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Effect of abrasive grains' size and their transport medium on the surface roughness in a) dry b) wet micro-blasting process
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Micro-blasting on PVD coated tools is an effective technology for improving their cutting performance. Through micro-blasting, compressive stresses are induced into the film, thus increasing the coating hardness, but its brittleness too. Simultaneously, abrasion phenomena are activated, which may lead to roughness augmentation, film thickness decre...
Contexts in source publication
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... Abrasion mechanisms in wet and dry micro- blasting and developed film hardness Figure 1. explains schematically the effect of dry or wet micro-blasting by fine Al 2 O 3 grains of an average diameter of approximately 10 µm and by ten times larger in diameter as well, on the coated tools' surface integrity. ...
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... schematically the effect of dry or wet micro-blasting by fine Al 2 O 3 grains of an average diameter of approximately 10 µm and by ten times larger in diameter as well, on the coated tools' surface integrity. In dry micro-blasting process (see figure 1a), a larger roughness Rt develops, if fine grains are employed. This can be explained by the repeated micro-chippings of the film's surface considering the large concentration of the fine particles, as it is schematically shown in this figure. ...
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... abrasive effect exerted by dry blasting using Al 2 O 3 particles is expected to be less intense for both, fine and coarse grain sizes compared to the corresponding one when a wet process is applied. In dry micro-blasting, the grains bounce from the coated surface after the impact almost perpendicular (see figure 1), thus affecting the film integrity slightly. This effect results in larger coatings' nanohardness compared to wet micro-blasting, where the grains are dragged along the coating surface. ...
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... determine the effect of wet micro-blasting conditions on the cutting performance of coated tools, milling investigations were conducted by a three-axis numerically controlled milling centre. The applied tool-workpiece system and the main characteristics of the undeformed chip geometry are illustrated in figure 10a. The flank wear development on coated inserts, which were wet micro-blasted by Al 2 O 3 grains of average diameters of ca. 10 μm and 100 μm at various pressures, is demonstrated in figure 10b and 10c respectively. ...
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... applied tool-workpiece system and the main characteristics of the undeformed chip geometry are illustrated in figure 10a. The flank wear development on coated inserts, which were wet micro-blasted by Al 2 O 3 grains of average diameters of ca. 10 μm and 100 μm at various pressures, is demonstrated in figure 10b and 10c respectively. Cutting inserts wet micro-blasted with fine Al 2 O 3 grains at 0.2MPa show a similar cutting performance with the as deposited coated tool, reaching a tool life of ca. ...
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... the case of the coarse Al 2 O 3 grains (see figure 10c), the micro-blasted tools at a pressure of 0.2 MPa exhibited the best cutting performance, reaching a tool life of approximately 130 000 cuts up to a flank wear width of 0.2 mm. A slight tool life reduction at 120 000 cuts up to the same flank wear of 0.2 mm was encountered at a pressure of 0.3 MPa. ...
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... achieved number of cuts up to a flank wear width of ca. 0.2 mm of coated tools subjected to micro- blasting by fine or coarse sharp-edged Al 2 O 3 grains, employing different micro-blasting grain transport media is illustrated in figure 11. According to these results, wet micro-blasting, when coarse grains are used, contributes to coated tool cutting performance improvement. ...
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Citations
... The results of studies on this matter were presented, inter alia, by Kulkarni et al., Ciftsi, Endrino et al. [11,23,24]. In terms of tool coatings, the studies are conducted also on the impact of grain size of the coating on the cutting performance of the tools, and the results of such studies have been presented by, inter alia, Bouzakis et al. and Tillmann et al. [25,26]. ...
... Moreover, in the tool industry, micro-blasting has been registered as an efficient method for increasing the life of coated tools [15][16][17]. However, the applied micro-blasting conditions have to be carefully selected since this process can lead to an augmentation of the cutting-edge radius, resulting in reduced cutting tool ability [18,19]. In the frame of the conducted research, the potential of an effective application of micro-blasting on tools applied for cheese cutting was investigated. ...
... The importance of micro-blasting as a technique to increase the life span of tools has been registered in the past [18,19]. This process has as a target to induce residual stresses in the material structure and, in this way, to increase the mechanical properties [14]. ...
The potential to increase the life span of tools applied in cheese cutting machines is of great importance, considering their cost and the risk of fragmented metallic parts of the tool being inserted into the cheese. Such tools are commonly manufactured using stainless steel 405 and are subjected to dynamic loads during their operation, leading to fatigue failure. An efficient method to improve the fatigue properties of such tools is the application of micro-blasting. In this work, for the first time, an experimental–analytical methodology was developed for determining optimum micro-blasting conditions and ascertaining a preventive replacement of the tool before its extensive fracture. This methodology is based on the construction of a pneumatic system for the precise cutting of cheese and simultaneous force measurements. Additionally, the entire cheese-cutting process is simulated by appropriate FEA modeling. According to the attained results, micro-blasting on steel tools significantly improves the resistance against dynamic loads, whilst the number of impacts that a tool can withstand until fatigue fracture is more than three times larger. Via the developed methodology, a preventive replacement of the tool can be conducted, avoiding the risk of a sudden tool failure. The proposed methodology can be applied to different tool geometries and materials.
... But working at elevated temperatures, the sustainability of coated cutting tools is of prime concern. Various surface treatments such as mechanical treatment, thermal treatment, laser treatment, etc. are employed to improve the mechanical and physical properties of the coated tools [2,3]. ...
It has been widely reported that cutting tools showed improved mechanical properties and better machining performance with different pre-and post-treatments. The performance of hard thin coatings can be optimized by knowing the effect of surface pre-and post-treatments on the coating properties. Hard thin coatings are characterized by their hardness, effective young’s modulus, and elastic recovery. This study aimed to evaluate the effect of the microblasting and/or cryogenic treatment as a pre-and/or post-surface treatments on the nanohardness, modulus of indentation, and percent elastic portion of the nanoindentation of single layer PVD-AlTiN coating deposited on the tungsten carbide insert. The characteristics of hard thin coatings have been determined from loading/unloading curves measured by a computer controlled Fischerscope PICODENTOR HM500 nanohardness tester and a maximum depth of the diamond indenter impression into the coating at a given load of 30 mN for 20 s. It has been observed that the value of the indentation depth and the area between the loading/unloading curve decreases with an increase in the nanohardness and modulus of indentation (effective Young’s modulus) of the thin hard coating. It has been observed that the coated-microblasted as a post-treatment produced higher nanohardness (2833.6H.V.) and better resistance to plastic deformation (0.08 GPa) as compared to other pre-and/or post-treatments considered in the present study.
... During micro-blasting process, the transport medium is usually air or wear, namely dry microblasting or wet micro-blasting. Bouzakis et al. [11] found that under the same process parameter conditions, the wet microblasting resulted in a rougher surface and a lower hardness, but a higher cutting performance compared with the dry micro-blasted coating. ...
... This illustrates that big particle size can result in higher Ra. Similar results were also found in ref. [11]. Under low working pressure conditions, the small particle size has a small kinetic energy. ...
The cutting performance of coated tools can be significantly improved by appropriate post-treatment of coated surface. To determine the effects of micro-abrasive slurry jet (MASJ) and micro-abrasive air jet (MAAJ) on the performance of coated tools, single-factor tests were conducted to investigate the effects of micro-abrasive jet processing parameters on surface roughness of coated tools and thickness of coating removed. Based on the single-factor results, multi-process tests were designed, and two types of coated tools were obtained after micro-abrasive jet post-treatment. Based on the results of wear tests and the effect of cutting parameters on the surface roughness of the turning workpiece, the cutting performance of the three different tools on hardened die steel was evaluated. Turning tests showed that the micro-abrasive jet post-treatments effectively improved the surface morphology of the coating and the surface quality of the coated tools. Under the same machining parameters, the coated tools treated with the MASJ show better cutting performance than the tools post-treated by MAAJ.
... Coating exposure was not that much significant at 0.2 MPa. However, above this pressure, a significant amount of coating removal was observed by some researchers [23]. Hence, the proper selection of these parameters plays a pivotal role. ...
This work investigates the variation in surface and sub-surface characteristics of the AlTiN coated tools in comparison to the micro abrasive blasted AlTiN coated tools. The coatings were deposited through a newly developed hybrid technique that combines the benefits of the two conventional physical vapour deposition techniques. The coated inserts were subjected to micro abrasive blasting (MAB) at 0.1 MPa and 0.2 MPa blasting pressure using alumina (Al2O3) abrasive grains. The physical, metallurgical and mechanical properties of the AlTiN films were studied using various characterization techniques. The deposited film is free from surface defects like holes or pores. MAB of these films lead to surface flattening at localized sites leading to the film surface uniformity. The impact of hard abrasives onto the film surface has also improved subsurface properties along with an escalation in the surface roughness value. Nano-indentation results showed that the nano-hardness exhibited by the AlTiN coated tools subjected to micro blasting is high, around 35 GPa, in comparison to only coated samples, which show a value of around 29 GPa. MAB of films also resulted in an improvement of film crystallinity. These results indicate that the micro blasted films have improved properties and hence may be more beneficial in enhancing the machining performance of the tools.
... Macro-blasting on cemented carbide substrates has been also proved as an efficient method for reconditioning coated cemented carbide tools [1,4,5]. The conduct of micro-blasting on the already coated surfaces has been documented as an efficient method for improving further the coated tool life [6,7,8,9,10,11,12,13]. For assessing the effectiveness of all these methods, innovative coating's characterization procedures providing information concerning the film and substrate properties as well as adhesion have to be applied [1]. 1 Substrate's pre-treatments ...
... More specifically, wet micro-blasting with Al 2 O 3 grains was conducted on the cemented carbide inserts after the laser machining. For ensuring negligible substrate material removal, thus not affecting the cutting edge geometry attained by the laser treatment, the micro-blasting process lasted only 4 s at a pressure of 0.3 MPa [6]. The wear evolution of coated tools with laser pre-treated and micro-blasted substrates are presented in figure 6. ...
... These potential effects of micro-blasting are schematically demonstrated in figure 7 and have to be taken into account for optimising the coated tools cutting performance. Micro-blasting parameters such as pressure, time as well as blasting grains' size and shape have a pivotal effect on the film strength properties and thus on the coated tools' cutting performance [6,7,8]. Figure 8 explains schematically the effect of dry or wet micro-blasting by fine Al 2 O 3 grains of an average diameter of approximately 10 μm and by ten times larger in diameter as well, on the coated tools' surface integrity. ...
The cutting performance of PVD coated tools can be significantly improved by appropriate pre- and post- treatments of the substrates and coated surfaces respectively. Substrate pre-treatments aim, among others, at improving the coating adhesion. In this way, lower coating loads develop during cutting leading to a decelerated wear evolution. Furthermore, the potential to increase the wear resistance of coated tools via micro-blasting is presented. Micro-blasting parameters such as of grain material, pressure, dry or wet etc., affect significantly the superficial coatings' hardness and brittleness and in this way their wear behaviour. To check the effectiveness of all these methods, innovative coating's characterization procedures providing information concerning the film and substrate properties as well as adhesion are applied, thus reducing the required experimentation time.
... AlTiN coatings have higher hardness and thermal conductivity at elevated temperature [11,12] while oxidation and abrasion resistance for AlCrN coatings were found to be higher [13]. Substrate surface treatments, e.g., drag grinding [14], sand blasting [15][16][17], chemical etching [18,19], laser treatment [8,20] and ultrasonic surface treatment [21] helps in promoting better adhesion of coating due to surface cobalt removal, mechanical anchoring and substrate oxides/scale removal. Laser texturing creates uniform texture patterns that help in improved mechanical properties, coating growth and adhesion by different underlying mechanisms. ...
Owing to increased demands of more efficient cutting tools for machining difficult to cut materials and environment-friendly cutting operations, laser textured tools have become necessary. The characterization and machining
studies with such laser textured tools coated with hard ceramic coatings are the prime motivation for
this present work. The main aspect of the study is to evaluate two different PVD coated (AlTiN and AlCrN) laser
textured tools. In the first stage, laser textured tools were prepared with novel chevron shaped textures on tool
rake face using nanosecond pulse laser. This stage is followed by PVD coatings of AlTiN and AlCrN coatings by
cathodic arc evaporation (CAE) technique. Coating characterization studies were conducted considering coating
morphology, surface roughness, coating elemental analysis and phase analysis of coated and coated textured
tools. The performance of the different tools thus manufactured was evaluated by carrying out suitable turning
experiments on cylindrical Ti6Al4V work material under dry cutting environment. Machining results were evaluated
in terms of cutting force, flank wear progress, rake surface analysis, and chip underside study. Further, static
diffusion couple test (SDCT) has been conducted to understand diffusion wear mechanism in plain and textured
tools. A new concept of derivative cutting or interfacial multipoint micro-cutting (IMP-μC) on chip underside
surface due to texture patterns and a reduction of derivative cutting due to coatings on the textured tools have
been proposed.
... The conduct of micro-blasting on the already coated surfaces has been documented as an efficient method for improving further the coated tool life [12][13][14][15][16][17]. Finally, the cuttings edges of coated tools with sharp cutting edges mainly of small diameter can be rounded after the film deposition via grinding. ...
... These potential effects of micro-blasting are schematically demonstrated in Fig. 15 and have to be taken into account for optimising the coated tools cutting performance. Micro-blasting parameters such as pressure, time as well as blasting grains' size and shape have a pivotal effect on the film strength properties and thus on the coated tools' cutting performance [12][13][14]. Figure 16 explains schematically the effect of dry or wet micro-blasting by fine Al2O3 grains of an average diameter of approximately 10 μm and by ten times larger in diameter as well, on the coated tools' surface integrity. In dry micro-blasting process (see Fig. 16a), a larger roughness Rt develops, if fine grains are employed. ...
The cutting performance of PVD coated tools can be significantly improved by applying optimized PVD processes, film architectures, as well as appropriate pre-and post-treatments of the substrates and coated surfaces respectively. Substrate pre-treatments aim, among others, at improving the coating adhesion. In this way, lower coating loads develop during cutting leading to a decelerated wear evolution. Furthermore, the effect of various PVD process parameters and film architectures such as of adhesive interlayers, Ar+ ions bombardment, thickness distribution and multi-layer structure on the coated tool life is demonstrated. Finally, the potential to increase the wear resistance of coated tools via micro-blasting and to render sharp cutting edges mainly of small diameter tools more stable by rounding them via grinding is presented. Micro-blasting parameters such as of grain material, pressure, dry or wet etc., affect significantly the superficial coatings’ hardness and brittleness and in this way their wear behaviour. To check the effectiveness of all these methods, innovative coating’s characterization procedures providing information concerning the film and substrate properties as well as adhesion are applied, thus reducing the required experimentation time. © 2017, Editorial Institution of Wrocaw Board of Scientific. All right reserved.
Machining of difficult to cut material leads to excessive amount of tool wear owing to dynamic nature of stresses. The amount of tool wear affects the machinability as well as tolerances during the cutting operation. Thus, monitoring of the flank wear is necessary under sustainable cutting environment. However, such monitoring in industrial and practical applications is a tedious task. The current study focuses on development of pseudo analytical model to predict the wear behaviour during the machining operation for the coated as well as surface modified (coated/micro blasted) tools. The model is possibly the first of its kind which incorporates the hardness of the coating, workflow stress and forces acting on the tool, while predicting the tool wear values. The developed model was calibrated and validated experimentally during the turning of Nimonic C 263 using AlTiN coated tools (treated and untreated) at varying cutting conditions. During the analysis it was found that the experimental results were very much in agreement with predicted values of the flank wear, and the flank wear progression also followed the similar pattern as that of the later.
