Cryogenic Machining Research Articles

Influences of size effect and workpiece temperature during cryogenic micro milling of soft viscoelastic polymer: an experimental assessment

Application of tool-based micromachining in soft polymer has been limited due to high adhesion and low elastic modulus of this material at room temperature. This study aims to evaluate the machinability of a typical viscoelastic soft polymer and understand the effect of material and process parameters on machining performances. In this study, a micro-milling process using cryogenic-assisted cooling is proposed and the importance of temperature control toward glass transition zone was particularly addressed. To identify insight of machinability in micro domain, this article also determines minimum uncut chip thickness (MUCT) and size effects by considering the variations of cutting force and surface integrity with the ratio of h/re (uncut chip thickness (h) to cutting edge radius (re)). The experimental results reveal that consideration of size effect during micromilling of soft viscoelastic polymer helps in reduction of machined surface roughness (Sa) value. Based on the cutting force pattern, it is evaluated that higher machining stability can be achieved during cryogenic machining by reduction of specific cutting force value. Moreover, temperature range around glass transition zone yields more promising experimental outcomes, outperforming other cooling zones.

Characterization of surface integrity of 7075-T6 aluminum alloy subjected to microbiologically induced corrosion during high-speed machining

Microbiologically Influenced Corrosion (MIC) is one of the primary causes of corrosion damage and equipment failure in industrial environments. This paper aims to investigate the impact of microbiologically influenced corrosion on the surface integrity of 7075-T6 aluminum alloy. Through experiments involving cryogenic treatment and machining, the study systematically compares the effects of different microbiologically influenced corrosion environments on 7075-T6 aluminum alloy. Techniques such as X-ray Diffraction (XRD), surface roughness measurement, Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and work hardening were used to elucidate the influence of natural seawater (Planktonic microorganisms, PM) and marine sediment (Benthic microorganisms, BM) corrosion on the surface integrity of 7075-T6 aluminum alloy.The results indicate that, compared to PM corrosion, BM corrosion results in a smaller surface roughness of 7075-T6 aluminum alloy. Specifically, the BM-10d specimen exhibits the smallest roughness at 0.353 μm. XRD and EDS analyses show that the corrosion products after microbiological corrosion are primarily a mixture of Al2O3, AlO(OH), and Al(OH)3. The peak intensity of AlO(OH) in the (200) crystal plane of the BM-5d corrosion product is notably higher than that of the 7075-T6 aluminum alloy under other conditions. In the PM environment, the corrosion products fully cover the entire surface of the workpiece and are accompanied by significant cracking. In contrast, in the BM environment, the corrosion products mainly exhibit a granular structure, are scattered across the workpiece surface, and the exposed substrate can be observed.The microhardness of the aluminum alloy after microbiological corrosion shows a trend of increasing initially, then decreasing, and finally stabilizing. The maximum depth of the hardened layer for PM-10d is 120 μm, with a maximum hardness of 178.74 HV. Compared to PM corrosion, BM corrosion results in a significantly greater hardened layer depth for 7075-T6 aluminum alloy, with the BM-10d hardened layer depth reaching approximately 140 μm and the peak hardness at 185.36 HV. Additionally, in the BM environment, the precipitates are fewer compared to those in the PM environment and exhibit a non-continuous, non-grain-boundary precipitation band.

Modified constitutive models and cutting finite element simulation of Ti-6Al-4V alloy at cryogenic

Mastering the high strain characteristics at cryogenics and constructing an accurate constitutive model are critical for establishing a cryogenic cutting simulation of Ti-6Al-4V alloy. The traditional constitutive model is inadequate for accounting for high and cryogenic conditions. In this paper, cryogenic split Hopkinson pressure bar (SHPB) experiments are conducted, specifically for Ti-6Al-4V alloy, to develop a modified Johnson–Cook (J–C) constitutive model that incorporates the cryogenic effect. A coupled two-dimensional orthogonal finite element simulation involving temperature displacement was conducted for the cryogenic cutting of Ti-6Al-4V alloy. This simulation was performed using ABAQUS, based on a modified J–C constitutive model subroutine. It was observed that the smallest discrepancy between the simulation results and the data from ice-fixed milling experiments was just 2.12%. The modified J–C constitutive model is more adept at simulating the chip morphology under cryogenic conditions. It was also found that cryogenic machining enhances the distribution of temperature and stress within the chip. For every 5°C reduction in processing temperature, the tool temperature diminishes by more than 2%.

Cryogenic and conventional milling of AZ91 magnesium alloy

Use of magnesium is the need of the hour due to its low density as well as its high strength-to-weight and stiffness-to-weight ratio etc. This study focuses on the effectiveness of liquid nitrogen (LN2) assisted cryogenic machining on the surface integrity (SI) characteristics of AZ91 magnesium alloy. Face milling using uncoated carbide inserts have been performed under liquid nitrogen (LN2) assisted cryogenic condition and compared with conventional (dry) milling. Experiments are performed using machining parameters in terms of cutting speeds of 325, 475, 625 m/min, feed rates of 0.05, 0.1, 0.15 mm/teeth and depth of cuts of 0.5, 1, 1.5 mm respectively. Most significant surface integrity characteristics such as surface roughness, microhardness, microstructure, and residual stresses have been investigated. Behaviour of SI characteristics with respect to milling parameters have been identified using statistical technique such as ANOVA and signal-to-noise (S/N) ratio plots. Additionally, the multi criteria decision making (MCDM) techniques such as additive ratio assessment method (ARAS) and complex proportional assessment (COPRAS) have been utilized to identify the optimal conditions for milling AZ91 magnesium alloy under both dry and cryogenic conditions. Use of LN2 during machining, resulted in reduction in machining temperature by upto 29% with a temperature drop from 251.2 °C under dry condition to 178.5 °C in cryogenic condition. Results showed the advantage of performing cryogenic milling in improving the surface integrity to a significant extent. Cryogenic machining considerably minimized the roughness by upto 28% and maximised the microhardness by upto 23%, when compared to dry machining. Cutting speed has caused significant impact on surface roughness (95.33% – dry, 92.92% – cryogenic) and surface microhardness (80.33% – dry, 82.15% – cryogenic). Due to the reduction in machining temperature, cryogenic condition resulted in compressive residual stresses (maximum σ║ = -113 MPa) on the alloy surface. Results indicate no harm to alloy microstructure in both conditions, with no alterations to grain integrity and minimal reduction in the average grain sizes in the near machined area, when compared to before machined (base material) surface. The MCDM approach namely ARAS and COPRAS resulted in identical results, with the optimal condition being cutting speed of 625 m/min, a feed rate of 0.05 mm/teeth, and a depth of cut of 0.5 mm for both dry and cryogenic environments.

Perbandingan Keutuhan Permukaan Bahan Inkonel 718 dalam Pemesinan Kriogenik dan Kering

Inconel 718 is a nickel-based alloy that has been developed with superior mechanical strength, creep resistance, and corrosion, as well as erosion resistance at temperatures above 649 ˚C. It is suitable to be used for aircraft engine components such as turbine discs. However, it also has low heat conductivity and the presence of hard carbide particles in its alloy worsens the machining conditions with high cutting temperature, and high shear force and promotes work hardening. Thus, this study aims to evaluate the surface integrity of Inconel 718 in terms of surface roughness, plastic deformation, and micro-hardness alterations after the turning process. Cryogenic CO2 cooling was supplied along the cutting process to reduce cutting temperatures and the machining performances were compared with dry machining. The experimental works show that the dry machining resulted in lower surface roughness by up to 42.15% as compared to cryogenic. However, the depth of plastic deformation under dry machining was much more severe than in cryogenic machining driven by higher cutting temperatures and pressure from the worn tool. The depth of plastic deformation became more distinct as the cutting speed increased. While the microhardness alteration of the machined surface was higher under cryogenic machining due to extensive cooling capacity by the CO2 flow. Thus, this study reveals that cryogenic cooling during metal cutting can produce products that have better wear resistance as well as higher surface hardness.

Elevating Sustainability: The Role of Machining in Modern Eco-Friendly Manufacturing Processes

Sustainable manufacturing has become a critical concern across various industries, including aerospace, automotive, and services. It involves the creation of manufactured products through economically sound processes that minimize negative environmental impacts while conserving energy and natural resources. Additionally, sustainable manufacturing aims to enhance employee, community, and product safety.This paper focuses on the machining process as a key component of sustainable manufacturing. Machining is widely used in manufacturing industries to fabricate components, but it also significantly contributes to environmental pollution. Sustainable machining has been a topic of discussion for over a decade. In sustainable machining processes, every factor acts differently like, the tool life, productivity, and effective utilization of resources must be increased. In contrast, the machining cost, machine cutting power, and adverse effect of cooling and lubrication fluids will be decreased. Important aspects of sustainable machining include dry and near-dry machining, cryogenic machining, and minimum quantity lubricant (MQL) were presented in this article. The effectiveness of these processes is assessed based on cutting tool life and the quality of machined components. In addition, the advancements consideration such as novel process variations, process hybridization, the use of sustainable tools and green transfer mediums, and the optimization of process parameters. Recommendations include increasing efficiency and reducing waste by incorporating recyclable tools in the machine industry implementing either stand alone or hybrid sustainable lubrication machining techniques.

Cryogenic Machining Performance of M303 at High Cutting Speeds

The material M303 is commonly used in the fabrication of machinery, automotive components, locomotive axle housings, and injection moulds. It is a stainless martensitic chromium steel known for its high strength, wear resistance, and corrosion resistance. The primary purpose of this study is to investigate the machinability of M303 under cryogenic conditions, specifically focusing on high cutting speeds. By exploring the effects of cryogenic machining on M303, the study aims to provide insights into the performance and characteristics of this material under extreme cutting conditions. This study investigates the influence of cutting parameters on the machinability of M303 in a cryogenic environment using liquid nitrogen (LN2) and coated carbide cutting tools in a high-speed turning process. The study focuses on high cutting speeds and examines essential machinability factors, including cutting forces, surface finish, and tool life. The experimental design utilises a Taguchi L4 orthogonal array to systematically study feed rates (0.1-0.2 mm/rev), depth of cut (0.2-0.6 mm), and high cutting speeds (260-340 m/min). Notably, at a low cutting speed of 260 m/min, coupled with low feed rates and depth of cut, the study reveals the longest tool life of 48.57 mintues was achieved. This condition is characterized by a good surface finish and low cutting forces with Ra of 0.9 µm and cutting force of 100 N respectively. The predominant wear occurs on the flank face, primarily due to fracturing and chipping, especially under high combinations of cutting parameters. Conversely, gradual wear is observed under low combinations of cutting parameters, resulting in an extended tool life. In conclusion, the application of LN2 proves effective under conditions of low cutting parameters. The study suggests that the risk of fracturing the cutting tool increases at higher feed rates and depths of cut, especially when combined with elevated cutting speeds. This research provides valuable insights into optimizing the machining of M303 for enhanced efficiency and tool longevity.

Microstructure, aging behavior, and friction and wear properties of ultrafine-grained 7050 aluminum alloy produced by cryogenic temperature extrusion machining

Cryogenic temperature extrusion machining (CT-EM), as a novel cryogenic temperature severe plastic deformation (CT-SPD) process, is an effective method to produce ultrafine-grained (UFG) materials. In this paper, the microstructure, microhardness, friction and wear properties of the UFG chips prepared by CT-EM and room temperature extrusion machining (RT-EM) were analyzed. The results show that CT-EM has a better grain refinement effect. The grain size of the CT-EM samples is smaller, the dislocation density is larger, and the microhardness is higher. After aging treatment, a large number of small secondary precipitates (η '/η) appear in the microstructure of the samples, which further improves the microhardness. This is the result of a synergistic effect of fine grain, dislocation, and precipitation strengthening. Cryogenic treatment can increase the precipitation kinetics of the secondary phase and shorten the time for the samples to reach peak hardness. The CT-EM samples have a lower friction coefficient and wear mass. With the increase of the machining velocity, the wear mechanism of the samples changes from abrasion wear to oxidation, adhesion, and fatigue wear.

Numerical analysis of machinability and surface alterations in cryogenic machining of additively manufactured Ti6Al4V alloy

Metal additive manufacturing (AM) technology has been utilized in many industries including automotive, aerospace, and medical. AM Ti6Al4V (Ti64) alloy is highly noticed for production of medical instruments such as dental implants and the machining process is mostly needed during the production or post-processing of these components. Numerical model, as a powerful tool, can be efficiently used for analyzing the machining process. A customized model was employed using a user-written subroutine in this work to evaluate machinability and microstructural changes in cryogenic machining of AM Ti64 alloy. For this purpose, the microstructural changes were simulated as the new numerical outputs. The numerical results of cutting forces, temperature, nano-hardness, and alpha lamellae thickness (grain size) were successfully verified by corresponding experiments from literature. Then, the impact of tool geometry (including rake and clearance angles, cutting edge radius, and nose radius) on the machinability performance was examined. It was found that, the variation of clearance and rake angles were more effective on depth of the hardened layer compared to the other parameters. Thickness of alpha lamellae phase near the machined surface and depth of the affected layer by nano-hardness changes were changed from 0.9 to 1.58 µm, and from 18 to 40 µm, respectively. Overall, it was concluded that the variation of insert positioning made by tool holder (change in rake and clearance angles) was an effective parameter on the process outputs when machining AM Ti64 alloy.

Tuned Windings: the window of opportunity for the implementation of solid conductors in high frequency cryogenic electric machines

Optimization techniques can significantly improve the performance of electrical machines. The analysis and the optimization algorithms focus on computational efficiency. In this paper, the optimization of a high frequency electrical machine in cryogenic conditions is proposed. The losses introduced by AC current in a conductor are directly proportional with the applied frequency in terms of skin effect and proximity effect. The stator coil, made from two aluminium (Al) turns, in the presence of cryogenic coolants has been analysed at frequencies up to 1000 Hz. In order to reduce the AC losses introduced by the magnetic fields, Nonlinear Conjugate Gradient (NCG) method has been applied for the stator coil thickness optimization. Frequency dependence is observed in most simulations. In the presence of Liquid Hydrogen (LH2) coolant, Al 1100 conductor presents the minimum power loss.

Effect of liquid nitrogen assisted milling on AZ91 magnesium alloy

The objective of the present work is to study the effect of liquid nitrogen (LN2) cryogenic on the performance of face milling for producing quality surface in AZ91 magnesium alloy. Machining AZ91 alloy has been a challenging domain due to the risk of ignition or spark during machining, which affects surface finish. In this study, face milling is carried using uncoated carbide inserts in cryogenic condition, and the performance is compared with dry condition based on the surface integrity (SI) characteristics. The findings of this study reveal that use of LN2 results in enhanced surface integrity. Observations showed no harm to alloy microstructure in both conditions, with no alterations to grain integrity in the near machined area. Cryogenic machining resulted in reduction in machining temperature ranging from 146.7 °C to 178.5 °C, when compared to dry condition temperature ranging from 219.4 °C to 251.2 °C. Cryogenic machining considerably generated smoother (Ra = 0.0606 μm) and harder (HV = 116.5) surfaces, and also resulted in compressive residual stresses. This study concludes that cryogenic-assisted milling is an excellent alternative for the production of superior-quality surface in AZ91 alloy.

Surface integrity analysis of Si3N4 under cryogenic assisted femtosecond laser ablation

Femtosecond laser is suitable to process Si3N4, but heat effect forming during machining process could degrade the performance of specimen. To reduce heat damage, in this study, the effects of cryogenic assisted laser machining on the surface quality and micro-structures of Si3N4 was investigated. The femtosecond laser was employed to ablate Si3N4 at various low temperatures, accompanied with comprehensive analysis of the surface roughness, material removal rate and SEM topography. To further illustrate the formation mechanism of surface structure, finite element analysis was conducted. Results indicated that while low temperature exerted negligible effects in single-layer ablation, multi-layer laser machining benefits from improved surface quality. Low temperature mitigated thermal effects and reduced the recast layer area, resulting in decreased surface roughness. The lowest surface roughness was obtained during the machining of the specimen at −60 °C of 1.072 μm, representing a 54.6 % reduction compared to ambient air machining. However, further decreasing the temperature below −60 °C led to an increase in surface roughness. This was attributed to the combined effects of Gaussian beam energy distribution and low temperature, resulting in incomplete ablation of the surface region between two scanning pitches, thereby decreasing surface quality. This research provides valuable insights into the cryogenic assisted femtosecond laser machining.

A review of the use of cryogenic coolant during machining titanium alloys

Titanium alloys are considered difficult-to-machine materials, and much effort has been made to improve their machinability through various approaches. The use of cryogenic coolants during machining, sometimes referred to as cryogenic machining, is a popular environmentally friendly technique that promises to reduce cutting zone temperatures, reduce friction, and enhance tool life during machining operations. This review article explores the use of cryogenic coolants during titanium machining and presents an overview of research progress and knowledge gaps. The various coolants and methods for cryogenic machining are reviewed, along with the effectiveness of these methods in terms of key machinability criteria, including tool wear, tribological properties, and heat transfer. Issues in sustainability are also explored.

On the chip formation mechanism when cutting Ti6Al4V with localised supply of liquid nitrogen

In cryogenic machining, employing internal supply cooling through the tool not only diminishes tool wear and enhances workpiece machining quality but also offers the benefits of reduced liquid nitrogen consumption and more precise cooling. These advantages are particularly noteworthy for efficiently machining challenging materials. However, prevailing research on internal supply cooling through tools predominantly concentrates on aspects such as tool wear and surface integrity, with a relatively limited exploration of material removal mechanisms. The material removal process stands as a crucial factor influencing cutting stability and surface smoothness. Thus, this study focuses on the Ti-6Al-4 V alloy, utilizing numerical modeling to investigate the impact of liquid nitrogen cooling methods on the cutting deformation zone. In addition to its benefits for difficult-to-machine materials, internal supply cooling through the tool presents a promising avenue to enhance machining efficiency. Consequently, this study strategically selected the Ti-6Al-4 V alloy as the research subject, employing numerical modeling to delve into the influence of liquid-nitrogen cooling methods on the cutting deformation zone. Furthermore, employing a combination of cutting experiments and simulations, we analyzed the evolution of temperature fields and microstructures within the deformation zone to elucidate the chip formation mechanism under liquid nitrogen cooling conditions. The outcomes of this investigation reveal that in comparison to liquid nitrogen external supply cooling, internal supply cooling through the tool effectively restrains chip serration, thereby contributing to an enhancement in machining quality. The analysis demonstrates that, under conditions of internal supply cooling through the tool, chip formation is predominantly influenced by the adiabatic shear effect induced by low temperatures. In contrast, under external supply cooling conditions, susceptible to the low-temperature embrittlement effect, the chip's free surface tends to undergo brittle cracking. This shift in the chip formation mechanism toward the co-dominance of adiabatic shear and brittle cracking results in a more pronounced serration of the chips. This study establishes a theoretical foundation and guides the industrial application of cryogenic machining.

Machinability and Surface Properties of Cryogenic Poly(methyl methacrylate) Machined via Single-Point Diamond Turning.

Poly(methyl methacrylate) (PMMA), with a glass transition temperature (Tg) over 100 °C, shows good mechanical and optical properties and has broad applications after being machined with single-point diamond turning (SPDT) at room temperature. Because of the high Tg, current efforts mostly focus on optimizing machining parameters to improve workpiece precision without considering the modification of material properties. Cryogenic cooling has been proven to be an effective method in assisting ultra-precision machining for certain types of metals, alloys, and polymers, but has never been used for PMMA before. In this work, cryogenic cooling was attempted during the SPDT of PMMA workpieces to improve surface quality. The machinability and surface properties of cryogenically cooled PMMA were investigated based on the mechanical properties at corresponding temperatures. Nanoindentation tests show that, when temperature is changed from 25 °C to 0 °C, the hardness and Young's modulus are increased by 37% and 22%, respectively. At these two temperature points, optimal parameters including spindle speed, feed rate and cut depth were obtained using Taguchi methods to obtain workpieces with high surface quality. The surface quality was evaluated based on the total height of the profile (Pt) and the arithmetic mean deviation (Ra). The measurement results show that the values of Pt and Ra of the workpiece machined at 0 °C are 124 nm and 6 nm, respectively, while the corresponding values of that machined at 25 °C are 291 nm and 11 nm. The test data show that cryogenic machining is useful for improving the form accuracy and reducing the surface roughness of PMMA. Moreover, the relationship between temperature, material properties and machinability weas established with dynamic mechanical analysis (DMA) data and a theoretical model. This can explain the origin of the better surface quality of the cryogenic material. The basis of this is that temperature affects the viscoelasticity of the polymer and the corresponding mechanical properties due to relaxation. Then, the material property changes will affect surface profile formation during machining. The experimental results and theoretical analysis show that cryogenically cooled PMMA has good machinability and improved surface quality when using SPDT compared to that at ambient temperature.

Development of a numerical cutting model for understanding the chip formation in cryogenic machining

The aim of this study is to develop a finite element model of metal cutting that includes fluid structure interaction. The proposed model is used to improve the physical comprehension of the chip formation during cryogenic assisted machining. This is performed based on the coupled-Eulerian-Lagrangian formulation. An algorithm is also developed to ensure heat exchange between the fluid and the structure. It also allows decoupling the mechanical and thermal effects induced by liquid nitrogen. The titanium alloy Ti17 is used as a work material, and uncoated tungsten carbide is used as a tool under dry and cryogenic conditions with cutting speeds of 50 m/min and 70 m/min and feeds of 0.1 mm/rev and 0.2 mm/rev. Simulation is validated by comparison with the experimental results. Standard deviations of both forces and chip thickness are low; they stay under 15% and 35% of the average value, respectively. The chip formation, the cutting force and the temperature are studied. It is shown that cryogenic machining has a significant effect on the chip formation and the temperature distribution in the cutting zone. A remarkable temperature reduction by up to 500 °C is observed at the tool rake face. However, the tool tip temperature slightly decreases with the application of liquid nitrogen when compared to dry machining.

On the performance of cryogenic technology in milling of hardened H13 tool steel.

Cryogenic machining gained interest as a clean, and effective cooling technique for machining hard-to-cut materials. Hardened H13 steel is widely used in tool and die applications due to its superior properties at high temperatures. However, its low machinability and post machining tensile residual stress remains a major challenge. A comparative techno-economic and environmental analysis was performed to evaluate the performance of cryogenic and flood machining of H13. Process simulation was performed to select the optimum cutting conditions. Cryogenic showed significant improvement in the overall process productivity, part integrity, tool life and environmental performance as compared to flood.

Performance of Liquid Nitrogen (LN2) on Machining Pure Titanium (Grade 2): A Comparative Study

The biggest challenge for manufacturing industries is machining super alloys due to their properties. Titanium grade 2 also comes under the category of difficult cut material. In this present investigation, the green manufacturing technology was applied to cut the titanium grade 2. The comparison study was carried out between dry and cryogenic machining. The turning trails were performed using TiN-coated carbide cutting tools. Cutting force measurements surface roughness as well as the tool wear studies were carried out with the Kistler dynamometer, SURFCOM and SEM analysis. From the responses, under cryogenic cooling 32.5% of main cutting force reduction was observed when contrasted to dry condition at a cutting speed of 282 m/min. The 24 % of improved surface quality was observed under cryogenic cooling approach, more fracture on tool rake face was observed under dry condition and the favorable chip formations were also noted under cryogenic cooling approach.

Precision machining performance and mechanism of Ni/Ni3Al alloy under cryogenic temperature

Nickel-based superalloys are extensively used in extreme environments due to their excellent mechanical properties, which are attributed to the large volume fraction of the γ' phase. However, the manufacturing process of these alloys is still challenging and can be improved by cryogenic machining. Despite numerous experimental studies on this topic, experimental methods are not sufficient to analyze the ultra-precision machining of Ni-based alloys at low temperatures. There is a lack of mechanistic understanding of the low-temperature nano-cutting process of Ni-based alloys. Thus, we performed a simulation analysis of cryogenic nano-cutting on a Ni/Ni3Al alloy using molecular dynamics (MD). We investigated the stability of cutting forces and microstructural evolution of this two-phase single-crystal alloy. We found that appropriate low temperatures can significantly improve the cutting performance of Ni/Ni3Al two-phase single-crystal alloy. Specifically, we found that the stability of cutting at 123 K is the best for workpiece A, while the cutting stability at 173 K is the best for workpiece B. Additionally, we calculated the machined surface roughness and precision. The minimum surface roughness is observed at 123 K in workpiece A, followed by 223 K. In workpiece B, the minimum roughness is observed at 223 K, while the roughness at 123 K is considerably higher compared to other temperature levels. This study outlines a reference method for determining the optimal temperature during the material removal process. This approach is significant as it helps in understanding the micro-removal mechanism of Ni-based alloys better.

A process-reliable tailoring of subsurface properties during cryogenic turning using dynamic process control

Considering the current demands for resource conservation and energy efficiency, innovative machining concepts and increased process reliability have a significant role to play. A combination of martensitic hardening of the subsurface and near-net-shape manufacturing represent a great potential to produce components with wear-resistant subsurfaces in an energy- and time-saving way. Within the scope of the present study, the influence of cryogenic machining of metastable austenitic steel on the martensitic transformation and surface quality was investigated. Different cooling strategies were used. A soft sensor based on eddy current in-process measurements was used to determine and subsequently affect the martensitic transformation of the subsurface. The feed rate and component temperature were identified as significant factors influencing the martensitic transformation. However, a high feed rate leads to an increase in surface roughness, and thus to a reduction in component quality. For this reason, a roughing process for achieving maximum martensitic transformation was carried out first in the present study and then a reduction in the surface roughness by maintaining the martensitic subsurface content was aimed for by a subsequent finishing process. With the knowledge generated, a dynamic process control was finally set up for designing the turning process of a required subsurface condition and surface quality.