Close Tolerances Research Articles

Film mulched furrow-ridge water harvesting planting improves agronomic productivity and water use efficiency in Rainfed Areas

Film fully-mulched ridge–furrow (FMRF) water harvesting, film mulched conventional flat planting with one-half (FMCF) and two-thirds (FTMCF) has been widely adopted in Northern China. However, it is unclear whether sustainability are. An 8-year corn yield in these three systems was investigated at Zhenyuan of East Gansu in 2008 to 2015, and a 4-year location study with FMRF and FMCF, three corn hybrids, and three densities was conducted at Pengyang of South Ningxia from 2012 to 2015. The results indicated that FMRF with rain-harvesting efficiency of 65.7%–82.7% makes rainwater infiltrate deep soil and soil moisture double increase in furrow root-zone. The 8-year average grain yield increased by 22.7% in FMRF and 14.5% in FTMCF compared with FMCF. In the 4-year field trail, rainfall and its seasonal distribution highly impacted grain yield and water-use efficiency (WUE), but order of importance for grain yield and WUE increases were density > mulching type > hybrid. Grain yield and WUE increased by 20.0% and 3.45 kg ha−1 mm−1 and 12.0% and 2.97 kg ha-1 mm−1 from low to medium density and medium to high density; ET and grain yield and WUE increased simultaneously from low to medium density, however grain yield and WUE improved but ET changed slightly from medium to high. Soil water content of the 0–200 cm layer during growing season was always higher in FMRF than in FMCF, and ET did not differ. FMRF kept more than 50–90 mm soil water in the 0–200 cm during grain filling period. Neither higher grain yield in the FMRF depleted soil water, nor resulted in soil desiccation regardless of the year of precipitation. On the contrary, the FMRF kept much more water into soil layers at corn harvest, and negative effects to soil water balance were not observed. Thus, the package of FMRF combining with close planting and density tolerance hybrids is climate-smart technique for coping with droughts and ensuring corn yield in rainfed areas.

Machinability Assessment of Inconel 800HT and its prediction using a hybrid fuzzy controller in EDM

Abstract In the pursuit of the establishment of the fact that the traditional machining techniques are shying away to meet the challenges posed by the demand for precise and economic machining of ultra-hard and high strength materials to close tolerances which in turn has resulted in the development of several unconventional machining systems. Of all such newer machining methods, EDM (Electrical Discharge Machining) is one of the most versatile and universally acceptable techniques being used extensively for electrically conductive materials. The present work investigates the management and quantification of Surface Roughness and MRR of Inconel 800HT when machined with copper electrode on EDM. The surface roughness of the alloy was measured by using Talysurf and Material removal rate is figured out as the extent of the change of weight of the work piece prior and afterward machining. The current, flushing pressure and pulse-on-time were taken as process parameters. Later anova analysis was carried out to analyze the effect of these variables. It was found that current and Pulse-on-time were the most influencing factors which affect the surface roughness most while in case of MRR the most influential factor is current.

An Experimental Study of Grinding Performances of a Mild Steel under Different Environmental Conditions using Various Types of Nozzles

Grinding is a mechanical metal removal process used in manufacturing industries. In this process, the material is removed from a work-piece material by an abrasive wheel. This process gives better surface finish and close tolerance. Grinding process removes material by shearing, ploughing, rubbing and brittle fracture with high- speed and a high input of energy per unit volume. The coolant or grinding fluid is used to reduce the temperature in grinding zone and also it is used as a lubricant into grinding zone. In present work, a five port multi-nozzle system has been developed and performance of this nozzle has been compared with flood type copper cooling nozzle under different environmental conditions. Two parameters (chip characteristics, surface roughness) of grinding are considered to find the suitable process for grinding of a mild steel specimen. From this experimental investigation, it can be observed that in wet condition, five port multi-nozzle system provides better surface finish as well as it is more economical.

Novel Hot-Rolled Structural Plate Steels with Yield Strength of 700 Mpa and Excellent Usability

Hot rolled structural plate steels with yield strength of 700 MPa are an excellent choice for a variety of demanding applications that require excellent toughness and welding properties. SSAB has developed novel hot-rolled plate steels that are produced using precision controlled rolling and an innovative cooling and tempering strategy that ensures invariable mechanical properties in the width and the length directions of the plate. The recently developed steel meets or exceeds the requirements of EN 10025-6 for the S690QL grade. The minimum yield strength (ReH) is between 630 MPa and 690 MPa depending on plate the thickness, and the interval of tensile strength is 760 - 940 MPa, while the minimum elongation at fracture is 14 %. Further, an impact energy of 69 J at-40 °C on transverse V-notch specimen is guaranteed. The novel grades represent superior bendability and surface quality, weldability with excellent HAZ strength and toughness with very low CET and CEV values, exceptional consistency of properties within a plate guaranteed by close tolerances. In addition to the excellent formability, the novel hot rolled steels exhibit greatly improved toughness properties which provides for good resistance to fracture. These outstanding properties are achieved through carefully controlled manufacturing processes. In the present study, a sophisticated recrystallization based hot rolling process optimization method is presented. With the final aim to improve the impact toughness of the novel steel, recrystallization analyses and modelling of austenite grain size development through the rolling pass schedule is performed.

Physical insights about magnetic flux distribution and its effect on surface roughness in MR fluid based finishing process

A novel magnetorheological (MR) fluid based experimental system was designed to finish Ti–6Al–4V cylindrical rods. Here, the finishing action is achieved by rotating the rod to be finished which is in contact with MR fluid (mixed with silicon carbide loose abrasives) while applying a magnetic field across the finishing zone. Magneto-static field analysis was carried out using finite element method to design the magnetic circuit and predict the flux density around the finishing area. Practical results showed that the magnetic flux density of 0.2 T with a workpiece rotation of 3000 rpm provided the maximum change in average surface roughness. This paper focuses on studying the influence of magnetic flux distribution on the uniformity of the surface roughness along the axial length of the finished rods. The experiments revealed that the surface roughness significantly varied throughout the finishing rod length. The maximum change in surface roughness was seen at the lower part of the finished rod and progressively reduced towards the top of the rod. The magnetic flux distribution controls the mechanism of material removal and reveals its role to achieve close final surface roughness tolerance. With this understanding, a strategy is proposed to reduce the non-uniformity of surface roughness along the entire length of the cylindrical rod.

Discovery of 4-Hydroxy-3-(3-(phenylureido)benzenesulfonamides as SLC-0111 Analogues for the Treatment of Hypoxic Tumors Overexpressing Carbonic Anhydrase IX.

Herein we report the 2-aminophenol-4-sulfonamide 1 and its ureido derivatives 2-23 as inhibitors of the carbonic anhydrase (CA, EC 4.2.1.1) enzymes as analogues of the hypoxic tumor phase II entering drug SLC-0111. This scaffold may determine preferential rotational isomers to selectively interact within the tumor-associated CAs. Most of the compounds indeed showed in vitro selective inhibition of the tumor associated CA isoforms IX and XII. The most potent derivative within the series was 11 ( KIs of 2.59 and 7.64 nM on hCA IX and XII, respectively), which shares the 4-fluorophenylureido tail with the clinical candidate. We investigated by means of X-ray crystallographic studies the binding modes of three selected compounds of this series to CA I. The evaluation of therapeutic efficacy of compound 11 in an orthotopic, syngeneic model of CA IX-positive breast cancer in vivo showed close matching antitumoral effects and tolerance with SLC-0111.

Comparative Study of Al-TiB2 Composite Fabricated by Different Powder Metallurgical Methods

Aluminium Metal Matrix Composites (AMMCs) are the new class of materials substituting many industrial materials. It is due to its superior qualities compared to conventional materials. AMMCs has found a versatile application because it has aluminium in matrix phase hence light in weight and also it can acquire different properties as per reinforcements used. Sintering is one of the prominent methods used to manufacture AMMCs. Sintering process is used in Powder Metallurgy in which small powdered particles are heated to bond together. The process enhances the strength as well as other mechanical and tribological properties. The technology enables us to shape materials difficult to machine, parts with complex geometries, materials having high melting point, parts with close dimensional tolerances, or to combine different materials which is not possible with any other process. The most important part is that the density of the product can be controlled according to the requirements and thus self-lubricating and wear-resistant parts are possible. The present study has attempted to see if TiB2 can be used as reinforcement in AMMCs produced through powder metallurgy route and the changes in the properties of AMMCs by the different sintering methods adopted. The compacted preforms of varying compositions of reinforcement were prepared and sintered through three different methods i.e. Microwave sintering, Conventional sintering and Hot-pressing to study the changes in the properties. A comparative study has been done between the three sintering methods to see the limitations and scope for improvement.

Tapping Tool Life Assessment in Vertical Milling Centre in the CNC Production Centre

Tapping process in Computer Numerical Centre, is a key for the process because of its difficult to hold the close tolerance. During this study different types of tapping tool manufacturer have taken with same tapping tool material specification for the consideration. And also to find the relationship between the previous operational performances with tool and its parameter influence in the computer numerical control system has also taken for the consideration. During drilling process the new drill bit (drill bit 4) have higher tool life than the regained tool bits (Drill bit 1, 2 & 3). During tapping process, Emuge tool 2 and Emuge tool 3 have has higher production rate such as 434 and 356 components respectively. This Emuge tool 2 and tool 3 have previous working tool in the drilling process is drill bit 4 (New Drill Bit). Which has improved the surface roughness than the other drill bit. Due to reduced surface roughness causes the taping tool to ease in there processing which resulted in the higher production rate in tapping tool than the other conditions.

Finite Element Analysis for the Roll Forming Process of Rib

Roll forming is a continuous profile production process to form sheet metal progressively into the desired shape with closer tolerances. The process offers several advantages such as complex geometrical shapes, high strength, dimensional accuracy, closer tolerances, better quality and consistency, high production rate, improved conformity, and good surface finish. Several parts of automobile body are produced with this process. Nowadays roll forming technology draws more attentions than before in the automotive industry. In this paper, A Finite Element Method applied to study von mises stress, equivalent plastic strain, thickness, plastic strain, longitudinal strain and spring back of the metal sheet with ribs formed by roll forming process. The thickness variation was almost -6.144%.

Distortion control in 20MnCr5 bevel gears after liquid nitriding process to maintain precision dimensions

Robotic and automotive gears are generally very high precision components with limitations in tolerances. Bevel gears are more widely used and dimensionally very close tolerance components that need stability without any backlash or distortion for smooth and trouble free functions. Nitriding is carried out to enhance wear resistance of the surface. The aim of this paper is to reduce the distortion in liquid nitriding process, though plasma nitriding is preferred for high precision components. Various trials were conducted to optimize the process parameters, considering pre dimensional setting for nominal nitriding layer growth. Surface cleaning, suitable fixtures and stress relieving operations were also done to optimize the process. Micro structural analysis and Vickers hardness testing were carried out for analyzing the phase changes, variation in surface hardness and case depth. CNC gear testing machine was used for determining the distortion level. The presence of white layer was found for about 10-15μm in the case depth of 250± 3.5μm showing an average surface hardness of 670 HV. Hence the economical liquid nitriding process was successfully used for producing high hardness and wear resistant coating over 20MnCr5 material with less distortion and reduced secondary grinding process for dimensional control.

Design and analysis of plastic gears in rack and pinion steering system for formula supra car

Plastic gears have positioned themselves as serious alternatives to traditional metal gears in a wide variety of applications. The use of plastic gears has expanded from low power, precision motion transmission into more demanding power transmission applications. In an automobile, the steering system is one of the most important systems which used to control the direction and stability of a vehicle. In order to have an efficient steering system, one should consider the material and properties of gears used in rack and pinion. Using plastic gears in a vehicle’s steering system has many advantages over the current traditional use of metallic gears. High performance plastics like, glass fiber reinforced nylon 66 have less weight, resistance to corrosion, noiseless running, lower coefficient of friction and ability to run without external lubrication. Moreover, plastic gears can be cut like their metal counterparts and machined for high precision with close tolerances. In formula supra vehicles, weight, simplicity and accuracy of systems have prime importance. These requirements make plastic gearing the ideal option in its systems. An effort is made in this paper for analyzing the possibility to rebuild the steering system of a formula supra car using plastic gears keeping contact stresses and bending stresses in considerations. As a conclusion the use of high strength engineering plastics in the steering system of a formula supra vehicle will make the system lighter and more efficient than traditionally used metallic gears.

Laser dressing of grinding wheels - a review

Grinding is one of the commonly used surface-finishing operations in the manufacturing industries to produce surfaces with close tolerances, high precision, and high quality. Selection of appropriate dressing technique with optimised dressing conditions can result in effectively opening up of the cutting edges of the abrasive grits. Several experimental investigations have hailed the laser dressing to be prosperous in generating improved grinding wheel topology that results enhanced grindability. This paper presents a comprehensive review on the developments and advances of the novel laser dressing techniques, starting from a brief introduction of basic concept, material removal mechanism, experimental arrangements, and advantages over mechanical dressing techniques. The progress in diverse laser dressing, focusing on material aspects, is thoroughly reviewed and discussed.

Laser dressing of grinding wheels A review

Grinding is one of the commonly used surface-finishing operations in the manufacturing industries to produce surfaces with close tolerances, high precision, and high quality. Selection of appropriate dressing technique with optimised dressing conditions can result in effectively opening up of the cutting edges of the abrasive grits. Several experimental investigations have hailed the laser dressing to be prosperous in generating improved grinding wheel topology that results enhanced grindability. This paper presents a comprehensive review on the developments and advances of the novel laser dressing techniques, starting from a brief introduction of basic concept, material removal mechanism, experimental arrangements, and advantages over mechanical dressing techniques. The progress in diverse laser dressing, focusing on material aspects, is thoroughly reviewed and discussed.

Aluminium Alloy Composites and its Machinability studies; A Review

In the recent years, composite materials have emerged as one of the functional material with improved properties, contributing to the wide range of applications. However shaping and machining of these materials leftover a challenge due to combination of various dissimilar reinforcements and its abrasive nature. So far conventional machining process like milling, turning or drilling are adopted for machining of metal matrix composites. But, due advancement in the manufacturing of composites with the combination of novel materials, there will be always new challenges for machining of such materials with close tolerance. The current article gives an overview about the advances in the composite material and its properties, recent development in the machinability analysis of metal matrix composite. Most of the discussions presented in this review article focuses on aluminum and its alloy based composites.

Optimization of turning parameters for the finest surface roughness characteristics using desirability function analysis coupled with fuzzy methodology and ANOVA

Evolution of technology is as essential as it is inevitable, and as technology improves so does the advancements in the materials used. Fundamentally, the need for light yet strong material is the one we need to address. One such material is Glass Fiber Reinforced Plastic (GFRP). This composite material is being widely used in various industries like aerospace, chemical and construction industries. Eventually, this calls for an economical manufacturing method for GFRP in order to facilitate an automated and therefore, quick production of this composite. However, it is also vital to maintain the accuracy in these methods to obtain close fits and tolerances. This paper is an attempt to demonstrate the implementation of Desirability Functional Analysis combined with Fuzzy logic to optimize the machining parameters for turning of GFRP. Aim of the experimentation was to achieve the best surface characteristics for the given input parameters. The input parameters which we selected were cutting speed, tool nose radius, feed rate and depth of cut at three different levels of each. L27 orthogonal array based on Taguchi philosophy was used to conduct the experiment and output parameters selected were three surface roughness characteristics Ra, Rt and Rsm. Optimum combination of input parameters for best surface finish characteristics is obtained at A1B3C1D2, i.e. tool nose radius at level 1 (0.4mm), cutting speed at level 3 (200mm/min), feed rate at level 1 (0.05mm/rev) and depth of cut at level 2 (1mm). Analysis of Variance (ANOVA) was also performed to find the input parameter of which the impact is maximum on the output response and found it to be feed rate. A confirmation test is also carried out to validate the results obtained from this optimization. Therefore, the implementation of Desirability Functional Analysis coupled with Fuzzy logic is an effective approach in optimizing the machining parameters of GFRP.

Study of Laser Drilled Hole Quality of Yttria Stabilized Zirconia

The Yttria Stabilized Zirconia ceramic is extensively used in aerospace, automotives, medical and microelectronics industries. These applications demand manufacturing of different macro and micro features with close tolerances in this material. To make miniature holes with accurate dimensions in advanced ceramics such as Yttria Stabilized Zirconia is very difficult due to its tailored attributes such as high toughness, hardness, strength, resistance to wear, corrosion and temperature. Due to inherent characteristics of laser drilling, researchers are working to fulfill the requirement of creation of micro holes in advanced ceramics. The present research investigates the laser drilling of 2 mm thick Yttria Stabilized Zirconia with the aim to achieve good micro holes with reduced geometrical inaccuracies and improved hole quality. The results show that multiple quality response comprising hole circularity, hole taper and recast layer thickness has been improved at optimally selected process parameters.

Development of a 2-stage shear-cutting-process to reduce cut-edge-sensitivity of steels

The edge cracking sensitivity of AHSS and UHSS is a challenging factor in the cold forming process. Expanding cut holes during flanging operations is rather common in automotive components. During these flanging operations the pierced hole is stretched so that its diameter is increased. These flanging operations stretch material that has already been subjected to large amounts of plastic deformation, therefore forming problems may occur. An innovative cutting process decreases micro cracks in the cutting surface and facilitates the subsequent cold forming process. That cutting process consists of two stages, which produces close dimensional tolerance and smooth edges. As a result the hole expanding ratio was increased by nearly 100 % when using thick high strength steels for suspension components. The paper describes the mechanisms of the trimming process at the cut edge, and the positive effect of the 2-stage shear-cutting process on the hole extension capability of multiphase steels.

Evaluation of the effects of machining parameters on MQL based surface grinding process using response surface methodology

Grinding is a precision machining process widely used for close tolerance and good surface finish. Due to aggregate of geometrically undefined cutting edges and material removal in the form of microchips, grinding requires more specific energy as friction is greater in the grinding interface. The optimum use and proper penetration of coolant is the prime requirement which is achieved by effective cooling and lubrication. In this research, a greater focus is on MQL technique, which is economical and eco-friendly. The paper presents important aspects of the grinding process considering the surface roughness and cutting force. The experiments were carried out on horizontal surface grinding machine using Response surface methodology (RSM). In addition, evaluation of grinding performance parameters like coefficient of friction, cutting forces, temperature and specific grinding energy for different machining environments has been discussed. The lowest surface roughness and coefficient of friction observed was 0.1236 μm and 0.3906, respectively for MQL grinding, whereas lowest specific grinding energy was found as 18.95 N/mm2 in wet grinding. The temperature recorded in MQL grinding was 29.07 °C, which is marginally higher than wet condition. The response obtained as cutting forces, temperature and surface roughness under MQL mode encourages its use for machining AISI D3 type material compared to other grinding environments. Mathematical modeling showing the relation between the factors and response variables was established using Response surface methodology. Regression analysis was performed to determine the accuracy of mathematical model, significant factors and interaction effects of parameters on responses.

Capabilities of industrial computed tomography in the field of dimensional measurements

The paper discusses the capabilities of industrial computed tomography (CT) in the field of dimensional measurement of products with close tolerances. Computed tomography is a method that allows inspection and measurements of both reachable and unreachable characteristics which makes it very desirable and interesting for application in wide range of industries. In order to evaluate the quality of measurement results obtained by industrial CT, two objects with the same geometry, and made from different materials, were measured. Results obtained with CT were compared with the results obtained by coordinate measuring machine, which were considered to be reference values, and deviations between the results have been analysed. Measurements were repeated five times under repeatability conditions. Repeatability is expressed quantitatively in terms of the dispersion characteristics of the results. Statistical analysis showed that in majority of cases, there were no statistically significant differences between measurement results of equal characteristics obtained at different materials. Obtained deviations in the research could be explained by the fact that the measurements were performed at the industrial CT for general applications. Much better results can be achieved by using a metrology CT device.

Implementation of Taguchi Method for Parametric Optimization of Springback in Cold Drawing of Seamless Tubes

In tube drawing process, a tube is pulled out through a die and a plug to reduce its diameter and thickness as per the requirement. Dimensional accuracy of cold drawn tubes plays a vital role in further quality of end products and controlling rejection in manufacturing processes of these end products. Springback phenomenon is the elastic strain recovery after removal of forming loads, causes geometrical inaccuracies in drawn tubes. Further this leads to difficulty in achieving close dimensional tolerances. In the present work springback of EN 8 D tube material is studied for various cold drawing parameters. The process parameters in this work include die semi angle, land width and drawing speed. The experimentation is done using Taguchi’s L36 orthogonal array and then optimization is done in data analysis software Minitab 17. The results of ANOVA shows that 15 degree die semi angle, 5 mm land width and 6 m/min drawing speed yields least springback.