily flow out of the hole through the flutes of drill. As the result, the performance of the drill ...is improved considerably, especially when the depth of hole exceeds its diameter. Experiments in this paper show the effects of nicks such as lowered torque, smoother surface finish, diminished bur at the outlet of hole and the prolonged drill life : In a series of drilling test of φ 6 holes in 0. 45% C steel, nicks prolong the drill life up to ten times as long or even more. For the higher productivity, feed rate can be increased by about 30% without shortening drill life.
In the machining of difficult-to-cut alloys, such as titanium-based alloys, the delivery of a cutting fluid with high pressure can increase machining efficiency and improve process stability through ...more efficient chip breaking and removing. Proper selection of machining conditions can increase the productivity of the process while minimizing production costs. To present the influence of cutting fluid pressure and chip breaker geometry on the chip breaking process for various chip cross-sections Grade 5 ELI titanium alloy turning tests were carried out using carbide tools, H13A grade, with a -SF chip breaker geometry under the cutting fluid pressure of 70 bar. Measurements of the total cutting force components for different cutting speeds, feeds, and cutting depth in finishing turning were carried out. The analysis of the obtained chips forms and the application area of the chip breaker have been presented. It was proved that for small depth of cut (leading to small chip cross-section) the cutting fluid pressure is the main cause of the chip breakage, since the insert chip breaker does not work. On the other hand, for bigger depths of cut where the chip breaker goes in action, the cutting fluid pressure only supports this process. For medium values of depths of cut the strength of chip is high enough so that the pressure of the cutting fluid cannot cause chip breaking. A chip groove is not filled completely so the chip breaker cannot play its role.
Conventional cutting fluids are being used to control the amount of heat generated during machining. The use of these cutting fluids results in a higher machining cost and poses a hazardous effect on ...the operator and environment. The application of vegetable oils-based minimum quantity lubrication (MQL) is one promising alternative to avoid the use of conventional cutting fluids. Considering these facts, in this work, turning operations are performed on AISI 4140 using coated carbide insert and using castor oil under MQL. The MQL parameters (lubricant type, air pressure, and flow rate) are optimized with the Taguchi design of experiments L
9
orthogonal array, signal-to-noise (S/N) ratio, and analysis of variance (ANOVA) by considering surface roughness. In the second section, cutting speed, feed, and depth of cut are selected as input parameters, while surface roughness, power consumption, and chip-tool interface temperature are chosen as output responses with optimized MQL parameters. Jaya algorithm, which requires only the common control parameters and does not require any algorithm-specific control parameters, is utilized for the multi-objective optimization of output responses. The optimum results are achieved at high cutting speed, low feed rate, and increased depth of cut. Finally, an experimental investigation is carried out to analyze the performance of MQL and solid lubricant-assisted MQL with the optimized MQL and machining parameters. The findings revealed the effectiveness of MQL and MQL-solid lubricant application in form of reduction in flank wear and surface roughness. Also, the improved surface finish and favourable chip forms are obtained under MQL and MQL-solid lubricant application. The presented approach with optimized parameters can be utilized to achieve improved machining performance.
Sustainability has been a major concern of today’s manufacturing industries. Various efforts have been made to improve the productivity and performance of machining. It is always aimed to reduce the ...heat generated during machining by various cooling and lubrication approaches. In the present work, efforts have been made to assess the effectiveness of minimum quantity lubrication and solid lubricants in machining. Experiments have been performed under MQL and MQSL environment with selected flow rate (300 ml/hr), 20 wt% of calcium fluoride (CaF2) and 10µm particle size of solid lubricant and results are compared with dry and flood cooling environment. The process performance is observed by measuring surface roughness produced, tool flank wear, the microhardness of machined workpiece, and forms of the chip produced. Results revealed the superiority of lubricant mixture applied in form of MQSL due to enhanced lubricating properties imparted by solid lubricant added with MQL.
Purpose
This study aims to detect the temperature distribution in the cutting zone during the machining process. Furthermore, temperature influence in the cutting zone on the forms of chip shapes ...during the turning of Steel 30CrNiMo8 was evaluated. It is very important to use optimal machining parameters to get the best production results or for high control of the machining process.
Design/methodology/approach
Temperature distribution in the cutting zone during the machining process could affect the forms of chip shapes. Forms of chip shapes could be considered as the most important indicator for the quality of the machining process.
Findings
Therefore, in this study, the forms of chip shapes based on the temperature distribution in the cutting zone were examined.
Originality/value
It was found that the snarled chip type and the loose chip type have the highest temperature variation during the machining process.
White layers formed in machining of hardened alloys are known to be very hard and resistant to standard etchants used in metallographic studies. Many studies have been performed on this subject, but ...only with little progress showing definite results concerning the actual effectiveness of white layer formation. Hence, the basic question that remains unanswered is: are the white layers a tribological advantage for the manufacturing industry producing parts/components from hard alloys? The focus of this study is to investigate the evolution of white layers produced during progressive tool flank wear in dry hard turning with CBN (cubic boron nitride) tools, and to correlate this with the surface integrity of the machined surface. The following four materials were machined: X160CrMoV12 cold work steel (AISI D2), X38CrMoV5 hot work steel (AISI H11), 35NiCrMo16 high toughness steel and 100Cr6 bearing steel (AISI 52100). Samples of chips were metallographically processed and observed under an electronic microscope to determine whether white layers are present or not. More specifically, chip-forms/shapes were studied to determine how they developed during machining with potential appearance of white layers, with a view to correlating the chip-forms/shapes with the white layer formation. Finally, by using scanning electron microscopy and EDS techniques on these chip samples, properties and microstructures of white layers were deduced in order to verify some of the prevalent theories.
This paper presents recent developments in chip control research and provides major applications in tuming operations involving the use of complex grooved tool inserts. On the basis of the basic chip ...morphology presented by
Nakayama (1984), four major parameters contributing to complex 3-D chip curl are identified: chip back-flow, chip up-curl, chip side-flow, and chip side-curl. A summary of past research in each of these four categories is presented as well as a description of an attempt to combine these parameters into one readily measured variable. An analysis of cyclic chip formation is then presented with experimental evidence from high-speed filming of the chip curling and breaking processes. The most commonly known “chip chart” technique is then described. The paper concludes with details of an attempt to develop a computer-aided process planning system incorporating a predictive capability for chip breakability in turning operations.
PDF
