Cryogenic Machining

An overview is represented of the cryogenic technologies implementation in the heat treatment and deformation of metals. The areas are determined of most effective application of the cryogenic liquids and gases in the steel rolling production and heavy machines building with the aim of product quality improving, equipment and tools durability and reducing ecology impact on environment and working personnel.

The paper presents an update of the recent literature on advances in machining of difficult to machine materials such as nickel and titanium-based alloys, and composites used in aeroengine and aerostructure applications. The review covers the following issues: advances in high-performance cooling techniques as cryogenic machining, minimum quantity lubrication, the combination of MQL and cryogenic cooling, and high-pressure lubricoolant supply and hybrid cutting processes-vibration assisted machining (both low and high frequency), laser, plasma and EDM assisted machining. Examples of applications in industrial processes are also given.

The paper presents an update of the recent literature on advances in machining of difficult to machine materials such as nickel and titanium-based alloys, and composites used in aeroengine and aerostructure applications. The review covers the following issues: advances in high-performance cooling techniques as cryogenic machining, minimum quantity lubrication, the combination of MQL and cryogenic cooling, and high-pressure lubricoolant supply and hybrid cutting processes-vibration assisted machining (both low and high frequency), laser, plasma and EDM assisted machining. Examples of applications in industrial processes are also given.

Abrasive waterjet machining (AWJM) is a new machining process, the advantages of which include low cutting temperatures, no heat damage to the material being cut, minimal dust, and low cutting forces. This paper presents a state of the art review of research in this new process. The main topics discussed are mechanics of material removal, productivity, cutting forces, surface quality and nozzle wear.

The process of cryogenic machining, due to increased demand for environmentally friendly manufacturing processes, has seen a growing interest in the machining community. This article presents an overview of cryogenic machining and its induced surface integrity characteristics such as surface roughness, topography, grain refinement and machining-induced layer, microhardness, phase transformation, residual stress and fatigue life in machining of various materials including difficult-to-machine materials, aerospace alloys, lightweight materials, etc. The effect of cryogenic machining on surface integrity characteristics is discussed, and compared with dry, Minimum Quantity Lubrication (MQL), and flood-cooled machining processes. In addition to being an environmentally friendly process, this study shows that cryogenic machining significantly contributes to improved functional performance of machined components through its superior and more desirable surface integrity characteristics.

In the modern manufacturing process metalworking fluid is an essential part of the cutting process. The application of coolant in between the tool and workpiece reduces the friction and carried out heat generated during the process. These cutting fluids are not only harmful to the workers and the environment but also increases the total cost of manufacturing. The cost associated with coolant handling and disposal is nearly 7% to 17% of the manufacturing cost. It is already proven that coolant is the main source of pollution in the manufacturing industries. But, Coolant plays an important role in lubrication, reducing friction and heat dissipation between the workpiece and the tool. Over the years, coolants are found a non-sustainable source in the manufacturing process. In the cryogenic machining process, the cryogenic liquid evaporates and becomes a part of the atmosphere which leaves zero residues. This characteristic makes cryogenic machining a sustainable solution for the industry. Thus, cryogenic machining can be an environmentally friendly alternative to the coolant. This paper is a review of cryogenic machining which will help in understanding the concept and mechanism of cooling in the cutting process.

Machining operations are very common for the production of auto parts, i.e., connecting rods, crankshafts, etc. In machining, the use of cutting oil is very necessary, but it leads to higher machining costs and environmental problems. About 17% of the cost of any product is associated with cutting fluid, and about 80% of skin diseases are due to mist and fumes generated by cutting oils. Environmental legislation and operators’ safety demand the minimal use of cutting fluid and proper disposal of used cutting oil. The disposal cost is huge, about two times higher than the machining cost. To improve occupational health and safety and the reduction of product costs, companies are moving towards sustainable manufacturing. Therefore, this review article emphasizes the sustainable machining aspects of steel by employing techniques that require the minimal use of cutting oils, i.e., minimum quantity lubrication, and other efficient techniques like cryogenic cooling, dry cutting, solid lubricants, air/vapor/gas cooling, and cryogenic treatment. Cryogenic treatment on tools and the use of vegetable oils or biodegradable oils instead of mineral oils are used as primary techniques to enhance the overall part quality, which leads to longer tool life with no negative impacts on the environment. To further help the manufacturing community in progressing towards industry 4.0 and obtaining net-zero emissions, in this paper, we present a comprehensive review of the recent, state of the art sustainable techniques used for machining steel materials/components by which the industry can massively improve their product quality and production.

Conventional machining of polymeric composite materials is often both technically and economically less effective because the structural characteristics inherent in fibre reinforcement promote excessive tool wear. In recent years, abrasive waterjet machining (AWJM) has been proving to be successful in the machining of such materials. This paper presents a state of the art review of research in AWJM of polymeric composite materials. Among the main topics discussed are mechanisms of material removal, productivity and surface quality

— In modern competitive world the ultimate goal of manufacturing industries, is to manufacture products at low cost and high quality in short time. Automated and flexible manufacturing systems are employed for that purpose along with CNC machines that are capable of achieving high quality and very low processing time. Metal cutting process is one of the complex process which has several factors contributing towards the quality of the finished product. Turning is one of the most common methods for cutting and especially for machining cast parts. Furthermore, in order to produce any product with high cutting performance, selection of proper cutting parameter is very important. To select the cutting parameters, several mathematical models based on statistical techniques and neural networks have been developed to establish a relation between cutting parameters and cutting performance. The objective of this paper is to review of application of Taguchi method and other statistical method for optimization of turning Parameters to meet the customers' demands.

Multiresponse optimization of process parameters in drilling is focused in this article using the TOPSIS technique to obtain minimum cutting temperature (T), thrust force (Ft), torque (Mt) and surface roughness (Ra), Circularity (Cir), Cylindricity (Cyl). The experiments were performed on Titanium alloy Ti-6Al-4V in different cooling environments: Wet cooling and cryogenic cooling conditions. Liquid nitrogen (LN2) as a coolant is used in cryogenic machining. The control factors selected were machining environments, cutting speed (Vc) and feed rate (f). Eighteen experiments were conducted in wet and cryogenic LN2 conditions based on L18 orthogonal array, respectively.
The optimization results indicate drilling at Vc = 40 m/min and f = 0.02 mm/rev which is of the lowest value in cryogenic LN2
condition. A better performance is achieved too. The optimum multiresponses show that TOPSIS method is the most effective performance in the drilling process.

Nowadays, aluminum alloy 7075-T6 has received a high demand in the automotive industry due to its advantages in the aerospace industry, which possessing exceptional mechanical combinations and chemical elements such as high tensile strength, high strength, high corrosion resistance, zinc, magnesium, and copper to increase their strength. Nevertheless, environmentally friendly approaches are necessary to improvise surface quality and machining performances as well as minimize the adverse environment. This has directly influenced the trend of approach or strategy of cutting fluids towards the machining of high-performance material in the automotive industry. There have been some probations to decrease the volume of cutting fluid application in machining. The approach of cutting fluids become prominent indicator in contribution to minimize the application of cutting fluid so that the machining of aluminum alloy 7075-T6 become more effective and environmental friendly. Thus, results can be found in the low tool wear, minimum heat energy generated and reduced machining cost in encouraging the application of MQL as viable formulations to enhance the machining performance and machined surface quality. The primary objective of review work is summarized all the emerging environmentally friendly approaches towards the high-performance material. Impact of machining process parameters on dependent variables such as surface integrity, tool wear, chip formation, and mechanical properties have been discussed in the light of the findings of the recent study.

Despite the large number of abrasive waterjet machining (AWJM) models developed so far, there still has been confusion about the nature by which workpiece surfaces are eroded. The finite element method (FEM) could provide both qualitative and quantitative means in order to explain the AWJ erosion process. This paper presents an attempt to model the AWJM process using the powerful tool of the finite element method. The main objective is to develop an FE model which would enable to predict the depth of cut without any cutting experiments. The new model takes into account the precise representation of the constitutive behaviour of the workpiece material under AWJ dynamic loading conditions. Interaction of the abrasive particle with the workpiece material is traced at small time increments. The model accurately predicts the depth of cut as a result of AWJ impact and the results are in good agreement with experimental results.

Understanding the exact nature of erosion of workpiece materials by abrasive waterjet machining (AWJM) is still confused, although it is important for successful modeling of this promising process. This paper presents a first attempt to model the AWJM process using the powerful tool of the finite element method (FEM) in order to explain the abrasive particle-workpiece interaction. Also the model predicts the behaviour of the process. The main objective is to develop an FE model which would enable to predict the depth of cut without any cutting experiments. The new model takes into account the precise representation of the constitutive behaviour of the workpiece material under AWJ dynamic loading conditions which was ignored in previous AWJM models in which the flow stress was represented by a constant value. Additionally, deformations, stresses and strains occurring in the workpiece material in the vicinity of the cutting interface as a result of the erosion impact by AWJ, could be obtained. In the present model, forces acting on the abrasive particle need not be initially determined, as in previous AWJM studies, as they are automatically calculated at each time step. The results show that the finite element method is a useful tool in predicting abrasive-material interaction and AWJ depth of cut.

The purpose of the present investigation was to evaluate the abrasive water jet cutting performance by the application of a cryogenic liquid nitrogen jet in the cutting process. This technique was developed for improving the process capability of conventional abrasive water jet machining and enable a higher depth of cut and material removal rate, and better kerf profile and surface integrity. The experiments were conducted on AA5083-H32 aluminium alloy, using two different cutting methods, namely, abrasive water jet cutting and cryogenic assisted abrasive water jet cutting. Both cutting conditions were investigated by varying the water jet pressure, the abrasive mesh size and the abrasive water jet impact angle. Optical microscopy and Scanning Electron Microscope with Energy Dispersive X-ray Spectroscopy was used for studying the micro structure and morphology of the cut surfaces under both cutting conditions. There was an improvement in cutting performance features such as depth of penetration, material removal rate and kerf profile with the use of cryogenic assistance cutting approach. These results were produced due to the beneficial modification of erosion mechanism in the cutting zone as well as a reduction in particle embedment with the cut surface by about 56%.

This paper presents an analysis of experimental results on cutting forces, surface quality, phase transformation temperatures, mechanical properties, as well as microhardness of NiTi shape memory alloys (SMAs) from cryogenic machining, and comparison with results from dry machining. It has been revealed that cryogenic machining significantly improves the surface integrity of machined components in terms of increased microhardness, phase transformation temperatures, surface quality and strength of the material. It also improves the cutting performance by reducing cutting force requirements. In broad perspective, cryogenic machining, being a sustainable process, also helps to improve the product sustainability.

Temperature relation of interlamellar spacing of pearlite, with the supercooling in carbon steels, based on previously theoretically foundation has been determined by the pearlite and bainite phase volumes in the alloy steels from the degree of supercooling. Calculated data corresponds to the experimental results with a sufficient accuracy. Development of a diffusion model of discontinuous transformation of austenite makes possible to theoretically explain formation of bainitic ferrite in low carbon steel in the same temperature range. These models

Erosion of ductile materials by abrasive waterjet machining (AWJM) is still a complex phenomenon. This paper presents a first attempt to simulate the abrasive waterjet machining (AWJM) process using the finite element method (FEM) in order to determine the workpiece response in this erosive wear process. Additionally, deformations occurring in the workpiece material in the vicinity of the cutting interface as a result of the high speed AWJ impact could be obtained. The results indicate that the finite element method is a useful tool in the prediction of the AWJ deformations.

This work presents a comprehensive structure for evaluating the sustainability of machining processes. Industries can contribute towards developing a sustainable future by using algorithms that evaluate the sustainability of their processes. Inspired by the literature, the proposed model involves a set of metrics that are critical in evaluating the impact of a process on society, environment, and economy. The flexibility of this model allows decision-makers to use the available responses to identify the most favorable process. The entropy weight method was suggested for objectively calculating the weights of each indicator. A multi-criteria decision-making method i.e., Technique for Order Preference based on Similarity to Ideal Solution (TOPSIS), was used to rank processes in the decreasing order of their sustainability. The proposed algorithm was successfully validated with case studies from the published literature. A MATLAB code was also created so that industries may expeditiously apply this method to evaluate the sustainability of machining processes.

Modeling of abrasive waterjet machining (AWJM) has been finding widespread interest for the past twenty years. Due to the complex interaction of several AWJM parameters, combined with the nonlinear dynamic high speed impact of several thousands of small abrasive particles on the workpiece surface, the mechanism of material removal has not yet been fully understood. The current paper presents an attempt to explain the mechanism of material removal in AWJ, as a result of abrasive particle impact through step by step tracing of the abrasive particle as it is interacting with the workpiece material. The new model considers the elastic-plastic behavior of the workpiece material. Also the non linear dynamic loading conditions which are characteristic feautres of AWJM are accounted for in the pesent study. The failure of the workpiece material is examined analytically, by means of a virtual finite element (FE) AWJ experiment, and experimentally, by means of scanning electron microscopy (SEM) and surface topographies. Stress results indicate that the workpiece material is subject to severe highly localized plastic deformation and as a result, small overlapping craters are generated. These craters are formed by high compressive stresses at the cutting interface. The finite element results indicate a good agreement with experimental results.

Although several theoretical and experimental models have been developed for abrasive waterjet machining #AWJM), the exact nature of
erosion is not yet understood. This paper presents an attempt to model AWJM using the ®nite element method #FEM) in order to explain the
abrasive particle±workpiece interaction process. Also, the model predicts the depth of deformation as a result of abrasive particle impact.
The main objective is to develop an FE model which would enable the prediction of the depth of cut without any cutting experiments. The
new model takes into account the precise representation of the constitutive behavior of the workpiece material under AWJ dynamic loading
conditions which was ignored in the previous AWJM models. In the present model, forces acting on the abrasive particle need not be
initially determined, as in previous AWJM studies, as they are automatically calculated at each time step. The results show that plastic
deformation is very localized. Finally, the present FE results are consistent with experimental results.

The abrasive waterjet machining (AWJM) process is so complex, due to the interaction of several working parameters, that its micro erosion mechanisms have not yet been completely understood. Understanding the interaction of a single abrasive particle with the workpiece material constitutes the basic step in understanding the occuring complex erosion phenomena. This paper presents the results of an extensive program of AWJ experimentation, which was recently carried out at the department of Machine Technology.

Customary mineral based liquids are as a rule broadly utilized in cooling and greases in machining activities. Nonetheless, these cutting liquids are the suitable wellspring of numerous natural and organic issues. To kill the evil impacts related with cutting liquids, it is important to move towards practical machining methods. Such sustainable machining techniques utilize minimize the amount of cutting liquid, fluid nitrogen, vegetable oil or packed air as a cooling-oil medium. The liquids utilized in economical machining strategies are viewed as absolutely biodegradable and Eco-friendly. This paper is a careful survey of the relative multitude of current environmental friendly machining methods as of now rehearsed in the metal cutting cycle. It has been likewise discovered that these economical machining strategies more often than not give better outcomes as far as improved surface nature of the machined part, upgraded apparatus life, less cutting temperatures and slicing powers when contrasted with traditional wet machining techniques. The principle motivation behind this survey work is to recognize the diverse supportable strategies and empower the utilization of such procedures in metal machining, so that, the reducing interaction turns out to be more expense powerful and climate inviting.

This work presents a comprehensive structure for evaluating the sustainability of machining processes. Industries can contribute towards developing a sustainable future by using algorithms that evaluate the sustainability of their processes. Inspired by the literature, the proposed model involves a set of metrics that are critical in evaluating the impact of a process on society, environment, and economy. The flexibility of this model allows decision-makers to use the available responses to identify the most favorable process. The entropy weight method was suggested for objectively calculating the weights of each indicator. A multi-criteria decision-making method i.e., Technique for Order Preference based on Similarity to Ideal Solution (TOPSIS), was used to rank processes in the decreasing order of their sustainability. The proposed algorithm was successfully validated with case studies from the published literature. A MATLAB code was also created so that industries may expeditious...

In this paper, a 4-PPPS redundantly actuated parallel mechanism and its motion planning method are
proposed. The mechanism can be applied to the positioning and alignment of large subassembly in
engineering assembly. The optimization of the positioning and alignment trajectory is performed with the
minimum energy consumption as the objective function. The system test data shows that the assembly
platform and the motion planning method can satisfy the requirements of accuracy, efficiency and
stability of the positioning and alignment operations.

Friction and wear behaviours of Ti-6Al-4V (Ti64) and Ti-5Al-4V-0.6Mo-0.4Fe (Ti54) alloys sliding against a tungsten carbide wheel under dry and cryogenic sliding conditions were investigated at different sliding speeds, loads, and distances. Mathematical models utilizing response surface methodology were developed as a function of sliding conditions for predicting the friction and wear characteristics of both titanium alloys. The controlling variables were determined by utilizing design of experiments. The developed models are able to predict the measured friction coefficient and wear volume with reasonable degree of accuracy for both titanium alloys within the ranges of studied parameters.

Results showed no substantial difference between tribo-characteristics of both titanium alloys. Under cryogenic sliding condition, tribo-characteristics were lower than those obtained under dry sliding, except at higher load, cryogenic sliding surprisingly gave higher friction coefficient. Analyses of worn surfaces and wear debris by using scanning electron microscopy and energy-dispersive spectroscopy revealed that the role of cryogenic conditions at the sliding interface was partially attributed to changing material properties and possible hydrodynamic effect. Under dry sliding, the main wear modes were adhesion and delamination, while under cryogenic sliding, in addition to delamination, abrasion wear mode dominated.

Friction and wear behaviours of Ti-6Al-4V (Ti64) and Ti-5Al-4V-0.6Mo-0.4Fe (Ti54) alloys sliding against a tungsten carbide wheel under dry and cryogenic sliding conditions were investigated at different sliding speeds, loads, and distances. Mathematical models utilizing response surface methodology were developed as a function of sliding conditions for predicting the friction and wear characteristics of both titanium alloys. The controlling variables were determined by utilizing design of experiments. The developed models are able to predict the measured friction coefficient and wear volume with reasonable degree of accuracy for both titanium alloys within the ranges of studied parameters.
Results showed no substantial difference between tribo-characteristics of both titanium alloys. Under cryogenic sliding condition, tribo-characteristics were lower than those obtained under dry sliding, except at higher load, cryogenic sliding surprisingly gave higher friction coefficient. Analyses of worn surfaces and wear debris by using scanning electron microscopy and energy-dispersive spectroscopy revealed that the role of cryogenic conditions at the sliding interface was partially attributed to changing material properties and possible hydrodynamic effect. Under dry sliding, the main wear modes were adhesion and delamination, while under cryogenic sliding, in addition to delamination, abrasion wear mode dominated.

The abrasive waterjet machining (AWJM) process is so complex, due to the interaction of several working parameters, that its micro erosion mechanisms have not yet been completely understood. Understanding the interaction of a single abrasive particle with the workpiece material constitutes the basic step in understanding the occuring complex erosion phenomena. This paper presents the results of an extensive program of AWJ experimentation, which was recently carried out at the department of Machine Technology.

Erosion of ductile materials by waterjet machining is still a complex phenomenon. This paper presents a finite element model of the waterjet machining (WJM) process. Cutting forces, deformations and stresses occurring in the workpiece material in the vicinity of the cutting interface as a result of erosion impact by the waterjet could be obtained. The results indicate that the finite element method is a useful tool in the analysis of  this process. Further research work is currently being conducted by the authors.

In this study, the surface integrity of nickel-titanium (NiTi) shape memory alloys (SMAs) was investigated after face milling processes with cryogenically treated/untreated cemented carbide cutting tools at the conditions of dry cutting and minimum quantity lubrication (MQL) of cutting fluids depending on the changing cutting parameters. The integrity of surface layer of the workpiece material was evaluated according to the mean surface roughness, microstructure and hardness, as well as according to the resultant cutting force and flank wear of inserts. Cutting tests were carried out at three different cutting speeds (20, 35 and 50 m/min), feed rates (0.03, 0.07 and 0.14 mm/tooth) and a constant axial cutting depth (0.7 mm). The influence of these parameters on the surface integrity was extensively investigated. The face milling tests of NiTi SMA at optimal cutting parameters show that the surface integrity enhanced at a cutting speed of 50 m/min and feed rate of 0.03 mm/tooth using boron-added cutting fluid (EG + %5BX) with deep cryogenic heat treated (2 196°C) CVD coated S40T grade cutting tool. Under MQL conditions, the minimum mean surface roughness (0.278 lm), resultant cutting force (268.2 N) and flank wear (0.18 mm) were obtained due to the high thermal conductivity and lubrication property of EG + %5BX cutting fluid. The highest hardness values (343 HV) were measured at the zone subjected to the highest deformation, while the lowest one (316 HV) was measured at the zone at the least deformation.