Hard Milling Research Articles

Investigation of Nano Cutting Oil Effects on Hard Milling Under Minimum Quantity Lubrication

The presented work aims to investigate minimum quantity lubrication (MQL) using cutting oil with/without Al2O3 nanoparticles for hard milling of 60Si2Mn steel (50-52 HRC) using carbide inserts. The effects of three different types of based cutting oils including emulsion, soybean oil and rapeseed oil on surface roughness Ra, Rz and tool life were studied and investigated. The experimental results show that the use of Al2O3 nano cutting oil has improved lubrication capability compared to base cutting oil, contributing to improve machined surface quality and tool life. Al2O3 emulsion-based nanofluid exhibited the best performance among the three surveyed oils, followed by rapeseed oil and finally soybean oil. Furthermore, the cutting speed of the carbide inserts was improved and the tool life was significantly increased with the help of nano cutting oil due to the improvement in lubrication effects in the cutting zone, thereby helping to reduce cutting forces and cutting heat.

Analysis of Face Milling of Hard Steel 55NiCrMoV7 by Studying Rough and Semi-Finished Machining and the Influence of Cutting Parameters on Macroscopic Chip Dimensions.

Hard milling is being increasingly used as an alternative to EDM due to its high productivity. The present paper presents the results of theoretical-experimental research on the face milling of hard steel 55NiCrMoV7. A comprehensive analysis of cutting temperatures and forces during single-tooth milling and a morphological examination of the resulting chips are conducted for roughing and semi-finishing operations. The temperature is analyzed in the chip formation area, and the detached chips and the cutting force are analyzed through their tangential, radial, and penetration components, depending on the contact angle of the cutter tooth with the workpiece. The analysis of chip morphology is carried out based on the dimensional and angular parameters of chip segmentation and their degree of segmentation. Based on the central composite design and the response surface method, it is shown that it is possible to mathematically model the dependence of the macroscopic dimensions of the detached chips on the cutting parameters. The determined process functions, the maximum chip curling diameter, and the maximum chip height allow for establishing the influence of the cutting parameters' values on the chips' macroscopic dimensions and, thus, guiding the cutting process in the desired direction.

Optimization of Al2O3 nanoparticle concentration and cutting parameters in hard milling under nanofluid MQL environment

The high cutting heat and cutting forces are still the big obstacles in hard machining technology, which puts more pressure to find out the alternative solution for these problems. The work content presents an experimental study on the effect of nanoparticle concentration and cutting parameters on surface roughness and cutting force during hard milling under MQL environment using Al2O3 nano-cutting oil. The Box-Behnken experimental designs for response surface methodology was used to evaluate the influence of the input parameters and determine the optimal values. The obtained results show that the nanoparticle concentration, cutting speed, and feed rate all have the great influences on surface roughness R z and resultant cutting force F, so the study of the influence of these parameters on the efficiency of the hard milling process is very significant. The proposed reasonable value ranges will help technicians quickly choose to meet their demands for specific objective functions. Furthermore, the optimal parameter set of nanoparticle concentration of 1.27 wt%, cutting speed V c = 103 m/min, and feed rate [Formula: see text] = 0.09 mm/tooth was determined. It revealed that the use of MQL with nano-cutting oils contributed to improve the lubrication and cooling performance in the cutting zone.

An Experimental Investigation of Cutting Condition Influences on Hard Milling of AISI D2 Tool Steel

The presented work aims to study the effects of cutting speed, feed rate and depth of cut on surface roughness Ra in hard milling of AISI D2 steel (58 ÷ 60 HRC) using carbide inserts. A factorial experimental design was used to evaluate the influence of input variables. The obtained results indicated that feed rate causes the most significant effect on surface roughness, whereas cutting speed and depth of cut have little influence. The interaction effects between cutting speed and depth of cut as well as between feed rate and depth of cut have the significant influences on surface roughness Ra. Moreover, the cutting speed of 92 ÷ 100 m/min, feed rate of 0.1 ÷ 0.11 mm/tooth, and cutting depth of 0.1 ÷ 0.12 mm should be recommended for reaching the smaller surface roughness Ra values, which play an important role for further studies on hard milling process.

Machine learning models for enhanced cutting temperature prediction in hard milling process

Machine learning models for enhanced cutting temperature prediction in hard milling process

Pasta Drying Defects as a Novel Ingredient for Hard Dough Biscuits: Effect of Drying Temperature and Granulation on Its Functionality.

Various drying temperatures impact the texture of pasta and cause different drying defects. These by-products could reflect techno-functional characteristics which are suitable for cereal products. This research addresses the influence of low (LT) and high (HT) drying pasta defects with two granulations on the theoretical and functional characteristics of hard dough biscuits. By shifting from a LT to HT drying temperature, a higher onset and peak temperature was found due to the higher mobility of starch molecules with increasing crystalline stability. The lowest transition enthalpy of biscuit formulation was also observed for higher incorporation of fine HT pasta regrinds. The algebraic model of dough with consistography determined the poor-extensible gluten and a high resistance with a greater value of P/L and P indices for LT regrinds. Scanning electron microscopy revealed a heavy and dense texture with immersed starch granules for additional fine regrinds while coarse samples caused swell granules with greater diameter. Moreover, fine HT regrinds reflected the lowest L* value for biscuit due to heat gradient tension with the hard milling process which leads to protein denaturation with decreasing nitrogenous.

An Experimental Investigation of the Effects MQL Using Nanofluids on Surface Roughness of Hard Milling Process

High cutting force and cutting heat are challenging problems that need to be overcome for the hard milling process. Minimum quantity lubrication (MQL) has been shown to be effective and suitable for use in hard milling due to the improving lubrication in the cutting zone. The content presented in this article is to investigate MQL using emulsion cutting oil with/without Al2O3 nanoparticles for hard milling of 60Si2Mn steel (50-52 HRC) using carbide tools. Factorial experimental design is used to evaluate the cooling condition, cutting speed and feed rate on surface roughness. Experimental results show that feed rate has the greatest influence on surface roughness among the parameters investigated, followed by cooling mode and cutting speed. MQL technique using nano cutting oil gives better machined surface quality than MQL using pure cutting oil, which has proven that the additives of Al2O3 nanoparticles to the base cutting oil has improved cooling and lubrication capability. Furthermore, the applicability of MQL method is expanded to apply for hard milling.

Optimizing SKD-61 steel machining for marine component manufacture: A grey-Taguchi study on nanofluid minimum quantity lubrication

SKD-61 steel finds extensive application in various sectors, including the marine industry where materials must withstand harsh aquatic conditions. In this study, we employ the Grey-Taguchi approach to optimize surface roughness (Ra), cutting force (Fc), and material removal rate (MRR) when hard-milling SKD-61 steel in pure minimum quantity lubrication (MQL) and nanofluid MQL environments, aligning with the demands of marine engineering. The orthogonal array method generates a set of experiments based on four input parameters: cutting speed, depth of cut, feed per tooth, and cutting condition, which are essential factors in marine component manufacturing. Our approach combines Grey relational analysis (GRA) with the Taguchi method to enhance multi-objective outcomes in machining. The results of this marine-focused study reveal that the lowest surface roughness, cutting force, and highest material removal rates are attained when the cutting conditions align with the principles of nanofluid MQL at a cutting velocity of 80 m/min, a depth of cut of 0.2 mm, and a feed per tooth of 0.01 mm/tooth. Keywords: hard milling, nanofluid MQL, optimization machining parameters; Grey relational analysis; Taguchi

Evaluation the Effect of Heat Treatment on Corrosion Resistance of Cobalt Chromium Alloys

The purpose of present study is to evaluate and comparison the effect of different milling technique surface of CAD/CAM for milled Co-Cr alloy specimens.Material and Methods: The diagnostic divides 20 disc-shaped specimens into 2 main groups, each consisting of 10 specimens for Co/Cr alloys according to their construction, the material used in hard milling and soft milling. All samples for further examination were prepared as drilled discs (diameter 15 mm, height 3 mm) whose surfaces were then finished and polishing with a diamond polisher. Scanning electron microscopy (SEM) images with energy-dispersive beam spectroscopy (EDS) were acquired for one sample in each set to assess the surface topography of the metal framework. All samples were degreased, and steam cleaned samples and heat treated in accordance with the complete firing procedure. Then scanning electron microscopy (SEM) after heating. Samples prepared in the lab for electrochemical corrosion testing were polarized and corroded in accordance with their electrical potential. Results were recorded using Levenes test and anova, with appropriate data analyzed for differences between groups. Results: The results of this study presented that the Descriptive statistics for corrosion test (mmpy) for all experimental groups revealed that the hard milling group mean was the lowest among all groups of the study is recorded (0005), followed, Group soft milling (.0071). The data were statistically analyzed using Welch’s ANOVA and Levene’s test which revealed highly significant differences (p<0.01) among groups. Conclusion: Corrosion resistance decreases in the following order: soft metal milling > hard metal milling, according to the obtained corrosion parameter values.

Investigation of hard milling performance of 60Si2Mn steel under nanofluid minimal quantity lubrication environment

One of the promising solution to improve the hard machining performance is the application of Nanofluid Minimal Quantity Lubrication (NF MQL). The presence of nanoparticles not only improve the cooling lubrication of the based cutting oil but also create more lubricating mechanisms in the cutting zone. This paper aims to study effect of MQL using nano cutting oil on the hard milling process. The Box-Behnken experimental design was utilized to investigate the effects of input variables on the responses. The obtained results indicated that the concentration of nanoparticles, cutting speed and feed rate cause the strong influences on the surface roughness and cutting forces. Also, the appropriate ranges of input variable values can be determined for the required outputs. Moreover, the better cooling and lubricating effects were reported and the machinability of carbide inserts was improved by using Nanofluid Minimal Quantity Lubrication.

Surface integrity optimization for ball-end hard milling of AISI D2 steel based on response surface methodology.

This study focuses on systematically revealing how cutting parameters influence the surface integrity of ball-end hard milled surface of AISI D2 steel and proposing optimization scheme from surface integrity, wear resistance and fatigue resistance perspective based on response surface methodology respectively. Results can be summarized into three aspects. Firstly, radial depth of cut with percent contribution ratio (PCR) 62.05% has a decisive influence on surface roughness, followed by spindle speed 13.25% and feed per tooth 6.63%. The work hardening degree was raised from 12.5% to 38.4% when spindle speed changed from 8000 rpm to 2000 rpm. Spindle speed and radial depth of cut are the most significant factor influencing residual stress. The PCR of spindle speed and radial depth of cut reached 73.47% and 18.63% for residual stress in feed direction, 47.11% and 37.51% in step-over direction, respectively. High residual compressive stress can be generated by lowering spindle speed and radial depth of cut benefiting from the aggravated squeeze between ball-end milling cutter and workpiece. Secondly, too small feed per tooth or too small radial depth of cut should be avoided from wear resistance point because though the surface microhardness can be improved, the surface quality will also be deteriorated. The combination of high spindle speed, small feed per tooth together with small radial depth of cut can meet the wear resistance and the machining efficiency requirement. Finally, a medium-sized cutting parameter combination should be adopted to realize satisfying material removal rate and fatigue resistance. This study can be used to guide the selection of cutting parameters during ball-end milling of hardened AISI D2 steel for dies/molds manufacturing industries.

A review on effects of process parameters in milling challenging materials under nanofluid-based MQL conditions

PurposeThe purpose of this paper is to analyze the literature that is currently available and take a glance at minimum quantity lubrication (MQL) with nanofluids (NFs) as viable candidates to improve the efficiency of various milling operations on challenging materials.Design/methodology/approachThe extensive literature review is carried through the existing literature, which shows the effect of various process parameters in the milling operation of challenging materials under NF-MQL conditions. The manuscript also deals with identifying the inferences and research gaps from the literature review. The role and potential of NF-MQL in milling challenging materials are identified in this work.FindingsThe conclusion has also derived some recommendations for future study from the prior research, which will be helpful for any further research in this area.Research limitations/implicationsThis research work is limited to milling operations in challenging materials.Practical implicationsNF-MQL applications in milling operations are comparatively underexplored and merit considerable research. The amount of effort industry practitioners put into sustainable manufacturing will surely be greatly reduced by thorough research on the milling of challenging materials under NF-MQL settings.Social implicationsMQL system has a great potential to perform well in the experimental endeavor. Despite that fact, majority of the small and medium scale manufacturing industries are still using the conventional flood system for the machining of the workpieces because of the unaffordable initial cost and requirement of expertise involved as compared to the flooded lubrication. This issue might be solved when more works will be accomplished in industries for small as well as medium scale production.Originality/valueThese are novel study approaches because there are so many variables that affect cutting efficiency; therefore, more research is required to assess and provide direction for the advancement of hard milling technology.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2023-0010/

An investigation on machinability of AISI D2 steel during hard milling with multi-resolution analysis of vibration

Vibration is a major concern in hard milling process as it adversely affects productivity, surface finish, tool wear, energy consumption, etc. The aim of this paper is to investigate the effects of cutting parameters on acceleration of vibration, acoustic pressure, surface finish, and tool flank wear in face milling of AISI D2 steel. Each cutting parameter was varied in four levels while keeping the maximum value of the other two parameters as constant. Wavelet transform was used to decompose the signals of vibration. Acceleration of vibration has been found to rise with increasing cutting speed in the range of 100 to 180 m min−1. In general, acoustic pressure was found to increase with increasing depth of cut and cutting speed. The results showed that increasing cutting speed leads to reduction in surface roughness while feed rate and cutting depth have opposite effects. It was revealed that while flank wear increases with increasing depth of cut and feed rate, it reduces when cutting speed is raised in the range of 100 to 180 m min−1.

Hard Milling Process Based on Compressed Cold Air-Cooling Using Vortex Tube for Sustainable and Smart Manufacturing

Improving machining performance and meeting the requirements of sustainable production at the same time represents a major challenge for the metalworking industry and scientific community. One approach to satisfying the above challenge is to apply different types of cutting fluids or to optimise their usage during the machining process. The fact that cutting fluids are well known as significant environmental pollutants in the metalworking industry has encouraged researchers to discover new environmentally friendly ways of cooling and lubricating in the machining process. Therefore, the main goal is to investigate the influence of different machining conditions on the efficiency of hard machining and find a sustainable solution towards smart manufacturing. In the experimental part of the work, the influence of various machining parameters and conditions on the efficiency of the process was investigated and measured through the surface roughness, tool wear and cutting force components. Statistical data processing was carried out, and predictive mathematical models were developed. An important achievement is the knowledge of the efficiency of compressed cold air cooling for hard milling with the resulting lowest average flank wear of 0.05 mm, average surface roughness of 0.28 µm, which corresponds to grinding procedure roughness classes of N4 and N5, and average tool durability increase of 26% compared to dry cutting and conventional use of cutting fluids. Becoming a smart machining system was assured via technological improvement achieved through the reliable prediction of tool wear obtained by radial basis neural networks modelling, with a relative prediction error of 3.97%.

Porovnanie geometrickej presnosti obrobkov po tvrdom frézovaní a brúsení

This paper deals with surface integrity after hard milling of bearing steel 100Cr6. Surface integrity is expressed in terms of shape deviation as well as Barkhausen noise emission. Furthermore, components of cutting forces are also measured as a function of tool wear. Non homogeneity of cutting force distribution within the contact between the milling cutter and workpiece is discussed. The results of measurements indicate that the shape as well as structure remarkable non homogeneity should be expected after hard milling due to missing full contact between milling cutter and workpiece. This non homogeneity can be monitored via Barkhausen noise technique. On the other hand, the competitive grinding cycles produced more homogenous surface and surface state is a function of infeed speed.

Selective Laser Melting-Sintering Technology: From Dental Co-Cr Alloys to Dental Ceramic Materials

The general term of CAD/CAM technology (i.e., Computer-Aided Design/Compute-Aided Manufacturing) comprises several aspects, such as subtractive manufacturing processes, like milling (soft and hard milling), and additive manufacturing processes, like Selective Laser Melting (SLM), which refers to metallic materials, or Selective Laser Sintering (SLS), which refers to glasses/glass-ceramics/ceramic, or polymeric, or related composite materials produced via powder metallurgy technique. In biomaterials fabrications, the first step in SLM or SLS technology is the digital design of the prosthetic restoration, whereby the patient's individual anatomical and morphological features are precisely described. Afterwards laser-aided melting or sintering is repeated (layer-by-layer) until the complete restoration item is fabricated. A wide range of dental materials can be produced by SLM or SLS technology, e.g., metals and alloys, thermoplastic polymers, glasses/ceramics, waxes, and thermoplastic composites. Thus, it is a promising technology for producing a variety of dental restorations, such as metal-ceramic restorations, all-ceramic restorations, maxillofacial prostheses, functional skeletons, individual scaffolds for tissue engineering, etc. SLM technology is already widely applied for fabricating metal objects for dental (e.g., Co-Cr alloy) and orthopedic prostheses. As a subsequence, in the last decade, researchers' interest has been shifted to SLS of ceramic powders, such as SiO2, Al2O3, SiO2/Al2O3, and ZrO2/Y2O3. This article comprehensively reviews the SLS process and its prospects for producing glasses/glass-ceramic/ceramic materials for biomedical/dental applications. The experimental results clearly show that this very modern additive manufacturing technology does not jeopardize the properties of the ceramic biomaterials' properties.

Study on milling performances of 3Y-TZP ceramics using PCD and PCBN tools

ABSTRACT The 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) is regarded as a superior bioceramic being extensively used in modern denture restoration. However, the material possesses extremely poor machinability and are prone to serious cracking and failure formation due to its exceptionally high hardness and inherent brittleness. Hard milling is a feasible strategy to shape fully-sintered 3Y-TZP to desired quality and target dimensions. The present paper aims to study the milling behaviors and mechanisms of 3Y-TZP ceramics by using superhard PCD and PCBN tools. The fundamental milling responses, including cutting forces, temperatures, and surface morphologies, were all examined. The parametric effects on the 3Y-TZP machinability outputs were addressed. A particular focus is placed on comparing the cutting performances of different tools in milling 3Y-TZP. It is found that the PCD tool outperforms the PCBN tool from the perspective of reducing cutting forces, specific cutting energy consumption, and milling temperatures. To get smooth surface morphologies with minimal damage, the spindle speed lower than 5000 rpm and the feed per tooth lower than 9 μm/z should be adopted for the PCD tools. However, under large milling parameters, the PCBN tools show advantages in ensuring the stability of machined surface quality for 3Y-TZP ceramics over the PCD ones.

Optimal Approaches for Hard Milling of SKD11 Steel Under MQL Conditions Using SIO2 Nanoparticles

Productivity and quality are always two goals in the production process. In metal cutting, two prominent representatives of quality and productivity are roughness and material removal rate (MRR). In this study, the Response Surface method was used to perform single-objective and multiobjective optimizations during the hard milling of SKD11 steel. From there, comparative analyzes are carried out to give effective advice for different approaches in actual production. The selected inputs are the nanoparticle concentration in the cutting oil and three typical cutting parameters including cutting velocity, depth of cut, and feed rate. Each input will have three levels including low, high and average. The L27 orthogonal array developed by Taguchi was applied to the experimental design. In addition, ANOVA was also used to evaluate the statistical indicators of the study. The results of single-objective optimization show that the feed rate is the main influencing factor for the roughness followed by the nanoparticle concentration. They contribute 51.2% and 21.12% of the total roughness effect, respectively. On the other hand, the main factors affecting the material removal rate are the depth of cut and feed rate. In multiobjective optimization, a compromise solution has also been proposed to achieve small roughness and high material removal rate. The minimum roughness was 0.1956 μm and the maximum material removal rate was 1479.8688 mm3/min when applying the multiobjective optimal machining condition.

Machining feasibility and Sustainability study associated with air pressure, air flow rate, and nanoparticle concentration in Nanofluid minimum quantity lubrication-assisted hard milling process of 60Si2Mn steel

In recent years, more efficient hard machining processes have notably increased in demand for higher productivity but environmental friendliness. High hardness and strength as well as the enormous amount of cutting temperature are still the biggest obstacles. Nanofluid minimum quantity lubrication (NFMQL)–assisted hard machining has become a feasible and promising solution to overcome these problems. The work presents the experimental study on the effects of air pressure (5, 6, and 7 bar), air flow rate (150, 200, and 250 L/min), and Al2O3 nanoparticle concentration (0.5, 1.0, and 1.5%) on minimum quantity lubrication (MQL) hard milling process of 60Si2Mn (50÷52HRC) using vegetable oil as the based fluid. Box–Behnken experimental design and ANOVA analysis were employed to investigate the influences and interaction effects of input parameters on cutting forces, surface roughness, and surface microstructure. This study will be used for selecting the optimum air pressure, air flow rate, and Al2O3 nanoparticle concentration for efficient cooling lubrication performance of MQL in sustainable hard machining. The obtained results show that the optimal values for air pressure and nanoparticle concentration. For Q = 200 L/min, the optimal p is 6.0 bar and the optimal nanoparticle concentration (NC) is 0.9%. For Q = 250 L/min, the optimal p is 5.2 bar, and the optimal NC is 1.2%. Furthermore, using air flow rate Q = 250 L/min gives better results than Q = 200 L/min, but the selection will be depended on the specific equipment conditions.

Measurement and analysis of sustainable indicators in machining of Armox 500T armor steel

Armox 500T is a special type of armor steel possessing superior mechanical properties suitable for use in vehicles and buildings need for first priority protection. Since these products are large-scale, a welding groove needs to be created before joining which can be done by milling operations. This study aims to address this point by questioning the impact of clean environments, namely, dry, minimum quantity lubrication (MQL), and LN2-based cryogenic cooling on the machining performance measures during milling. The novelty of this paper is the investigation of the effects of different cutting environments on the milling performance of Armox 500T armor steel. The results from this study showed that cryogenic medium has an impressive impact on controlling the temperatures at tool-chip interface which directly reduces flank wear development. In addition, cryogenic and MQL-assisted machining is much better than dry environment in achieving improved surface properties, chip shape, and energy consumptions. Cryogenic cooling seems as the best option for hard milling pursued by MQL and dry environments, respectively, from the sustainability and machinability point of view.