Large Nose Radius Research Articles

Experimental Investigation and Optimization of Coaxiality Error Analysis with CNC Turning Process on Delrin for Assembly Fit

This paper mainly deals with the machining operation like turning operation, Material Removal Rate and Surface Roughness are the important parameter which is to be considered for quality product. The material selected for the experiment is DELRIN 500. Turning is one of the important processes that is widely used to create cylindrical components and it is also used for surface finish the product to make it smooth. Nowadays, plastic materials are widely used for making variety of components. To make a component with high dimensional accuracy, turning operation is used. The main concerns of turning are tooling cost and the effect of process on machinability characteristics. It can be seen that the output responses value has a minimum roughness average and a high degree of geometrical quality precision. High degree surface finish is induced by medium speed, feed rate, and small nose radius. The coaxial error was minimized by using medium speed, feed and larger nose radius. Experimentally found that third specimen (RPM -750) (FEED -0.08 mm/Rev) and (NOSE RADIUS 0.8) obtained minimum geometrical error along with minimum Surface roughness. Delrin is a crystalline plastic that offers an excellent balance of properties that bridge the gap between metals and plastics. Delrin possesses high tensile strength, creep resistance and toughness. It also exhibits low moisture absorption

Investigation and Statistical Analysis for Optimizing Surface Roughness, Cutting Forces, Temperature, and Productivity in Turning Grey Cast Iron

This paper investigated the influence of cutting parameters, including feed rate, cutting speed, tool nose radius, and wet or dry cutting conditions, on the resultant force, cutting edge/workpiece temperature, and surface roughness when turning grey cast iron. Results showed that increasing the feed rate increased the resultant force, cutting temperature, and surface roughness. At the same time, increasing the cutting speed and nose radius increased the cutting temperature, which in turn reduced the resultant force. For practical applications, basic mathematical calculations based on the sole effect of each parameter on the output of the experiments were used to estimate the extent of percentage increase in cutting temperature due to increasing feed rate, cutting speed, and nose radius. Similarly, the same approach was used to estimate the effect of increasing feed rate, cutting speed, and nose radius on average surface roughness. Results showed that increasing the feed rate increases the cutting temperature by 5 to 11% depending on the nose radius and cutting speed. On the other hand, increasing the cutting speed was found to have limited effect on cutting temperature with small nose radius whereas this effect increases with increasing the nose radius reaching about 11%. Increasing the nose radius also increases the cutting temperature, depending mainly on cutting speed, reaching a maximum of 21% at higher cutting speeds. Results also showed that increasing the feed rate increased the average surface roughness considerably to about 120% at high cutting speeds and a large nose radius. On the other hand, increasing the cutting speed and nose radius reduced the surface roughness (i.e., improved surface quality) by a maximum of 29 and 23%, respectively. In order to study the combined effects of the cutting parameters on the three responses, namely, the resultant cutting force, cutting temperature, and surface roughness, full factorial design and ANOVA were used, where it was found to be in good agreement with mathematical calculations. Additionally, the desirability function optimization tool was used to minimize the measured responses whilst maximizing the material removal rate.

Application of Taguchi’s Orthogonal Array and S/N Ratio on Surface Roughness Optimization

Surface finish plays an important role in making quality products in the manufacturing sector. A turning experiment is conducted by cutting tool of nose radii (1 mm and 0.65 mm) to find its influence on surface roughness. Eight experiments were performed with Taguchi’s Orthogonal Array (OA) technique. The prime objective was to investigate the tool nose radius effects in the prediction of the optimum value of surface roughness. Cutting speed (V), feed (F), depth of cut (D), and tool nose radius (NR) were selected for the experimental work having two levels each. To find out the influential parameters analysis of variance (ANOVA) was carried out. Signal to noise ratio and average performance graph was analyzed to obtain optimum response values. The results concluded that the large nose radius develops a superior finish in comparison to the smaller one.

A Numerical Model for Predicting the Effect of Tool Nose Radius on Machining Process Performance during Orthogonal Cutting of AISI 1045 Steel.

This paper presents the development of a numerical model for predicting and studying the effects of tool nose geometries and its interactions with cutting parameters during orthogonal cutting of AISI 1045 steel. The process performance characteristics studied were cutting temperature, effective stress, cutting forces and tool wear. The cutting simulations were done using the commercial DEFORM-2D R V 11.3 software, based on the finite element method (FEM). The cutting tool used had a round nose with various nose radii (0.01–0.9 mm), while the machining parameters tested were the feed rate (0.1–0.3 mm/rev), the cutting speed (100–500 m/min) and the rake angle (–5° to +10°). The interactions between the tool nose radius and the cutting parameters (speed, feed) were found to affect mostly the cutting stress and, slightly, the tool wear rate. These interactions did not much influence the cutting temperature, that was found to be high when the tool nose radius and/or the cutting speed were high. The maximum temperature was found to occur at the middle of the tool-chip contact length and at the interaction of nose radius and flank face of the tool. Except for some fluctuations, there was no significant difference in tool wear rate between small and large nose radius scales.

Effect of Tool Geometry and Turning Parameters on Cutting Force during Ultra-Precision Diamond Machining of Rapidly Solidified Aluminum (RSA) Alloy 6061

The most important goal of advanced diamond machining is to improve precision and product integrity. Cutting force could have a strong effect on diamond machining performance and hence, it can be used as an indicator for monitoring tool condition for achieving successful machining. Moreover, diamond machining process parameters such as cutting speed, depth of cut and feed rate may strongly influence the process outcomes in terms of surface roughness and tool failure. Diamond machining parameters have a significant role on the cutting force values, and machine-tool stability during ultra-high precision machining that makes use of a natural diamond cutting tool. The main objective of this research work is to investigate the effect of cutting speed, feed rate, depth of cut and nose radius on the cutting force generated during diamond turning of a rapidly solidified aluminum alloy grade called RSA 6061. The effect of nose radius and cutting parameters on cutting force during the ultra-high precision diamond turning process was monitored. The study shows that low speed, low depth of cut and an increase in feed rate at large nose radius consequently results in increase in the cutting force.

Novel geometrical design of turning inserts for high-efficiency smooth-surface high-chatter-stability cutting

This paper presents a novel geometrical design of inserts to realize high-efficiency smooth-surface high-chatter-stability turning. Inserts with a nose radius are used in turning to realize a smooth surface since the theoretical surface roughness Rth=f2/(8r) where f is the feed rate and r is the radius of the nose part. Since the size of the nose radius is limited because of the chatter stability, i.e. a large nose radius tends to cause chatter, the feed rate has to be kept small so that the acquired roughness is acceptable. Hence, the efficiency is limited. In this study, a novel turning insert geometry is proposed to realize high chatter stability along with a high efficiency and a smooth surface. The proposed insert geometry is verified by analyses and experiments.

Prediction of surface roughness and cutting forces using RSM, ANN, and NSGA-II in finish turning of AISI 4140 hardened steel with mixed ceramic tool

This paper aims at modeling surface roughness and cutting force in finish turning of AISI 4140 hardened steel with mixed ceramic tool. For this purpose, an attempt is made to improve prediction by using Artificial Neural Networks (ANN) technique. The effects of the process inputs, namely cutting speed, depth of cut, feed rate, and tool nose radius on the output responses are evaluated using response surface methodology (RSM). Also, this paper provides a profound examination of the surface roughness through the bearing area curve analysis (BAC) of the three-dimensional topographic maps of the machined surfaces, where relevant criteria representing surface roughness are used. It was established that machining with larger nose radius and lower feed rate produces surfaces with better functional characteristics and that the undesired effect of feed rate can be reduced by increasing the cutting speed. Desirability function approach (DF) and the Non-dominated Sorting Genetic Algorithm (NSGA-II) coupled with ANN models are used to solve different multi-objective optimization problems. It is found that NSGA-II is more efficient than DF method and offers diverse sets of non-dominated solutions that satisfy the requirements of parts quality, productivity, and cutting force, which lead to better competitiveness. Furthermore, the NSGA-II coupled with ANN models allowed to predict minimal value of Ra much less than the values of the experimental data.

Precision cutting of single crystal silicon using CBN tool with large top corner radius

A lot of studies on the ultra-precision cutting of single crystal silicon have been reported and they used the diamond cutting tools. However, the diamond cutting tools are very expensive. Therefore, if the single crystal diamond tools were replaced with sintered CBN tools, the cost of machining could be fairly reduced. However, it is easily expected that the CBN tools wear out faster than the diamond tools. Therefore, it is very important to find out the optimum cutting conditions in order to reduce tool wear. In this study, precision cutting of single crystal silicon was machined with using CBN cutting tools having chamfer at cutting edge and large nose radius, and the effect of feed rate, cutting speed, depth of cut and nose radius on the tool wear were studied. As a result, the local minimum of width of flank wear land appeared at the feed rate of 30~50 µm/rev.

Precision cutting of single crystal silicon using CBN tool with large top corner radius

A lot of studies on the ultra-precision cutting of single crystal silicon have been reported and they used the diamond cutting tools. However, the diamond cutting tools are very expensive. Therefore, if the single crystal diamond tools were replaced with sintered CBN tools, the cost of machining could be fairly reduced. However, it is easily expected that the CBN tools wear out faster than the diamond tools. Therefore, it is very important to find out the optimum cutting conditions in order to reduce tool wear. In this study, precision cutting of single crystal silicon was machined with using CBN cutting tools having chamfer at cutting edge and large nose radius, and the effect of feed rate, cutting speed, depth of cut and nose radius on the tool wear were studied. As a result, the local minimum of width of flank wear land appeared at the feed rate of 30~50 µm/rev.

Evaluating the Effect of PCD End Mill’s Nose Radius on Machinability of Titanium Alloy Ti-6Al-4V in High Speed Milling

Tool nose radius is an important geometrical parameter in the design of the tool. Due to its direct contact with the workpiece surface it have significant effect not only on the resulting surface quality but also on the tool life. Use of an end mill without nose radius can easily blend during machining due to a lot of stresses acting on the edge of the tool while the large nose radius end mill can increase the strength and rigidity of the tool but can also contribute in increasing the friction between the tool and the workpiece. Therefore careful selection of tool nose radius is important and especially important for Polycrystalline Diamond, PCD insert as this tool material has recently shown great success in terms of tool life, surface roughness and productivity over coated and uncoated carbide tools in high speed end milling of titanium alloy Ti-6Al-4V and with the use of correct tool geometry it can be further helpful in increasing tool life and surface quality. This study therefore investigates the effect of various nose radii’s (R0.1,0.2,0.4,0.8,1.2,1.6,2.4,3.2) and complete round insert end mill on cutting forces and heat distribution between tool and the chip for PCD insert and compare the results with multi-layer (Al2O3+TiAlN+TiN) coated carbide tool at high speed cutting conditions using 3-D finite element numerical simulations. Results have shown that both tools due to their difference in thermal and mechanical properties have different behavior under the conditions studied especially when the complete round insert tool is used. The use of small nose radius tool when nose radius rn is less than the axial depth of cut ap, the forces and the temperature remains quite low and slightly increases with the increase of radius until rn is smaller than ap but when rn gets larger than ap and only some portion of nose radius is involved in cutting, then forces and temperature increases considerably. While when complete round insert end mill is used the forces and temperature significantly drops (more than 50% than the largest nose radius tool studied) at the same ap for PCD insert but for multi-layer coated carbide tool it drops only slightly (20% than the largest nose radius tool studied). The reason for this difference lies in the fact that PCD tool has lower toughness, high hot strength and is more brittle than carbide tools and therefore maximum advantage can be taken only when small nose radius is used or when complete round insert tool is used as complete round insert have uniform stress distribution and also provides more stability for PCD tool material while large nose radius tool increases friction and also has more heat penetration in the tool thus resulting in higher cutting forces and temperature thus ultimately contributing in high wear of tool. While on the other hand carbide tools are only beneficial when smaller nose radius tool is used rather than round shape because of lower hot strength of the material.

Effect of Cutting Edge Geometry on Thermal Stresses and Failure of Diamond Coated Tools

This study considers the residual thermal stresses induced by cooling in diamond coated carbides after the chemical vapor deposition process. Finite element analysis and simulation of thermally induced residual stresses was conducted using a transient thermo-mechanical coupled solver. Cutting tool geometry parameters including cutting edge angle, nose radius and film thickness were varied and the resulting thermal stresses were analyzed and compared. Both radial and hoop stresses were found to be compressive along the bisector of the cutting edge angle of sharp cutting tools with zero nose radius. Radial stresses were tensile and hoop stresses were compressive for honed tools with large nose radius. It was found that thermal stresses are mainly affected by the ratio of nose radius to film thickness (r/h). But the effect of cutting edge angle was most influential for cutting tools with sharp edges. Increasing the cutting edge angle for these tools generally resulted in an increase in the magnitude of thermal stresses. Qualitative criteria for film fracture was also applied, which revealed that film failure is most likely to occur in thick films and for cutting tools with large cutting edge angles and r/h ratios less than 1.0. Some experimental validation of these criteria was also provided.

CFD Analysis of Mars Phoenix Capsules at Mach Number 10

Numerical simulations are performed for flow over Phoenix entry vehicle at Mars at zero angle of Attack and Mach number 10. Flow field features like bow shock, shear layers, expansion fan and separation bubble will be captured using CFD commercial package FLUENT. The computed wall data of pressure and temperature will be compared with experimental results at Mars atmospheric conditions. This project deals with the study of flow over Phoenix entry vehicle at Mach number 10. The concept of atmospheric entry has applications in various fields. Vehicles that typically undergo this process include exo-orbital trajectories. In this project, the type of entry vehicle considered is entry capsule, which enters Mars atmosphere from an orbit. The primary design consideration of entry capsule requires large spherical nose radius of their fore body that gives high aerodynamic drag and a short body length for reducing the total structural weight and the ballistic coefficient.

Investigation and modeling of cutting forces and surface roughness when hard turning of AISI 52100 steel with mixed ceramic tool: cutting conditions optimization

The increasing industrial demand for hard materials and their wide range of applications requires significant investigations to improve their machinability. Therefore, the current study addresses cutting forces and surface roughness during hard turning of AISI 52100 steel (59 hardness Rockwell C (HRC)) using ceramic tool. Turning experiments were held out by varying cutting speed, depth of cut, feed rate, and tool nose radius. For so doing, a central composite design (CCD) was adopted including 30 tests. Cutting forces and surface roughness were modeled using response surface methodology (RSM). The effects of each input parameter on output responses were investigated using analysis of variance (ANOVA) and response surface graphics. The findings of this study demonstrated that the force components were significantly influenced by depth of cut, followed by feed rate with a lower degree. Likewise, the negative result of the small undeformed chip thickness on surface roughness was reduced by the employment of large nose radius. Conclusively, a correlation between cutting force behavior and surface roughness was established and confirmed by the three-dimensional topographic maps of the machined surfaces. The RSM was utilized to define the optimal machining parameters.

Elliptical Vibration Cutting of Hardened Steel with Large Nose Radius Single Crystal Diamond Tool

It has been verified that ultra-precision diamond machining of hardened steel can be realized by applying the elliptical vibration cutting process. This innovative machining technology enables direct machining of steel dies and molds with a single crystal diamond tool and makes the indispensable nickel-plating step in the conventional diamond machining process unnecessary. This not only increases mold tool life, but also reduces the machining cost and cycle time. Therefore, elliptical vibration cutting has been considered as a very promising manufacturing technology for high precision die and mold machining. However, progress in elliptical vibration cutting has been hampered by bottlenecks in machining of large-size steel workpieces owing to the low machining efficiency. This study proposed an efficient machining method, elliptical vibration cutting with a large nose radius single crystal diamond tool. Experimental findings revealed that the proposed machining method had great potential to realize efficient ultra-precision diamond machining of hardened steel. However, it was found that the ploughing phenomenon affected the finished surface quality significantly. To minimize the ploughing effect an analytical model was developed. This model enabled minimization of the ploughing effect by optimizing the machining conditions. Finally, the analytical model was qualitatively validated with a series of plane cutting experiments and the experimental results demonstrated good agreement with the analytical model.

Monitoring of Wear Land Width of Diamond Tool Cutting Edge with Large Nose Radius in Ultra-Precision Cutting Using Static Cutting Forces

Large wear of diamond tools for ultra-precision cutting of soft metals deteriorates quality of machined surface, and the worn tools have to be replaced with new tools when the tool wear reaches limited wear land width of cutting edge generating finished surface. However, it is difficult to predict the tool life since all cutting tools have individual tool life. Therefore, the purpose of this study is to estimate wear land width of cutting edge of a single crystal diamond tool having large nose radius by using static cutting forces during machining. As a result of the cutting tests and measurements, it was found that the ratio of thrust force to principal force had good relation with the ratio of flank wear land area to cutting cross section area. Furthermore, according to some detailed observation of flank wear, width of flank wear land was greatly related to uncut chip thickness obtained under different cutting conditions and it was found that width of flank wear land could be estimated by measured static cutting forces and cutting conditions.

The Influence of Process Variables on Machinability of Hardened Tool Steel during the Hard Turning under Eco-Friendly Cooling Environment

Recent developments in cutting tool technology and its environmental impact have made significant revolutions in hard turning process thereby increasing the productivity level and enhancing the surface integrity of machined components competitively. In this experimental work, the machinability aspects, surface finish and tool life w`ere investigated during hard turning of hardened AISI D3 tool steel work materials with wiper geometry ceramic inserts under eco-friendly compressed air cooling environment. The process variables such as cutting speed, feed rate, tool nose radius, hardness levels of work materials and compressed air pressure were considered for this study. Since the tool nose design influences the machinability aspects, the cutting tool nose radius was considered as one of the vital process parameters. The design of experimental sequence and analysis of experiment data were carried with the help of Design Expert, DOE software. The combinations of Taguchi L16 orthogonal array and ANOVA technique have been applied for evaluating the process outcomes with reference to cutting variables. From the current experiment results, it is observed that combination of wiper ceramic insert with large nose radius and lower levels of compressed air pressure and work piece hardness (HRC) were resulting in higher surface quality with prolonged cutting tool life.

Modeling and experimentation on multistage work-hardening mechanism in machining with nose-radiused tools and its influence on machined subsurface quality and tool wear

The paper reports on the modeling and respective experimental validation for the formation of the machined subsurface layer in turning with nose-radiused and round tools. An experimental work on the mechanisms of work-hardening of the machined surface and related wear of the cutting tools was conducted for high-speed turning of aged Inconel 718 with whisker-reinforced alumina tools. The model shows that multiple deformations of the machined surface occur when machining with small feeds and tools with large nose radius, thus changing the mechanics of surface formation. Experimental results confirm the localized increase in subsurface hardness in the vicinity of the tool tip. The variation in the degree of work-hardening and the extent of the area affected by it fully agree with the predictions of the model. The model also shows that a significant part of the cutting tool may cut through the extra work-hardened material. Tool wear tests show that the local increase in workpiece hardness results in a localized increase in the wear rate of the cutting tools.

Analysis of residual stress and work-hardened profiles on Inconel 718 when face turning with large-nose radius tools

Surface integrity (SI) and, particularly, the residual stress profile, has a great influence on the fatigue life of machined aeronautical critical parts. Among the different cutting parameters that affect the final SI, tool geometry is one of the most important factors. In particular, tool nose radius determines the surface roughness, as well as the thermoplastic deformation of the workpiece. Indeed, the use of large tool nose radius in the industry enables (1) increasing the feed rate while keeping the roughness values below specifications and (2) reducing the influence of the tool wear in the surface roughness. Therefore, in this study, the influence of tool nose radius in the induced residual stress profile and work-hardened layer when face turning Inconel 718 is analysed for a cutting speed range between (30–70 m/min) and a feed rate range of (0.15–0.25 mm/rev). For this purpose, residual stress profiles and work-hardened layer were measured by x-ray diffraction method after machining with a 4 mm nose radius. Then, results have been compared against different tool nose radius studies carried out by other authors for the specified working conditions. Results revealed that residual stress profiles varied when machining with different nose radius for the studied range. In particular, the increase of the nose radius brought to a higher difference between surface tensile stress and subsurface compressive peak stress, which is attributed to an increase of the thermal effect. Moreover, thicker work-hardened layer (around 100 μm) was observed when machining with large-nose radius for the studied working conditions.

Combind Effect of Machining Parameters With Nose Radius of the Custting Tool on Surface Roughness of 304- Austenitic Stainless Steel Alloy Produced by Cnc-Turning Machin

It is well known that machining parameters have strong effect on the properties of surface roughness. Many investigations have done on this area. This work studies of combining effect of turning process parameters (cutting speed, feed rate, and depth of cut) with on surface roughness. Where, nose radius of the tool and machining parameters have taken as input variables and the surface roughness (Ra) as response or output. Three experiments were conducted; they were used to investigate the surface roughness resulted by tool corner radiuses of the values: 0.4mm, 0.8mm, and 1.2mm Response surface methodology (R.S.M) is applied as a tool to show the cause and effect of output (response) and input control and relationship between them as a two or three dimensional hyper surface. A three factor with five level central composite rotatable factors design was used. The results showed that R.S.M is a strong tool and capability tool to predict the effect of machining parameters on surface roughness. Results improved that the five level factorial designs can be employed for developing statistical models to predict surface roughness by controllable machining parameters. Results showed that the combined effect of cutting speed at its higher level, feed rate and depth of cut at their lower values, and large nose radius can result in better surface roughness.

Tool-Life of Wiper and Standard Cutting Tool in Finish Turning of SAE 4140

Vibration tendency can rise in turning process when selecting a cutting tool with larger nose radius and/or increasing the feed rate. As consequence, it may affect the process performance by reducing the tool-life and causing damage to the machined surface finish. Moreover, the generated surface roughness strongly depends on the relation between feed rate and cutting tool nose radius. The wiper cutting tool is a recent technological advancement which is claimed to allow both the feed rate and the depth of cut to be doubled while maintaining the same surface finish value in comparison with standard tools. Thus, the objective of this paper is to benchmark tool-life of standard and wiper cutting tools in dry finish turning of SAE 4140 steel. The analysis consists of successive measurements of workpiece roughness and tool corner wear after each turning pass while using combined machining parameters for a target roughness average value close to 2 μm with both inserts being used under the manufacturers recommended cutting conditions. It is noted that the two inserts presented good performance both in the workpiece finish and in tool-wear.