Finite element modeling of microstructural changes in turning of AA7075-T651 Alloy

The surface characteristics of a machined product strongly influence its functional performance. During machining, the grain size of the surface is frequently modified, thus the properties of the machined surface are different to that of the original bulk material. These changes must be taken into account when modeling the surface integrity effects resulting from machining. In the present work, grain size changes induced during turning of AA7075-T651 (160 HV) alloy are modeled using the Finite Element (FE) method and a user subroutine is implemented in the FE code to describe the microstructural change and to simulate the dynamic recrystallization, with the consequent formation of new grains. In particular, a procedure utilizing the Zener–Hollomon and Hall–Petch equations is implemented in the user subroutine to predict the evolution of the material grain size and the surface hardness when varying the cutting speeds (180–720 m/min) and tool nose radii (0.4–1.2 mm). All simulations were performed for dry cutting conditions using uncoated carbide tools. The effectiveness of the proposed FE model was demonstrated through its capability to predict grain size evolution and hardness modification from the bulk material to machined surface. The model is validated by comparing the predicted results with those experimentally observed.     

Simulation of retention and transport of copper,lead and zinc in a paddy soil of the Red River Delta,Vietnam

Heavy metal (HM) contaminations in the topsoil around handicraft villages with non-ferrous heavy metal recycling in the Red River Delta can impose serious threats to the subsoil as well as to the groundwater quality. This feature is very important for paddy soils due to relatively high leaching rates and the dissolution of Fe–Mn oxides under reducing conditions which can accelerate the amount of HM translocated to the subsoil and groundwater.The transport of Cu, Pb and Zn in paddy soils was simulated by numerical modeling of non-equilibrium solute transport with an adaptation of the Hydrus-1D model. For the simulation, a water layer on the soil surface was included, from which HM can infiltrate into the soil depending on the soil hydraulic properties. Sorption coefficients, obtained from batch experiments were used as input data for the simulations. Calculated leaching rates were compared with the binding forms of HM in the samples.The simulations show that leaching rates decrease in the order: Zn > Cu > Pb. This order is confirmed by the results of sequential extractions. Under constant flooded conditions at a water table of 20 cm, Cu, Pb and Zn were estimated to reach the soil depth of 1 m within 470, 495 and 370 days, respectively, emphasizing that reactive pollutants can reach groundwater in a relatively short time. A change of the water layer from 1 to 30 cm can accelerate the leaching rate of HM up to 36%. The hard pan layer was observed to induce a hysteresis in hydraulic conductivity and slow down the movement of HM. Uncertainties in modeling arise as several parameters in the simulation can be determined only with significant errors. However, Hydrus-1D is a suitable tool for simulation of the transport of HM in paddy soils.     

Numerical modelling of electrohydraulic free-forming and die-forming of DP590 steel

Electrohydraulic forming (EHF) is a high energy rate forming process in which the strain rate in the sheet metal can vary from 5 × 10² to 10⁵ s⁻¹ depending on various factors. Several mechanisms have been reported to cause an improvement in formability in EHF such as material deformation mechanisms, inertial effects and the dynamic impact of the sheet against the die. EHF is a complex high speed forming process and experimental work alone is not sufficient to properly understand this process. To understand the variation of some influential variables in EHF, electrohydraulic die-forming (EHDF) and free-forming (EHFF) of DP590 dual phase steel were simulated in ABAQUS/Explicit by considering the fluid/structure interactions. Three-dimensional finite element simulations were conducted by modelling the water with Eulerian elements with a view to investigating the effect of released energy on the sheet deformation profile history, strain distribution, loading path and damage accumulation type. The Johnson–Cook constitutive material model was used to predict the sheet behaviour and the parameters in this model were calibrated based on experimental test results available for DP590 at various strain rates. The Johnson–Cook phenomenological damage model was also used to predict the ductile failure (damage accumulation) in both EHDF and EHFF. Predicted final strain values and damage accumulation type showed good agreement with the experimental observations.     

High speed ball nose end milling of hardened AISI A2 tool steel with PCBN and coated carbide tools

High speed machining (HSM) of tool steels in their hardened state is emerging as an attractive approach for the mold and die industry due to its potential for significant cost savings and productivity improvement. An experimental study was conducted to investigate the tool wear mechanism and surface integrity in high speed ball nose end milling of hardened AISI A2 tool steel using coated tungsten carbide and polycrystalline cubic boron nitride (PCBN) tools. It is found that coated carbide tools can only be used at low speed (120 m/min) while high content PCBN tools are suitable for HSM range (470 m/min). PCBN tools produce a damage free workpiece with better surface finish and less work hardening. Despite the higher tool cost, HSM with PCBN tools lead to reduction in both total cost and production time per part.     

Metal-cored arc welding process for joining of modified 9Cr-1Mo (P91) steel

In the present work, metal-cored arc welding process was used for joining of modified 9Cr-1Mo (P91) steel. Metal-cored arc welding process is characterized by high productivity, slag-free process, defect-free weldments that can be produced with ease, and good weldability. Toughness is essential in welds of P91 steel during hydro-testing of vessels. There is a minimum required toughness of 47 J for welds that has to be met as per the EN1557:1997 specification. In the present study, welds were completed using two kinds of shielding gases, each composition being 80% Argon + 20% CO₂, and pure argon respectively. Microstructural characterization and toughness evaluation of welds were done in the as – weld, PWHT at 760 °C – 2 h and PWHT at 760 °C – 5 h conditions. The pure argon shielded welds (‘A2’ and ‘B2’) have higher toughness than 80% argon + 20% CO₂ shielded welds (‘A1’ and ‘B1’). Pure argon shielded welds show less microinclusion content with low volume fraction of δ-ferrite (<2%) phase. Themo-calc windows (TCW) was used for the prediction of equilibrium critical transformation points for the composition of the welds studied. With increase in post-weld heat treatment (PWHT) duration from 2 h to 5 h, there was increase in toughness of welds above 47 J. Using metal-cored arc welding process, it was possible to achieve the required toughness of more than 47 J after PWHT at 760 °C – 2 h in P91 steel welds.     

Modeling residual flood risk behind levees,Upper Mississippi River,USA

Flood protection from levees is a mixed blessing, excluding water from the floodplain but creating higher flood levels (“surcharges”) and promoting “residual risk” of flood damages. This study completed 2D hydrodynamic modeling and flood-damage analyses for the 459 km² Sny Island levee system on the Upper Mississippi River. These levees provide large economic benefits, at least $51.1 million per year in prevented damages, the large majority provided to the agricultural sector and a small subset of low-elevation properties. However these benefits simultaneously translate into a large residual risk of flood damage should levees fail or be overtopped; this risk is not recognized either locally in the study area nor in national policy. In addition, the studied levees caused surcharges averaging 1.2–1.5 m and locally as high as 2.4 m, consistent with other sites and studies. The combined hydraulic and economic modeling here documented that levee-related surcharge + the residual risk of levee overtopping or failure can lead to negative benefits, meaning added long-term flood risk. Up to 31% of residential structures in the study area, 8% of agricultural structures, and 22% of commercial structures received negative benefits, totaling $562,500 per year. Although counterintuitive, structures at the margin of a leveed floodplain can incur negative benefits due to greater flood levels resulting from levees purportedly built to protect them. National levee policies and plans for local projects are unbalanced, crediting levee benefits but rarely fully planning for adverse impacts or considering alternatives.     

Shape calibration of high strength metal sheets by electromagnetic forming

Electromagnetic (EM) forming is an emerging technique that is gaining acceptance for its complementary benefits to conventional metal forming techniques. In this work an innovative application of this impulse forming technique has been demonstrated: the EM shape calibration and correction of springback (sidewall curl) of DP600 and TRIP700 high strength steel (HSS) workpieces. This method has been applied as a second corrective step to previously deep drawn U-channels. The experimental results confirm the sidewall curl angle correction, achieving them with a 22 kJ discharge for DP600 samples and 24 kJ for TRIP700.On the other hand, an uncoupled multiphysical simulation strategy has been carried out in order to virtually validate the EM shape calibration method. The EM fields were simulated by Maxwell 3D and then the Pamstamp code was used to obtain the deformation process.     

Assessing the recycling potential of glass fibre reinforced plastic waste in concrete and cement composites

At present glass fibre reinforced plastic (GRP) waste recycling worldwide is very limited due to its intrinsic thermoset properties, lack of characterisation data and non availability of viable recycling and recovery routes. In the present study, efforts were made to recycle GRP waste powder and fibre in concrete and cement composites and assess its quality to comply with the British standards for use in construction applications. Results revealed that the mean compressive strength of concrete composites using 5%–50% GRP waste powder under water curing varied from 37 N/mm² to 19 N/mm². Increase in the concentration of GRP waste decreased the compressive strength. However, increase in curing duration (14–180 days) resulted in improving the compressive strength of concrete with 5% GRP application to 45.75 N/mm². Moreover, the density of concrete with 50% GRP waste was reduced by about 12% as compared to the control sample. The bending strength in terms of modules of rupture (MOR) of 12 mm thickness cement composites developed using 5% GRP waste fibre attained 16.5 N/mm². The findings of this work pave the way for further GRP waste recycling in precast construction products for use in various applications.     

Exceedance of modern ‘background’ fine-grained sediment delivery to rivers due to current agricultural land use and uptake of water pollution mitigation options across England and Wales

Excessive loss of fine-grained sediment to rivers is widely recognised as a global environmental problem. To address this issue, policy teams and catchment managers require an estimate of the ‘gap’ requiring remediation, as represented by the excess above ‘background’ losses. Accordingly, recent work has estimated the exceedance of modern ‘background’ sediment delivery to rivers at national scale across England and Wales due to (i) current agricultural land cover, cropping and stocking, and (ii) current land use corrected for the uptake of on-farm mitigation measures. This sectoral focus recognises that, nationally, agriculture has been identified as the principal source of fine sediment loss to the aquatic environment. Two estimates of modern ‘background’ sediment loss, based on paleolimnological evidence, were used in the analysis; the target modern ‘background’ (TMBSDR) and maximum modern ‘background’ (MMBSDR) sediment delivery to rivers. For individual (n = 4485) non-coastal water bodies, the sediment ‘gap’ in excess of TMBSDR and MMBSDR, due to current land cover, cropping and stocking, was estimated to range up to 1368 kg ha⁻¹ yr⁻¹ (median 61 kg ha⁻¹ yr⁻¹) and 1321 kg ha⁻¹ yr⁻¹ (median 19 kg ha⁻¹ yr⁻¹), respectively. The respective ranges in conjunction with current land cover, cropping and stocking but corrected for the potential impact of on-farm sediment mitigation measures were up to 1315 kg ha⁻¹ yr⁻¹ (median 50 kg ha⁻¹ yr⁻¹) and 1269 kg ha⁻¹ yr⁻¹ (median 8 kg ha⁻¹ yr⁻¹). Multiplication of the estimates of excess sediment loss corrected for current measure uptake, above TMBSDR and MMBSDR, with estimated maximum unit damage costs for the detrimental impacts of sediment pollution on ecosystem goods and services, suggested respective water body ranges up to 495 £ ha⁻¹ yr⁻¹ and 478 £ ha⁻¹ yr⁻¹. Nationally, the total loss of sediment in excess of TMBSDR was estimated at 1,389,818 t yr⁻¹ equating to maximum environmental damage costs of £523 M yr⁻¹, due to current structural land use, compared to 1,225,440 t yr⁻¹ equating to maximum damage costs of £462 M yr⁻¹ due the uptake of on-farm sediment control measures. The corresponding total loss of sediment in excess of MMBSDR was estimated at 1,038,764 t yr⁻¹ equating to maximum damage costs of £462 M yr⁻¹, compared with 890,146 t yr⁻¹ and £335 M yr⁻¹ correcting excess agricultural sediment loss for current implementation of abatement measures supported by policy instruments. This work suggests that the current uptake of sediment control measures on farms across England and Wales is delivering limited benefits in terms of reducing loadings to rivers and associated environmental damage costs.     

Model-Based Design of Motorized Spindle Systems to Improve Dynamic Performance at High Speeds

High-speed motorized spindle systems are subjected to several effects during high-speed rotations that can cause substantial changes in their dynamic and thermal behaviors, leading to chatter, bearing thermal seizure, or premature spindle bearing failures. Therefore, it is important to consider these high-speed effects in the design stage of high-speed motorized spindles. This paper first develops a design flow chart to represent the overall spindle design problems. Based on this flow chart, eight design parameters are identified. A design sensitivity analysis of these eight design parameters is then conducted based on an integrated finite element method model to investigate their influence on the natural frequencies of the spindle system. Based on the rule of Maximum Improvement First, a set of systematic design procedures is proposed to suggest design changes to a custom-designed motorized spindle rated at 32 kW and 25,000 rpm. Based on the simulation results, it is shown that the first-mode frequency of this spindle system can be improved from 790.7 Hz to 934 Hz at 25,000 rpm by simply adjusting the front and rear bearing locations. At the optimal design, the first-mode frequency can reach 1454.3 Hz at 25,000 rpm, which represents more than 80 percent improvement over the original design.     

Soil C storage as affected by tillage and straw management: An assessment using field measurements and model predictions

Soil tillage and straw management are both known to affect soil organic matter dynamics. However, it is still unclear whether, or how, these two practices interact to affect soil C storage, and data from long term studies are scarce. Soil C models may help to overcome some of these problems. Here we compare direct measurements of soil C contents from a 9 year old tillage experiment to predictions made by RothC and a cohort model. Soil samples were collected from plots in an Irish winter wheat field that were exposed to either conventional (CT) or shallow non-inversion tillage (RT). Crop residue was removed from half of the RT and CT plots after harvest, allowing us to test for interactive effects between tillage practices and straw management. Within the 0–30 cm layer, soil C contents were significantly increased both by straw retention and by RT. Tillage and straw management did not interact to determine the total amount of soil C in this layer. The highest average soil C contents (68.9 ± 2.8 Mg C ha^?1) were found for the combination of RT with straw incorporation, whereas the lowest average soil C contents (57.3 ± 2.3 Mg C ha^?1) were found for CT with straw removal. We found no significant treatment effects on soil C contents at lower depths. Both models suggest that at our site, RT stimulates soil C storage largely by decreasing the decomposition of old soil C. Extrapolating our findings to the rest of Ireland, we estimate that RT will lead to C mitigation ranging from 0.18 to 1.0 Mg C ha^?1 y^?1 relative to CT, with the mitigation rate depending on the initial SOC level. However, on-farm assessments are still needed to determine whether RT management practices can be adopted under Irish conditions without detrimental effects on crop yield.     

Probing system for measurement of micro-scale components

The need for quality control of the complex micro-structure has been growing due to increased production of parts with complex 3D micro-scale features. However, wide use of 3D metrology of miniature parts is difficult due to the lack of cost-effective and precise probing system at the micro-scale. This paper introduces a new probing system using a wire-based probe and acoustic emission (AE)-based sensing method. The design of the probing system allows the size of the probe to be varied relatively easily. Repeatability of less than 1 μm has been achieved with the proposed probing system.     

Effect of Silicon Powder Mixed EDM on Machining Rate of AISI D2 Die Steel

In this paper, the effect of silicon powder mixing into the dielectric fluid of EDM on machining characteristics of AISI D2 (a variant of high carbon high chrome) die steel has been studied. Six process parameters, namely peak current, pulse-on time, pulse-off time, concentration of powder, gain, and nozzle flushing have been considered. The process performance is measured in terms of machining rate (MR). The research outcome will identify the important parameters and their effect on MR of AISI D2 in the presence of suspended silicon powder in a kerosene dielectric of EDM. The study indicated that all the selected parameters except nozzle flushing have a significant effect on the mean and variation in MR (S/N ratio). Optimization to maximize MR has also been undertaken using the Taguchi method. The ANOVA analysis indicates that the percentage contribution of peak current and powder concentration toward MR is maximum among all the parameters. The confirmation runs showed that the setting of peak current at a high level (16 A), pulse-on time at a medium level (100 μs), pulse-off time at a low level (15 μs), powder concentration at a high level (4 g/l), and gain at a low level (0.83 mm/s) produced optimum MR from AISI D2 surfaces when machined by silicon powder mixed EDM.     

Changes in soil fertility parameters and the environmental effects in a rapidly developing region of China

An extensive knowledge of the temporal variability of soil fertility parameters and how this variation affects the environment is imperative to a wide range of disciplines within agricultural science for optimal crop production and ecosystem preservation. This paper examines the temporal variability of soil pH, organic matter (OM), cation exchange capacity (CEC), total nitrogen (TN), total phosphorus (TP), available phosphorus (P_Av), and available potassium (K_Av) on Cambosols (Entisols) (n = 179) and Anthrosols (Inceptisols) (n = 95) in Zhangjiagang County, China from 1980 to 2004. Nutrient input was monitored from 1983 to 2004. Annual N fertilizer rates were significantly different during three periods (1983–1989, 1989–1999, 1999–2004), where annual rates increased significantly after 1989 and then decreased after 1999. Annual P fertilizer rates were significantly different during two periods (1983–1993, 1993–2004) where annual rates increased after 1993. No change was found in K fertilizer rates. Soil pH marginally increased by 0.14 units in Cambosols, but significantly decreased by 1.02 units in Anthrosols. OM, CEC, and TN increased in both soil orders an average of 2.15 g kg^?1, 1.6 cmol kg^?1, and 0.21 g kg^?1, respectively. TP decreased in Anthrosols by 70 mg kg^?1, P_Av increased in Cambosols by 4.83 mg kg^?1, and K_Av decreased in Cambosols by 15 mg kg^?1. Fertilizer input rates are causing nutrient imbalances, contributing to acidification in Anthrosols, and decreasing C/N ratios. Nutrient loading of N and deficiency of K is also a potential problem in the area. Efforts should be made to readjust soil nutrient inputs to reach an optimal, sustainable level.     

Irrigation of olive groves in Southern Italy with treated municipal wastewater: Effects on microbiological quality of soil and fruits

The use of municipal wastewater in agriculture requires a careful monitoring of a range of hygiene parameters. Yearly hygienic impact assessments on soil and fruit were made between 2000 and 2006 in an olive (Olea europaea L.) grove established near a municipal wastewater treatment plant in Southern Italy (Ferrandina–Basilicata region, 40°29′ N, 16°28′ E). The experimental grove was managed in two plots. The first plot, non-tilled, was drip irrigated daily with reclaimed wastewater. The second plot was unirrigated (i.e. rainfed) and subject to conventional management for the region. Samples of wetted soil from different depths and of treated wastewater were analysed for Escherichia coli, enterococci, sulphite-reducing Clostridium spores and Salmonella spp. Fruits were collected both from the canopy and from nets spread on the ground and analysed for faecal contamination. The average annual quantity of wastewater distributed was 293 mm. E. coli concentration in the wastewater varied considerably, being frequently above the stringent Italian mandatory limit of 10 CFU 100 mL^?1 and also the WHO limit of 1000 MPN 100 mL^?1. Salmonella was never detected in the wastewater, the soil or on the fruit samples. Slight increases in the other bacteria were observed in the wastewater-irrigated soil during the irrigation season and especially in the top 10 cm. Soil resilience and bacterial mortality/inactivation probably explains the seasonal decrease of soil bacteria content over the 7 years of the study. Because of their high resistance to disinfection treatments and to environmental conditions, the spores of the sulphite-reducing bacterium Clostridium could be useful as an indicator of contamination in future guidelines that might be enacted for the use of wastewater in agriculture. No significant microbial contamination was recorded on fruit harvested directly from the canopy of the wastewater-irrigated trees. Contaminations on fruits sampled from the ground in the wastewater-irrigated plot were always low and usually similar to, or lower than those observed on drupes collected from the rainfed plot. In the rainfed plot, the recorded occasional contaminations were probably due to a number of factors, such as grazing of farm stock, presence of wild animals and surface water runoff from adjacent agricultural areas. This work confirms that, under suitable conditions, low-quality wastewater can be useful as an additional water resource for olive irrigation in water-scarce Mediterranean environments.     

Simultaneous removal of arsenic and antimony from mining wastewater using granular TiO2: Batch and field column studies

Coexisting arsenic (As) and antimony (Sb) in mining wastewater is a common and great concern. On-site simultaneous removal of As and Sb from mining wastewater was achieved by using a reusable granular TiO₂ column in this study. To evaluate the accuracy of the scale-up procedure, As and Sb adsorption from wastewater was studied in both large (600 g TiO₂) and small columns (12 g TiO₂) based on the proportional diffusivity rapid small-scale column tests (PD-RSSCTs) design. The comparable As and Sb breakthrough curves obtained from small and large columns confirmed the accuracy of the PD-RSSCT theory in the design of large-scale columns. Meanwhile, the consistent As and Sb adsorption results from batch and column experiments suggested that TiO₂ adsorption for As and Sb can be predicted from bench-scale tests. Charge distribution multi-site complexation (CD-MUSIC) and one-dimensional transport modeling integrated in the PHREEQC program were performed to study the adsorption behaviors of As and Sb on the TiO₂ surface. Coexisting ions, such as Ca^2 +, Mg^2 +, and Si^4 +, play an important role in As and Sb adsorption, and the breakthrough curves were well simulated after considering the compound ion effects. The results from this study highlight the surface reactions of As and Sb on TiO₂ and provide a practical way for on-site remediation of industrial wastewater.     

Are soils of Iowa USA currently a carbon sink or source? Simulated changes in SOC stock from 1972 to 2007

Upscaling the spatial and temporal changes in carbon (C) stocks and fluxes from sites to regions is a critical and challenging step toward improving our understanding of the dynamics of C sources and sinks over large areas. This study simulated soil organic C (SOC) dynamics within 0–100 cm depth of soils across the state of Iowa in the USA from 1972 to 2007 using the General Ensemble biogeochemical Modeling System (GEMS). The model outputs with variation coefficient were analyzed and assembled from simulation unit to the state scale based upon major land use types at annual step. Results from this study indicate that soils (within a depth of 0–100 cm) in Iowa had been a SOC source at a rate of 190 ± 380 kg C ha^?1 yr^?1. This was likely caused by the installation of a massive drainage system which led to the release of SOC from deep soil layers previously protected under poor drainage conditions. The annual crop rotation was another major force driving SOC variation and resulted in spatial variability of annual budgets in all croplands. Annual rate of change of SOC stocks in all land types depended significantly on the baseline SOC levels; soils with higher SOC levels tended to be C sources, and those with lower levels tended to be C sinks. Management practices (e.g., conservation tillage and residue management practices) slowed down the C emissions from Iowa soils, but could not reverse the general trend of net SOC loss in view of the entire state due mainly to a high level of baseline SOC stocks.     

On wear resistance of tool steel

Maintaining a reasonably low cutting tool wear when producing forming tools is a general challenge in the development of new forming tool materials. The tool life of a hot forming tool steel (H13) has been significantly improved by reducing its Si-content from 1.0 to 0.06 wt.%. However, this modified H13 (MH13) also displays a reduced cutting tool life due to higher cutting forces and a stronger tendency to form built up layers (BUE) on the cutting edge. This paper explains why.Gleeble tests of MH13 revealed a significantly higher flow stress in the 820–900 °C temperature interval in MH13 compared to H13. Thermo-Calc simulations showed that when reducing the Si-content from 1.0 to 0.06 wt.% the initial temperature for ferrite-to-austenite transformation (A1) was reduced from 900 °C to 820 °C. Knowing that austenite has totally different mechanical and thermal properties than ferrite, the difference in A1 between the two steels explains the higher cutting forces and higher tendency for BUE-formation. The conclusion is that the difference in machinability between H13 and MH13 is primarily related to their difference in A1.An attempt was also made to find a new tool material composition that can combine the wear resistance of MH13 and the good machinability of H13. Thermo-Calc simulations were performed with slightly modified alloying content without changing its properties as a good forming tool material, with the aim to increase A1. For instance, reducing the Mn content from 0.5 to 0.05 wt.% proved to increase A1 from 820 to 850 °C.     

Comparison of absorption rates and absorption capacity of ammonia solvents with MEA and MDEA aqueous blends for CO2 capture

In this work we present the experimental results of absorption rates and absorption capacity for the CO₂ absorption by ammonia (NH₃) aqueous solutions. Experiments are carried out in a thermoregulated Lewis-type cell reactor and are achieved in temperature and concentration ranges of 278–303 K and 2–5wt.% NH₃ respectively. The obtained values for absorption kinetic rates and absorption capacity are compared with those available for alkanolamine solvents, commonly used to absorb CO₂. In order to achieve this comparison, data available in studies about alkanolamine solvents at 303–333 K and 5–50wt.% for alkanolamines solutions were considered. Results show that CO₂ absorption by NH₃ is faster than the one carried out by MDEA, except for 2wt.% NH₃ at 288 K. At 278 K and using aqueous solutions of 3wt.% NH₃, the absorption rate is almost identical to the one reached with MDEA solvent. The highest absorption capacity, also compared with alkanolamine solution, is reached with aqueous solutions of 5wt.% NH₃ at 278 K and 303 K.     

Micro-flood (MF) technology for sustainable manufacturing operations that are coolant less and occupationally friendly

This paper presents a new technology for minimizing the use of metalworking fluids (MWFs) during the machining process that is atomization-less and occupational friendly. Micro-flood (MF) technology utilizes direct contact between the cutting tool and the MWF without the interaction of a gas medium. Experiments were conducted in high volume mass production environment turning HSLA (high strength low alloy) SAE 070Y steel. Machining performance and total air mass particulates were investigated in dry machining, Near dry machining (NDM) via atomized spray mist and MF technology. Open-atmosphere air monitoring indicated that total mass particulates behaved in an almost linear fashion with respect to gas atomization pressure, whereas the MWF flow rate demonstrated logarithmic trends in NDM applications using an atomized spray. Nozzle orientations directed upward into the air also produced higher mg/m³ concentrations (such as flank) than chip and rake face orientations that were directed down. Greater separation existed at higher gas atomization pressures, MWF flow rates and by changing the MWF type. At extreme limits, nozzle orientation affected mg/m³ concentration as much as 4–5 mg/m³ for water-miscible MWFs and 15–22 mg/m³ for non-water-miscible MWFs. Tool-life performance varied greatly among MWF type and flow rate, and in all cases MF technology performed better than NDM using an atomized spray mist. Direct and consistent MWF penetration to cutting zone using MF technology lowered tool-wear on the average of 12–75% compared to NDM at the same MWF flow rate. Compared to dry machining, NDM improved tool-wear on the average by 20–243%. In one case, tool-wear performance was improved by 616% at 0.15 mm using MF technology compared to dry machining at a nominal 0.925 mm tool-wear. Overall, a large mass reduction of particulates can be achieved employing MF technology that would have been unrealistic for an open-atmosphere machining environment employing an atomized spray mist. On the average, MF technology can maintain a total air mass particulate of less than 0.4 mg/m³ in the occupational work zone using MWF flow rates up to 1260 ml/h, regardless of the MWF classification. Atomized spray mist applications are capable meeting the 5 mg/m³ OSHA limit if MWF flow rates are less than 160 ml/h, air pressures are less than 0.137 MPa (20 psi) using water-miscible MWFs and air pressures are less than 0.0344 MPa (5 psi) using non-water-miscible MWFs.