Higher Depth Of Cut Research Articles

Mathematical model for cutting force in ultrasonic-assisted milling of soda-lime glass

Ultrasonic-assisted milling (UAM) has an outstanding performance in machining hard and brittle materials, such as glass. The cutting force which has been investigated both experimentally and theoretically is the key factor that affects the machined surface quality. This paper presents a mechanistic mathematical model for the axial cutting force in UAM of soda-lime glass. This model is based on the process mechanism of material removal and can be used to predict the cutting force without the need of performing actual experiments. The mathematical model is proposed taking into consideration two different material removal mechanisms, that directly affect the final material removed volume for the brittle material. The first model is the ductile model which is described by the ductile mechanism where the material is removed by the plastic flow, while the other is the brittle model described by the brittle mechanism where the material is removed due to the crack formation that cause material fracture. In the present models, the effects of both the rotation and ultrasonic vibration motion of the cutting tool were taken into consideration through their effects on the indentation volume, by each diamond grain, into the workpiece. The development of the model started by the analysis of the behaviour of a single diamond grain and obtaining the cutting force for an individual diamond grain first. The total cutting force then was derived by summing up the forces caused by all diamond grains taking part in the cutting process. From the developed models results, the trends of the predicted results from the ductile model agree well with the results determined experimentally at low feed rates and low depths of cut. However, the predicted results from the brittle model agree well with the results determined experimentally at high feed rates and high depths of cut. These results explain that the ductile mode of the material removal is occurring at low feed rates and low depths of cut. Then it changes to the brittle mode of material removal by further increasing of the feed rate and depth of cut.

Investigation into the performance of eco-friendly graphite nanofluid as lubricant in MQL grinding

In this study, the lubrication and cooling properties of eco-friendly graphite nanofluids in MQL grinding were investigated. Grinding forces, subsurface temperature of workpiece, surface roughness, micro-hardness and metallographic observations of ground surfaces were employed to evaluate the performance of synthesized nanofluids as lubricant under different grinding parameters. The results were also compared with grinding in dry, pure MQL and flood cooling conditions. The results showed that the tangential forces and force ratios in grinding using graphite nanofluid MQL are lower than that of other lubricating methods especially at extreme cutting parameters. Also, application of graphite nanofluid MQL reduced the grinding temperature at high velocities of workpiece. These reductions could be attributed to the formation of a tribofilm on the ground surface by the present of graphite nanoparticles in the wheel-workpiece interface. Additionally, the presence of this tribofilm in the contact area generated a smooth surface even at high depth of cut and velocity of workpiece. Furthermore, the micro-hardness of ground surfaces increased in graphite nanofluid MQL grinding because of infiltration of graphite nanoparticles in the grinding surface and the plastic deformation of subsurface of workpiece.

Investigation on Cutting Force, Flank Wear, and Surface Roughness in Machining of the A356-TiB2/TiC in-situ Composites

This article reveals the experimental investigation on the machinability of A356-TiB2/TiC in-situ composites prepared by a mixed salt reaction system. The fabricated composites are characterized by Energy dispersive analysis (EDAX), X-ray Diffraction (XRD), scanning electron microscopy (SEM) and micro-hardness analysis. Multi-coated tungsten carbide tool was used to examine the influence of TiB2/TiC reinforcement ratio on machinability behaviour of composites. The variations in cutting speed, feed rate and depth of cut upon cutting force, surface roughness and flank wear were examined. The experimental results revealed that the enhancement of a reinforcement ratio causes the decrease in cutting force and increase in flank wear and surface roughness. Higher flank wear is observed, when machining the A356-TiB2/TiC composites at higher cutting speed due to the generation of high temperature at the machining interface. The increment in surface roughness, flank wear and cutting force is experienced at higher depth of cut and feed rate. Further, the mechanisms of chip formation and surface generation under different machining parameters are addressed. The outcome of this experimental investigation helps to utilize the turning process for machining the in-situ composites at economic machining rate without compromising the surface quality.

Impact of Tool Geometry and Tool Feed on Machining Stability

Tool-workpiece dynamics is characterized by aperiodic responses in- cluding period-doubling bifurcation and chaos. As a state signifying the extent of machining instability, tool chatter in longitudinal turn- ing operation is a function of nonlinear regenerative cutting force, instantaneous depth-of-cut (DOC), and workpiece whirling. The ef- fects of tool geometry and feed rate per revolution on cutting stability are investigated using a comprehensive model previously reported in References [1–3]. The model configuration allows the coupled tool- workpiece motion relative to the machining surface to be studied in the Cartesian space as a function of spindle speed, instantaneous DOC, rate of material removal, tool geometry, and material imbal- ance induced whirling. It is found that chatter can be eminent using one set of tool geometry while, at the same DOC, be sufficiently sup- pressed by employing tool inserts of different geometric parameters. Nonlinearity of tool structure is shown to have a dominant effect on tool vibration amplitude. High feed rate contributes to stability at high DOCs, thus indicating that feed rate is among the parameters that impact cutting stability.

Surface roughness analysis of greater cutting depths during hard turning

Abstract Literally, hard machining describes machining of parts having hardness over 45 HRC. Besides its advantages like high metal removal rate, easiness of adapting to complex part geometries, possibility of dry cutting; this operation, which can substitute grinding in most cases, has some disadvantages. One of them is the significant increase of surface roughness due to tool wear even when the tool life limit is not exceeded. In this study, considering hard turning praxes, higher depths of cut (0.5 to 1.0 mm) were examined when dry turning AISI D2 cold work tool steel, through-hardened to 62 HRC. TiN coated mixed ceramic inserts (Al2O3 + TiCN) were employed in the operations. Relationship between surface roughness and cutting parameters (cutting speed, feed and depth of cut) was modeled and analyzed using a Box-Behnken response surface methodology (RSM) design. A linear model best described this relationship. Despite the higher depths of cuts, the surface roughness values achieved were comparable to th...

Investigating tool performance and wear when simulating bandsawing of nickel-based superalloy under interrupted orthogonal turning condition

© 2017, IMechE 2017. The manufacturing industries still face the most challenging job at hand to machine nickel-based superalloy, Inconel 718, efficiently and economically. In contrast to the extensive research efforts in secondary machining processes such as turning, milling and drilling, very little or no attention is paid on bandsawing of Inconel 718. This article presents an experimental investigation of machining Inconel 718 using carbide-tipped bandsaw teeth in a custom-made experimental facility. Cutting forces were measured during the bandsawing operation using a dynamometer, and the wear modes and mechanisms in the bandsaw teeth were investigated in a scanning electron microscope. Three different feeds or depths of cut (10, 20 and 30 μm) were employed with a cutting speed of 30 m/min during the machining tests. At smaller feed or depth of cut (10 μm), abrasive wear, adhesive wear and some degree of plastic deformation were identified as the governing mechanisms of tool wear. The higher depth of cut (30 μm) could cause cracking, chipping or premature failure of the carbide tip in bandsaw tooth. Strong welding of workpiece material to the cutting edge formed a built-up edge, which would impair the bandsawability due to the modification of the cutting edge. The higher depth of cut significantly improved the machining performance due to the reduction in specific cutting energy. However, it was not recommended to apply higher depth of cut as there were obvious possibilities of premature tooth failure. Machining force and specific cutting energy results along with chip characteristics were correlated with the tool performance and tool wear. The results of this investigation would be helpful for bandsaw manufacturers and end users to get a fundamental understanding of the bandsawability of Inconel 718 with the carbide-tipped bandsaw.

Optimisation of End Milling Machining Parameters Using the Taguchi Method and ANOVA of AlSi/AlN Metal Matrix Composite Material

Abstract. The purpose of this research is to determine the optimum machining parameter for Aluminium silicon alloy (AlSi) matrix composite, which has been reinforced with aluminium nitride (AlN), with three types of carbide inserts present. Experiments were conducted at various cutting speeds, feed rates and depths of cut, according to the Taguchi orthogonal array L27. The signal-to-noise (S/N) ratio and analysis of variance are applied to study the characteristic performance of cutting speeds, feed rates, depths of cut and types of tool in measuring the tool life during the milling operation. The analysis of wear was done using a Sometech SV-35 video microscope according to ISO 3686. Through Taguchi analysis, it is concluded that a combination of high feed rate, high depth of cut, low cutting speed and insert TiB2 give a longer tool life. Therefore, the cutting speed of 230 m/min, feed rate of 0.8 mm/tooth, depth of cut of 0.5 mm and type of insert of TiB2 were the optimum machining parameters. These optimum parameters will help the automotive industry to have a competitive machining operation from both economical and manufacturing perspectives.

A coupled dynamics, multiple degree of freedom process damping model, Part 1: Turning

Self-excited vibration, or chatter, is an important consideration in machining operations due to its direct influence on part quality, tool life, and machining cost. At low machining speeds, a phenomenon referred to as process damping enables stable cutting at higher depths of cut than predicted with traditional analytical models. This paper describes an analytical stability model which includes a process damping force that is dependent on the surface normal velocity, chip width, cutting speed, and an empirical process damping coefficient. Model validation is completed using time domain simulation and turning experiments. The results indicate that the multiple degree of freedom model is able to predict the stability boundary using a single process damping coefficient.

A coupled dynamics, multiple degree of freedom process damping model, Part 2: Milling

Self-excited vibration, or chatter, is an important consideration in machining operations due to its direct influence on part quality, tool life, and machining cost. At low machining speeds, a phenomenon referred to as process damping enables stable cutting at higher depths of cut than predicted with traditional analytical models. This paper describes an analytical stability model for milling operations which includes a process damping force that depends on the surface normal velocity, depth of cut, cutting speed, and an empirical process damping coefficient. Model validation is completed using time domain simulation and milling experiments. The results indicate that the multiple degree of freedom model is able to predict the stability boundary using a single process damping coefficient.

Experimental Investigations on Effect of Ceramic B4C Particulate Addition on Cutting Forces and Surface Roughness during Turning of 6061Al Alloy

ABSTRACTAluminium matrix composites are of great interest for researchers in recent years because of their excellent combinations of engineering properties over traditional materials. The machinability of these aluminium matrix composites has become vital for manufacturing industries. During machining of aluminium matrix composites, the cutting forces and surface roughness are dependent on machining parameters (feed rate, cutting speed and depth of cut) and manufacturing parameters (size of the particles, volume fraction, porosity, hardness). With this backdrop, the present work is aimed at investigating the effect of machining parameters, viz. cutting speed, feed rate and depth of cut on the cutting force components, namely, feed force (Ff), radial force (Fd), cutting force (Fc) and surface roughness. The experiments were performed on 0, 5, 7 and 9 wt% B4C particulate of 88 µm size reinforced composite specimens. The prepared specimens were subjected to turning operation on a conventional lathe machine using polycrystalline diamond (PCD) tool to evaluate the effect of B4C particulate addition with varying percentages on cutting forces and surface roughness. Results reveal that the cutting force components decrease with the increase in the wt% of ceramic B4C particulate reinforcement, which can be attributed mainly to increase in porosity, hardness and dislocation densities. SEM image obtained from composite having low wt% of ceramic B4C particulates (5 wt%), which is machined at higher cutting speed and higher depth of cut, has clearly shown the presence of built-up edge (BUE) at the tip of polycrystalline diamond tool. Further, cutting forces increased with increase in feed rate and depth of cut for both 6061Al matrix and 6061Al-B4C composites. It is observed that the surface quality is significantly improved when the cutting speed is increased, and depth of cut and feed rate are decreased.

Receptance coupling based algorithm for the identification of contact parameters at holder–tool interface

To identify stable cutting conditions with a high depth of cut, stability lobe diagrams are used. In order to predict these diagrams, frequency response functions (FRF) at the tool tip are required for every tool, holder and machine combination. To reduce the number of experimental tests, receptance coupling substructure analysis (RSCA) is proposed in the literature. In order to take full advantage of this method, contact parameters between holder and tool must be known. To identify these parameters this paper presents a new method based on free-free measurements. The obtained contact parameters led to good results for various tool lengths. Based on this, an extensive investigation is performed for the ER32 holder interface. Afterwards, the RCSA method is tested. Therefore, different spindle–holder–tool assemblies are modeled for two machine tools. Prediction and measurement of obtained tool-tip FRF shows a good match, especially for the frequency position.

Influence of nanofluid application on wheel wear, coefficient of friction and redeposition phenomenon in surface grinding of Ti-6Al-4V

Difficulties in the grinding of Ti-6Al-4V originate from the three basic properties: poor thermal conductivity, high chemical reactivity and low volume specific heat of the material. Under severe grinding conditions, all these factors together lead to the accelerated wheel loading and redeposition of chips over the work surface. Redeposition and wheel loading have a significant effect on the surface finish, grinding forces, power consumption and wheel life. In this study, water-based Al2O3 nanofluid as metalworking fluid is applied during the surface grinding of Ti-6Al-4V under minimum quantity lubrication mode after dressing the wheel with different dressing overlap ratios. The severity of the redeposition over the work surface was observed by measuring various surface profiles taken perpendicular to the grinding direction at several locations on the ground surface. The nanofluid application was able to prevent redeposition over work surface that became evident from the measured surface finish parameters that results along the grinding direction. Coefficient of friction was estimated On-Machine using the measured forces for different wheel work speed ratios, depth of cut and dressing overlap ratios. The results showed the effectiveness of nanofluid in reducing friction at high material removal rate (i.e. high depth of cut and high speed ratio) conditions when compared to the dry environment. From the measured forces variation with respect to the number of passes, it became evident that, nanofluid application delayed the frequency of wheel loading and grit fracturing cycle, which leads to the increase in the wheel life.

Performance of Silicon carbide whisker reinforced ceramic inserts on Inconel 718 in end milling process

An experimental investigation is planned in order to study the machinability of Inconel 718 with silicon carbide whisker reinforced ceramic inserts in end milling process. The relationship between the cutting speed, feed rate, and depth of cut against the response factors are studied to show the level of significance of each parameter. The cutting parameters are optimized by using Taguchi method. Implementing analysis of variance, the parameter which influences the surface roughness the most is determined to be the cutting speed, followed by the feed rate and depth of cut. Meanwhile, the optimal cutting condition is determined to have high cutting speed, low feed rate, and high depth of cut in the range of selected parameters.

TRIZ approach for machining process innovation in cryogenic environment

This paper presents the utilisation of TRIZ approach in machining process of AISI 4340 in cryogenic environment which lead to product improvement in turning process. The machining study is carried out in two stages; FEM simulation for finding the optimum condition and machining experiment to visualise the product improvement that involved plastic deformation. The simulation result revealed that at moderate to high cutting speed, high feed rate and high depth of cut will result in high temperature that enable for the change in phase of AISI 4340 from retained austenite to fully martensite. A sample from machining experiment at optimum cutting condition found that the microstructure changes beneath the machined until at the depth of ~7 µm with high hardness to 8,500 N/mm2 Martens hardness at the machined surface. This hardness is equivalent to the hardness obtained in conventional case hardening process that is required after the machining of AISI 4340 in their application as automotive engine parts in order to enhance these parts in their service lives. This study reveals that the TRIZ approach helps to systematically analyse the various outcomes in this study started with process limitation, problem identification, axiomatic and Su-field analysis.

Effect of reinforcement on the cutting forces while machining metal matrix composites–An experimental approach

Hybrid metal matrix composites are of great interest for researchers in recent years, because of their attractive superior properties over traditional materials and single reinforced composites. The machinabilty of hybrid composites becomes vital for manufacturing industries. The need to study the influence of process parameters on the cutting forces in turning such hybrid composite under dry environment is essentially required. In the present study, the influence of machining parameters, e.g. cutting speed, feed and depth of cut on the cutting force components, namely feed force (Ff), cutting force (Fc), and radial force (Fd) has been investigated. Investigations were performed on 0, 2, 4, 6 and 8 wt% Silicon carbide (SiC) and rice husk ash (RHA) reinforced composite specimens. A comparison was made between the reinforced and unreinforced composites. The results proved that all the cutting force components decrease with the increase in the weight percentage of the reinforcement: this was probably due to the dislocation densities generated from the thermal mismatch between the reinforcement and the matrix. Experimental evidence also showed that built-up edge (BUE) is formed during machining of low percentage reinforced composites at high speed and high depth of cut. The formation of BUE was captured by SEM, therefore confirming the result. The decrease of cutting force components with lower cutting speed and higher feed and depth of cut was also highlighted. The related mechanisms are explained and presented.

Characterization of grinding wheel grain topography under different robotic grinding conditions using confocal microscope

Knowing the grain geometry in grinding wheels is an asset for better understanding the grinding processes. This study investigates the grain protrusion and rake angles of two self-dressing zirconia-alumina grinding wheels in a robotic grinding process. The topography of the wheel is measured using a confocal scanning laser microscope. An optical image of the surface is used to create a mask of the grains with image processing techniques. Grain geometry information is then obtained by applying the mask to the entire surface. A vertex normal technique is used to find the cutting edges facing the cutting direction and only consider those edges in grain rake angle calculations. Surface parameters, including grain density, width, protrusion height, and rake angle, are extracted from the topography. The grinding wheel is characterized in low, medium, and high depths of cut in the range of robot operation. Results indicate that grain density, width, and protrusion height distribution are not affected by the depth of cut. It is also found that in shallow grinding, grain rake angle shifts slightly to higher negative angles; whereas, with a higher depth of cut, sharper edges exist on the wheel surface, which improve process efficiency.

Effects of Abrasive Types on Grinding of Chopped Strand Mat Glass Fiber-Reinforced Polymer Composite Laminates

A grindability study of chopped strand mat glass fiber reinforced polymer laminates (CSM GFRP) has been carried out to evaluate the effects of abrasive types on grinding force ratio and area roughness at varying grinding parameters such as speed, feed and depth of cut. Performances of alumina (Al2O3) and cubic boron nitride (CBN) wheels were compared. Both wheels delivered the maximum grinding force ratios at low speed, high feed and low depth of cut. Alumina wheel produced smoother surface when grinding at low speed, low feed and high depth of cut. CBN wheel, on the other hand, gave smoother surface at high feed and low depth of cut conditions, regardless of speed. With CBN wheel, it is likely that a single grinding condition exists that maximizes grinding force ratio and minimizes area roughness. The findings indicate that CBN wheel exhibited higher grinding force ratio than alumina grinding wheel in general. CBN grinding wheel also outperformed alumina grinding wheel by producing smoother ground surface in most cases.

Surface Roughness of Milled Sheet Molding Compound Composites

Sheet molding compounds (SMC) are alternative materials in manufacturing of structural components, automotive components and electrical resistant parts, due to their high strength, light weight, easy formation and low material cost. However, machining is demanded as a secondary process for achieving the nal shape of the part for assembly. During machining of SMC composites, some problems are faced because of the di erent machining characteristics of polymer matrix and ber reinforcement. In this study, commercial SMC composite including 25 wt.% polyester, 30 wt.% glass ber and 45 wt.% calcium carbonate, was milled under di erent depth of cut, feed and cutting speed. Taguchi experimental design was used to determine the e ectiveness of the parameters. After the slots were milled, the roughness of the machined surfaces was investigated and it was found that lower feed, higher depth of cut were more e ective than cutting speed in decreasing surface roughness.

Thermal Analysis of Creep Feed Grinding

Creep feed grinding is an abrasive finishing process characterized by low feed speeds (0.05-0.5 m/min) and very high depths of cut (0.1-30mm). Thanks to the extraordinary material removal rate provided together with a high shape accuracy obtained over complex profiles, this process has become the main competitor of milling. However, creep feed grinding has also some limitations that should be overcome. The major limitation is the thermal damage on the machined part and the rapid wheel wear. Since heat distribution depends strongly on the workpiece geometry, a 3D FEM thermal model has been programmed for the generation of a square in order to study the effect of the side wall height on the heat distribution on both, the wall and the ground part. Thermal model has been validated by means of experimental tests being the heat ratio to the workpiece the adjusting parameter. General results show that the higher the side wall, the higher the temperatures. Friction between the wheel and the side wall contributes to higher power consumption.

Analysis and optimisation of machining parameters in micro turning using RSM

Miniaturisation of industrial products has been the trend of technological development for creating smaller and precision components which plays an important role in today's need. Titanium alloy Gr.2 is one of the most extensively used Ti alloys for high temperature application components, because of its low weight and high strength even at elevated temperatures for applications like aerospace gas turbine compartments. In this paper, the performance of micro turning of titanium alloy with cermet insert is investigated using response surface methodology and Box-Behnken design (BBD). Two empirical models have been developed for predicting the tool wear and surface roughness. The analysis reveals that the cutting speed and feed rate are more influencing parameters on responses. The optimisation results showed that the combination of medium spindle speed, feed rate, and high depth of cut are necessary to minimise the tool wear and surface roughness. A verification experiment is conducted and compared.