Excellent Surface Finish Research Articles

Development of functionally graded material by fused deposition modelling assisted investment casting

In order to attain sound geometrical details, excellent surface finish and required dimensional accuracy, investment casting (IC) process is one of the best options available commercially in the manufacturing sector. The IC process has got all the attentions for the development of metal matrix composites, as one is getting finished product for tailor made applications. In the present research work an attempt has been made for development of Al/Al2O3 composite as a functionally graded material (FGM) by using an alternative reinforced fused deposition modelling (FDM) pattern in IC process. The study is made with six controllable parameters (12 and 53 levels) to highlight their affect on wear resistance and micro-hardness of composite prepared. The X-ray diffraction analysis was performed to understand wear, micro-hardness of FGM and for establishing the novelty of proposed route.

Modeling and prediction for 3D surface topography in finish turning with conventional and wiper inserts

Wiper insert have the characteristics of achieving an excellent surface finish and improving the productivity in turning processes. Wiper insert can provide twice feed rate while maintaining the comparable surface roughness compared to that provided by the conventional insert. In the present study, surface topographies in finish turning with conventional and wiper inserts are investigated. The key element of this work is that the cutting edge path equation in the cutting tool coordinate system is transformed into the machine tool and workpiece coordinate system by the use of spatial coordinate transformation. Following that a surface topography simulation algorithm based on the cutting edge path equation and cutting parameters is put forward. The output of this work is that both the simulated surface topography and surface roughness profile are good agreement with the experimental results. Both the simulated and the actual machined surface results show that better surface topography is obtained in finish turning with the wiper insert than that with conventional insert. Burnishing effect of the wiper insert leads to half decrease of the Ra and Rz. The actual surface profiles are no longer regular wave shapes due to ploughing effect and side flow existing in the cutting zone. In addition, a surface roughness map has also been developed to optimize the selection of wiper radius and feed rate to satisfy the requirement of surface finishing with higher productivity. From the viewpoint of cutting tool design, the wiper radius with five times larger than tool nose radius can fully come into its role. This provides a novel insight into the design of wiper insert over conventional techniques. Above all, the proposed model gives a better prediction of surface roughness in finish turning process compared to the previous empirical and regression roughness models. The prediction of surface roughness in finish turning with wiper insert is also realized.

Resíduo industrial como matéria-prima alternativa para a produção de filtros cerâmicos refratários

ResumoO desenvolvimento de atividades de valorização de resíduos sólidos pode viabilizar a produção de produtos industriais com elevado potencial de reaproveitamento como fonte alternativa mineral. Atualmente, os resíduos sólidos industriais tornaram-se uma importante linha de pesquisa na área de Engenharia. Apesar disso, poucos estudos têm sido realizados com interação efetiva de parâmetros ambientais, econômicos e sociais que demonstram aplicações destas matérias-primas pela indústria de transformação. Neste trabalho são apresentados e discutidos os resultados de investigação relacionados à valorização de um resíduo sólido industrial (casca cerâmica) gerado no processo de fundição de precisão por cera perdida. Este material apresenta características muito interessantes e adequadas à produção de filtros cerâmicos refratários. Desta forma, cerâmicos porosos foram obtidos através do processo da réplica poliméricae o seu desempenho testado industrialmente na filtragem de ferro fundido no estado líquido (1,76 kg/s). Os componentes metálicos produzidos apresentaram excelente acabamento superficial.

About the numerous cost and processing advantages of the microcellular foam injection molding process for thermoplastics materials in the automobile industry

Today one of the goals of the automobile industry is to reduce weight. And physical foaming has already demonstrated its potential in this sector, improving the value and performance of applications under the bonnet: engine and gearbox cases, inlet air filters, cockpits, radiator baffles and so on. Around the world, the microcellular injection molding (MuCell) is used in thousands of applications in the automotive, packaging, technical molding, office machinery and electric and electronic component industries. The research opportunities purpose is to obtain even lighter pieces, with greater dimensional stability and with an excellent surface finish, in other words, perfect plastic parts. More component functionality with reduced weight, and cost control at the same time: MuCell is a process to physically foam thermoplastics, which combines technical and economic objectives. Besides weight reduction, it also provides improved dimensional stability of the moulded parts.

EDM Process Parameters Optimization Using Taguchi Method

In this paper , the parameters of Electrical Discharge Machine (EDM) are investigated during the machining of Inconel 718 by using different sizes of circular Aluminum electrode. Demand for better surface finishes are increasing recently for all materials, the low rigidity and high material removal rate of Inconel alloys offers a challenging task in obtaining better Surface Finish. The analysis of surface characteristics like Surface Roughness (SR) of Inconel 718 material is carried out an excellent surface finish can be obtained by setting the machining parameters at optimum level. Experimentation was carried out by using Taguchi’s L9 orthogonal array under different conditions of parameters. The response of SR is considered for improving the machining efficiency. Optimal combination of parameters was obtained Taguchi Optimization technique. The confirmation experiments results shows that the significant improvement in Surface Finish was obtained. ANOVA have been used to analyze the contribution of individual parameters on Surface Roughness. The experimental result demonstrates that the Taguchi method satisfies the practical requirements.

Diamond turning of diffractive microstructures

Diamond machining is a suitable technology for manufacturing of diffractive optics with excellent surface finish. The machining result depends on the workpiece material to a large extent. Many materials are commonly applied in diamond machining. One material of particular interest is nickel silver, which offers a comparably higher hardness than aluminium or copper. Especially for machining of sharp edges this is an advantageous property. However, not all alloys are equally suited for machining. Therefore, this paper investigates the influences of different material properties on process forces, burr and chip formation, and most importantly the surface finish. The machining experiments demonstrate that burr and chip formation are predominantly influenced by the machining strategy. The process forces on the other hand, largely depend on the material composition, which also affects the surface finish, especially local surface defects. It was also found that an increasing surface hardness, which was generated by deep rolling, supports the reduction of plastic deformations of the machined microstructures.

An automated Guilloche machining technique for the fabrication of polygonal Fresnel lens array

Fresnel lenses are gaining wider applications in optoelectronics and photonic devices. They have been evolved into arrays of individual elements with better performance and better capabilities. These arrays may also be realized with individual elements having polygonal shapes such as rectangular, hexagonal, etc to achieve a high fill factor. Due to the fact that the polygonal Fresnel lens arrays are not rotationally symmetrical, they are manufactured by using expensive lithography techniques or time consuming method of having multiple molds assembled together. This paper presents an automated 4-axis ultraprecision machining technique for manufacturing an array of hexagonal Fresnel lenses. In the proposed method, a diamond tool moves as a fixed point on a circle rolling inside a fixed circle which is analogous to a Guilloche machine. The proposed automated machining technique has been experimentally verified through successful manufacturing hexagonal Fresnel lens array in a single process, without having separated sections assembled as a single master mold. From the results, an excellent surface finish and good profile accuracy are also achieved. The developed automated Guilloche machining technique also paves the way for the promising challenges to remove manufacturing barriers of machining freeform surfaces with complex curvatures.

A Study of the Functionality of Hydrated Lime as an Admixture

It is known that hydrated lime improves the workability and water retention of Portland cement (PC) mortars. PC-lime mixes can be reworked without increasing entrained air thus not undermining durability. In addition, lime lowers strength and stiffness making PC mortars more deformable. However, the use of hydrated lime in PC composites has largely decreased due to the use of plasticisers. These enhance workability and lower cement content reducing heat of hydration. As they are water reducers, they are expected to decrease permeability, minimise shrinkage, enhance ultimate strength and accelerate early-strength gain; leading to stronger, durable composites. Despite these advantages, plasticisers have drawbacks related to wastage and environmental protection. This paper studies the properties of PC-lime mortars and their plasticised equivalents. It concludes that lime raises mortar water demand however, this does not reduce strength but on the contrary, mortars of low lime content (lime amounting 1/4 th the cement), have superior flexural and compressive strengths than their plasticised equivalents. The use of lime delivered PC mortars with excellent workability and surface finish and lack of segregation and bleeding. It is concluded that, when lime amounts 1/4 th the cement, the mortars are stronger (in tension and compression, at both early and mature age) and gain strength at a faster rate than plasticised mixes. However, when lime equals the cement content, strengths are lower than those of plasticised mixes. It was also noted that lime enhanced bond strength at all ages; and that the ultimate bond strength is greater for the low lime than for the high lime content mortars.

An Innovative Approach for Manufacturing of Thin Welded Blanks and Coils

This study presents a novel approach for fabricating thin welded plates with excellent surface finish and physical properties using friction stir welding process. Similar and dissimilar materials were welded under various conditions, followed by cold-rolling operations to the desired thicknesses. For welding of similar material, an ultimate thickness of 70 µm was achieved from 1 mm raw aluminum alloy-1100. In the next stage, where aluminum and copper sheets with the thickness of 0.5 mm were welded together, bi-material foils with final thickness of 200 µm were fabricated. Results indicate that the presented approach can be replaced with costly fusion processes especially for ultra-thin joints.

Enhancement of Porosity of the Ceramic Shell in Investment Casting Process Using Needle Coke and Camphor

Investment casting process has been a widely used process for centuries. It is known for its ability to produce components of complex shapes with dimensional accuracy and excellent surface finish. Investment casting has been used to make manufacture weapons, jewellery and art castings during the ancient civilization and today it is used to manufacture engineering components. In Investment casting wax patterns are made by wax injection and then coating of the wax patterns are done by ceramic slurry, made with silica flour and binder. After dewaxing and firing molten metal is poured in the shell and solidified casting can be achieved. Investment casting can be cast any ferrous and non ferrous metal which is difficult in die casting. Finishing operations are negligible and very thin sections as.75mm can also be cast which is not possible in sand casting but there are many challenges in Investment casting. It is relatively slow process because preparation of ceramic shell consumes a lot of time, permeability of shell is very low which causes gas permeability. Incorporation of chills is very difficult. Among all these challenges gas porosity is main problem because of poor permeability, entrapment of gases due to complex geometry of the shell, reuse of scrap metal. In the present work porosity of the shell can be increase by addition of mixture of Camphor and needle coke. After firing of the shell camphor and needle coke will be burnt leaving pores for the escape of entrapped gases. Mechanical properties of the both shell will be compared with each other.

An Investigation of Lapping Characteristics for Mirror-Like Finish Using a Lathe with Linear Motor

Lapping is possible to produce excellent surface finish with higher geometrical form. Additionally, automated lapping process is perfectly suited with todays industry requirements and also economically advantage over other manufacturing processes. This research is devoted to study the characteristics of the lapping process for mirror-like surface finishing by using the linear motor lathe. In the process of mirror-like finish, various factors that effect on rate of material removal, limit surface roughness and geometrical form improvement were examined on low, medium and high hardness materials by series of experiments. The conclusion shows that active grain characteristics, hardness ratio, lapping pressure, lapping speed, residual stress and chatter vibration on the work surfaces all have influenced on the mirror-like surface finishing process.

Remanufacturing with ECH – A Concept

A concept of remanufacturing is develops for expensive saving for new components. The cost of spare parts for aerospace and automobile engine are very high, in many cases repair of parts is cost effective. A lot of components are reused, which results in decreasing the amount of materials, energy and waste. This paper aims to find the remanufacturing possibilities with electrochemical honing (ECH) process, for difficult to machined alloy of engine parts. ECH process have their own advantages to remove any hard material with controlled surface generation with excellent surface finish. Furthermore, it provides highest productivity and increasing the service life of critical components. This paper presents a unexplored concept with some direction for future research with an objective to mature the remanufacturing engineering.

Empirical Determination of Roughness Parameters Using Wiper Tool Inserts in Finish Turning of AISI 4140

The surface finishing resulting from metal cutting processes is associated with the surface texture and integrity. Texture can be quantified by roughness parameters as Roughness Average (Ra), Total Roughness (Rt), Maximum Surface Depth (Ry) and Surface Depth (Rz) which are directly related to cutting magnitudes and tool characteristics. This work assesses empirically the roughness generated by wiper cutting tools in dry finishing turning operations of AISI 4140 steel. By keeping a constant cutting speed and using depths of cut greater than 2/3 of the cutting tool radius (rε), four feed rates (f) are used with three rε, both combined in a way to ascertain the equations which allows the evaluation of Ra, Rt, Ry and Rz values. In order to determine the equations for roughness prediction a multiple linear regression method in function of f and rε is applied, showing good agreement with experimental results. Also, achieved results allows to prove the effectiveness of wiper tools to generate excellent surface finish without grinding operations and consequently showing that its use can increase significantly the material removal rate without compromising the surface roughness in high feed rate operations.

A review of rapid prototyping integrated investment casting processes

Investment casting is competitive with all other casting processes where the size of the product is within a mutually castable range. Though investment casting is used to produce metal parts of any intricate shapes with excellent surface finish, it suffers from long lead time and high tooling costs, which makes it uneconomical for the production of either single casting, or small and medium production units. These problems could be overcome by the applications of rapid prototyping and rapid tooling technologies for low-volume investment casting production runs. The present article analyzes different classifications of rapid prototyping techniques and it reviews various investigations made on the usability of rapid prototyping- and rapid tooling-integrated investment casting process, with their advantages and limitations. The emerging areas of applications of rapid prototyping like dentistry, jewelry, surgical implants, turbine blades, etc., are accordingly discussed. Further, an elaborate discussion is made on the application of newer technologies for directly developing ceramic shells. This article also emphasizes on various future scopes possible in rapid prototyping-integrated investment casting process.

Direct Sinter Bonding of Metal Injection-Molded Parts to Solid Substrate Through Use of Deformable Surface Microfeatures

In the metal injection molding (MIM) process, fine metal powders are mixed with a binder and injected into molds, similar to plastic injection molding. After molding, the binder is removed from the part, and the compact is sintered to almost full density. Though able to create high-density parts of excellent dimensional control and surface finish, the MIM process is restricted in the size of part that can be produced, due to gravitational deformation during high-temperature sintering and maximum thickness requirements to remove the binding agents in the green state. Larger parts could be made by bonding the green parts to a substrate during sintering; however, a primary obstacle to this approach lies in the sinter shrinkage of the MIM part, which can be up to 20%, meaning that the MIM part shrinks during sintering, while the conventional substrate maintains its dimensions. This behavior would typically inhibit bonding and/or cause cracking and deformation of the MIM part. In this work, we present a structure of micro features molded onto the surface of the MIM part, which bonds, deforms, and allows for shrinkage while bonding to the substrate. The micro features tolerate plastic deformation to permit the shrinkage without causing cracks after the initial bonds are established. In a first series of tests, bond strengths of up to 80% of that of resistance welds have been achieved. This paper describes how the authors developed their proposed method of sinter bonding and how they accomplished effective sinter bonds between MIM parts and solid substrates.

AFM Nano Analysis of Inconel 825 with Single Wall Carbon Nano Tube in Die Sinking EDM Process Using Taguchi Analysis

A carbon nanotube has high mechanical and electrical properties, and specifically, high electrical conductivity. By using these properties in Electrical Discharge Machining, the single-wall carbon nanotube is mixed with dielectric fluid to analyse the surface characteristics of Inconel 825, which is very much used in moulds and dies. Carbon nanotube will absorb the heat from electrically discharged material and also minimize the white layer formation in the work piece. Experimental results indicate that the surface texture after electrical discharge machining (EDM) is increased very much due to discharge energy. An excellent machined nanolevel surface finish can be obtained by setting the machine parameters at low pulse energy. The surface roughness and the depth of the microcracks were proportional to the power input, especially the input current. Furthermore, the AFM tests yielded information about the surface morphology which is particularly important in the post treatment of Inconel 825 machined by EDM. Analysis of variance and F test were used to determine the significant parameter affecting the surface roughness.

Low-Cost Thin Glass Interposers as a Superior Alternative to Silicon and Organic Interposers for Packaging of 3-D ICs

Interconnecting integrated circuits (ICs) and 3-D-ICs to the system board (printed circuit board) are currently achieved using organic or silicon-based interposers. Organic interposers face several challenges in packaging 2-D and 3-D-ICs beyond the 32-nm node, primarily due to their poor dimensional stability and coefficient of thermal expansion (CTE) mismatch to silicon. Silicon interposers made with back-end of line wafer processes can achieve the required wiring and I/O density, but their high-cost limit them to high-performance applications. Glass is proposed as a superior alternative to organic and silicon-based interposers for packaging of future ICs and 3-D-ICs with highest I/Os at lowest cost. This paper presents for the first time a novel thin and large panel glass interposer capable of scaling to 700 mm and larger panels with potential for significant cost reduction over interposers made on 200-mm or 300-mm wafers. The formation of small through vias at high speed has been the biggest technical barrier for the adoption of glass as an interposer and system substrate; and this paper describes pioneering research in via-formation in thin glass substrates, using a novel “polymer-on-glass” approach. Electrical modeling and design of through package vias (TPVs) in glass is discussed in detail, and the feasibility of 50-μm pitch TPVs in 180-μm thin glass substrates has been demonstrated. The excellent surface finish and low CTE of glass leads to increased I/O density, and increased functionality per unit area leading to system miniaturization.

Sustainable High Speed Dry Cutting of Magnesium Alloys

Magnesium (Mg) components can significantly reduce energy use due to their low densities compared to the majority alloys. Mg alloys are often machined to fit individual cases. However, process mechanics by high-speed dry cutting of Mg alloys are poorly understood. This study focuses on machining ability of biomedical magnesium-calcium (Mg-Ca) alloys. First, it presents a modeling approach of mechanical behavior of Mg-Ca0.8 (wt %) alloy under cutting regimes using the internal state variable (ISV) plasticity model. Then, the ISV plasticity model is implemented to simulate high speed dry cutting of Mg-Ca0.8 alloy by finite element method. Last, machining performance in the context of sustainability is discussed. Excellent surface finish can be achieved in the range of high cutting speeds. Continuous chip formation predicted by the finite element simulation is verified by high speed dry cutting of Mg-Ca0.8 using polycrystalline diamond (PCD) inserts. Chip ignition as the most hazardous aspect in machining Mg alloys does not occur for in high-speed dry cutting with sharp PCD tools. The predicted temperature distribution well explains the reason for the absence of chip ignition in high speed dry cutting of Mg-Ca0.8 alloy. A mechanism of built-up layer (BUL) formation is proposed.

Finishing process analysis between honing and hard hobbing in pinion gears applied to a steering system

Among the techniques used in surface finish machining of gears, the honing process has been highlighted due to high efficiency in the finishing of hardened gears and ease of adjusting the involutes profile and incident angle in the counter-part. The gear honing process is used to eliminate errors that appears after the heat treatment on the tooth surface and. Although the material and cutting speed of the tool are similar to the grinding process, honing the process simulates true cinematic movement of the mesh gear, which provides a better surface roughness compared to the Hobbing process. Consequently, it is hard to correct anomalies in the gear teeth. This process has been used to improve the mechanisḿs hydraulic steering pinion / rack system. For the experiments, it were compared two processes, namely honing and hard Hobbing in order to assess the adequate strength in the direction of clockwise rotation and counter clockwise, which represents the actual effort exerted by the driver of the vehicle. The honing process was lead using a 400 Fassler HMX machine tool. In order to assess the significant difference between the experiments, it was used ANOVA and Tukey test. The results obtained from the experiments using the honing process were satisfactory as compared the results obtained from hard hobbing process. Thus, it can be concluded that this process provides an excellent surface finish of the sprockets having a direct impact on the returned vehicle steering system

English

This paper develops a single order mathematical model for correlating the various electrical discharge machining (EDM) parameters and performance characteristics utilizing relevant experimental data as obtained through experimentation. Besides the effect of the peak ampere, pulse on time and pulse off time on surface roughness has been investigated. Experiments have been conducted on titanium alloy Ti-6Al-4V with copper electrode retaining negative polarity as per Design of experiments (DOE). Response surface methodology (RSM) techniques are utilized to develop the mathematical model as well as to optimize the EDM parameters. Analysis of Variance (ANOVA) has been performed for the validity test of fit and adequacy of the proposed models. It can be seen that increasing pulse on time causes the fine surface until a certain value and afterward deteriorates in the surface finish. The excellent surface finish is investigated in this study in the case of the pulse on time below 80 >s. This result guides to pick the required process outputs and economic industrial machining conditions optimizing the input factors.