Tool Holder Research Articles

Stability of Micro-Milling Tool Considering Tool Breakage

Micro-milling, widely employed across various fields, faces significant challenges due to the small diameter and limited stiffness of its tools, making the process highly susceptible to cutting chatter and premature tool breakage. Ensuring stable and safe cutting processes necessitates the prediction of chatter by considering the tool breakage. Crucially, the modal parameters of the spindle–holder–tool system are important prerequisites for such stability prediction. In this paper, the FRFs of the micro-milling tool are calculated by direct frequency response functions (FRFs) of the micro-milling cutter and cross-FRFs between a point on the shank and one on the tool tip. Additionally, by utilizing a cutting force model specific to micro-milling, the bending stress experienced by the tool is computed, and the tool breakage curve is subsequently determined based on the material’s permissible maximum allowable stress. The FRFs of the micro-milling tool, alongside the tool breakage curve, are then integrated to generate the final stability lobe diagrams (SLDs). The effectiveness and reliability of the proposed methodology are confirmed through a comprehensive series of numerical and experimental validations.

Design of High Precision CNC Vertical Lathe Turning Tool Holder

Design of High Precision CNC Vertical Lathe Turning Tool Holder

Numerical analysis of machinability and surface alterations in cryogenic machining of additively manufactured Ti6Al4V alloy

Metal additive manufacturing (AM) technology has been utilized in many industries including automotive, aerospace, and medical. AM Ti6Al4V (Ti64) alloy is highly noticed for production of medical instruments such as dental implants and the machining process is mostly needed during the production or post-processing of these components. Numerical model, as a powerful tool, can be efficiently used for analyzing the machining process. A customized model was employed using a user-written subroutine in this work to evaluate machinability and microstructural changes in cryogenic machining of AM Ti64 alloy. For this purpose, the microstructural changes were simulated as the new numerical outputs. The numerical results of cutting forces, temperature, nano-hardness, and alpha lamellae thickness (grain size) were successfully verified by corresponding experiments from literature. Then, the impact of tool geometry (including rake and clearance angles, cutting edge radius, and nose radius) on the machinability performance was examined. It was found that, the variation of clearance and rake angles were more effective on depth of the hardened layer compared to the other parameters. Thickness of alpha lamellae phase near the machined surface and depth of the affected layer by nano-hardness changes were changed from 0.9 to 1.58 µm, and from 18 to 40 µm, respectively. Overall, it was concluded that the variation of insert positioning made by tool holder (change in rake and clearance angles) was an effective parameter on the process outputs when machining AM Ti64 alloy.

Determination of Optimal Machining Parameters Based on Roughness and Vibration Measurements of Pieces Produced by Whirling on a Lathe Machine

Worms can be produced using special machines or standard lathes equipped with a whirling thread-cutting device. A blank is placed on the mandrel and tightened using the three-jawed chuck of the standard lathe. If the workpiece diameter is excessively large, passage through the driven pulley is not possible, and the workpiece cannot be supported. Therefore, a new tool holder for whirling devices is needed. During the whirling process, vibrations in the form of machine velocity amplitudes were measured. After whirling was complete, roughness values were calculated. Using numerical procedures of Wolfram Mathematica 10, vibration peaks were extracted, from which frequencies and maximum amplitudes were determined. The data were then inputted into Design Expert, and the rotational speed and amount of separated material were optimized. The results of the study showed that the quality of the processed surface did not improve with processing in two passes of the tool. The measured vibration amplitudes on the lathe carrier and thread whirling attachment increased with cutting speed at the same cutting depth, whereas the quality of the machined surface was best at the smallest and largest cutting depths.

Five-Axis Finish Milling Machining for an Inconel 718 Alloy Monolithic Blisk

Blisks subjected to rough machining for channel creation must undergo finishing processes, and such processes must achieve the required tolerance limits. A high-quality surface finish and predictable long tool life are critical for the finish milling of blisks. Accordingly, the aim of this study was to optimize parameters for the finish machining of an Inconel 718 alloy monolithic blisk. Ball-cone mills were used to machine the blade surface at a constant depth. A sensory tool holder was used to collect cutting force signals during machining, and a digital microscope was used to examine tool wear. The surface texture measuring instrument was used to measure blisk blade surface roughness to evaluate processing quality. This study manipulated two cutting parameters, namely cutting speed and feed per tooth, and investigated their effects. The relationship between cutting conditions and machining efficiency was analyzed. According to the experimental results, we identified a set of optimal parameters at effective cutting speeds of 46.53 m/min, feed per tooth of 0.1 mm/tooth, and depth of cut of 0.05 mm for marginal tool wear and fast cutting speeds. Then the corresponding tool life was estimated by using the derived parameters.

Impact of Cutting Data on Cutting Forces, Surface Roughness, and Chip Type in Order to Improve the Tool Operation Reliability in Sintered Cobalt Turning.

The authors present the results of laboratory tests analysing the impact of selected cutting data and tool geometry on surface quality, chip type and cutting forces in the process of orthogonal turning of sintered cobalt. The selected cutting data are cutting speed and feed rate. During the experiments, the cutting speed was varied in the range of vc = 50-200 m/min and the feed rate in the range of f = 0.077-0.173 mm/rev. In order to measure and acquire cutting force values, a measuring setup was assembled. It consisted of a Kistler 2825A-02 piezoelectric dynamometer with a single-position tool holder, a Kistler 5070 signal amplifier and a PC with DynoWare software (Version 2825A, Kistler Group, Winterthur, Switzerland)). The measured surface quality parameters were Ra and Rz. The components of the cutting forces obtained in the experiment varied depending on the feed rate and cutting speed. The obtained test results will make it possible to determine the optimal parameters for machining and tool geometry in order to reduce the machine operating time and increase the life of the cutting insert during the turning of sintered cobalt, which will contribute to sustainable technology.

A Physics-Based Model-Data-Driven Method for Spindle Health Diagnosis, Part I: Modeling of Geometric Faults

Abstract The spindle determines the performance of machine tools; hence, monitoring its health is essential to maintain machining productivity and avoid costly downtimes. The magnitudes and locations of wear and cracks in the bearing balls and races gradually develop which are difficult to detect. This article presents a physics-based digital model of the spindle with bearing faults, worn contact interface between the shaft and tool holder, and spindle imbalance. The wear of races and balls is considered in the bearing model. The worn taper contact interface and the spindle imbalance are included in the digital model. The spindle's dynamic model is used to simulate the vibrations at any location in the spindle assembly where sensors can be mounted for online monitoring. The wear type and bearing location are correlated with the frequency spectrum of vibrations at operating speeds. The proposed fault models are used to analyze the critical signal features and experimentally validated by the frequency extracted from a damaged spindle in Part II. The physics-based digital model is used to train data analytic models to detect spindle faults in Part III.

A Physics-Based Model-Data-Driven Method for Spindle Health Diagnosis, Part II: Dynamic Simulation and Validation

Abstract Mathematical modeling of bearing faults, worn tool holder taper contact interface, and unbalance are presented and integrated into a digital dynamic model of spindles in Part I of this paper. These faults lead to changes in preload and dynamic stiffness over time, consequently resulting in observable vibrations. This paper predicts the vibrations of a spindle at a particular measurement location by simulating the presence of a specific fault or multiple faults during spindle rotation. The vibration spectra generated by the digital spindle model at the spindle speed and its harmonics, the changes in the natural frequencies, and dynamic stiffnesses are correlated to faults with experimental validations. The simulated vibration spectrums are later used in training an artificial neural network for fault condition monitoring presented in Part III of the paper.

Effect of metallic substrate and rubber elastic materials over passive constrained layer damping on tool vibration during boring process

Tool vibration is a key factor that affects surface finish, generates noise, and reduces the tool life during conventional boring because of the excessive overhanging length of the tool holder. The interaction between the dynamics of the machine tool and the boring process led to progressive vibration. The creation of appropriate mechanisms in reducing tool vibration will help manufacturing industries to become more productive. In this research, in order to control vibration in the overhanging boring bar, a passive vibration control method was employed. Constrained layer dampers consist of boring bar, substrate, and elastic materials and it is used to minimize tool vibration produced during boring operation. The investigation utilized computational analysis through the ANSYS Workbench platform, employing key parameters such as the overhanging length of the tool holder (100, 150, and 200 mm), substrate material (aluminum, brass, and copper), and elastic material (Nitrile rubber, Natural rubber, and polyurethane). A comprehensive series of 27-run boring experiments were conducted to assess the impact of the constrained layer damper on tool vibration and cutting properties. The results of the study revealed remarkable improvements in various performance metrics. The constrained layer damper demonstrated an impressive 98% reduction in tool vibration, signifying its efficacy in dampening vibrational forces during the boring operation. Furthermore, a substantial 83% decrease in surface roughness was observed, indicating enhanced machining precision and surface finish. The constrained layer damper also exhibited a noteworthy 97.5% reduction in tool wear, highlighting its ability to significantly prolong tool life under challenging machining conditions.

Development of Machining Device with Real-Time Visualization of Boundary Surface on Tool Rake Face and Cutting Chip

Analysis of cutting phenomena has been conducted for a long time and many researchers have elucidated the phenomena that may occur at the cutting-edge during machining; for example, built-up edges and welding phenomena on cutting edge. However, the existing research has focused on observing the tool and chips after machining, when the tool and work material have been cooled, and are under atmospheric pressure. Therefore, we consider that it is different from the phenomenon that occurs during cutting. Because the cutting edge of a tool is in a high-temperature and high-pressure environment during machining and is released from such an environment after machining, the cutting edge must be visualized to discuss the actual cutting phenomena. There have been research reports in the past that have visualized the backside of cutting chips; however, that experiment was far from actual cutting phenomena and was conducted at significantly low cutting speed. Thus, the visualization of the cutting phenomenon is physically extremely difficult at the cutting edge. Under such circumstances, this study developed a device that observed the behavior of the boundary surface between cutting chips and the rake face in real time from the backside of the rake face during machining. By using the developed device, we could visualize this phenomenon to acquire the data directly and visually, which can otherwise be grasped only indirectly. In this device, a camera was mounted on a tool holder, and a cutting tip made of a transparent material was used to observe rake face, cutting edge, and flank face which can be visualized during machining from the backside of the rake face within one field of view. This paper reports on the outline of the developed device, its method, and the results of experimental observation of the state of two-dimensional cutting using a lathe.

Structural design and experimental research of a micro-feed tool holder based on topology optimization

Abstract. In the present study, a new configuration for a micro-feed tool rest driven by piezoelectric ceramics with a rigid–flexible phase is designed. The flexible driving part of the micro-feed tool rest is optimized using the topology optimization method, which not only improves the driving stiffness, resolution and structural stability but also increases the maximum displacement. The structural stiffness achieved in finite element simulation analysis is 16.28 N µm−1, and the first natural frequency reaches 2521 Hz. A prototype of a piezoelectrically driven micro-feed tool holder and a testing platform are constructed, and the structural stiffness of the prototype is determined to be 15.53 N µm−1 via analysis and testing, resulting in an error of 4.8 % compared with the finite element simulation results. The first-order natural frequency is 2636 Hz given a resolution of 12 nm and a maximum output displacement of 12.983 µm. Compared with the double-parallel flexible hinge, the maximum stroke of the micro-feed tool holder increases by about 5.4 µm and the resolution is improved by about 50 %. The new micro-feed tool holder developed in this paper features a cross-plate-type flexible mobile guiding mechanism. Combining stiffness, maximum travel and displacement resolution, it is applicable to precision and ultra-precision machining.

Deep Rolling of Al6061-T6 Material and Performance Evaluation with New Type Designed WNMG Formed Rolling Tool

In deep rolling, ball and roller type burnishing tools are generally used. It is generally difficult to deep roll contours with curved and conical shapes with the existing rolling tools. The aim of this study is to design experiments with a roller insert that will be an alternative to deep rolling inserts being used now and that can be fixed on the present tool holders; and to investigate the usability of them including curve and conical formed workpieces with the help of this designed tool. For this purpose, a spherical insert with a radius of 1 mm in the form of WNMG was designed based on the WNMG insert model and used in deep rolling of Al6061-T6 material using different forms and parameters. 143, 330, 495 N rolling force, 0.04, 0.08, 0.12 mm/rev feed and 400, 600, 800 rpm spindle speed were selected as rolling parameters. By examining the microhardness and surface structure of deep-rolled Al6061 parts, the achievability of the results of existing tools in deep rolling was investigated. At the end of the study, it was determined that the new type of rolling tool produced results similar to the existing tools in deep rolling in terms of microhardness and surface morphology, which enabled that the workpieces with curve and conical forms could also be rolled, and that this rolling tool could be used as an alternative in deep rolling.

Dynamic Modeling for Chatter Analysis in Micro-Milling by Integrating Effects of Centrifugal Force, Gyroscopic Moment, and Tool Runout.

During micro-milling, regenerative chatter will decrease the machining accuracy, destabilize the micro-milling process, shorten the life of the micro-mill, and increase machining failures. Establishing a mathematical model of chatter vibration is essential to suppressing the adverse impact of chatter. The mathematical model must include the dynamic motions of the cutting system with the spindle-holder-tool assembly and tool runout. In this study, an integrated model was developed by considering the centrifugal force induced by rotational speeds, the gyroscopic effect introduced by high speeds, and the tool runout caused by uncertain factors. The tool-tip frequency-response functions (FRFs) obtained by theoretical calculations and the results predicted by simulation experiments were compared to verify the developed model. And stability lobe diagrams (SLDs) and time-domain responses are depicted and analyzed. Furthermore, experiments on tool-tip FRFs and micro-milling were conducted. The results validate the effectiveness of the integrated model, which can calculate the tool-tip FRFs, SLDs, and time responses to analyze chatter stability by considering the centrifugal force, gyroscopic effect, and tool runout.

Thermal Error Measurement and Compensation with Torque Limit Skip in Swiss-type Lathe Manufacturing

This paper presents a new methodology for the measurement of thermal errors of Swiss-type lathes. The basis of the proposed method is the torque limit skip function integrated in the lathe’s control which stops the motion of a linear axis if the torque on the corresponding axis servo is exceeded. The skip signal is triggered via a slow contact between a bar in the lathe’s spindle and an artefact in the lathe’s tool holder. Experimental results indicate that when a sufficiently low torque override limit is applied, the axis positioning repeatability under the repeated application of the torque limit skip is within ±1μm. The relative change in position of the axis after the skip measured over several hours is the thermal error which can be compensated. The proposed measurement technique offers significant advantages over conventional thermal error measurement with a touch-trigger probe or linear displacement sensors: if available on the machine’s control, it does not require any specialized installation, can be used during production, and delivers comparable results without high additional equipment costs.

Experimental Study on New Tool Holder Design to Reduce Vibration in Turning Operations

Experimental Study on New Tool Holder Design to Reduce Vibration in Turning Operations

Fabrication of polycrystalline diamond micro-milling cutter with different grain sizes by picosecond laser

Polycrystalline diamond (PCD) is an excellent material for machining micro-tools due to its high hardness and wear resistance. However, the diameter of micro-milling tools is generally required to be less than 500 μm. When preparing micro-milling tools with a large aspect ratio, the processing load introduced by traditional grinding methods is easy to cause tool fracture. Therefore, a composite structure of carbide tool holder and diamond tool head is proposed in this paper. A technique of picosecond laser machining PCD micro-milling tool was studied, and the overall manufacturing process of tool blank preparation, nanosecond laser roughing and picosecond laser finishing was formed. A two-dimensional ablation mathematical model for tangential machining of PCD with a multi-pulse picosecond laser was established, and experiments verified the reliability of the mathematical model. In addition, the effects of picosecond laser pulse pitch, pulse energy, and track spacing on the surface quality of PCD materials with different particle sizes and cutting edge radius were studied by orthogonal experiments. The results showed that after picosecond laser processing, the surface roughness (Sa) of PCD with a particle size of 2 μm was the best, which can reach 0.33 μm, and the cutting edge radius of PCD micro-milling tool with a particle size of 25 μm was the smallest, which can get 1.67 μm. Using the optimized picosecond laser parameters, the high-sharpness single-edge micro-milling cutters with different particle sizes PCD with a diameter of 100 μm, aspect ratio greater than 3, and a cutting edge radius less than 3 μm were successfully fabricated.

Sensorless loaded test for machine tool 2D compliance characterization using a tool-mounted roller bearing

Machine tool compliance may affect a machined part's accuracy. Volumetric compliance is measured by a test apparatus, named ball-roller bearing device (BRBD). The volumetric compliance measurement procedure consists of a loaded circular test with a commanded radial interference displacement between a roller bearing mounted at the tool holder and a ball attached to the table causing a radial force to develop. The interference displacement and force are calculated from internal CNC data such as the encoder readings and the servo motor current. Disturbance from non-compliant effects is reduced by analyzing the data from at least two interference displacement levels. The estimated forces are validated using a dynamometer table while the estimated compliances are validated with a compliant rig made of a parallelogram flexure mechanism. At the maximum displacement, approximately 55 % and 45 % of volumetric compliance came from the machine and the BRBD, respectively. In the most compliant direction, the machine volumetric, machine volumetric with the rig, and predicted machine volumetric with rig compliance values are 0.12, 0.49, and 0.50 μm/N, respectively.

Formula Optimal dalam Penentuan Aspek Penting pada Desain Alat Pemotong Ring AMDK Gelas Plastik Menggunakan Metode Quality Function Deployment (QFD)

Drinking water waste in plastic cups is increasing every year, which has an impact on environmental sustainability, so there is a need for equipment solutions for processing this waste. The aim of this research is a formulation to determine important aspects in the design of ring-cutting tools for plastic cup bottled drinking water. The method used is Quality Function Deployment (QFD) by considering user aspects through Voice of Customers (VoC) with 10 needs. This data is converted into 9 technical data which is analyzed with the House of Quality (HoQ). The results show priority improvements for the development of these tools, namely: manual cutting tool design (46,318), intuitive cutting tool design (45,227), adjustable tool holders and cutters (43,636), portable cutting tool design (33,591), components using standard parts (25,136 ), steel material (25,091), affordable tool manufacturing costs (20,455), non-corrosive material (17,955) and cylindrical and non-slip handle shape (12,273). This data is used as a basis for further research to design this tool. Keywords: Plastic Cups, QFD, Ring Cutting

CNC Machine Tool Focused Edge Computing in Manufacturing

This paper presents a method for standardized integration of external sensors and actuators into CNC machine tool systems utilizing edge computing technology. Different communication protocols and various means for triggering external devices at a chosen machining operation were studied and evaluated using a sensory tool holder. The benefits of the presented architecture are the independence of the host operating system, easy customization, lightweight architecture, and standard protocols. Focusing on the demands for modern edge devices led to containerized modules with customizable interfaces. During manufacturing processes, the system was evaluated in terms of performance and reliability.

A State-of-the-art Review on the Intelligent Tool Holders in Machining

A State-of-the-art Review on the Intelligent Tool Holders in Machining