High Speed Cutting Research Articles

Evaluation of the impact of the natural seasoning process on post-machining deformation of thin-walled elements made of aluminium alloy EN AW-2024

The study attempts to evaluate the impact of short-term natural seasoning process on the state of post-machining deformations of thin-walled elements made of the EN AW-2024 aluminium alloy. Analyses were made of the impact of the technological history of the semi-finished product, in this case – the rolling direction of the plate (perpendicular and parallel to the feed direction) as well as high-performance machining strategies, such as High Speed Cutting (HSC) and High Performance Cutting (HPC) on the value of deformations of thin-walled samples, directly after machining and after seasoning. Application of natural seasoning at reducing deformations of thin-walled elements made of aluminium alloys may prove an alternative to the difficult intermediate heat treatment. The expected reduction of deformations is a result of reducing residual stresses in the material, in the course of the relaxation process. The dynamics of the natural relaxation is highly correlated with the properties of materials. The study includes an analysis of the effects of a short-term relaxation, accepted in industrial conditions (up to 1 month since the end of machining) for the EN AW-2024 alloy. If the proposed solution gives positive effects, it can bring measurable economic benefits in industrial applications. The study is completed with general and practical conclusions.

Hybrid Spindle – An approach for a milling machine tool spindle with extended working range for HSC and HPC

Commercial motor-driven spindles for milling machine tools are generally developed for specific machining operations, such as HPC (High Performance Cutting) or HSC (High Speed Cutting). HPC and HSC require significantly different working ranges regarding spindle speed and torque. E.g. in HPC operations, high torque at low spindle speeds is needed. The two working ranges are covered only limited by a conventional spindle so far. However, a spindle system that can switch the working range allows cost-effective manufacturing of a wider range of materials within the same machine tool. The spindle bearings and the power electronics supply are challenges, when switching between both working ranges. HPC operation requires high bearing stiffness in order to transmit high forces occurring during the cutting process. However, the associated high bearing preload leads to high frictional losses at high speeds for HSC operations. Furthermore, the wide operating range generates contrary requirements for the motor winding. To increase the spindle speeds with a winding being assembled for high torques, the current has to be increased. For this purpose, expensive and non-standardized motor inverters are required. This paper introduces a concept to overcome these challenges. Firstly, an approach to adjust the bearing preload is presented, using a compact, electrically controlled bearing preload element, which is suitable for industrial applications. Next, an approach for a reconfigurable winding design of the spindle motor is shown. This allows electrical switching between the working ranges using conventional motor inverters. Finally, an analysis of the conditions of use of the hybrid spindles is presented.

The HSC machining mechanism for TC17 under multimedia mixed minimum quantity lubrication

This study is intended to fill up the deficiency of the high-speed cutting (HSC) machining mechanism for TC17 Ti alloy. In this study, as the study object, TC17 Ti alloy is placed in room temperature (20 °C), ultra-low temperature (− 60 °C), and ultra-high temperature (350 °C) for HSC experiment, respectively, both through single-medium minimum quantity lubrication (SMMQL) and oil-water minimum quantity lubrication (OWMQL). The experimental results show that the main cutting force decreases by 33% during oil-medium MQL to 50% during water-medium MQL as compared to machining during dry cutting at room temperature; the cutting force decreases by 25% at the low temperature to 55% at the high temperature as compared to machining during OWMQL at room temperature; the cutting roughness decreases by 27% at the low temperature to 43% at the high temperature as compared to machining during OWMQL at room temperature. In the temperature of − 60 °C, the abrasion of the cutter mainly shows thermal cracking and adhesive wear during dry cutting. The cutter mainly shows crater wear during SMMQL of water; the abrasion mainly shows boundary and notching wear during SMMQL of oil, and the cutter also presents self-repairing function. In the temperature of − 60 °C, cutting layer TC17 titanium alloy produced a large dislocation, chip form appears collapse broken chip during OWMQL. In room temperature, there are more coarse second-phase precipitated in the cutting layer metal, the chip form is cracked during OWMQL. In the temperature of 350 °C, the material properties of the TC17 titanium alloy of the cutting layer will be restored to the state after the solution treatment in a short time. A large amount of the diffuse phase disappears. At the same time, grain boundaries show excellent continuity, and the Guinier-Preston enrichment area formed in the grain boundary, and the chip form exhibits a crumb during OWMQL.

Milling operations in continuous flow production lines

Within the Collaborative Research Center CRC 666 at the TU Darmstadt bifurcated structures in integral style are produced out of steel sheet band. In this context, the cutting technology is used to prepare the semi‐finished product for subsequent forming and machining operations as well as to even manufacturing induced shape and dimensional inaccuracies. In contrast to conventional cutting processes, the workpiece is constantly moved because of the continuous flow production. Thus, high dynamics of the machining process are required. To meet this demand, special built machine tools and the high speed cutting (HSC) technology are applied. This article shows the achieved results in sheet metal and edge milling.

Determination of physical characteristic in vanadium carbon nitride coatings on machining tools

The aim of this work is to determinate the mechanical and tribological behavior of V-C-N coatings deposited on industrial steel substrates (AISI 8620), by using the carbon nitride coatings as a protective materials. The coatings were deposited on silicon (100) and steel substrates via magnetron sputtering system and by varying the applied bias voltage. The V-C-N coatings were characterized by x-ray diffraction (XRD), exhibiting the crystallographic orientations (111) FCC for V-C-N conjugated by VC (111) and VN (111) phases and (200) FCC for V-C-N conjugated by VC (200) and VN (200) phases. X-ray photoelectron spectroscopy (XPS) was used for determinate the chemical composition of metallic carbon nitride materials. Atomic force microcopy (AFM) was used for determination of the change in grain size and roughness with deposition parameters. By using nanoindentation, pin-on-disk, and scratch test curves, it was possible to estimate the hardness, friction coefficient and critical load of V-C-N surface material. Scanning electron microscopy (SEM) was performed to analyze morphological surfaces changes. Mechanical and tribological behavior in VCN/steel[8620] system, as function of bias voltage deposition, showed an increase of 58 % in the hardness, and reduction of 39% in the friction coefficient, indicating thus that the V-C-N coatings may be a promising material for industrial applications such as high-speed cutting (HSC) coated with VCN layer tested in machining processes against heat-treated steels AISI 8620.

Nonlinear propagation of stress waves during high speed cutting

Stress waves induced by high speed cutting (HSC) were demonstrated visually, and the dependence of their nonlinear propagation characteristics on cutting speed was studied. The time-resolved photoelasticity imaging technique in the bright-field mode was used to observe stress waves in the workpiece, and the obtained photoelastic images were evaluated semi-quantitatively. The experimental results were quantitatively reproduced via the lattice model, which helped explain our observations by analyzing the superposition of stress waves. According to the further simulation, we find that as the cutting speed increases, the stress intensity of the workpiece near the cutting tool is not in a linear enhancement process, with strong distortion of stress field under the superposition of different stress wave components. These help us have a deep understanding about the HSC mechanism under stress waves' effects.

Morphology of the Chip Formation at Orthogonal High Speed Milling of AISI H13

High-speed cutting (HSC) or high-speed machining (HSM) is an issue that the scientists deals with in long-term. To demonstrate the explicitness, that a full HSC machining process is considered, it is necessary to monitor the series of factors. In particular, the process of chip formation, cutting forces, cutting temperature, vibration, tool life and surface finish quality in relation to the method of machining, machined material and its properties. The article deals with the detailed analysis and evaluation of the chip formation in order to determine the hard area, transition area and veritable HSC machining. The evaluation process is based on the proposed experimental model, which is confronted with the measurement results.

High Speed Cutting of Carbon Fibre Reinforced Plastics

The effects of high speed cutting (HSC) on metallic workpiece materials have been widely studied and the benefits are commonly employed in the machining industry. However, in the machining of composite materials, these effects have not yet been a focus of significant research work and core questions such as what impact HSC cutting parameters have on tool wear, process forces and workpiece quality remain open. As such, the work described in this paper shall focus on the use of HSC cutting parameters with spindle speeds up to 60000 rpm for the machining of carbon fibre reinforced composites. Workpiece quality and tool wear are quantified in dependence of cutting speed and feed rate and the known phenomena of reduced cutting forces at high cutting speeds are examined in the case of CFRP machining.

A friction model having multiple factors for high-speed cutting of aluminum alloy 6061-T6

Tool–chip friction of high-speed cutting (HSC) is complex and involves nonlinear problems. This paper proposes a new friction model having multiple factors for HSC and investigates the multiple effects affecting the tool–chip friction coefficient. An experimental method of high-speed friction and an inverse method of obtaining the temperature of the friction interface are proposed. The proposed friction model reveals the inherent relationship between the friction coefficient and the multiple factors, and describes tool–chip friction in the HSC of aluminum alloy 6061-T6 accurately and improves the cutting simulation accuracy. It is also found that an increase in friction speed increases the friction coefficient and that an increase in friction temperature reduces the friction coefficient. However, an increase in ambient temperature clearly increases the friction coefficient at high temperature, and an increase in the normal load reduces the friction coefficient at low temperature and increases the friction coefficient at high temperature. The results provide a clear understanding of the mechanisms of friction speed and temperature, the ambient temperature, and the actual contact area in tool–chip friction of HSC.

HSC Linear Motor Machine Dynamic Stiffness

In this paper a model of the feed drive system with disturbance force for High Speed Cutting (HSC) linear motor machine is given. The dynamic stiffness for the proposed model is analysed. A simulation of the influence of some parameters on feed drive dynamic stiffness is performed with the simulation program MATLAB & SIMULINK. Correctness of the proposed model is verified with an experimental measurement of the dynamic stiffness of the feed drive on the prototype HSC linear motor machine (HSC 11).

An improved material constitutive model for simulation of high-speed cutting of 6061-T6 aluminum alloy with high accuracy

Material constitutive model is one of the basic scientific fundamentals for simulation accuracy of high-speed cutting (HSC). A high-speed orthogonal cutting method (HS-OCM) based on the shear slip distance, aided by split Hopkinson pressure bar (SHPB) experiments, is proposed in this paper to obtain the shear slip deformation characteristics in the HSC of 6061-T6 aluminum alloy. The Johnson–Cook (JC) model was modified in three ways according to the variation tendencies of the effect curves of strain hardening, strain rate strengthening, and thermal softening, and an improved material constitutive model was obtained. The simulation validations of the obtained material constitutive models were executed. It was found that the modified JC model improves simulation accuracy, i.e., the maximum simulation errors of the cutting force and cutting temperature are 18.5 and 12.2 %, respectively. The HS-OCM avoids the cutting speed limitation (<700 m/min) of the quick-stop test usually used in conventional OCM and the difficulty of predicting tendency inflection points of the inverse identification method employing a finite element simulation model, and allows the experimental measurement of the deformation characteristics of 6061-T6 aluminum alloy in high-speed (2000 m/min) cutting. During HSC of 6061-T6 aluminum alloy, the shear stress, shear strain rate, and deformation temperature in the primary deformation zone increase with increasing cutting speed, whereas the shear strain decreases.

Experimental Research Regarding Rigidity Improvement of Hollow Machine Tools Structures Using Aluminum Foam

Abstract The paper studies a method for improving the static rigidity of hollow critical mechanical structures, without greatly affect its weight. There are many applications for this type of structural parts, where mass is critical and are needed increased rigidity properties. The results are obtained by using alternative technologies and composite materials such as filling the interior hollow spaces with metallic expanded aluminum foam. The study is experimentally implemented to a large HSC (High Speed Cutting) CNC machine tool structural moving part. The benefits obtained by reducing its weight and increasing rigidity properties are: better dynamic performance [1] , energy efficiency, mechanical parts less expensive for drive systems [2] .

An Integral Approach to the Investigation of High Speed Metal Cutting

High speed cutting (HSC) has been used widely in the metal machining industry. However, applications and investigations have shown that to optimize an HSC process, many issues need to be understood, such as the fluctuations of cutting forces and residual stresses. Extensive studies have found that these fluctuations are originated from the shear banding during chip formation and from the work-material properties influenced by the coupled attack of high strain rate and high temperature rise during cutting. Due to the complexity of the material deformation mechanisms during HSC, both experimental examination and theoretical analysis are essential. This keynote presentation reviews an integral approach of the author’s team to establishing the investigation chain of experimental analysis, constitutive modelling and numerical simulation to tackle the intricacy of HSC-induced deformation. It points out that while an experimental examination can provide insightful understanding of the deformation mechanisms, it is often limited to a narrow range of testing conditions. A numerical simulation can overcome such experimental difficulties through large-scale parametric studies, but can also bring about erroneous results if the constitutive behavior of a workpiece material is improperly described.

Research on chip formation parameters of aluminum alloy 6061-T6 based on high-speed orthogonal cutting model

Chip formation, an important aspect of the high-speed cutting (HSC) mechanism, is generally accepted as the result of shear deformation in the shear zone and tool-chip friction. In order to accurately study chip formation process in HSC, a theoretical model for the high-speed orthogonal cutting of aluminum alloy 6061-T6 was built, which can be used to calculate the important parameters of chip formation, such as shear angle, friction angle, length of shear plane, tool-chip contact length, and width of the first shear zone. A series of orthogonal cutting experiments, with the YG6 carbide tool and on a wide range of cutting speed (100–1,900 m/min) and feed (0.06–0.15 mm/r), were performed in order to obtain the parameters required in the model, including the cutting forces, the chip thickness, and the shear slip distance. Seven kinds of chip formation parameters were obtained with different cutting parameters in the experiment, and the built theoretical model can well explain the formation process and the morphology characteristics of these chips, which proves that the combined method of theoretical model and orthogonal cutting experiment is an effective and easy approach to obtain the parameters of chip formation in HSC, avoiding the cutting speed limitation and the safety risk in quick-stop test. Within the range of parameters set in the experiments, the chip mainly appears to be continuous chip, curling chip, or discontinuous chip. And the chip thickness, friction angle, length of shear plane, and width of the first shear zone decrease with the increase of the cutting speed; meanwhile, the shear slide distance and shear angle increase.

Estimation of the rotational speed limit of milling cutters with screwed indexable inserts

During the process of high speed cutting (HSC), fast rotating milling cutters are subject to much higher centrifugal forces than cutting forces. This fundamental factor requires to take into account more stringent safety considerations when working on the concept and design of HSC tools. This paper focuses on the operational safety and speed limit of commonly used HSC milling head cutters with indexable inserts being clamped by high-strength countersunk head screws. The spin burst test results of those tools with radial and tangential insert connections are summarized. The analytical formulas to estimate the failure speeds of both insert connections are developed and discussed based on theoretical analysis on insert connection mechanism. Calculation results show a good correlation with the experimental results from spin burst tests. Finally, a new analytical-empirical approach to determine the speed limits and maximum permissible rotational speeds of both types of tools based on a high confidence level is presented. The approach proposed is suggested for a reliable estimate of the speed limits and maximum permissible rotational speeds for fast rotating tools with screwed radial or tangential indexable inserts.

Performance of WC- inserts coated with nanometric [TiN/TiAlN]n- multilayer for the cutting processing of hardened AISI 4340 steel

In the present work wear resistance of 4 μm uncoated tungsten carbide inserts (WC) and coated with [TiN/TiAlN]n multinanolayered or with commercial TiCN-Al2O3-TiN monolayers (TINAL) are examined. Life tests, cutting area temperature analysis, surface roughness measurements on work pieces, roughness measurements on the attacked surface, contact track analysis between chip-insert and chemical composition analysis (EDS) were carried out. Mechanical tests were conducted on AISI 4340 steel parts using cutting regime and applying high speed cutting (HSC). Machining results showed that for a distance of 8,000 m the inserts coated with 300 bilayers exhibited wear values of 0.117 mm, inserts coated with 200 bilayers showed values of 0.138 mm and those coated with TINAL presented wear values of 0.174 mm. Moreover, the temperature values for cutting speed at 176.6 m/mim for 300 bilayers was 522.6 oC, for 200 bilayers was 721.4 oC and 1,327.6 oC for inserts coated with TINAL. Lower temperatures, caused by a lower friction coeffi cient and cutting force, contribute to life-time increasing at WC inserts.

COMPARISON OF MECHANICAL PROPERTIES AND CALCULATION OF CUTTING FORCE BETWEEN UNCOATED TUNGSTEN CARBIDE &amp; Ti COATED TIP TUNGSTEN CARBIDE WITH THE HELP OF LATHE TOOL DYNAMOMETER

The keyword for manufacturers of cutting tools and coatings for cutting tools is productivity: a 30%; reduction of tool costs, or a 50%; increase in tool lifetime results only in a 1%; reduction of manufacturing costs. But an increase in cutting data by 20%; reduces manufacturing costs by 15%;. In order to achieve higher productivity different approaches – High Performance Cutting (HPC) and High Speed Cutting (HSC) can be chosen. The performance of Carbide tools was studied to investigate the tool life and wear behavior at various machining parameters. This study presents tool wear characterization of carbide cutting tool inserts coated with titanium nitride (TiN) on a single point turning operation on copper, aluminum. A set of experiments with conditions of cutting speed, depth of cut and feed rate were performed on a lathe machine. Force analysis is done on Lathe Tool Dynamometer. From the result, cutting speed was found to be the main factor to have significant effect on surface roughness. At the end of this study, optimization was made by suggesting the most suitable sets of parameter settings to produce minimum surface roughness. Suggestion on parameter settings to obtain minimum surface roughness made.

A reliable method for predicting serrated chip formation in high-speed cutting: analysis and experimental verification

Serrated chip formation influences almost every aspect of a high-speed cutting (HSC) process. This paper aims to develop a reliable method to accurately predict such chip formation processes. To this end, a systematic finite element analysis was carried out and a series of HSC experiments were conducted on a heat treated AISI 1045 steel. It was found that the integrative use of the Johnson–Cook thermal-viscoplastic constitutive equation, Johnson–Cook damage criterion for chip separation, and the modified Zorev’s friction model can precisely predict the serrated chip formation in HSC without artificial assumptions. This advancement has removed the major barrier in the current machining investigations by numerical simulation. The present study also found that the tool rake angle has a significant effect on serrated chip formation. As the rake angle increases, the chip sawtooth degree and cutting forces decrease, but the chip segmentation frequency increases.

Deep-Hole Drilling in Stainless Steel with Small Diameter Twist Drills

In this paper results of manufacturing tests are described done in order to evaluate the performances of twist drills of diameter d = 1.2 mm and 1.4 mm respectively, if boring into stainless steel X90CrMoV18 (1.4112). Deep-hole drilling was realized thus, that the depth of the bore hole was greater than 10 times the diameter of the twist drill (L/d &gt;10). In order to reduce the impact on the environment caused by the coolant, it was found that minimum quantity lubrication (MQL) can be applied. Hence, the ecology of the mass production of perforated discs for the food processing industry can be improved. The performance of the several small diameter twist drills was determined and evaluated by, firstly, their deep-hole drilling capability, e.g. assessed by the variation or even increase of cutting forces with increasing depth and travel, whether the forces exceed a critical level due to poor chip extraction. In addition, the suitability to use or rather implement the different small diameter twist drills for high-speed cutting (HSC) and finally the individual tool service life for each investigated twist drill. This research project has shown that the accomplishable performance and operating time are strongly dependent on tool cutting material and the tool geometry, especially the size of the chip flutes of a twist drill, as well as the individual coating of the cutting tools.

The analysis and computing of geometry object in information integration

Advanced manufacturing technology has been adopted to reduce the production cost, to improve product quality, and to shorten development time in enterprise. High-speed cutting (HSC) offers the most appropriate opportunity for reduction of run times (Schulz and Moriwaki, 1993). It is difficult to predict tool wear of HSC, section parameters of chip geometry contains key parameters that affect tool wear calculation. It is possible to predict chip forms before cutting and calculation. The paper presents an algorithm to analyse chip forms for HSC, defines chip categories and prediction result can be used to analyse tool wear and tool safety.