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Bu çalışmada konvansiyonel yöntemlerle delinmesi maliyetli ve zor olan yüksek sertlikteki (60-62HRC) X153CrMoV12 soğuk iş takım çeliğine elektro erozyonla hızlı delik delme tezgahında 3 mm pirinç elektrotlar kullanılarak delikler delinmiştir. Bu kapsamda üç farklı amper (5, 6, 7 A), üç farklı voltaj (1, 2, 3 V), altı farklı ark süresi (18, 22, 24, 26, 28, 29 μs), dört farklı bekleme süresi (3, 6, 8, 10 μs) parametrelerinin işleme süresi ve delinen deliklerde oluşan kerf üzerine etkileri makro analizler ve analitik ölçümlerle tespit edilmiştir. Yapılan analizler neticesinde kerf açısına ve işleme zamanına etkisi en yüksek parametrenin işleme akımı olduğu tespit edilmiştir. Akım, voltaj ve ark süresinin artması işleme süresini azaltırken, bekleme süresinin artmasıyla işleme süresi artmıştır. Genel olarak elektrot malzemesinin içerisinden ve dışarısından dielektrik sıvı püskürtülmesiyle aşınan partiküllerin ortamdan tahliye edilmesine bağlı olarak işleme parametrelerinin kerf üzerinde doğrusal olmayan bir etki yaptığı tespit edilmiştir. En düşük kerf açısı ve en yüksek işleme süresine maksimum akım değeri 7A, 3V voltaj, 29 μs ark süresi ve 3 μs bekleme süresi çalışma parametreleri kullanılarak ulaşılmıştır. Ayrıca delik giriş çapında 170 μm, çıkış çapında ise 220 μm boyutsal tamlık elde edilmiştir., In this study, holes were drilled on X153CrMoV12 cold work tool steel with high hardness (60-62HRC), which is difficult and costly to drill with conventional methods, using 3 mm brass electrodes on a fast hole drilling machine by electro-erosion. In this context, the effects of three different amperes (5, 6, 7 A), three different voltages (1, 2, 3 V), six different pulse on-time (18, 22, 24, 26, 28, 29 μs), four different pulse off-time (3, 6, 8, 10 μs) parameters on the processing time and the Kerf formed in the drilled holes were determined by macro analysis and analytical measurements. As a result of the analysis, it has been determined that the parameter with the highest effect on the kerf angle and machining time is the machining current. The processing time increased with the increase of the pulse off time on the other hand the increase in current, voltage and pulse on time decreased the machining time. In general, it has been determined that the processing parameters have a non-linear effect on the kerf due to the pressure flushing of dielectric liquid from the inside and outside of the electrode material, and the evacuation of the abraded particles from the environment. The lowest kerf angle and the highest processing time were achieved using the operating parameters of 7A maximum current, 3V voltage, 29 μs pulse on time and 3 μs pulse off time. In addition, a dimensional accuracy of 170 μm in the hole inlet diameter and 220 μm in the output diameter was obtained.

Purpose The purpose of this study is to obtain strong materials with multiwall carbon nanotubes (MWCNTs) doped and investigate laser cut of MWCNTs also find the effect of the laser cutting parameters on composite materials. Design/methodology/approach The laminated composite plates were manufactured by using a vacuum infusion process. The mechanical properties of the composite materials produced were determined according to American Society for Testing and Materials (ASTM) D3039M, ASTM D3171, ASTM D 792 and ASTM D2583. A 130 Watts carbondioxide (CO2) laser cutting machine was used for drilling the two different composite plates with a thickness of 1.6–1.5 mm. Three variables were considered as process parameters including laser power (in three levels of 84.50, 104.00 and 127.40 W), cutting speed (in three levels of 4, 6, 8 mm/s) and 14 mm fixed focal position. Findings The fibers could not be cut due to insufficient melting in the experiments performed using 84.50 and 104.00 W laser power but the cutting was successfully completed when the laser power was 127.40 W. However, as the cutting speed increased, the contact time of the laser beam with the material decreased, so the kerf decreased, but the increased laser power created a thermal effect, causing an increase in hardness around the cutting surface. This increase was lower in MWCNTs doped composites compared to pure composites. It has been found that the addition of nanoparticles to layered glass fiber composite materials played an effective role in the strength of the material and affected the CO2 laser cutting quality. Originality/value This study is a unique study in which the CO2 laser cutting method of MWCNT-doped composite materials was investigated and the machinability without cutting errors, such as delamination, splitting, distortion and burring using the most suitable laser cutting parameters was revealed.

In this study, the holes of glass fiber reinforced polymer (GFRP) and multi-walled carbon nanotubes (MWCNTs) doped GFRP composite materials were drilled using abrasive water jet (AWJ), CO2 laser cutting, orbital drilling, and punching methods; the effects of these methods on hole quality were determined. The hole entry and exit dimensions were obtained equal and in the desired size by orbital drilling; thus, kerf formation was prevented due to the lateral and face milling of the end mill. The surface hardness change was not observed in the hole circles obtained with the orbital drilling and punching methods. However, epoxy hardening was observed in the hole circles obtained by laser cutting due to the heat effect of laser beam. In AWJ method, matrix-fiber integrity was disrupted, and delamination was observed due to the effect of water pressure and kinetic energy; consequently an increase in material thickness was observed and surface hardness decreased. It was determined that MWCNTs additive increased the surface hardness of composites and maintained its hardness and durability in post-cutting measurements. Splintering and burring were not seen in any method, but fiber carbonization was observed in the inner parts of the hole due to thermal effects in laser cutting.

The novelty of EDM machining as a drilling operation for composite materials means that there is no consensus on the influence of the parameters that optimise the final quality. For these reasons, a characterisation of the EDM drilling process of a unidirectional composite material has been developed. The influence of several cutting parameters has been related to the quality of the final hole obtained. Thus, macrogeometric aspects in terms of conicity and final diameter and microgeometric aspects in terms of surface quality have been evaluated. In addition, the final state of the material and the wear of the electrode have been evaluated by visual inspection, allowing the range of cutting parameters that offer the best performance to be established. Finally, a series of contour diagrams based on predictive models have been obtained to establish a direct relationship between input and output variables.

The need for soft polymer (such as acrylonitrile butadiene rubber (ABR)) components in mating applications is increasing in several sectors, viz. automobile, mining, and marine, due to their viscoelastic nature with improved surface quality and tighter geometric tolerances. Therefore, this paper aims to compare the effect of cryogenic conditions on the performance parameters of the suspension-type abrasive water jet (S-AWJ) machining and investigate the kerf characteristics of the top and bottom surface by comparing the waviness of the cut profiles and abrasive contamination of the top surface near the vicinity of the slot under conventional (room temperature) and cryogenic (liquid nitrogen (LN2)) conditions. The study found that the use of LN2 positively affected the performance parameters (Kerf taper ratio (KTR) and material removal rate (MRR)) due to a sudden increase in Young’s modulus and a decrease in elasticity of the machining zone. The cryogenic-assisted S-AWJ at the highest water jet pressure (WJP) (250 bar) produced better kerf characteristics through uniform and waviness-free top and bottom kerf profiles than the other experimental sequences. The use of LN2 resulted in the embrittlement of ABR, due to which less garnet abrasive particle contamination was observed during cryogenic-assisted S-AWJ machining.

This study presents an application of feedforward and backpropagation neural network (FFBP-NN) for predicting the kerf characteristics, i.e. the kerf width in three different distances from the surface (upper, middle and down) and kerf angle during laser cutting of 4 mm PMMA (polymethyl methacrylate) thin plates. Stand-off distance (SoD: 7, 8 and 9 mm), cutting speed (CS: 8, 13 and 18 mm/sec) and laser power (LP: 82.5, 90 and 97.5 W) are the studied parameters for low power CO2 laser cutting. A three-parameter three-level full factorial array has been used, and twenty-seven (33) cuts are performed. Subsequently, the upper, middle and down kerf widths (Wu, Wm and Wd) and the kerf angle (KA) were measured and analysed through ANOM (analysis of means), ANOVA (analysis of variances) and interaction plots. The statistical analysis highlighted that linear modelling is insufficient for the precise prediction of kerf characteristics. An FFBP-NN was developed, trained, validated and generalised for the accurate prediction of the kerf geometry. The FFBP-NN achieved an R-all value of 0.98, in contrast to the ANOVA linear models, which achieved Rsq values of about 0.86. According to the ANOM plots, the parameter values which optimize the KA resulting in positive values close to zero degrees were the 7 mm SoD, 8 mm/s CS and 97.5 W LP.

This study focuses on optimizing cutting parameters of NiTiHf high-temperature shape memory alloys using a multi-objective optimization method. The empirical models are used to predict outputs in a turning process of Ni-rich NiTiHf and compared to experimental data. Cutting parameters, such as cutting speed, feed rate, and depth of cut, have found a great effect on performance criteria of turning processes in machining process of this alloy. These parameters were optimized by using Genetic Algorithm to obtain maximum tool life, minimum energy consumption, and maximum surface quality. TUBITAK (The scientific and Technological Research Council of Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [116M346]; NASA Aeronautics Research Mission Directorate (ARMD) Transformational Tools & Technologies (TTT) project Financial support from TUBITAK (The scientific and Technological Research Council of Turkey) under Project number 116M346 is greatly acknowledged. OB acknowledges support and funding from the NASA Aeronautics Research Mission Directorate (ARMD) Transformational Tools & Technologies (TTT) project. WOS:000653611400001

Carbon dioxide (CO2) laser cutting finds one of its most relevant applications in the processing of a wide variety of polymeric materials like thermoplastics and thermosetting plastics. Different types of polymeric materials like polypropylene (PP), polymethyl methacrylate (PMMA), low- and high-density polyethylene (LDPE, HDPE), are processed by laser for different household as well as commercial products in the industry. The reason is their easy availability and economical aspect in the market. The problems associated with laser cutting include heat-affected zone (HAZ) generated on the cut surface, kerf width (KW), surface roughness (SR), dross formation, and striations formation. Furthermore, other related problems include taper cutting for deep parts and high-power consumption. The primary purpose of this work is a comprehensive literature review in CO2 laser cutting of polymeric materials. The influence of parametric variation on the cut quality is also explained. Cut quality in terms of KW, SR, HAZ, dross formation, and striations formation is analyzed by optimizing cutting variables like laser power (PL), cutting speed (CS), assist gas pressure (Pg), pulse frequency, nozzle type and its diameter, and stand-off distance (SOD). The effects of the laser cutting on the properties of different thermoplastics/thermosetting materials are also reported. However, this topic requires further studies on exploring the range of polymeric materials, and their optimal parameters selection to improve the cut quality. Therefore, the research gaps and future research directions are also highlighted in the context of CO2 laser cutting for polymeric materials.

In this study, the machinability characteristics of Al/B4C-Gr hybrid composite were investigated using wire electrical discharge machining (WEDM). In the experiments, the machining parameters of wire speed, pulse-on time and pulse-off time were varied in order to explaiın their effects on machining performance, including the width of slit (kerf) and surface roughness values (Rz and Rt). According to the Taguchi quality design concept, a L18 (21×32) orthogonal array was used to determine the S/N ratio, and analysis of variance (ANOVA) and the F-test were used to indicate the significant machining parameters affecting the machining performance. From the ANOVA and F-test results, the significant factors were determined for each of the machining performance criteria of kerf, Rz and Rt. The variations of kerf, Rz and Rt with the machining parameters were statistically modeled via the regression analysis method. The optimum levels of the control factors for kerf, Rz and Rt were specified as A1B1C1, A1B1C2 and A1B1C2, respectively. The correlation coefficients of the predictive equations developed for kerf, Rz and Rt were calculated as 0.98, 0.828 and 0.855, respectively., Bu çalışmada, Al/B4C-Gr karma kompozitin tel elektro erozyon tezgâhında işlenebilirlik karakteristikleri araştırılmıştır. Deneylerde; kesim genişliği (kerf) ve yüzey pürüzlülük değerlerini (Rz ve Rt) içeren işleme performansı etkilerinin incelenmesinde tel hızı, vurum süresi ve vurum ara süresi işleme parametreleri olarak seçilmiştir. Taguchi kalite tasarım konseptine göre, S/N oranını tanımlamak için bir L18 (21×37) ortogonal dizi ve işleme performansını etkileyen anlamlı işleme parametrelerini belirlemek için varyans analizi (ANOVA) ve F-testi kullanılmıştır. ANOVA ve F-testi sonuçlarından, işleme performansı kriterleri kerf, Rz ve Rt'nin her biri için anlamlı faktörler belirlendi. İşleme parametreleri ile kerf, Rz ve Rt'nin değişimleri regresyon analizi metodu yardımıyla istatistiksel olarak modellenmiştir. Kerf, Rz ve Rt için kontrol faktörlerinin optimum seviyeleri sırasıyla A1B1C1, A1B1C2 ve A1B1C2 olarak belirlendi. Kerf, Rz ve Rt için geliştirilen tahminsel denklemlerin korelasyon katsayıları sırasıyla 0.98, 0.828 ve 0.855 olarak hesaplanmıştır.

Abrasive water jet (AWJ) can be effectively employed on a broad selection of work materials, ranging from polymers to lapideous materials and high grade steels. The AWJ cutting process involves several variables, including hydraulic, abrasive, mixing and cutting parameters. Moreover workpiece properties, mainly modulus and hardness, affect material removal type (cutting and deformation wear mode). This paper concentrates on the influence of the mechanical properties of the workpiece on kerf roughness that is achieving more and more attentions from manufacturers, aiming towards near net shape production. In particular, the same carbon steel (C40 UNI EN 10083-2) was used for all tests; two heat treatments were performed on different specimen sets. AWJ cuts on 'as is' (normalised) and hardened specimens (water-quenched) were realised using different traverse speed. The surface roughnesses of the kerfs at different depths were measured to evaluate process performance. A statistical analysis was carried out to assess the significance of the results. It was found that workpiece hardness affects surface finish in different ways, depending on water pressure, traverse rate and depth of measurement across the kerf. Such results support the theory about two different material removal mechanisms, activated at different levels of jet erosive power.