Cryogenic Machining Research Articles

Sustainability aspects of machining operations: A summary of concepts

Studies on sustainable manufacturing engineering accumulate a growing body of knowledge, driven by an increasing interest in processes’ long-term viability. The quality enhancement and optimization of manufacturing operations have become a pressing need for sustainability. As a result, new renewable technology and work method proposals are required; they must combine the ecological and social aspects at an industrial level of manufacturing processes while preserving the economic and technological viability. There is no single structure for orienting study lines of optimization when it comes to sustainability. So, this paper focuses on a summary of concepts related to sustainable machining operations. In this framework, sustainable machining can be described as a part of sustainable manufacturing. The different alternative machining technologies such as dry machining, cryogenic machining, and high-pressure jet assisted machining, etc., are discussed briefly concerning sustainable machining. The problem and synergy between economic and environmental considerations and the effect of cooling fluids in the machining operations, optimization of power/energy responses in determining optimal machining conditions are outlined for sustainable machining. This paper offers a broad assessment of sustainable machining technology’s value in achieving sustainable manufacturing goals and implementing them at the ground level.

The Effect of Flood, High-Pressure Cooling, and CO2-Assisted Cryogenic Machining on Microhardness, Microstructure, and X-ray Diffraction Patterns of NiTi Shape Memory Alloy

The Effect of Flood, High-Pressure Cooling, and CO2-Assisted Cryogenic Machining on Microhardness, Microstructure, and X-ray Diffraction Patterns of NiTi Shape Memory Alloy

PDMS material embrittlement and its effect on machinability characteristics by cryogenic abrasive air-jet machining

Abstract The use of cryogenic abrasive jet machining (CAJM) technology for polydimethylsiloxane (PDMS) materials is increasing rapidly due to its high material removal rate and high surface quality. However, how the material properties of PDMS affect the machining properties under cryogenic conditions is still an unsolved problem. Firstly, the thermodynamic and mechanical properties of PDMS materials are studied by dynamic thermo-mechanical analysis and universal material testing. The results show that the PDMS material’s embrittlement temperature is 126 K. Secondly, evaluation of cooling temperature of PDMS during CAJM shows that the machined area has reached embrittled state. Thirdly, the effect of PDMS material’s embrittlement on the machining behaviour is studied. The experimental results show that the PDMS material exhibit increased abrasive erosion at medium-angle under cryogenic conditions and shows a semi-brittle wear mechanism. Furthermore, the erode surface’s roughness is evaluated. The result shows that the roughness decreases with decreasing air pressure at the same impact angle; with increasing impact angle, the roughness shows a trend of increase initially and then decreases. This work shows that the PDMS material’s embrittlement and the erosion response behaviour during CAJM are due to the combined effects of thermo-mechanical properties and material removal mechanisms, providing a better understanding of CAJM technology.

The effect of cryogenic machining of S2 glass fibre composite on the hole form and dimensional tolerances

S2 glass fibre reinforced epoxy composites are widely used in aeronautical applications owing to their excellent strength to weight ratio. Drilling glass fibres can be cumbersome due to their abrasive nature and poor thermal conductivity. Moreover, the use of conventional coolants is not desirable due to contamination and additional costs for cleaning the machine part. An alternative is to use environmentally friendly coolants such as liquid nitrogen (LN2) which have been previously employed in machining metals and composites. The current study investigates the effect of drilling S2 glass fibre composite in a bath of LN2. The study aims to evaluate the effect of spindle speed, feed rate and the presence of cryogenic cooling on the form and dimensional tolerances of the hole (hole size, circularity, cylindricity and perpendicularity). Design of experiments and analysis of variance (ANOVA) were used to determine the contribution of the input parameters on the analysed hole quality metrics. Results indicated that drilling S2 glass fibre in a cryogenic bath increased hole size significantly beyond the nominal hole diameter. The hole circularity and cylindricity were reduced compared to holes drilled under dry condition under all cutting parameters due to enhanced thermal stability during the drilling process. The current study aims to provide the scientific and industrial communities with the necessary knowledge on whether cryogenic bath cooling strategy provides better hole quality output compared to dry drilling and other cryogenic cooling strategies which were previously reported in the open literature.

A COMPREHENSIVE REVIEW ON EVALUATION OF ENVIRONMENTAL FRIENDLY MACHINABILITY, CUTTING FLUIDS AND TECHNIQUES IN METAL CUTTING OPERATION

Todays, due to the environmental concerns, growing contamination and pollution regulations, the demand for renewable and biodegradable cutting fluids is increasing day by day. Environmental friendly machining is one of the latest approach which is economical and also eco-friendly that improve the machinability. Different types of environmental friendly machining techniques are available e.g. MQL machining, cryogenic machining, dry machining and high pressure cooling approach. In this article, an attempt is made regarding environmental friendly machining processing, including different types of cutting fluids and machining techniques. The Knowledge of cutting fluid and its processing conditions is of critically importance to maximize the efficiency of cutting fluids in any machining process. In general, the generation of heat in the cutting zone due to friction at the tool-chip interface and the friction between the safety surface of the tool and the work piece is always the deciding factor on the quality of the work piece surface. In any manufacturing industries or company two factors play important role in machinability and productivity e.g. surface quality and tool wear. The main objective of this review article that analysis the different environmental friendly machining techniques and encourages the cooling approach in metal cutting operation. So finally, after the literature survey found that environmental friendly machining approach is cost effective machining process and also eco-friendly machining process.

Role of environmental friendly machining on machinability

The present for supporting in market any industries need to bring the balance among ecological, social viewpoints and efficient. Environmental friendly machining e.g. high pressure cooling, MQL machining, cryogenic machining, dry machining is one of the latest approach which is economical and also eco-friendly that improve machinability. In present article main focus on understanding of environmental friendly machining techniques and investigate various experiences from the past writing which can help the better appropriation of ecological friendly machining approach. For study and examination of environmental friendly machining approach, roughly 100 papers are chosen. They chose articles are ordered dependent on climate of machining, year, diaries, distributor, and ecological friendly machining approach measurements. After the literature survey it was observed that in metal cutting operation heat are generated in the cutting zone due to tool chip interface so quality of surface finish are poor and tool wear. In any manufacturing industries two factors play important role in term of quality e.g. surface roughness and tool wear so in this situation some techniques are need which is environmental friendly and also improve machinability. So finally, it was observed that environmental friendly machining techniques are cost effective and eco-friendly machining compared to other convention machining approach. The main motives of this paper that studies and encourage environmental friendly machining approach.

Sustainability and tool wear of titanium alloy thread cutting in dry and cryogenic conditions

The article is devoted to the study of the effect of cryogenic cooling on the tool wear in thread turning tests. The tool wear and its influence on the thread accuracy were investigated. Two different grades of titanium alloys were used for comparative purposes. The excellent performance characteristics of titanium alloys pose machining problems, causing high unit forces at the edge of the tool leading to chipping and premature tool failure. In turn, the low thermal conductivity of pure titanium affects the heat distribution in the cutting zone. The heat is not absorbed by the material being machined but accumulates in the tool, causing an increase in diffusion and chemical wear. The results of cutting tests using liquid nitrogen showed lower values of wear on the major and minor tool flank. The edge reduction of the tool was also significantly less during cryogenic machining. The analysis of the formation of wear marks and the blade wear mechanisms was carried out for the tool rake face. The tests were carried out using the SEM method and confirmed by EDS analyses. In order to compare the course of tool wear over time, a mathematical model was developed, which results from the course of phenomena during cutting. It consists of two complementary equations. The first equation is characteristic for the first cutting phase and results from the loads imposed on the blade and aims at thermodynamic equilibrium. It is a period of stable tool operation and constant wear intensity. The second equation concerns crossing the equilibrium point followed by the process of accumulation of elementary wear phenomena. These phenomena accumulate until the blade is completely worn-out. The use of blade wear development models to determine the expected blade life allowed to confirm the beneficial effect of cryogenic cooling on the course of the blade wear process when cutting threads for two different titanium alloys.

Prediction of erosion volume of PDMS by cryogenic micro-abrasive jet machining based on dimensional analysis method and experimental verification

The polymer polydimethylsiloxane (PDMS) is used widely in microfluidic chips. At room temperature, when PDMS is machined by micro-abrasive jet machining (MAJM), its high elasticity means that it often suffers from processing defects such as abrasive embedding and a surface deterioration layer. Cryogenic micro-abrasive jet machining (CMAJM) based on the glass transition has been proposed, but a model for predicting the volume of material removed is yet to be established. In this study, orthogonal experiments are used to investigate how different processing parameters influence the material removal volume. The results show that the material removal volume is largest when the jet pressure is 0.6 MPa, the erosion angle is 60°, the erosion distance is 3.5 mm, and the scanning speed is 0.2 mm/s. A model is established to predict the material removal volume during the CMAJM of PDMS, and single-factor experiments are used to assess the model qualitatively. The results show that the model offers good predictions of how the material removal volume changes with the scanning speed and jet pressure.

Cryogenic machining to enhance surface finish of a biomedical grade ultra-high-molecular weight polyethylene

In recent years, polymeric materials are being used at an increasing rate in the biomedical industry. In particular, Ultra-High-Molecular Weight Polyethylene (UHMWPE), a thermoplastic polymer characterized by high toughness, good chemical stability and self-lubricating properties, is an ideal candidate for the manufacture of bearing implants used in hip or knee replacements. Nevertheless, it is difficult to achieve a good level of surface finish when turning it, because of its high instability at increasing temperature. In the present study, cryogenic machining was applied instead of dry cutting to machine a biomedical grade UHMWPE at different cutting speeds. The surface finish was assessed in terms of surface roughness, crystallinity degree and hardness in correspondence of the surface. To correlate machinability results with the UHMWPE mechanical behaviour, uniaxial tensile tests were performed in a wide range of temperatures. The obtained results showed that the application of cryogenic machining was an efficient mean to increase the surface finish: in fact, smoother and harder surfaces were obtained regardless of the adopted cutting parameters.

Numerical investigations of cutting temperature and cutting forces in cryogenic assisted turning of magnesium alloy

Magnesium alloys are biocompatible materials that are not only used in biomedical implants but also in many engineering load-bearing applications due to their high strength to density ratio. However, machining of these alloys is somehow challenging, for example, magnesium alloy (AZ31B) is prone to ignition risk at relatively low temperatures during various machining processes. This ignition risk can be avoided by performing machining under cryogenic conditions. In the present research work, 2D finite element-based analysis of orthogonal cutting process of magnesium alloy (AZ31B) is performed considering both cryogenic and dry machining environments. Finite element simulations are performed by varying the cutting speed and uncut chip thickness. A widely employed, damage-based Johnson-Cook flow stress model is exploited to perform coupled thermo-mechanical cutting simulations. Cutting forces and temperatures are the major output parameters of interest in the work. The resultant cutting forces predicted by FE analysis for cutting speed of 100 m/min and for uncut chip thickness of 0.1 mm vary by 19% and 16% for cryogenic and dry machining conditions, respectively, when compared with available experimental results from literature, whereas, in the workpiece body, temperature variations of 14% and 2% have been found for cryogenic and dry machining conditions, respectively. Promising results of numerical model may help to further investigate and optimize the process.

Investigation of cryogenic quenching of metal surfaces with various coatings

Cryogenic quenching is frequently encountered in many applications like LNG technology, cryogenic preservation of biomaterials, cryogenic material machining etc., in which one key issue is to accelerate the temperature decrease so as to achieve large cooling rate. In the present study, the cryogenic quenching experiments are conducted by immersing the metal rodlets with various coating layers at room temperature into a liquid nitrogen bath. It is found that fast cryogenic quenching of the aluminium alloy rodlet with a higher Leidenfrost temperature is achieved by coating a thin layer of nano-structure with nanopores on the outer surface. In addition, the similar method of surface fabrication is applied to the stainless steel rodlet and a moderate reduction of quenching time in liquid nitrogen is achieved. Furthermore, the cryogenic quenching of stainless steel rodlets coated with the Teflon layers is also investigated.

Deformation Resistance Performance of Carbon Fiber-Reinforced Plastic Machined by Controlling Drilling Area Temperature below the Glass Transition Temperature.

Drilling of carbon fiber-reinforced plastics (CFRPs) is a challenging task in aviation and aerospace field. Damages, which can reduce the strength of the structure, often occur during secondary machining operations due to the applied cutting force and generated heat. The main objective of this study was to investigate the drilling performance and the deformation resistance of CFRPs subjected to cryogenic treatment based on glass transition temperature (Tg). Therefore, a cryogenic machining approach was adopted by fixing the workpiece inside a cryogenic box to drill CFRPs. The machining performance was briefly evaluated. Moreover, a through-hole drilling method was promoted to analyze the mechanism of different deformation mechanical properties. The results showed that the cryogenic machining approach improved the machining performance of CFRPs. Nevertheless, the residual intensity of cryo-treated specimen decreased (about 7.14%) due to the Tg-based viscoelasticity. These results demonstrate the great potential of this approach in advanced industrial applications and further pave the way for efficient secondary machining operation of CFRP components.

Wear under brittle removal regime of an under-expanded cryogenic nitrogen jet machining of bio-composites

Machining of biocomposites using traditional techniques has shown some limitations due to the multiscale complex cellulosic structure of natural fibrous reinforcement. This paper aims to demonstrate the feasibility of the cryogenic nitrogen jet, which is a novel cutting process that combines sustainable resources and cryogenic temperatures from −175 °C to 150 °C, as a machining process for biocomposites made of unidirectional flax fibers and polylactic-acid polymer (PLA). A high-velocity stream of liquid nitrogen with and without abrasives (400–700 m/s) is hence directed onto the workpiece surface. For the abrasive jet, both conventional garnet abrasives and bio-based abrasives made from walnut shells were used for the nitrogen jet process. The kerf depth, which is representative of the erosion wear mechanisms, was calculated to assess the erosion rate of the biocomposite structure after the nitrogen jet cutting operation. Then, scanning electron microscope observations are performed to characterize the induced damages on the machined biocomposite surfaces. Results show that the pressure and the traverse speed of the nitrogen jet are the relevant process parameters that control the mechanical and thermal stresses viewed by the biocomposite during the machining operation. Each impinging abrasive particle removes a small amount of biocomposite material during the jet cutting process, which depends on the brittleness of the anisotropic work structure and the abrasiveness of the incorporated particles into the jet stream.

Numerical prediction of machining-induced surface residual stress for TC4 cryogenic turning

Liquid nitrogen(LN2) cryogenic machining is a green, sustainable, and high-performance machining technology. LN2 cryogenic machining of TC4 can significantly strengthen the local cooling environment of cutting, accelerate the heat dissipation, thus effectively reduce the cutting temperature, and suppress the generation of thermal stress, reduce the residual tensile stress on the workpiece surface. In this paper, a finite element model(FEM) of numerical prediction is established to analyze the effect of LN2 cryogenic machining on residual stress distribution. Firstly, mechanism analysis of surface residual stress is carried out to explore the source of residual stress during TC4 cryogenic turning. Next, to observe residual stress distribution clearly, the cutting zone separation model is designed, and then, the material model is built to reflect the change of material properties. Then, a FEM of the numerical prediction made up of explicit dynamic solution module and standard static solution module is established to simulate residual stress distribution; after that, residual stress can be ultimately acquired by linear superposing the above two module simulation results. Based on FEM proposed in this paper, the effect of LN2 cryogenic machining on surface residual stress distribution of TC4 is analyzed, and it is indicated that LN2 cryogenic machining can reduce the residual tensile stress effectively. Finally, the experiment is carried out, and the results show that the general trend of the prediction model is the same as that of the experimental results, which greatly verify the availability of the prediction model. Research provides some reference for the numerical prediction and suppression of residual stress in the future.

Cryogenic and hybrid induction-assisted machining strategies as alternatives for conventional machining of refractory tungsten and niobium

Tungsten (W) and niobium (Nb) belong to the refractory metal group and are used as alloying elements in steels and superalloys for high demand products. These metals are also used in a high purity single-phase state for products within nuclear, space, military and research facilities.In the current study, tool wear development and surface quality at different cutting conditions have been evaluated when machining high purity W 99.95% and Nb 99.7% in longitudinal turning. Cryogenic LN2 cooling and hybrid induction-assisted machining strategies were applied in order to alter W and Nb material state with respect to the ductile-to-brittle transformation temperature, and thus to attempt controlling their machinability. These advanced machining strategies were benchmarked against the more conventional machining solutions of dry, flood and high pressure cooling.It was found that the use of LN2 cooling demonstrated the best result in terms of tool life when machining W followed by induction-assisted heating, dry and flood. All machining strategies provided similar surface quality which is related to strong build-up edge formation and respective surface alteration. When machining Nb, high pressure coolant results in best performance in terms of tool life and surface quality, then followed by flood and cryogenic strategies. Overall, substantial improvement of surface quality (Ra = 0.4–0.6 μm) was observed for high cutting speeds vc ≥ 225 m/min.

Study of Power Devices for Use in Phase-Leg at Cryogenic Temperature

As air traffic has been increasing in recent years, the environmental impact of aviation is more obvious, forcing governments to impose stringent regulations on emissions. In order to meet these regulations, and reduce the carbon footprint, research has been directed towards the all-electric and hybrid aircraft, where the use of cryogenic HTS machines and cables has been proposed to reduce the overall size of the aircraft. With the cryogenic system already in place, research has been exploring the use of power electronics at lower temperatures in order to obtain systems with higher power densities and lower losses. In this paper several power semiconductor devices are tested at room and cryogenic temperature in order to evaluate their performance at lower temperature. One of the tested devices, a “CoolMOS” superjunction MOSFET, is used in a single voltage source phase-leg which is experimented with at room and cryogenic temperature to evaluate its efficiency as a primary indication of its usefulness in the All-Electric Aircraft.

Machinability analysis of nickel-based superalloy Nimonic 90: a comparison between wet and LCO2 as a cryogenic coolant

The usage of cryogenic fluid is increasing in the machining industries especially to cut the materials having a lower machinability like Nimonic 90, a nickel-based alloy. However, the comparison of flood coolant and LCO2 as a cryogenic fluid based on machining performance has not been found for machining Nimonic 90. In this regard, this study compares LCO2 and conventional mineral oil-based flood coolant on the basis of machining performance while turning Nimonic 90. The effect of turning process parameters (cutting speed (vc), feed (f), and depth of cut (ap)) and cutting fluids has been identified by analyzing machinability indicators like cutting force, flank tool wear, power consumption, surface roughness in terms of Ra, and chip morphology. Increment of 34%, 25%, and 24% in cutting forces has been observed for cryogenic turning using LCO2 in comparison with wet machining when the values of ap are 0.75, 0.50, and 0.25 mm, respectively. A decrement of 63% tool wear has been seen in LCO2 cryogenic fluid in contrast to wet machining at higher values of vc, f, and ap. The superior surface finish has been found in wet machining, while lesser power consumption was recorded for LCO2 as a cutting fluid. Cryogenic machining provided better chip breakability in comparison with wet machining.

A Review of Minimum Quantity Lubrication (MQL) Based on Bibliometry

Background: Minimum quantity lubrication (MQL) is one of the most promising machining techniques that can yield a reduction in consumption of cutting fluid by more than 90 % while ensuring the surface quality and tool life. The significance of the MQL in machining makes it imperative to consolidate and analyse the current direction and status of research in MQL. Objective: This study aims to assess global research publication trends and hot topics in the field of MQL among machining processes. The bibliometric and descriptive analysis are the tools that the investigation aims to use for the data analysis of related literature collected from Scopus databases. Methods: Various performance parameters are extracted, such as document types and languages of publication, annual scientific production, total documents, total citations, and citations per article. The top 20 of the most relevant and productive sources, authors, affiliations, countries, word cloud, and word dynamics are assessed. The graphical visualisation of the bibliometric data is presented in terms of bibliographic coupling, citation, and co-citation network. Results: The investigation reveals that the International Journal of Machine Tools and Manufacture (2611 citations, 31 h-index) is the most productive journal that publishes on MQL. The most productive institution is the University of Michigan (32 publications), the most cited country is Germany (1879 citations), and the most productive country in MQL is China (124 publications). The study shows that ‘Cryogenic Machining’, ‘Sustainable Machining’, ‘Sustainability’, ‘Nanofluid’ and ‘Titanium alloy’ are the most recent keywords and indications of the hot topics and future research directions in the MQL field. Conclusion: The analysis finds that MQL is progressing in publications and emerging with issues that are strongly associated with the research. This study is expected to help the researchers to find the most current research areas through the author’s keywords and future research directions in MQL and thereby expand their research interests.

Advantages of cryogenic machining technique over without-coolant and with-coolant machining on SS316

The analysis concentrated towards the influence of speed of the spindle along with a cryogenic (LN2) cooling technique in treating SS316 using CNC (Computerized numerical control) milling machine. An comparative study path was set and anlyised among three states i.e. Dry (Without coolant), wet (With coolant) and cryogenic (With liquid LN2) machining using coated carbide inserts. The coolant used in case of wet machining was water-soluble, referred to as cutting fluid. The experimental range falls in 3 different levels of spindle speed (SS), such as low level (1000 rpm), medium level (2000 rpm), and high level (3000 rpm), respectively. Meanwhile, feed rate (FR) and depth of cut (DOC) were reserved steadily with 450 mm min−1, 1 mm separately. This vital focus is towards cryogenic (LN2) machining effects and its perception of machinability on SS316, such as tool wear –TW (μm), cutting force–CF (N), cutting temperature–CT (ºC) and surface roughness–Ra (μm). The experiments were conducted and documented with cryogenic (LN2) techniques to establish the fairness and practicability of the method to compare with without-coolant (dry) and with-coolant (wet) machining. The attained statistical results in comparison of LN2 method over without-coolant and with-coolant machining concerned to test cases for CF- Fx (N), CT (ºC), Ra (μm) and FW (μm) are 53.21%–34.20%, 65.88%–44.51%, 75.43%–44.27%, & 59.76%–23.10%, respectively.

The effects of through tool cryogenic machining on the hole quality in GLARE® fibre metal laminates

GLARE® is a composite-metal laminate currently used in the Airbus A380 fuselage due to its excellent impact and fatigue performance. GLARE® undergo extensive drilling for riveting purposes making it prone to thermal effects and increased tool wear. Therefore, using coolants becomes necessary, however, conventional coolants can lead to moisture absorption. An alternative is to use cryogenic coolants due to their positive impact on machining aerospace materials in the past. In this study, through tool cryogenic machining technology is used for machining GLARE® laminates by delivering liquid nitrogen at −196 °C through the spindle allowing the coolant to be in direct and continuous contact with the cutting zone. The aim is to investigate the impact of drilling parameters and cryogenic cooling on surface roughness, hole size, circularity and hardness at hole entry and exit sides. In addition, microstructural evaluation using scanning electron microscopy. The results indicate that the cryogenic cooling improved hole surface finish and gave better hole size at the top, while it had no impact on hole circularity. The hardness was increased at the entry and exit sides of the hole compared to that observed in dry drilling tests while scanning electron microscopy revealed that burr formation was minimised.