As a multi-axis metal cutting operation, turn-milling has the combined characteristics of convent... more As a multi-axis metal cutting operation, turn-milling has the combined characteristics of conventional turning and milling operations involving rotating workpiece and milling tool with linear feed motion in the workpiece axis direction. Although turn-milling offers many advantages in machining complex and hard-to-cut materials due to its flexible kinematics, the process presents specific challenges. The main objective of this paper is to present an overview of turn-milling operations from different perspectives. In this regard, first, the advantages of turnmilling in terms of tool life are presented. An analytical approach is given based on process kinematics to achieve better surface quality and productivity simultaneously. Additionally, the uncut chip geometry and the cutting force models are presented with experimental verification.
Chatter vibrations result in reduced productivity, poor surface finish and decreased cutting tool... more Chatter vibrations result in reduced productivity, poor surface finish and decreased cutting tool life. Milling cutters with non-constant pitch angles can be very effective in improving the stability of the process against chatter. In this paper, an analytical stability model and a design method are presented for non-constant pitch cutters. An explicit relation is obtained between the stability limit and the pitch variation which leads to a simple equation for optimal pitch angles. A certain pitch variation is effective for limited frequency and speed ranges which are also predicted by the model. The improved stability, productivity and surface finish are demonstrated by several examples.
Models for machining processes can be used to predict cutting force and temperature. Cutting tool... more Models for machining processes can be used to predict cutting force and temperature. Cutting tool geometry and cutting conditions have significant effects on cutting mechanism, forces and temperatures, which affect tool wear and life, dimensional tolerances and surface integrity of machined parts. In order to have a comprehensive insight on cutting process and select proper cutting conditions a predictive model for forces and temperatures in orthogonal cutting is required. In the present study, an analytical method based on thermomechanical model is enhanced to predict the cutting tool temperatures considering important features of the tool geometry such as clearance angle and cutting-edge radius. To verify the model, experiments were performed and the results were compared with model predictions. Finally, the effect of cutting tool geometry on flank face temperature was investigated.
The objective of this paper is to experimentally investigate the micro-machinability of stainless... more The objective of this paper is to experimentally investigate the micro-machinability of stainless steel 316 under both dry and minimum quantity lubrication conditions. The machinability was assessed in terms of tool wear, tool life, cutting forces and surface finish. The tool life was characterised as the amount of material removed, instead of the conventional cutting times. The machining performance under MQL is superior to the dry machining for both process conditions in terms of the tool life. The magnitude of the machining forces showed cyclic pattern for both MQL and dry machining. The SEM images and the cutting force signals suggested that the dominant mode of the tool wear in micro-milling is edge chipping and abrasive wear at the tool tip. The surface roughness at the bottom of the slots improved significantly with the application of MQL for all levels of the tool wear.
Grinding force plays crucial role in choosing grinding parameters since it can be used for predic... more Grinding force plays crucial role in choosing grinding parameters since it can be used for predicting power, wheel wear, surface roughness, temperature etc. In this paper a force model was developed to predict average grinding force for Inconel 718 with electroplated CBN. Two methods, namely mechanistic and oblique cutting approaches were employed and results were compared with the experiments. There was a good agreement between predicted force in both approaches and experiment data although mechanistic approach gave a better prediction than mechanics of cutting approach. Furthermore, performance of CBN and aluminum oxide wheels was studied by comparing grinding force and force coefficients. Results showed that grinding with CBN wheel led to lower force and force coefficients.
The desired goal of this experimental research is to improve 3-axis machining operations in terms... more The desired goal of this experimental research is to improve 3-axis machining operations in terms of cycle time by optimizing feed-rates while taking CNC drive limits, such as maximum acceleration and jerk capabilities, into consideration. In order to achieve this, CNC drives’ velocity, acceleration and jerk limitations are measured with laser interferometer and laser displacement sensor. According to data obtained from experiments, at each cutter location, an answer to the question whether the desired feed-rate reached or not is found. With the new data obtained, a better approximate cycle time is predicted.
Selection of cutting conditions is of great importance for high productivity in metal cutting ind... more Selection of cutting conditions is of great importance for high productivity in metal cutting industry. Process twins which make use of physical models considering both mechanics and dynamics of metal cutting are useful tools in the context of Industry 4.0. In this paper, the use of science integrated machining approaches is demonstrated for selection of high performance cutting conditions. The results obtained from simulations of several industrial applications are utilized in selection of cutting parameters and the results are discussed through applications and experiments.
Please cite this article in press as: Rahimzadeh Berenji K, et al. Effects of turn-milling condit... more Please cite this article in press as: Rahimzadeh Berenji K, et al. Effects of turn-milling conditions on chip formation and surface finish.
ABSTRACT In this study, an experimental investigation of oblique cutting process is presented for... more ABSTRACT In this study, an experimental investigation of oblique cutting process is presented for titanium alloy Ti-6Al-4V, AISI 4340, and Al 7075. Important process parameters such as shear angle, friction angle, shear stress, and chip flow angle are analyzed. Transformation of the data from the orthogonal cutting test results to oblique cutting process is applied, and the results are compared with actual oblique cutting tests. Effects of hone radius on cutting forces and flank contact length are also investigated. It is observed that the shear angle, friction angle, and shear stress in oblique cutting have the same trend with the ones obtained from the orthogonal cutting tests. The transformed oblique force coefficients from orthogonal tests have about 10% discrepancy in the feed and tangential directions. For the chip flow angle, the predictions based on kinematic and force balance results yield better results than Stabler's chip flow law. Finally, it is shown that the method of oblique transformation applied on the orthogonal cutting data yields more accurate results using the predicted chip flow angles compared to the ones obtained by the Stabler's rule.
Micro-milling applications require high precision and dimensional accuracy. Chatter vibrations ar... more Micro-milling applications require high precision and dimensional accuracy. Chatter vibrations arising from unstable cutting conditions cause poor surface finish and damage to the cutting tools. Tool point frequency response functions (FRF); needed to generate stability diagrams, cannot be determined experimentally due to very small tool size. In this study an analytical model for tool point FRF of micro end mills is presented. An inverse algorithm is proposed to correct geometric representation and damping of the tool. The model and the correction methodology presented improve productivity and part quality in micro-milling through accurate prediction of chatter stability limits, enabling better cutting parameter selection.
Bu calismada, tornalama ile uretilen parca esas alinarak, bilgisayar destekli numerik kontrol (CN... more Bu calismada, tornalama ile uretilen parca esas alinarak, bilgisayar destekli numerik kontrol (CNC) sistemine sahip, paralel tornalama islevini gerceklestiren tezgah tasarlanmis ve imalati yapilmistir. Imalati yapilan CNC paralel tornalama tezgahinda paralel tornalama yonteminin, esas isleme zamani, kesici uc omru, parca kalitesi, sistem kararliligi ve kendinden kaynakli titresimler (tirlama) uzerindeki etkileri incelenmistir. Bu calisma sonuclarinda elde edilen verilerden yararlanarak; takim omrunde, isleme kalitesinde ve isleme surelerinde iyilesme sagladigi gorulen CNC paralel tornalama tezgahinin, seri imalat yapan isletmeler icin uygun oldugu degerlendirilmektedir.
Please cite this article in press as: Mohammadi Y, et al. Suppressing vibration modes of spindle-... more Please cite this article in press as: Mohammadi Y, et al. Suppressing vibration modes of spindle-holder-tool assembly through FRF modification for enhanced chatter stability. CIRP Annals-Manufacturing Technology (2018),
As a multi-axis metal cutting operation, turn-milling has the combined characteristics of convent... more As a multi-axis metal cutting operation, turn-milling has the combined characteristics of conventional turning and milling operations involving rotating workpiece and milling tool with linear feed motion in the workpiece axis direction. Although turn-milling offers many advantages in machining complex and hard-to-cut materials due to its flexible kinematics, the process presents specific challenges. The main objective of this paper is to present an overview of turn-milling operations from different perspectives. In this regard, first, the advantages of turnmilling in terms of tool life are presented. An analytical approach is given based on process kinematics to achieve better surface quality and productivity simultaneously. Additionally, the uncut chip geometry and the cutting force models are presented with experimental verification.
Chatter vibrations result in reduced productivity, poor surface finish and decreased cutting tool... more Chatter vibrations result in reduced productivity, poor surface finish and decreased cutting tool life. Milling cutters with non-constant pitch angles can be very effective in improving the stability of the process against chatter. In this paper, an analytical stability model and a design method are presented for non-constant pitch cutters. An explicit relation is obtained between the stability limit and the pitch variation which leads to a simple equation for optimal pitch angles. A certain pitch variation is effective for limited frequency and speed ranges which are also predicted by the model. The improved stability, productivity and surface finish are demonstrated by several examples.
Models for machining processes can be used to predict cutting force and temperature. Cutting tool... more Models for machining processes can be used to predict cutting force and temperature. Cutting tool geometry and cutting conditions have significant effects on cutting mechanism, forces and temperatures, which affect tool wear and life, dimensional tolerances and surface integrity of machined parts. In order to have a comprehensive insight on cutting process and select proper cutting conditions a predictive model for forces and temperatures in orthogonal cutting is required. In the present study, an analytical method based on thermomechanical model is enhanced to predict the cutting tool temperatures considering important features of the tool geometry such as clearance angle and cutting-edge radius. To verify the model, experiments were performed and the results were compared with model predictions. Finally, the effect of cutting tool geometry on flank face temperature was investigated.
The objective of this paper is to experimentally investigate the micro-machinability of stainless... more The objective of this paper is to experimentally investigate the micro-machinability of stainless steel 316 under both dry and minimum quantity lubrication conditions. The machinability was assessed in terms of tool wear, tool life, cutting forces and surface finish. The tool life was characterised as the amount of material removed, instead of the conventional cutting times. The machining performance under MQL is superior to the dry machining for both process conditions in terms of the tool life. The magnitude of the machining forces showed cyclic pattern for both MQL and dry machining. The SEM images and the cutting force signals suggested that the dominant mode of the tool wear in micro-milling is edge chipping and abrasive wear at the tool tip. The surface roughness at the bottom of the slots improved significantly with the application of MQL for all levels of the tool wear.
Grinding force plays crucial role in choosing grinding parameters since it can be used for predic... more Grinding force plays crucial role in choosing grinding parameters since it can be used for predicting power, wheel wear, surface roughness, temperature etc. In this paper a force model was developed to predict average grinding force for Inconel 718 with electroplated CBN. Two methods, namely mechanistic and oblique cutting approaches were employed and results were compared with the experiments. There was a good agreement between predicted force in both approaches and experiment data although mechanistic approach gave a better prediction than mechanics of cutting approach. Furthermore, performance of CBN and aluminum oxide wheels was studied by comparing grinding force and force coefficients. Results showed that grinding with CBN wheel led to lower force and force coefficients.
The desired goal of this experimental research is to improve 3-axis machining operations in terms... more The desired goal of this experimental research is to improve 3-axis machining operations in terms of cycle time by optimizing feed-rates while taking CNC drive limits, such as maximum acceleration and jerk capabilities, into consideration. In order to achieve this, CNC drives’ velocity, acceleration and jerk limitations are measured with laser interferometer and laser displacement sensor. According to data obtained from experiments, at each cutter location, an answer to the question whether the desired feed-rate reached or not is found. With the new data obtained, a better approximate cycle time is predicted.
Selection of cutting conditions is of great importance for high productivity in metal cutting ind... more Selection of cutting conditions is of great importance for high productivity in metal cutting industry. Process twins which make use of physical models considering both mechanics and dynamics of metal cutting are useful tools in the context of Industry 4.0. In this paper, the use of science integrated machining approaches is demonstrated for selection of high performance cutting conditions. The results obtained from simulations of several industrial applications are utilized in selection of cutting parameters and the results are discussed through applications and experiments.
Please cite this article in press as: Rahimzadeh Berenji K, et al. Effects of turn-milling condit... more Please cite this article in press as: Rahimzadeh Berenji K, et al. Effects of turn-milling conditions on chip formation and surface finish.
ABSTRACT In this study, an experimental investigation of oblique cutting process is presented for... more ABSTRACT In this study, an experimental investigation of oblique cutting process is presented for titanium alloy Ti-6Al-4V, AISI 4340, and Al 7075. Important process parameters such as shear angle, friction angle, shear stress, and chip flow angle are analyzed. Transformation of the data from the orthogonal cutting test results to oblique cutting process is applied, and the results are compared with actual oblique cutting tests. Effects of hone radius on cutting forces and flank contact length are also investigated. It is observed that the shear angle, friction angle, and shear stress in oblique cutting have the same trend with the ones obtained from the orthogonal cutting tests. The transformed oblique force coefficients from orthogonal tests have about 10% discrepancy in the feed and tangential directions. For the chip flow angle, the predictions based on kinematic and force balance results yield better results than Stabler's chip flow law. Finally, it is shown that the method of oblique transformation applied on the orthogonal cutting data yields more accurate results using the predicted chip flow angles compared to the ones obtained by the Stabler's rule.
Micro-milling applications require high precision and dimensional accuracy. Chatter vibrations ar... more Micro-milling applications require high precision and dimensional accuracy. Chatter vibrations arising from unstable cutting conditions cause poor surface finish and damage to the cutting tools. Tool point frequency response functions (FRF); needed to generate stability diagrams, cannot be determined experimentally due to very small tool size. In this study an analytical model for tool point FRF of micro end mills is presented. An inverse algorithm is proposed to correct geometric representation and damping of the tool. The model and the correction methodology presented improve productivity and part quality in micro-milling through accurate prediction of chatter stability limits, enabling better cutting parameter selection.
Bu calismada, tornalama ile uretilen parca esas alinarak, bilgisayar destekli numerik kontrol (CN... more Bu calismada, tornalama ile uretilen parca esas alinarak, bilgisayar destekli numerik kontrol (CNC) sistemine sahip, paralel tornalama islevini gerceklestiren tezgah tasarlanmis ve imalati yapilmistir. Imalati yapilan CNC paralel tornalama tezgahinda paralel tornalama yonteminin, esas isleme zamani, kesici uc omru, parca kalitesi, sistem kararliligi ve kendinden kaynakli titresimler (tirlama) uzerindeki etkileri incelenmistir. Bu calisma sonuclarinda elde edilen verilerden yararlanarak; takim omrunde, isleme kalitesinde ve isleme surelerinde iyilesme sagladigi gorulen CNC paralel tornalama tezgahinin, seri imalat yapan isletmeler icin uygun oldugu degerlendirilmektedir.
Please cite this article in press as: Mohammadi Y, et al. Suppressing vibration modes of spindle-... more Please cite this article in press as: Mohammadi Y, et al. Suppressing vibration modes of spindle-holder-tool assembly through FRF modification for enhanced chatter stability. CIRP Annals-Manufacturing Technology (2018),
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