Deterioration Of Surface Quality Research Articles

Study on energy input and its influences on single-track,multi-track, and multi-layer in SLM

Energy input is crucial in the manufacturing of high-density metal part with smooth surface. In this article, the authors had studied the single-track, multi-track, and multi-layer and had obtained four types of typical tracks, including regular and thick shape, regular and thin shape, regular but occasionally broken shape, irregular and pre-balling shape. The analysis of single- and multi-track experiments showed that the regular and thin shape was the most suitable for selective laser melting (SLM) fabrication. Multi-track experiments proved that dense and smooth surface can be obtained when the overlapping rate was around 30% based on the regular- and thin-shaped track. As a result of the heat accumulation effect during multi-track and multi-layer fabrication, it was possible to obtain ideal track type with less energy input. In multi-layer experiment, the gradually thicken layer was the reason for the surface quality deterioration. The inter-layer stagger scanning strategy, which can improve the quality of the end-use part, was used in this experiment. By testing the 316 L stainless steel samples fabricated by the SLM process, the microstructure can be identified as composed of fine equiaxed and columnar grains, and the samples had higher tensile strength and hardness than castings of the same material, but with lower elongation. The experiments had proved that SLM process can directly produce high dense 316 L stainless steel part with smooth surface.

工具姿勢と姿勢変化の影響を考慮した５軸制御ＣＡＭシステムの開発

5-axis control machining can realize high performance machining by considering the relative attitude between a tool and a workpiece. Thus, it enables to avoid the abnormal tool wear and the deterioration of machined surface quality. The influence that the tool attitude gives the machined surface has been investigated by some researchers, and the tool attitude to obtain good surface quality has been already proposed in previous studies. On the other hand, the tool attitude in 5-axis control machining cannot but change inevitably with the rotational axis motion, while keeping the relative attitude constant. The influence of not only the tool attitude to the machined surface but also the variation in tool attitude should be evaluated to obtain good surface quality, based on 5-axis control machining experiments. The study deals with the proposal of an evaluation formula by considering the influence of both the tool attitude and the variation in tool attitude. It is experimentally recognized that the devised CAM system can generate appropriate 5-axis control tool paths for finish machining by utilizing the evaluation formula.

Non-Contact Guide for Traveling Continuous Steel Plates in Loop Shaping Part Using Electromagnetic Force

In the factory, the continuous steel plates subjected to iron and steel processes are supported by a series of rollers during processes such as rolling. However, because roller comes in contact with the steel plates, the problem of surface quality deterioration arises. To solve this problem, we develop a non-contact guide for parts of the steel plate at which its traveling direction changes in high-speed traveling by applying an electromagnetic force from the direction of the edge of the steel plate, and experimentally examine the effectiveness of the system. Moreover, when the position of the plate is controlled, it is extremely difficult to determine the mass of the control target. We confirm the suppressive effect of a sliding mode control theory that has robustness in mass variation. The results indicate that the proposed system can be achieved.

Advances in the turning process for productivity improvement — a review

Increasing productivity and reducing manufacturing cost have always been keys to successful business. In machining, higher values of cutting parameters offer opportunities for increasing productivity, but this also involves greater risk of deterioration in surface quality and tool life. During the past decade significant advances have been made in the development of cutting tool materials for machining of ‘difficult-to-cut’ materials. The cost involved in the production of new turning tools is very high. To overcome this cost factor researchers have tried to bring about modifications in the turning process using existing tool materials. A good understanding of the cutting conditions, temperature generation, failure modes, and cutting forces leads to efficient control of the turning process. The literature reveals that modifications in the tool geometry (such as grooved/restricted contact tools (RCTs) and chamfered/honed edges), applications of cooling techniques, ultrasonic assisted turning (UAT), hot machining, and cryogenic treatment of inserts have led to efficient and economic machining of modern materials used for aerospace, steam turbine, bearing industry, nuclear, and automotive applications. This paper presents a review of the different techniques involved in turning which can supplement the performance of cutting tools for improved economics, good surface finish, and surface integrity during machining of the latest materials.

Tool Path Generation for Five-Axis Controlled Machining with Consideration of Movable Range of Machine Tool and Tool Attitude Change

A lot of techniques of tool path generation for 5-axis controlled machining that consider tool interference are already proposed. However, those methods have outputted impossible tool path for machine tool, because movable range of driving axes of machine tool is not considered. Moreover, discontinuous tool path threatens to cause deterioration of surface quality. This study has been aiming to generate the tool path considering movable range of machine tool and continuity of tool attitude change. We have already proposed the original 2-dimensional configuration space that indicates possible tool attitude at each cutting point. The method proposed in this report searches the shortest tool path using 3-dimensional configuration space that corresponds to available tool attitudes with consideration of tool interference and movable range of machine tool. As a result, usefulness of the devised method was experimentally confirmed.

Non-Contact Guide for Traveling Continuous Steel Plates in Loop Shaping Part Using Electromagnetic Force (1st Report, Fundamental Experiments on Positioning Performance)

In the factory, the continuous steel plates subjected to iron and steel processes are supported by a series of rollers during processes such as rolling. However, because roller comes in contact with the steel plates, the problem of surface quality deterioration arises. To solve this problem, we develop a non-contact guide for parts of the steel plate at which its traveling direction changes in high-speed traveling by applying an electromagnetic force from the direction of the edge of the steel plate, and experimentally examine the effectiveness of the system. Moreover, when the position of the plate is controlled, it is extremely difficult to determine the mass of the control target. We confirm the suppressive effect of a sliding mode control theory that has robustness in mass variation. The results indicate that the proposed system can be achieved.

Assessment and prediction of contaminant migration in ground water from chromite waste dump

Sukinda chromite valley is one of the largest chromite deposits of the country and produces nearly 8% of chromite ore. It greatly contributes towards the economic development but at the same time deteriorates the natural environment. It is generally excavated by opencast mining method. In the Sukinda mining area, around 7.6 million tons of solid waste have been generated in the form of rejected minerals, overburden material/waste rock and sub-grade ore that may be resulting in environmental degradation, mainly causing lowering in the water table vis-a-vis deterioration in surface and ground water quality. The study conducted in and around one of the chromite mine of the valley reveals that the concentration of hexavalent chromium is found in the water samples of ground and surface water, mine effluents and seepage water. Hexavalent Chromium (Cr+6) have been found varying between 0.02 mg/l and 0.12 mg/l in mine effluents and 0.03–0.8 mg/l in shallow hand pumps and 0.05 and 1.22 mg/l in quarry seepage. The concentration of Cr+6 in Damsal nalah, the main surface water source in the area, is found varying between 0.03 mg/l and 0.14 mg/l and a increasing trend, which is in the downstream of mining activities, has been observed. Leachate study clearly shows that the soil lying in the vicinity of mine waste dump shows highest concentration of Cr+6. Contaminant migration in ground water depends upon various geohydrological conditions of the area. The study shows that aquifer resistivity varies between 15 Ωm to 150 Ωm and aquifer depth varies from 4 m to 26 m below ground level. The ground water flow and mass transport models were constructed with the help of geo-hydrological and geophysical informations using Visual Modflow software. Contaminant migration and path lines for 20 years have been predicted in two layers model of ground water. The study provided an insight into the likely migration of contaminant in ground water due to leaching from overburden dump of chromite ore and will be helpful in making strategic planning for limiting the contaminant migration in the ground water regime in and around the mining areas.

Effect of coolant strategy on tool performance, chip morphology and surface quality during high-speed machining of A356 aluminum alloy

This paper describes the results of application of different coolant strategies to high-speed milling of aluminum alloy A356 for automotive industry. The paper investigates the effect of flood coolant, dry cutting, and minimum quantity of lubricant (MQL) technologies on tool wear, surface roughness and cutting forces. The cutting speed range was up to 5225 m/min. The feed rate used was up to 20 m/min. The result of MQL application is compared with dry milling and milling with flood coolant application. It was found that the MQL technology could be a viable alternative to the flood coolant application. The adhesive tool wear mechanism and adhesion activated surface quality deterioration are revealed and the role of lubricant in their reduction is defined.

724 6-Axis Ultrasonic Vibrational Cutting Using Bore Byte Tools

Usually a character line specifically on die and mold can only be done by electrical discharge machining (EDM) in finishing stages, but such process requires two or more setups resulting to have an effect on the accuracy by obtaining setup error, and also lengthening the machining time, thereby causing the cost of the product to increase. The aim of this study is to utilize the 6-axis controlled cutting using bore byte tool with the application of ultrasonic vibration. Experimental results have shown that the sharp character line and grooves can be machined in just one setup by 6-axis controlled machine using bore byte tool. However, this process causes the deterioration of surface quality so that with the application of ultrasonic vibration, the surface quality of the product is improved especially in the machining of malleable or soft material, and the burrs are also eliminated. This proves the potential of 6-axis controlled cutting using bore byte tool with the application of ultrasonic vibration in producing a good quality die and mold product.

Environmental impact assessment on water quality deterioration caused by the decreased Ganges outflow and saline water intrusion in south-western Bangladesh

This paper deals with an environmental impact assessment of low water flow in the river Ganges during a dry period at the Khulna and Mongla port areas in south-western Bangladesh. Large-scale surface water withdrawal in India after commissioning the Farakka Barrage causes a drastic fall in the Ganges low-flow condition within the Bangladesh territory during every dry period. The average lowest discharge in the Ganges is 552 m3/s, which is about 73% less than that in the pre-Farakka time. This has caused the deterioration of both surface and groundwater quality of the study area. Salinity is the principal cause of water quality degradation in the area. Present observation shows that the surface water of the area is sulphate-chloride dominated, which signifies high salinity whereas the groundwater is categorized as of medium to high salinity. To maintain the Rupsa River's maximum salinity below 1000 μS/cm the discharge in the Ganges should be ∼1500 m3/s, whereas that at Garai basin is ∼10 m3/s. If this present situation continues it will be a crippling blow to the environment of the area in the long term. An integrated multidisciplinary approach to hydrogeological research is urgently required to salvage the area from further deterioration.

Influences of strain rate and grain size on yield and serrated flow in commercial Al-Mg alloy 5086

The deterioration in surface quality due to the formation of Lüders lines is a typical phenomenon in 5xxx series Al–Mg alloys. Traditional efforts show that an increase of the grain size results in the suppression of the Lüders elongation. This paper presents that the suppression of the Lüders elongation can be realized at a smaller grain size by the addition of Zn/Cu elements in the 5xxx series alloys and by pre-aging treatment. The alloys with (Zn + Cu)/Mg ratios below 1.0 result in an increase of the strength by the precipitation of T-Mg32(AlZnCu)49 phase, and quite different from 7xxx series Al–Zn–Mg alloys strengthened by η-MgZn2 precipitates. The decisive measurement for suppressing Lüders elongation is based on the depletion of Mg atom concentrations in the matrix due to the formation of GP zones after pre-aging treatment.

工具切れ刃断面変化を利用した６軸制御曲面平滑仕上げ

6-Axis control machining by use of non-rotational cutting tools offers a variety of machining possibilities in combination with the conventional machining by use of rotational cutting tools. The study deals with sculptured surface finishing as one of typical 6-axis control machining applications, where a non-rotational cutting tool is fed along sculptured surfaces to finish a workpiece with the cusp height as low as possible. The machining by use of ball end mills often requires the tool change to adapt their cutting edge radius to a surface curvature of workpieces to be machined, which leads to the deterioration of surface quality. To carry out the surface finishing without tool change, a new concept is proposed that a cutting edge radius of non-rotational cutting tool is virtually varied by changing the cross-sectional configuration of cutting edge through the rotation and inclination around the tool axis. The method is put into the main processor to generate CL data. From experimental results, the method is found to be valid in finishing sculptured surfaces with a kind of non-rotational tools to some extent.

Characterization of ultraviolet excited Br*-radical etching of InGaAs/InAlAs material system

Dry selective photochemical etching of InGaAs/InAlAs material system, in HBr gas excited by a 172 nm excimer lamp, has been characterized. The etching is thought to be due to the formation of reactive Br*-radicals which are photocreated in the gas phase and then diffused into the solid semiconductor to create volatile products. The etching is temperature sensitive with best etching results at 50–110° C. Atomic force microscope and scanning electron microscope pictures reveal that the surface morphology at this temperature range is smooth and fine. Auger electron spectroscopy and x-ray photoelectron spectroscopy measurements show that at low temperatures the etch products are primarily salts of bromide and are in the liquid phase and thus remain at the surface and a desorption process stops further etching. At slightly elevated temperature range, the creation of oxides and deposition of bromine compounds reduces the etch rate and causes the surface quality to deteriorate. Etching at higher pressure range increases the etch rate of InGaAs but results in surface quality deterioration.

Ag+-Na+ exchanged waveguides from molten salts in a chemically durable phosphate glass

The authors report that Ag/sup +/-Na/sup +/ ion exchange has been performed for the first time from molten salt baths in a chemically durable phosphate glass. Characterisation of planar waveguides, fabricated at different temperatures, diffusion times and with varying melt concentrations, indicates large diffusion coefficients and higher index changes with no deterioration of surface quality.

Formability in the continuous casting-direct rolling process for high-Mn steels

The present study is concerned with an industrial problem related to transverse cracks in high-Mn steel slabs. To meet the strength requirement for the thick plate used in the construction of oil platforms, it has been necessary to add small amounts of the alloying elements Cu, Ni and Cr. Economically, the addition of Cu is favoured, but it leads to a deterioration in surface quality and an increase in the number of slabs affected by transverse cracking. The major objective of the present work is to investigate the formability limits of high-Mn steel, MnCu steel and MnCuNi steel, under thermomechanical conditions typical of the continuous casting-direct rolling process to reduce transverse cracks in steel slabs. The addition of Cu is found to decrease the formability limits of the high-Mn steel by increasing the amount of precipitation of sulphide particles and voids, resulting in intergranular cracks. The MnCuNi steel seems to have a higher formability limit than the high-Mn and MnCu steels. The addition of Ni to MnCu steel decreases the amount of precipitation of sulphide particles in the ferritic film, as evidenced by the increase in the number and size of dimples on the fracture surface.

Cross-sectional scanning tunneling microscopy of doped and undoped AlGaAs/GaAs heterostructures

Scanning tunneling microscopy (STM) was used to study the (NH4)2S-passivated (110) cross-sectional surfaces of both doped and undoped Al0.3Ga0.7As/GaAs heterostructures on n+-substrates. The ex situ (NH4)2S treatment of the cross-sectional surfaces of heterostructures was found to be very stable against oxidation. STM images showed no appreciable deterioration of surface quality in vacuum after more than 40 days. The spectroscopic results on the undoped epilayer showed diodelike behavior, confirming that an undoped large band gap region can be imaged by STM through carrier injection from the conductive regions.

Environmental consequences of land degradation in coastal drainage basins of north Queensland, Australia: Influence of farming practices

AbstractViews expressed by sugar cane farmers in the Johnstone Rivers system, north Queensland, are consistent with the broader community concern about the potentially adverse ecological effects of point source discharges to the Great Barrier Reef lagoon. the main link between agricultural land use and the deterioration of surface and groundwater quality in the region is perceived by the farmers to be a consequence of the influence exerted by new farm management strategies and economic constraints on local environmental variables, particularly soils. the effectiveness of the land use practices in relation to land capability and productivity thresholds is considered by farmers to be essential for developing new farm management strategies and for improving water quality in the north Queensland coastal regions. as a result of increasing inhomogeneity of land use practices involving the application of chemicals, catchment based investigation, including systematic interviews with the land users, is needed for the development of reliable databases on problems related to the discharge of agricultural chemicals to coastal waters.

Measurements Concerning the Influence of Surface Roughness and Profile Changes on the Performance of Gas Turbines

During operation the blading of turbines undergoes certain changes. Corrosion, erosion, and contamination cause deterioration of the surface quality and blade profile changes. As a result, the performance characteristics of the turbine, especially the efficiency, change during operation. Through measurements on a four-stage air turbine with artificially roughened blade surfaces and thinned and thickened profiles which simulate the effects of corrosion and pollution respectively, it has been possible to ascertain the influence of these profile changes on the flow conditions in the turbine. This paper shows the measuring results which are representative of the effects of surface roughness and profile changes.

Laser beam machining

30CrMnSiA high strength low alloy (HSLA) carbon structural steel is typically applied in equipment manufacturing and aerospace industries. In this work, the effects of continuous electron beam treatment on the surface hardening and microstructure modifications of 30CrMnSiA are investigated experimentally via a multi-purpose electron beam machine Pro-beam system. Micro hardness value in the electron beam treated area shows a double to triple increase, from 208 HV0.2 on the base metal to 520 HV0.2 on the irradiated area, while the surface roughness is relatively unchanged. Surface hardening parameters and mechanisms are clarified by investigation of the microstructural modification and the phase transformation both pre and post irradiation. The base metal is composed of ferrite and troostite. After continuous electron beam irradiation, the micro structure of the electron beam hardened area is composed of acicular lower bainite, feathered upper bainite and part of lath martensite. The optimal input energy density for 30CrMnSiA steel in this study is of 2.5 kJ/cm2 to attain the proper hardened depth and peak hardness without the surface quality deterioration. When the input irradiation energy exceeds 2.5 kJ/cm2 the convective mixing of the melted zone will become dominant. In the area with convective mixing, the cooling rate is relatively lower, thus the micro hardness is lower. The surface quality will deteriorate. Chemical composition and surface roughness pre and post electron beam treatment are also compared. The technology discussed give a picture of the potential of electron beam surface treatment for improving service life and reliability of the 30CrMnSiA steel.