Cutting Force Measurement Research Articles

High Speed Turning of H-13 Tool Steel Using Ceramics and PCBN

H-13 is the toughest tool steel used in machined die casting and forging dies. Due to its extreme hardness and poor thermal conductivity high speed cutting results in high temperature and stresses. This gives rise to surface damage of the workpiece and accelerated tool wear. This study evaluates the performance of different tools including ceramics and PCBN using practical finite element simulations and high speed orthogonal cutting tests. The machinability of H-13 was evaluated by tool wear, surface roughness, and cutting force measurements. From the 2D finite element model for orthogonal cutting, stresses and temperature distributions were predicted and compared for the different tool materials.

Turning specialities of ZrO2 ceramics

In place of brittle ceramics used so far have appeared up-to-date so called tough ceramicmaterials resisting better against mechanical effects [6]. Such material is the zirconium-dioxide, too. Theimportant advantage of hard-turning is the applicability of universal tool. Various outlines can be formed bya tool given. Machining ceramics in case of using traditional machining (turning, milling, drilling) requiresspecial technological conditions (tools, machine-tools, technological parameters, etc.) which are developingpresently [2]. We would like extending our research work in this course, too.To clarify the machinability – turning – of ZrO2 ceramics we developed a cutting force measurements for theapplied CBN and PCD cutting tools. The forces were studied in the function of cutting speed and feed, thesurfaces were analized by SEM and the cutting process was controlled by thermo-camera. The failure ofcutting edges were also studied. The summarized results suggest the possible turning possibilities of ZrO2ceramics.

Cutting-force measurement on the basis of the shaping trajectory

A new method is proposed for measuring the cutting force in a lathe. The method is based on the change in trajectory of the blank’s axis when the cutting force is applied.

Experimental Investigation on the Dynamic Cutting Forces in Internal Broaching

Cutting forces generated in broaching have a direct influence on the generation of heat, tool wear or failure, quality of machined surface and accuracy of the work piece. In this paper not only a cutting forces test scheme has been proposed but also a cutting forces measurement equipment has been designed with PCB 740B02 dynamical strain sensor and LMS SCADA III test system, respectively. Dynamical strain sensor was pasted on the cylinder type sensitive elements with which table and workpiece was connected. Experimental investigation on the dynamic cutting forces in the broaching direction of a hydraulic broaching machine had been carried out. Cutting forces measurement tests on Q235 steel workpiece material during broaching had been performed. Broaching in a variety of velocities, namely, 3.3m/min, 5m/min and 8m/min and in a variety of cutting depth, namely, 0.03mm, 0.04mm, 0.05mm and 0.07mm, were investigated. Output signal was analyzed both in time and frequency domains and the key characteristics of the cutting forces signal was obtained. Correlation between the frequency of broaching forces and the broaching velocity was also studied.

Design and development of a dynamometer for the simulation of the cutting forces in milling

The cutting forces produced during the machining of metals exert a direct influence upon the machining stability, the tool wear and the quality of the machined surface. In this paper, a dynamometer of the cutting forces measurement in milling has been designed and constructed. The latter is based on the utilisation of two extended octagonal rings upon which are stuck strain gauges able to measure the forces in three directions. The signals of the forces have been captured and treated by means a data acquisition system which has also been conceived. The dynamometer has been submitted to a series of tests in order to determine its static and dynamic characteristics. The calibration of this dynamometer has been verified by the finite element method while using the simulation software COSMOS/M. The obtained results have proved that the dynamometer could be used reliably to measure the static and dynamic forces.

Slip-line field model of micro-cutting process with round tool edge effect

This paper presents a slip-line field model which considers the stress variation in the material deformation region due to the tool edge radius effect. The Johnson–Cook constitutive model is applied to obtain the shear flow stress and hydrostatic pressure as functions of strain, strain-rate, and temperature in the primary shear zone. The friction parameters between the rake face and chip are identified from cutting tests. The sticking and sliding contact zones between the tool and chip are considered in the secondary shear zone. The total cutting forces are evaluated by integrating the forces along the entire chip-rake face contact zone and the ploughing force caused by the round edge. The proposed model is experimentally verified by a series of cutting force measurements conducted during micro-turning tests. Micro-cutting process is analyzed from a series of slip-line field simulations.

Development of a modular dynamometer for triaxial cutting force measurement in turning

Accurate and reliable measurement of cutting forces in turning is essential for tool geometry, tool trajectory and cutting parameters optimization, as well as for tool condition monitoring and machinabilty testing. In this work, an innovative dynamometer for triaxial cutting force measurement in turning, specifically designed to be applied at a milling–turning CNC machine tool endowed with an indexable head, is presented. The device is based on a piezoelectric force ring integrated into a commercial toolshank, and its modular design allows the easy change of the cutting insert without altering sensor preload. The prototype device was assembled and experimentally tested by means of static calibration and dynamic identification, which evidenced good static and dynamic characteristics. Eventually, the sensor was tested in operating conditions by machining a benchmark workpiece.

Study of the Method on Cutting-Force Modeling Based on the Current of High-Speed Electric Spindles

It is important to build the models for calculating the cutting-forces in high-speed machining, but it is difficult as the special test-bed with the cutting-force measurement system is complicated, cost much and cannot be applied directly on general machining tools. Aiming at the problems above, a new method was put forward about cutting-force modeling based on the current of high-speed electric spindles, in which the cutting-force models could be gained indirectly by analyzing the built-in motor current and the data gotten from cutting experiments on those general machining tools which are installed with electric spindles. Then on a vertical milling machine tool which is equipped with a high-speed electric spindle, a model for calculating the milling force was gotten using the method put forward by this paper. The results show that the method is simple and easy to be used in routine machine tools in plant spots and need no any special test-beds and any complicated measurement systems possessed only in the laboratory conditions.

Gear Precision and Cutting Force in Dry Hobbing Gear Cutting for Gears Made of Brass Material

Gear precision measurement was carried out for gear with tooth number z=17, gear module mn=0.5, tooth width b=10mm, spur gear design and made using JIS C 3604 brass material. Cutting force measurement was carried out for gear with z=30, mn=1.75, spur gear, and JIS C 3604 brass material. Main results are as follows: (1) Gear precision and cutting force was almost the same in both dry and wet cutting. (2) Process capability index Cp of tooth profile errors were almost the same in both dry and wet hobbing gear cutting, and 5.9 to 8.1. Cp of tooth lead errors was 5.8 to 10.7. It was concluded that dry hobbing gear cutting of brass material has a sufficient production capacity. (3) Almost the same gear precision in both dry and wet hobbing gear cutting was considered because cutting forces were also same.

High Frequency Correction of Dynamometer for Cutting Force Observation in Milling

Piezoelectric dynamometers are widely used for cutting force measurements. Indeed, this device has the largest bandwidth for this kind of measurement. Nevertheless, the behavior of this device is not very well-known and its use is sometimes inappropriate for static and high frequency dynamic measurements. In this paper, a piezoelectric dynamometer is used for cutting force measurements in a milling case. Cutting forces in milling are discontinuous by nature due to successive inward and outward movements of tool-teeth on the workpiece. As a result, a bandwidth criterion based on cutting parameters is defined in order to permit clear observation of the mean oscillation of the cutting force. The frequency response of a dynamometer is then analyzed over a wide frequency range. A 2 kHz bandwidth can be defined for an efficient correction of cutting force. The dynamometer appears to be exploitable for higher frequencies up to at least 16 kHz though a large number of factors must be taken into account in the analysis. Finally, several lateral milling tests are performed by changing cutting speed, feed rate, and lubricant conditions. The correction of measurements permits highlighting certain particularities in the cutting force signals, such as the effect of shock of inward tool-teeth strokes on the workpiece, the specific behavior for outward tool-teeth strokes, and the effect of a lubricant on the variation in cutting forces.

Emergent behavior of nano-multilayered coatings during dry high-speed machining of hardened tool steels

Abstract A multi-functional nano-multilayered Ti0.2Al0.55Cr0.2Si0.03Y0.02N/Ti0.25Al0.65Cr0.1N physical vapor deposited (PVD) adaptive hard coatings is presented. This novel coating consists of alternating layers with variable chemical composition but similar crystal structure and hardness. A comprehensive investigation of the microstructure and properties of the coating was performed. The structure of the coating before and after service has been characterized by high-resolution transmission electron microscopy (HRTEM). Various micro-mechanical characteristics (hardness, impact fatigue fracture resistance, and low cycling wear resistance) of the coating have been investigated. Oxidation resistance of the coating has been studied using Thermogravimetric–Differential Thermal Analysis (TG-DTA) within a temperature range of 25–1200 °C in air. Wear performance of the novel TiAlCrSiYN/TiAlCrN coating was evaluated through tool life studies, cutting forces measurements and identification of chips characteristics. To determine the causes of improvement in wear performance, the worn surface of the coated cutting tools was investigated using SEM/EDS. The characteristics of the surface tribo-films that were formed on the worn surface were studied using, X-ray photoelectron spectroscopy (XPS) and Extended Energy-loss Fine Spectroscopy (EELFS). One of the major features of this coating is enhanced formation of tribo-oxide films on the surface during friction. These oxides possess a sapphire and mullite structure with superb protective ability that acts simultaneously with high temperature lubricious Si–O and Cr–O phases. Due to emergent properties, the developed adaptive coating behaves as a higher ordered system under operation, capable of sustaining extreme operating conditions.

Development of a dynamometer for measuring individual cutting edge forces in face milling

Cutting force information may be used for several tasks, such as tool design and trajectory optimization, tool condition monitoring, machinability testing and many others. Accordingly, cutting force measuring has become a crucial activity aimed at enhancing process performance. In this work, the development of an innovative rotating dynamometer for cutting force measurement in milling is illustrated. The device is capable of providing independent triaxial cutting force information from each cutting edge with a good dynamic response. Static and dynamic behavior of a simplified single-edge device was first investigated through the static calibration procedure, pulse tests and preliminary cutting tests. Afterwards, the dynamic properties of the final prototype clamped on the spindle of a high speed milling machine were assessed by means of standard and rotating pulse tests – i.e. pulse tests performed during spindle rotation. Eventually, cutting tests were performed on a benchmark workpiece. The experimental tests highlighted the superior features of the new device.

Investigations in high speed blanking: cutting forces and microscopic observations

A new hopefull technique, called high speed blanking, has been investigated since few years. To understand the cutting process and how the tools have to be designed, this study is interrested in the cutting force measurement. A new cutting force measure- ment device has to be designed consider the industrial interest of such a study. The de- signed test bench induces a calibration process in order to stucy the cutting forces evo- lution. The paper is discussing the result that the peack load seems to decrease when the punch speed increases. Finally microscopic observations are made in order to find Adia- batic Shear Bands.

Development of Cutting Force Measurement Technique for Milling Process with Small Diameter End Mill

Milling is one of the most important metal cutting processes. If we measure the cutting force, we can make cutting process optimum, prevent tool breakage, and improve efficiency of process. However in the case of using an end mill with small diameter, it is very difficult to identify whether cutting process is good or not.In this paper, we proposed the cutting force measurement technique by using image processing. In the technique, we captured a image of the end mill during cutting process, determined deflection of the tool and then estimated cutting force. Finally, we can estimate small cutting force with high accuracy.

Indirect cutting force measurement in the micro end-milling process based on frequency analysis of sensor signals

In this study, a useful indirect cutting force measurement method using an acceleration sensor and current hall sensors is proposed. A series of experiments was performed on a precise micro machining stage with a high-speed spindle. A three-axis acceleration sensor was installed on the spindle head, and current hall sensors were connected to the motor current inlet cables. From the results obtained, the correlations of the tool teeth rotation and current amplitude showed a linearity of 92.0% precision for hall sensor signals, and 98.0% precision for acceleration sensor signals. Even though the results using the acceleration sensor showed better linearity than those of the current hall sensors, the signals can be easily affected by chattering, spindle vibration, and other external disturbances. From this perspective, the current hall sensor can provide more robust results.

Time-frequency analysis and detecting method research on milling force token signal in spindle current signal

The vast majority of tool condition monitoring systems use the motor current instead of the cutting force as the predictor signal. The measured motor current signal is time-dependant and instable. It is difficult to detect the cutting force token signal from such motor current signal. This paper presents a method that uses the wavelet transforms to reconstruct the cutting force token signal from the current signal based on the time frequency analysis of the cutting force signal. The result of the cutting force measurement experiment shows that the proposed reconstruct method could be used to analyze the spindle current and monitor the time-varying cutting force.

Effect of surface finishing such as sand-blasting and CrAlN hard coatings on the cutting edge's peeling tools’ wear resistance

The aim of this study is first to define the effect of a surface finishing such as sand-blasting on the geometry of a wood cutting tool and its wear resistance. In addition, the effectiveness of surface coatings like CrAlN deposited by physical vapor deposition (PVD) technique on conventional and sand-blasted cutting edges was studied. A reference tool and different sand-blasted ones were tested by micro-peeling of beech in a laboratory. Microscopic observations, cutting forces measurement and cutting wear tests were carried out to quantify the behaviour of these tools. The results obtained showed that the artificial wear by sand-blasting leads to an increase in the wear resistance and coating effectiveness, and completely changes the type of damage done to the tools. The sand-blasting application combined or not with CrAlN coating showed an improvement in the wear resistance of the tools and a modification of the forces during the peeling process. The effectiveness of the CrAlN layers was improved thanks to the sand-blasting treatment and then the duplex ones performed better.

Characteristics of cutting forces and chip formation in machining of titanium alloys

Chip formation during dry turning of Ti6Al4V alloy has been examined in association with dynamic cutting force measurements under different cutting speeds, feed rates and depths of cut. Both continuous and segmented chip formation processes were observed in one cut under conditions of low cutting speed and large feed rate. The slipping angle in the segmented chip was 55°, which was higher than that in the continuous chip (38°). A cyclic force was produced during the formation of segmented chips and the force frequency was the same as the chip segmentation frequency. The peak of the cyclic force when producing segmented chips was 1.18 times that producing the continuous chip. The undeformed surface length in the segmented chip was found to increase linearly with the feed rate but was independent of cutting speed and depth of cut. The cyclic force frequency increased linearly with cutting speed and decreased inversely with feed rate. The cutting force increased with the feed rate and depth of cut at constant cutting speed due to the large volume of material being removed. The increase in cutting force with increasing cutting speed from 10 to 16 and 57 to 75 m/min was attributed to the strain rate hardening at low and high strain rates, respectively. The decrease in cutting force with increasing cutting speed outside these speed ranges was due to the thermal softening of the material. The amplitude variation of the high-frequency cyclic force associated with the segmented chip formation increased with increasing depth of cut and feed rate, and decreased with increasing cutting speed from 57 m/min except at the cutting speeds where harmonic vibration of the machine occurs.

A35 Study on Micro End Milling Using Precise Cutting Force Measurement(M4 processes and micro-manufacturing for science)

In micro cutting, high efficiency and high precision processing are difficult, because a micro tool has very low strength and stiffness. Thus there is a cutting force measurement as one method to solve this problem. However, the problem of the cutting force measurement in micro cutting is that the cutting force is too small, and the frequency response of the cutting force measurement is required high. Therefore, the cutting force measurement using a conventional dynamometer is difficult. In this study, the problem on the precise measurement of the cutting force in micro end milling using micro tools is solved.

Monitoring of Diamond Mill Wear in Time Domain during Stone Cutting Using Cutting Force Measurements

The main focus of this study is to verify the possibility to monitor diamond mill wear by measuring the cutting force during stone machining. An ornamental stone was machined on an NC machining centre, retrofitted with a 3-axis dynamometer and data acquisition systems, to investigate the effects of variations in machining parameters. The sensor data include cutting force measurements, further divided into measurable components, such as x, y, and z. Those components were analysed to determine the sensory features that best correlate with diamond mill wear. Tool wear and machining parameters appeared significantly influencing cutting force signals. This suggests that even under the varying cutting conditions involving different values of process parameters, the identified cutting force feature can be used for the reliable and accurate control of diamond mill wear during stone cutting operations.