Increasing Productivity and Process Stability in Turning of Aerospace Materials with High Pressure Lubricoolant Supply

In the field of machining difficult-to-cut materials like titanium or nickel-based alloys, the use of a high-pressure lubricoolant supply may result in a significant increase of productivity and process stability. Due to enhanced cooling and lubrication of the cutting zone and thus reduced thermal tool load, tool wear can be decreased which allows higher applicable cutting speeds. Furthermore, the process stability can be increased as a result of effective chip breaking and chip evacuation. Since energy efficiency is very crucial, pressure and flow rate have to be adjusted carefully and in accordance with the cutting parameters to guarantee best results with less energy. For this purpose, experimental investigations were carried out under variation of the flow rate in order to find the minimum required value for a certain machining task with the overall aim to prevent waste of the media used. To maximize the positive effect of high pressure lubricoolant supply strategy on productivity and process stability, specially designed lubricoolant jet guidance geometry on the rake face was also investigated and compared to conventional turning inserts. To study the effect of high-pressure lubricoolant supply on tool temperature, reference tests also carried out using conventional overflood cooling (CoC). The results suggest that the tool temperature can be significantly decreased compared to CoC by applying the high pressure lubricoolant supply and using specially designed jet guidance geometry in turning the investigated aerospace materials TiAl6V4 and Inconel 718.

Download Full-text

Thermal Modeling of Tool Temperature Distribution during High Pressure Coolant Assisted Turning of Inconel 718

Materials ◽

10.3390/ma12030408 ◽

2019 ◽

Vol 12 (3) ◽

pp. 408 ◽

Cited By ~ 8

Author(s):

Doriana D'Addona ◽

Sunil Raykar

Keyword(s):

High Pressure ◽

Temperature Distribution ◽

Inconel 718 ◽

Tool Temperature ◽

Machining Processes ◽

Nickel Chromium ◽

Work Material ◽

Cutting Zone ◽

Overall Performance ◽

High Pressure Coolant

This paper presents a finite-element modeling (FEM) of tool temperature distribution during high pressure coolant assisted turning of Inconel 718, which belongs to the heat resistance superalloys of the Nickel-Chromium family. Machining trials were conducted under four machining conditions: dry, conventional wet machining, high pressure coolant at 50 bar, and high pressure coolant at 80 bar. Temperature during machining plays a very important role in the overall performance of machining processes. Since in the current investigation a high pressure coolant jet was supplied in the cutting zone between tool and work material, it was a very difficult task to measure the tool temperature correctly. Thus, FEM was used as a modeling tool to predict tool temperature. The results of the modeling showed that the temperature was considerably influenced by coolant pressure: the high pressure jet was able to penetrate into the interface between tool and work material, thus providing both an efficient cooling and effective lubricating action.

Download Full-text

Potential of Modern Lubricoolant Strategies on Cutting Performance

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.554-557.2062 ◽

2013 ◽

Vol 554-557 ◽

pp. 2062-2071 ◽

Cited By ~ 10

Author(s):

Fritz Klocke ◽

Dieter Lung ◽

Alexander Krämer ◽

Tolga Cayli ◽

Hubertus Sangermann

Keyword(s):

High Pressure ◽

Flow Rate ◽

High Performance ◽

Minimum Quantity Lubrication ◽

Cutting Parameters ◽

Cryogenic Cooling ◽

Fundamental Research ◽

The Media ◽

Tool Technology ◽

Positive Effect

Besides developments in the area of dry machining and minimum quantity lubrication, the use of coolant lubricants is still essential when machining high alloyed steels or heat resistant materials like titanium and nickel based alloys. Experts agree that this fact will not change in the next decade. For this reason it is necessary to use coolant lubricants as effectively as possible to maximise their positive effect on productivity and process stability. High-performance cooling strategies like high-pressure cooling and cooling with cold gases (cryogenic cooling) have received increased attention in the last years. Through the targeted supply of coolant lubricants to the cutting site it is possible to decrease tool wear, increase cutting speeds, guarantee defined chip breakage and chip transport and – in terms of cryogenic cooling – waive part cleaning. This paper shows current research results in the above mentioned field. Since the performance of a high-pressure coolant lubricant supply in turning difficult to cut materials has been shown in many previous papers, this paper focuses on the quantification of the potential in turning different steels, namely quenched and tempered but also stainless steel in comparison to the conventional flood cooling. Since energy efficiency is very crucial, pressure and flow rate have to be adjusted carefully and in accordance with the cutting parameters to guarantee best results with less energy. Moreover the effects of cryogenic cooling will be evaluated in comparison to high-pressure cooling and conventional flood cooling. In latter field, cutting tests were carried out under variation of the flow rate in order to find the minimum required value for a certain machining task with the overall aim to prevent waste of the media used. Especially in cryogenic cooling technologies, many fundamental research regarding the working mechanisms but also further developments in cutting tool and machine tool technology are still necessary to make this technology ready for industrial use.

Download Full-text

The Experimental Investigations of Centripetal Air Bleed With Tubed Vortex Reducer for Secondary Air System in Gas Turbine

Volume 5C: Heat Transfer ◽

10.1115/gt2014-26959 ◽

2014 ◽

Cited By ~ 1

Author(s):

Xiao Chen ◽

Ye Feng ◽

Lijun Wu

Keyword(s):

High Pressure ◽

Flow Field ◽

Gas Turbine ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Pressure Loss ◽

Experimental Investigations ◽

Pressure Losses ◽

Nozzle Guide

In a modern gas turbine, the air bled through High Pressure Compressor (HPC) rotor drums from the main flow is transported radially inwards and then transferred to cool the High Pressure Turbine (HPT). The centripetal air flow creates a strong vortex, which results in huge pressure losses. This not only restricts the mass flow rate, but also reduces the cooling air pressure for down-stream hot components. Adding vortex reducer tubes to the centripetal air bleed can reduce the pressure loss and ensure the pressure and mass flow rate of the supply air. Design optimization of the tubed vortex reducer is essential in minimizing the pressure losses. This paper describes experimental investigations of different configurations of tubed vortex reducers at different rotational speeds and mass flow rates. Particular attention is paid to the shape of the drum hole, the length of the tubed vortex reducers at the same installation location, and the angles of the nozzle guide vane outlets. The core section of test rig is comprised of two steel disks, one drum rotor and stationary cases with nozzle guide vanes. It operates at representative engine parameters, such as the turbulent flow parameter, λT(0.2–1.8) and the Rossby number Ro(0.05–0.08). Three conclusions can be drawn based on the experimental results. 1) The shape of the drum hole is a key factor of the bleed system pressure loss. An oval hole configuration has less flow resistance and results in lower pressure losses compared with a circular hole design. 2) The tests prove that tubed vortex reducers are instrumental in minimizing centripetal air flow. These components effectively restrain the free vortex development and decrease the pressure losses in the cavity. 3) Basically, the flow field consists of a free vortex and a forced vortex. The length of the tube influences the flow field and the pressure losses at the inlet and outlet of the tubed vortex reducer. However, the tube length is less important when compared with the shape of drum hole.

Download Full-text

The Effect of High Pressure Abrasive Water Jet Cutting Parameters on Cutting Performance of Granite

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.304-305.560 ◽

2006 ◽

Vol 304-305 ◽

pp. 560-564 ◽

Cited By ~ 15

Author(s):

Chuan Zhen Huang ◽

Rong Guo Hou ◽

Jun Wang ◽

Yan Xia Feng

Keyword(s):

High Pressure ◽

Mass Flow Rate ◽

Flow Rate ◽

Water Pressure ◽

Cutting Parameters ◽

Traverse Speed ◽

Kerf Width ◽

Standoff Distance ◽

Abrasive Water Jet ◽

Kerf Taper

The effect of cutting parameters such as water pressure, nozzle traverse speed and standoff distance on the granite cutting performance as characterized by kerf width, kerf taper, and striation drag angle are researched with a series of experiments using garnetabrasive and ultra high pressure abrasive water jet numerical control machine tool. The relationship between system pressure and abrasive mass flow rate is also studied. The research results show that the abrasive mass flow rate is only proportional to water pressure and the effect of other cutting parameters is not significant. It is found that an increase in water pressure is associated with an increased kerf width and a decreased kerf taper. The kerf width decreases with the enhancement of nozzle traverse speed, and resulting in a significant increase in kerf taper as the nozzle traverse speed increases. The kerf width increases with the enhancement of standoff distance, and hence it causes a significant increase in kerf taper at the standoff distance domain from 3mm to 4mm and then a little decrease in kerf taper at the standoff distance increasing from 4mm to 5mm. The striation drag angle decreases with an increase in water pressure and a decrease in nozzle traverse speed.

Download Full-text

Particle Size Effects on Selectivity in Confined Bed Comminution

Minerals ◽

10.3390/min11040342 ◽

2021 ◽

Vol 11 (4) ◽

pp. 342

Author(s):

Holger Lieberwirth ◽

Lisa Kühnel

Keyword(s):

Particle Size ◽

High Pressure ◽

Particle Size Distribution ◽

Size Distribution ◽

Size Effects ◽

Experimental Investigations ◽

Ore Processing ◽

Tumbling Mills ◽

Particle Bed ◽

Vertical Roller

Confined bed comminution in high-pressure grinding rollers (HPGRs) and vertical roller mills (VRMs) was previously used preferably for grinding comparably homogeneous materials such as coal or clinker. Meanwhile, it started to complement or even replace tumbling mills in ore beneficiation with ore and gangue particles of rather different breakage behaviors. The selectivity in the comminution of a mixture of particles with different strengths but similar particle size distribution (PSD) of the constituents in a particle bed was investigated earlier. The strength of a material is, however, also a function of particle size. Finer particles tend to be more competent than coarser ones of the same material. In industrial ore processing using confined bed comminution, this effect cannot be neglected but even be exploited to increase efficiency. This paper presents research results on this topic based on experimental investigations with model materials and with natural particles, which were stressed in a piston–die press. It appeared that the comminution result substantially depends on the material characteristics, the composition of the mixture and the PSD of the constituents. Conclusions will be drawn for the future applications of selective comminution in mineral processing.

Download Full-text

Temperature monitoring in the subsurface during single lip deep hole drilling

tm - Technisches Messen ◽

10.1515/teme-2020-0055 ◽

2020 ◽

Vol 87 (12) ◽

pp. 757-767

Author(s):

Robert Wegert ◽

Vinzenz Guski ◽

Hans-Christian Möhring ◽

Siegfried Schmauder

Keyword(s):

Cutting Parameters ◽

Drill Hole ◽

Machining Process ◽

Hole Drilling ◽

Drilling Process ◽

Deep Hole ◽

Machining Processes ◽

Deep Hole Drilling ◽

Feed Force ◽

Cutting Zone

AbstractThe surface quality and the subsurface properties such as hardness, residual stresses and grain size of a drill hole are dependent on the cutting parameters of the single lip deep hole drilling process and therefore on the thermomechanical as-is state in the cutting zone and in the contact zone between the guide pads and the drill hole surface. In this contribution, the main objectives are the in-process measurement of the thermal as-is state in the subsurface of a drilling hole by means of thermocouples as well as the feed force and drilling torque evaluation. FE simulation results to verify the investigations and to predict the thermomechanical conditions in the cutting zone are presented as well. The work is part of an interdisciplinary research project in the framework of the priority program “Surface Conditioning in Machining Processes” (SPP 2086) of the German Research Foundation (DFG).This contribution provides an overview of the effects of cutting parameters, cooling lubrication and including wear on the thermal conditions in the subsurface and mechanical loads during this machining process. At first, a test set up for the in-process temperature measurement will be presented with the execution as well as the analysis of the resulting temperature, feed force and drilling torque during drilling a 42CrMo4 steel. Furthermore, the results of process simulations and the validation of this applied FE approach with measured quantities are presented.

Download Full-text

Machining Ti-6Al-4V Alloy Using Nano-Cutting Fluids: Investigation and Analysis

Journal of Manufacturing and Materials Processing ◽

10.3390/jmmp5020042 ◽

2021 ◽

Vol 5 (2) ◽

pp. 42

Author(s):

Abdelkrem Eltaggaz ◽

Ibrahim Nouzil ◽

Ibrahim Deiab

Keyword(s):

Surface Finish ◽

Minimum Quantity Lubrication ◽

Weight Fraction ◽

Contact Length ◽

Al2o3 Nanoparticles ◽

Compressive Stresses ◽

Cutting Zone ◽

The Impact ◽

Cooling And Lubrication

Minimum Quantity Lubrication nanofluid (MQL-nanofluid) is a viable sustainable alternative to conventional flood cooling and provides very good cooling and lubrication in the machining of difficult to cut materials such as titanium and Inconel. The cutting action provides very difficult conditions for the coolant to access the cutting zone and the level of difficulty increases with higher cutting speeds. Furthermore, high compressive stresses, strain hardening and high chemical activity results in the formation of a ‘seizure zone’ at the tool-chip interface. In this work, the impact of MQL-nanofluid at the seizure zone and the corresponding effects on tool wear, surface finish, and power consumption during machining of Ti-6Al-4V was investigated. Aluminum Oxide (Al2O3) nanoparticles were selected to use as nano-additives at different weight fraction concentrations (0, 2, and 4 wt.%). It was observed that under pure MQL strategy there was significant material adhesion on the rake face of the tool while the adhesion was reduced in the presence of MQL-nanofluid at the tool-chip interface, thus indicating a reduction in the tool chip contact length (TCCL) and reduced seizure effect. Furthermore, the flank wear varied from 0.162 to 0.561 mm and the average surface roughness (Ra) varied from 0.512 to 2.81 µm. The results indicate that the nanoparticle concentration and the reduction in the seizure zone positively influence the tool life and quality of surface finish.

Download Full-text

Effect of Recirculation Device With Counter Swirl Vane on Performance of High Pressure Ratio Centrifugal Compressor

Volume 7: Turbomachinery, Parts A, B, and C ◽

10.1115/gt2011-45360 ◽

2011 ◽

Cited By ~ 1

Author(s):

Hideaki Tamaki

Keyword(s):

High Pressure ◽

Mach Number ◽

Flow Rate ◽

Centrifugal Compressor ◽

Pressure Ratio ◽

Negative Slope ◽

Tip Leakage Flow ◽

Recirculation Flow ◽

Operating Range ◽

High Pressure Ratio

Centrifugal compressors used for turbochargers need to achieve a wide operating range. The author has developed a high pressure ratio centrifugal compressor with pressure ratio 5.7 for a marine use turbocharger. In order to enhance operating range, two different types of recirculation devices were applied. One is a conventional recirculation device. The other is a new one. The conventional recirculation device consists of an upstream slot, bleed slot and the annular cavity which connects both slots. The new recirculation device has vanes installed in the cavity. These vanes were designed to provide recirculation flow with negative preswirl at the impeller inlet, a swirl counterwise to the impeller rotational direction. The benefits of the application of both of the recirculation devices were ensured. The new device in particular, shifted surge line to a lower flow rate compared to the conventional device. This paper discusses how the new recirculation device affects the flow field in the above transonic centrifugal compressor by using steady 3-D calculations. Since the conventional recirculation device injects the flow with positive preswirl at the impeller inlet, the major difference between the conventional and new recirculation device is the direction of preswirl that the recirculation flow brings to the impeller inlet. This study focuses on two effects which preswirl of the recirculation flow will generate. (1) Additional work transfer from impeller to fluid. (2) Increase or decrease of relative Mach number. Negative preswirl increases work transfer from the impeller to fluid as the flow rate reduces. It increases negative slope on pressure ratio characteristics. Hence the recirculation flow with negative preswirl will contribute to stability of the compressor. Negative preswirl also increases the relative Mach number at the impeller inlet. It moves shock downstream compared to the conventional recirculation device. It leads to the suppression of the extension of blockage due to the interaction of shock with tip leakage flow.

Download Full-text