Tool Lifetime Research Articles

Machining performance of TiSiN(Ag) coated tools during dry turning of TiAl6V4 aerospace alloy

One of the main opportunities to increase the tool life during the dry machining of “hard-to-cut” aerospace alloys is the possibility of protecting the components with self-lubricant coatings. Here, self-lubricant TiSiN(Ag) coatings deposited by HiPIMS working in DOMS mode were deposited onto two types of cutting inserts to assess the influence of the solid lubricant (Ag) on the dry machining performance during turning of the TiAl6V4 aerospace alloy. First type of cutting inserts were tested in laboratorial environment using a conventional lathe, whilst, second types of inserts were tested in an industrial automated computer numerical control – CNC machine in an enterprise premises. Tests in the CNC machine were performed to assess their performance benchmarked in relation to a commercial insert coated with AlTiN coating. In both of these tests, the same behaviour was found with the addition of silver clearly displaying an improvement in the tool life of the inserts, especially for higher cutting speeds. Addition of silver also showed its solid lubricant effect by reducing either the wear or the formation of built-up edges (BUE) during the tests and, thus, contributing to an increase in the tools lifetime. Ultimately, this work shows the potential use of TiSiN(Ag) coatings for machining TiAl6V4 aerospace alloy under dry conditions.

Tool lifetime when drilling Inconel 718 in dependence of the cooling channel design –Influence of the clearance angle, the channel diameter, number, and shape

When drilling Inconel 718, the drills are exposed to high mechanical and thermal loads. The cutting zone is located inside the workpiece, whichmakes it challenging to provide sufficient metalworking fluid to the cutting zone. To solve this, drills with internal cooling channels are commonly used. However, no standard on the design of those channels exists. In this work, the influence of different cooling channel designs and different second tool orthogonal clearance angles on tool life, process forces and bore quality have been investigated experimentally. The results reveal that tool lifetime can be influenced in particular by the size of the cooling channels.

Investigation on the turning process parameters for tool life and production time using Taguchi analysis

This study applies Taguchi method for optimizing process parameters using for SS304 material for better tool life and less production time. Feed rate, Cutting speed and Depth of Cut are the machining parameters are used with consideration of tool life and production time for application of Taguchi method, Analysis of Variance (ANOVA). Outcomes of the experimentations used for the measurement of S/N ratios, which are further used to optimize the tool life and production time parameters. The maximum tool life and minimum production are then predicted using confirmation test. Results revealed that feed rate has significant effect on tool life and cutting speed has significant effect on production time. The optimal parameter for maximize tool life is found to feed rate 0.14 mm/rev, depth of cut 0.40 mm and cutting speed of 350 m/min and For optimizing minimum production time, the optimum conditions are cutting speed 550 m/min., feed rate 0.14 mm/rev, and depth of cut 0.40 mm.

Energy Efficiency Assessment of Cryogenic Minimum Quantity Lubrication Cooling for Milling Operations

Cryogenic minimum quantity lubrication (CMQL) extends the application spectrum of cryogenic cooling by the possibility of lubrication. This enables the proportion of both cooling and lubrication capacity to be adapted to the process as required. Especially liquid CO2 has been established for the CMQL. This application enables a sustainable use of CO2 in a circular cycle opposed to its emission to the atmosphere. For a comparison of conventional flood cooling with CMQL, the specific energy has to be determined in addition to the process-related suitability. Specifications by the European Commission and the desire for sustainable production require a quantification of the environmental impact. For the determination of these product carbon footprints, energy demand forecasts are essential.This paper presents a method for calculating the energy demand for milling processes under CMQL and wet machining according to the life cycle assessment EN ISO 14044 taking the material flows into account. The considered material flows include the cutting energy of the process, the energy to provide the water for the emulsion for flood cooling, the energy to liquefy the CO2, the energy for the oil refining process for emulsion and CMQL, the energy for the coolant pumps and the energy for the manufacturing of the tools. The balancing is carried out for a defined functional unit. Due to the different tool lifetimes, there are large fluctuations in the energy requirements. It is shown that despite the high energy expenditure for the provision of CO2 and the energy supply for flood cooling, the most significant influence on the energy expenditure results from the manufacture of the tools. By increasing the tool life and increasing the number of tool regrinding cycles, the energy requirement for the functional unit can be reduced.

Application of preliminary low-temperature heating for cold forming of complex parts on cold former

The results of experimental studies of flow curves of 32CrB4, 20G2R and 1.4034 (analogue of 40Kh13 steel) steels at different heating temperature of workpieces are presented. Rational intervals of preliminary lowtemperature heating of workpieces made of studied steels are obtained. It allows to decrease forces during cold forging, loads on the working tool and to increase of tool life time up to 2 times.

Ultrasonic assisted drilling of cemented carbide

Precision bore holes in cemented carbide are often manufactured by using time-consuming or complex technologies such as grinding, eroding or laser ablation. The use of CVD-diamond coated drilling tools with defined cutting edges can increase the material removal rate. However insufficient process stability and deficient tool lifetime often occurs because of tool breakage. It is demonstrated that ultrasonic assistance can reduce cutting forces. The underlying effect is a micro crack induction inside the material. An ultrasonic related process adjustment by investigating the influence of different parameters was conducted to increase the productivity of the drilling process.

Effect of CAD-CAM tool deterioration on the trueness of ceramic restorations

Statement of problemTools will gradually deteriorate with repetitive milling. However, tool lifetime can vary depending on the type of milling machine, the hardness of the ceramic material, and the size of the restoration. Studies evaluating the effect of tool deterioration on the trueness of milled restorations are lacking. PurposeThe purpose of this study was to evaluate the effect of tool deterioration on the trueness of milled restorations. Material and methodsA patient requiring a ceramic crown was recruited. Repetitive milling of zirconia crowns (inCoris TZI; Dentsply Sirona) with tungsten carbide rotary instruments and glass-ceramic crowns (VITABLOCS mark II; Vita Zahnfabrik) with diamond rotary instruments was performed by using a 5-axis milling machine (inLab MC X5; Dentsply Sirona) until the machine software program indicated replacing the largest tool. The percentage of deterioration for the largest tool was recorded before each milling. The trueness for different crown areas was evaluated by using a 3-dimensional evaluation software program (Geomagic Control X; 3D systems), and the crowns were clinically evaluated. The crowns were grouped into 4 quadrants as per the deterioration percentage. The Pearson correlation (r) between the deterioration percentage and trueness and linear contrast analysis (partial eta squared [η]) among the groups were performed. ResultsGlass-ceramic crown areas had low correlation except for mesial (high, r=0.63, high, η=0.37) and distal (medium, r=0.42, high, η= 0.34) areas, whereas zirconia crowns had low correlation for inner and internal areas and medium to high correlation for mesial (r= -0.31, η=0.33), distal (r= -0.53, η=0.36), occlusal (r= -0.32, η=0.164), external (r= 0.69, η=0.52), and marginal (r= -0.44, η=0.19) areas. Zirconia crowns had excellent marginal fit and occlusal contact and light to excellent proximal contact, whereas glass-ceramic crowns had excellent marginal fit, minor to major occlusal correction, and heavy proximal contact. ConclusionsThe effect of tool deterioration on trueness depended on material type and crown area. Only proximal areas were affected in the glass-ceramic crowns, whereas external, proximal, occlusal, and marginal areas were affected in the zirconia crowns. Trueness did not necessarily reflect the clinical quality of the crown, as both crown types were clinically satisfactory. Although zirconia crowns were overmilled in comparison with the reference design and glass-ceramic crowns, they had better clinical quality.

Experimental and statistical analysis of the wear of diamond impregnated tools

Diamond impregnated tools are considered which are used to machine concrete. During their application, the bonding as well as the diamonds need to wear down in a certain way to gain a sharp tool. This required wear is called self-sharpening and means a continuous exposure of new diamonds. Within the development phase of diamond tools, time and cost intensive testing is necessary for the assessment of the tool performance. Hence, an extrapolation based on a minimal amount of testing is desirable to forecast the tool lifetime. A further reduction of the development and testing cost can be achieved by reducing the data needed to forecast the tool performance. Within this paper, the development of a statistical model is shown which was used to forecast the lifetime of the single diamonds on the tool. The statistical analysis is based on single segment tests which were carried out with different segment specification. During the tests, the exposed and broken out diamonds were counted to serve as the necessary input data for the statistical analysis. The counting of the diamonds on the segment was done in two different ways: based on the 2-dimensional microscopic pictures made after every minute of drilling and based on the 3-dimensional surface measurements made after every 5 min of drilling. It turns out that these two approaches of the wear analysis provide similar results.

Rapid Open-Air Fabrication of Perovskite Solar Modules

<h2>Summary</h2> We report on the open-air fabrication of perovskite solar modules with key advances, including scalable large-area spray deposition, new monolithic integration scribing techniques, advanced photoluminescence characterization, and reproducible high-throughput manufacturability. Perovskite deposition with linear speeds of 12 m/min without post-annealing is demonstrated, with improved device performance, luminescent yield, and >10× carrier lifetimes. Manufacturability using monolithic integration of series-connected modules is accomplished with a new indirect fiber laser ablation scribing method. A stable cell and module power output of 18.0% and 15.5%, respectively, was achieved with a subcell V_oc > 1.06 V. A comprehensive supporting technoeconomic analysis details the entire in-line manufacturing process from the glass substrate to the junction box of the encapsulated module. The module manufacturing cost, balance of system costs, and levelized cost of energy for a range of module efficiencies and lifetimes provide insights for the necessary tool speeds, efficiencies, and lifetimes for utility-scale energy generation.

Effect of SiC Addition to Al2O3 Ceramics Used in Cutting Tools.

In this study, the effect of the addition of silicon carbide to alumina ceramics commonly used in cutting tool applications is addressed. Performance of Al2O3–SiC composite cutting inserts during the machining of hardened steels and ductile iron was compared to the results obtained for a cutting tool made out of 99 wt.% Al2O3, Al2O3–TiC, Al2O3–TiC–ZrO2, and Al2O3–TiN. In almost all tests, the composite with silicon carbide demonstrated better wear resistance, longer tool lifetime, and the ability to cut at higher speeds. The enhanced properties of cutting tools with SiC can be attributed to the morphology and dimensions of the inclusions in the matrix as well as to the strength of the interphase boundaries, small porosity, and lack of high inner stresses in the volume.

In-situ investigation of the oxidation behavior of powdered TiN, Ti(C,N) and TiC coatings grown by chemical vapor deposition

Since hard coatings used in metal cutting applications are exposed to temperatures up to 1000 °C, their oxidation stability is a crucial parameter for the tool lifetime. Thus, within this work, the detailed oxidation mechanisms of chemical vapor deposited TiN, Ti(C,N) and TiC coatings were studied. Coating powders were subjected to a heat treatment between 420 and 940 °C in ambient atmosphere and their phase composition was monitored in-situ by X-ray diffraction. Rietveld refinement allowed to quantify the phase fractions of TiN, Ti(C,N), TiC, TiO2 rutile and TiO2 anatase at every measurement temperature. Combining this method with differential scanning calorimetry and thermo-gravimetric analysis allowed to precisely track the progress of the involved reactions during oxidation. TiN exhibits the highest oxidation onset temperature of 640 °C. This fact is attributed to the higher Gibbs free energy of the oxidation reaction compared to TiC and the large domain size of the nitride. The latter observation also explains the single-step reaction to rutile without anatase formation. In case of Ti(C,N) and TiC, rutile and anatase form in the course of the oxidation. Ternary Ti(C,N) displays the highest oxidation end temperature and is only entirely consumed at 880 °C. Owing to the lower Gibbs free energy of the oxidation and the lower domain size in comparison to the nitride, TiC exhibits the lowest oxidation onset and end temperature.

Influencing Microstructure of Vanadium Carbide Reinforced FeCrVC Hardfacing during Gas Metal Arc Welding

Vanadium carbide (VC) reinforced FeCrVC hardfacings have become important to improve the lifetime of tools suffering abrasive and impact loads. This is because the microstructural properties of such hardfacings enable the primary VCs to act as obstacles against the penetrating abrasive. Because dilution is supposed to be the key issue influencing the precipitation behaviour of primary carbides during surfacing, the development of deposit welding processes exhibiting a reduced thermal impact, and hence lower dilution to the base material, is the primary focus of the current research. By inserting an additional hot wire in the melt, an approach was developed to separate the material and energy input during gas metal arc welding (GMAW), and hence realised low dilution claddings. The carbide content could be increased, and a grain refinement was observed compared with conventional GMAW. These effects could be attributed to both the reduced dilution and heterogeneous nucleation.

The influence of the recycled wood proportion in particle boards to the tool life of milling tools

ABSTRACT The main factor influencing tool life in particleboard machining is mineral content, and therefore the aim of this investigation is to study the issue and evaluate the tool lifetime by machining different particleboards Also, the change of the mineral content of particle boards over a time frame of 30 years and the geographic origin of the boards should also be taken in account. For this purpose, the mineral content was determined on 600 samples which were produced between 1989 and 2018 in different countries. The influence of the mineral content to tool lifetime was examined with cutting tests at a special series of industrially produced boards with known recycled wood composition. Machining conditions and cutting material have been the same during the investigation. A comparison of the amount of recycled wood which is used in production of particleboard showed a higher mineral content for an increasing proportion of recycled wood, and thereby also an increased wear on the tools.

Electromagnetic coupling field strengthening of WC-TiC-Co cermet tools

This work proposes the application of pulsed electromagnetic coupling field processing (EMCFP) to enhance the lifetime and cutting performance of WC-15TiC-6Co cermet tool for the first time. Firstly, the developed electromagnetic field coupling equipment is introduced, the treatment process is analyzed, and the magnetization characteristics of WC-15TiC-6Co cermet tool are evaluated. Secondly, the strengthening effect of the EMCFP treatment is demonstrated by mechanical properties testing and cutting experiments, which reveal that the optimally treated tools exhibit a fracture toughness increased by 18%, an average cutting temperature decreased by 10%, and a friction coefficient for the rank face decreased by 7.9%. Collectively, these enhancements result in a tool lifetime increased by a factor of 1.92 relative to the lifetime of untreated tools. In addition, the results of simulation demonstrate that the simultaneously pulsed magnetic and electric fields contribute toward greater magnetic flux density and current density on the surface of the WC-15TiC-6Co cermet tool than would be obtained from the magnetic and electric fields alone.

Effects of carbide substrate properties and diamond coating morphology on drilling performance of CFRP composite

Abstract The properties of a cemented carbide tool substrate and diamond coating were studied for the precision drilling of carbon fiber-reinforced plastic (CFRP). The microstructures and mechanical properties of WC–6 wt.% Co substrates using different WC particle sizes were examined to determine correlations between the mechanical properties and the drilling performance. The results demonstrated that WC powders with an average particle size of 2.3 μm were suitable drill substrates. Coatings of either microcrystalline diamond (MCD) or gradient nanocrystalline diamond (NCD) were deposited using hot-filament chemical vapor deposition. A drilling test using T700-grade CFRP was conducted to evaluate the drilling performance, tool wear resistance, and CFRP hole quality achieved based on the diamond coating morphology. In the CFRP drilling tests, the diamond-coated drills showed superior tool lifetimes four times longer than that of the uncoated drill. The MCD-coated drill exhibited good wear resistance compared to the gradient NCD-coated drill; however, the gradient NCD-coated drill demonstrated better machining quality in terms of the delamination factor, surface roughness inside the machined hole, and accuracy of the machining dimensions. In this study, we aimed to develop the optimal tool substrate for the drilling of general-purpose CFRP and proposed directions for the development of diamond coatings to maximize drilling performance.

Characterisation and machinability of high chromium hardened white cast iron with and without the addition of niobium

High chromium white cast iron (HCWCI) is considered a hard machinable material because of its high carbide content, which when associated with a matrix, forms a rigid and very hard microstructure. This work evaluates the effect of the addition of 0.5% niobium (Nb) on the machinability of a HCWCI alloy with 25.6% chromium and 3.2% carbon. The alloys were cast, heat-treated and characterised. The characterisation was performed by X-ray diffractometry, scanning electron microscopy, hardness and carbide volumetric fraction (CVF). The machinability was analysed in materials with and without the addition of Nb during the turning process using polycrystalline cubic boron nitride cutting tools, while varying the cutting speed in dry cutting and lubri-cooling conditions. The output parameters analysed were the tool lifetime, roughness and wear mechanisms. The Nb addition promoted a decrease of CVF and hardness, also resulted in the microstructure refinement, contributing positively to the machinability of HCWCI under both cooling conditions. In general, the use of cutting fluid resulted in lower roughness values and improved life performance of cutting tools, influencing the reduction of the abrasion wear mechanism.

Assessment of selected properties of treated tool surfaces examined to increase tool life time

The article deals with the evaluation of interactions between abrasive particles and treated sample surfaces. It represents a summary of the knowledge gained from research the wear of tools for crushing unwanted growths. Samples of materials were tested under laboratory conditions. The hardness of HRC and HV10 was evaluated in the experiment, abrasive wear rate, assessed according to standard GOST 23.208-79. The depth of the track under test disc by using silicon abrasive particles was also evaluated. Furthermore, the hardness coefficient KT relative to the base material of the tool - 16MnCr5 steel and the hardness of abrasive were determined. By comparing the measured and calculated values the heat treatment procedures and hardfacing materials were assessment. By comparing the measured and calculated values the heat treatment procedures and hardfacing materials were as-sessment, which are expected to provide an increase the abrasion resistance towards to an abrasive, heterogeneous working environment in operation.

Design, preparation and cutting performance of bionic cutting tools based on head microstructures of dung beetle

Abstract Metal cutting plays an important role in modern machining industry, but the cutting tool wear strictly restricts the processing efficiency and tool lifetime. Some billions of years of evolutionary natural creatures have the anti-friction function that scientists are eager to have in their cutting tools. Thus, two kinds of bionic cutting tools were designed based on the surface structure of dung beetle head in this article. Moreover, such tools were fabricated with laser processing based on YS8 cemented carbide cutting inserts. Ti6Al4V dry cutting experiment was carried out at CA6136 turning machine by bionic cutting tool (ap = 0.3 mm, f = 0.1 mm/r). The main cutting force of Tool1 decreased 30.41 % than the non-microstructure tool when the cutting speed vc is 20 m/min, and the average friction coefficient at the tool-chip interface of Tool2 decreased by 14.53 % at 60 m/min.

Using Ensembles for Accurate Modelling of Manufacturing Processes in an IoT Data-Acquisition Solution

The development of complex real-time platforms for the Internet of Things (IoT) opens up a promising future for the diagnosis and the optimization of machining processes. Many issues have still to be solved before IoT platforms can be profitable for small workshops with very flexible workloads and workflows. The main obstacles refer to sensor implementation, IoT architecture, and data processing, and analysis. In this research, the use of different machine-learning techniques is proposed, for the extraction of different information from an IoT platform connected to a machining center, working under real industrial conditions in a workshop. The aim is to evaluate which algorithmic technique might be the best to build accurate prediction models for one of the main demands of workshops: the optimization of machining processes. This evaluation, completed under real industrial conditions, includes very limited information on the machining workload of the machining center and unbalanced datasets. The strategy is validated for the classification of the state of a machining center, its working mode, and the prediction of the thermal evolution of the main machine-tool motors: the axis motors and the milling head motor. The results show the superiority of the ensembles for both classification problems under analysis and all four regression problems. In particular, Rotation Forest-based ensembles turned out to have the best performance in the experiments for all the metrics under study. The models are accurate enough to provide useful conclusions applicable to current industrial practice, such as improvements in machine programming to avoid cutting conditions that might greatly reduce tool lifetime and damage machine components.

Influence of thermal ageing on the fracture and lifetime of additively manufactured mold inserts

Due to the significant technical benefits of additive manufacturing (AM), its application has grown considerably in recent years. In this respect, the integration of AM in the injection molding (IM) process chain for tooling purposes is an ongoing research topic. In the current study, the design, fabrication and use of a tool inserts for injection molding process fabricated by a vat photopolymerisation technique. Since molds during the injection molding process are subjected to cyclic thermal variation, accelerated thermal ageing was applied on the AM mold inserts to emulate the effect of continuous production on the tool lifetime. The additively manufactured mold inserts were exposed to thermal cycling loading in the range between room temperature up to 100 °C, and then, they were used in the actual injection molding process. According to the obtained results, effects of thermal ageing on behavior of the mold inserts are demonstrated. Moreover, fractographic analysis is performed on the fractured surfaces to determine crack initiation and propagation on the mold inserts. The current study provides insight about ageing and fracture of IM mold inserts produced by vat photopolymerisation , and these results can be used for the development of computational models, future material design and load-carrying capabilities of additively manufactured mold inserts to expand the use of AM for tooling purposes.