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Article
Publication date: 3 April 2007

S. Rahmati, J. Akbari and E. Barati

Dimensional accuracy analysis of wax model created by room temperature vulcanization (RTV) silicone rubber molding to be used in investment casting is presented. The…

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1196

Abstract

Purpose

Dimensional accuracy analysis of wax model created by room temperature vulcanization (RTV) silicone rubber molding to be used in investment casting is presented. The purpose of this paper is to discuss the effective parameters of dimensional accuracy in RTV tooling technique.

Design/methodology/approach

After producing a pattern by stereolithography (SLA) and then creating the RTV silicone rubber mold by the SLA pattern, dimensional accuracy of wax models produced by RTV tool are analyzed. Design of experiments (DOE) using the Taguchi approach is used for analysis and determination of optimum condition.

Findings

Experiments show that the dimensional accuracy in RTV technique is as accurate as in traditional molding. Hence, RTV tooling technique can be used in investment casting. Using Taguchi approach based on DOE, it was realized that the optimum condition to achieve acceptable accuracy is 35°C for mold temperature, 85°C for wax temperature, and −0.5 barG for vacuum pressure.

Practical implications

RTV silicone rubber mold is a useful alternative of metallic mold to produce wax patterns for investment casting. It has benefits such as reduction in production lead‐time and cost, compared with traditional metallic mold.

Originality/value

A case study for research of dimensional accuracy of wax patterns created by RTV silicone rubber mold had not been attempted as such. In addition to reduction in production lead‐time and cost, the dimensional accuracy of wax patterns using RTV tooling technique are as accurate as in traditional technique.

Details

Rapid Prototyping Journal, vol. 13 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 4 August 2014

Thomas Maeder, Caroline Jacq, Ludivine Ammon and Perer Ryser

The purpose of this paper is to study tuneable positive temperature coefficient (PTC) effect in polymer-wax-carbon composite resistors. The resistivity dependence on…

Abstract

Purpose

The purpose of this paper is to study tuneable positive temperature coefficient (PTC) effect in polymer-wax-carbon composite resistors. The resistivity dependence on temperature of composite resistors made of carbon fillers dispersed in an organic matrix is known to be strongly affected by the matrix thermal expansion. High PTC effects, i.e. essentially switching from resistive to quasi-insulating behaviour, can be caused by phase changes in the matrix and the assorted volume expansion, a behaviour that has been previously shown with both simple organic waxes and semi-crystalline polymers. However, waxes become very liquid on melting, possibly resulting in carbon sedimentation, and tuneability of semi-crystalline polymers is limited.

Design/methodology/approach

The authors therefore study a ternary polymer-wax-conductor (ethylcellulose-octadecanol-graphite) composite resistor system, where polymer and wax fuse to a viscous liquid on heating, and re-solidify and separate by crystallisation of the wax on cooling.

Findings

It is shown that with appropriate formulation, the resulting resistors exhibit strong PTC effects, linked with the melting and crystallisation of the wax component. The behaviour somewhat depends on sample history, and notably cooling speed.

Research limitations/implications

The phase equilibria and transformation kinetics of the polymer-wax system (including possible wax polymorphism), as well as the exact mechanism of the conductivity transition, remain to be investigated.

Originality/value

As many compatible polymer-wax systems with different melting/solidification behaviours are available, ternary polymer-wax-conductor composite PTC resistors allow a high tuneability of properties. Moreover, the high viscosity in the liquid state should largely avoid the sedimentation issues present with binary wax-conductor systems.

Details

Microelectronics International, vol. 31 no. 3
Type: Research Article
ISSN: 1356-5362

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Article
Publication date: 10 July 2017

Yanbao Guo, Shuhai Liu, Guibin Tan, Liu Yang and Deguo Wang

The wax deposition in oil wells and pipelines is very viciously negative to the petroleum extraction and crude oil transportation, and it even causes severe blockage…

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174

Abstract

Purpose

The wax deposition in oil wells and pipelines is very viciously negative to the petroleum extraction and crude oil transportation, and it even causes severe blockage accident. This study aims to describe cleaning experiments performed on wax deposition of different deposition layer and experimental conditions to investigate the removal and tribological properties and chip formation.

Design/methodology/approach

An optical arrangement was used to visually record the cleaning process, whereas the friction forces were measured by a custom-built tribometer. Various measurements were performed with tool rake angles of 45° and −30° and cleaning depths from 1 to 5 mm.

Findings

Results from experiments and modeling suggest that the transition of chip was dependent on rake angle, wax performance and cleaning depth. While the cleaning depth increased, the friction and cleaning resistant force also increased. With the increase of cleaning depth, the wax layer cleaning quantity increased and the chip strengthened; hence, the curvature radius of chip was enhanced to form platy chip. The chip of wax–oil mixture was discontinuous units, and it was easy to adhere on the rake face with the increasing depth of cut. With an increase in cleaning depth, the friction and cleaning-resistant force also increased.

Originality/value

It is concluded that for effectively cleaning and stabilizing of pipeline cleaning machine, different cleaning parameters should be applied to accommodate wax layer or wax–oil mixture.

Details

Industrial Lubrication and Tribology, vol. 69 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 3 April 2019

Yanqiu Xia, Wenyi Zhang, Zhengfeng Cao and Xin Feng

This paper aims to explore the leaf-surface wax as green lubricant additive and compare the tribological properties between coastal and inland leaf-surface waxes of the…

Abstract

Purpose

This paper aims to explore the leaf-surface wax as green lubricant additive and compare the tribological properties between coastal and inland leaf-surface waxes of the same species plant.

Design/methodology/approach

The leaf-surface waxes were extracted from the leaves of Robinia pseudoacacia cv. Idaho and Populus nigra in coastal and inland areas, and then the compositions of the four kinds of leaf-surface waxes were characterized using a gas chromatography–mass spectrometry. The tribological properties of these leaf-surface waxes as lubricant additives in the base oil of synthetic ester (SE) were investigated by an MFT-R4000 reciprocating friction and wear tester. As well as the surface morphologies and chemical compositions of the wear scars were characterized by a scanning electron microscope and time-of-flight secondary ion mass spectrometry, respectively.

Findings

The results indicate that all the leaf-surface waxes as additives can effectively improve the friction reduction and anti-wear performances of SE for steel–aluminum friction pairs. Therein, coastal leaf-surface waxes have better tribological performances than inland leaf-surface waxes, which are attributed to that the leaf-surface waxes extracted from coastal plants can form a better protective film on the worn surface throughout the friction process.

Originality/value

This paper investigated a new kind of environmentally friendly lubricant additive and compared the tribological properties of the leaf-surface wax extracted from coastal and inland plants. The associated conclusions can provide a reference to explore the tribological performances of leaf-surface wax as green lubricant additive.

Details

Industrial Lubrication and Tribology, vol. 71 no. 4
Type: Research Article
ISSN: 0036-8792

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Article
Publication date: 18 June 2018

Anil Panghal, D.N. Yadav, Bhupender S. Khatkar, Himanshu Sharma, Vikas Kumar and Navnidhi Chhikara

Fruits and vegetables, being good source of energy, health promoting and protecting compounds with unique taste and flavor, are attracting consumers since ages. These…

Abstract

Purpose

Fruits and vegetables, being good source of energy, health promoting and protecting compounds with unique taste and flavor, are attracting consumers since ages. These horticultural produces start deterioration just after harvest; therefore, their proper storage is must during transportation and storage to retain maximum quality parameters and for good market value. Best storage conditions are required to prevent growth of micro flora and to maintain the nutritional values of harvested produce. Retailers and processors in every corner of world want to move toward the cheaper ways to increase the shelf life and texture of horticultural crops for better consumer preference. The purpose of this paper is to make consumers and researchers aware about different post harvest malpractices in fresh fruits and vegetables.

Design/methodology/approach

Lot of chemicals like colors, artificial ripening agents, sweeteners and waxes are applied on surface of horticulture produce to siphon off money from consumers, and these have adverse health effects directly or indirectly. Various regulatory agencies have launched various programs, acts and laws for monitoring and avoiding such unhealthy ways. Regulatory bodies launched training programs also for the food handlers and consumers to ensure the food safety from farm to fork.

Findings

This paper will throw light on different malpractices followed by retailers to manipulate the quality which causes adverse health effects and to create consumer awareness regarding such malpractices.

Originality/value

The paper emphasizes on current malpractices followed by retailers to mislead the consumers about fruits’ and vegetable’ quality by using sweeteners, colors and other chemical. On prolonged consumption, such substances lead to major health issues such as attention disorder.

Details

Nutrition & Food Science, vol. 48 no. 4
Type: Research Article
ISSN: 0034-6659

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Article
Publication date: 8 March 2011

M. Vaezi, D. Safaeian and C.K. Chua

Conventional investment casting of turbine blades is a time consuming and expensive process due to the complications in wax injection steps and the complex shape of…

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1835

Abstract

Purpose

Conventional investment casting of turbine blades is a time consuming and expensive process due to the complications in wax injection steps and the complex shape of airfoil surfaces. By using rapid investment casting, a substantial improvement in the gas turbine blade manufacturing process can be expected. However, this process needs to be able to compete with conventional investment casting from a dimensional accuracy view of point. The purpose of this paper is to investigate the manufacture of gas turbine blades via two indirect rapid tooling (RT) technologies, namely epoxy (EP) resin tooling and silicon rubber molding.

Design/methodology/approach

The second stage blade of a Ruston TA 1750 gas turbine (rated at 1.3 MW) was digitized by a coordinate measuring machine. The aluminum‐filled EP resin and silicon rubber molds were fabricated using StereoLithography master models. Several wax patterns were made by injection in the EP resin and silicone rubber molds. These wax patterns were utilized for ceramic shell fabrication and blade casting.

Findings

Dimensional inspection of cast blades showed that silicone rubber molding was not a suitable approach for production of blade wax patterns. The maximum deviation for the final cast blade made using the silicone rubber mold was +0.402 mm. The maximum deviation for the final cast blade made using the EP resin mold was lower at −0.282 mm. This showed that EP resin tooling could enable new cost‐effective solutions for small batch production of gas turbine blades.

Practical implications

The research results presented will give efficient industrial approach and scientific insight of the gas turbine blade manufacturing by use of rapid technologies.

Originality/value

There are some general research works related to utilization of rapid technologies for manufacturing of gas turbine blade. However, this paper presents a unique procedure of integrated reverse engineering and RT technologies for rapid investment casting of gas turbine blade through presenting comprehensive comparison between two techniques from dimensional accuracy view of point.

Details

Rapid Prototyping Journal, vol. 17 no. 2
Type: Research Article
ISSN: 1355-2546

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Article
Publication date: 12 August 2021

Saravanan G., Shanmugam S. and Veerappan A.R.

This paper aims to determine the regression rate using wax fuels for three different grain configurations and find a suitable grain port design for hybrid rocket application.

Abstract

Purpose

This paper aims to determine the regression rate using wax fuels for three different grain configurations and find a suitable grain port design for hybrid rocket application.

Design/methodology/approach

The design methodology of this work includes different grain port designs and subsequent selection of solid fuels for a suitable hybrid rocket application. A square, a cylindrical and a five-point star grained were designed and prepared using paraffin and beeswax fuels. They were tested in a laboratory-scale rocket with gaseous oxygen to study the effectiveness of solid fuels on these grain structures. The regression rate by static fire testing of these wax fuels was analyzed.

Findings

Beeswax performance is better than that of paraffin wax fuel for all three designs, and the five-slotted star fuel port grain attained the best performance. Beeswax fuel attained an average regression rate ≈of 1.35 mm/s as a function of oxidizer mass flux Gox ≈ 111.8 kg/m2 s and for paraffin wax 1.199 mm/s at Gox ≈ 121 kg/m2 s with gaseous oxygen. The local regression rates of fuels increased in the range of 0.93–1.194 mm/s at oxidizer mass flux range of 98–131 kg/m2 s for cylindrical grain, 0.99–1.21 mm/s at oxidizer mass flux range of 96–129 kg/m2s for square grain and 1.12–1.35 mm/s at oxidizer mass flux range of 91–126 kg/m2 s for a star grain. A complete set of the regression rate formulas is obtained for all three-grain designs as a function of oxidizer flux rate.

Research limitations/implications

The experiment has been performed for a lower chamber pressure up to 10 bar.

Originality/value

Different grain configurations were designed according to the required dimension of the combustion chamber, injector and exhaust nozzle of the design of a lab-scale hybrid rocket, and input parameters were selected and analyzed.

Details

Aircraft Engineering and Aerospace Technology, vol. 93 no. 10
Type: Research Article
ISSN: 1748-8842

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Article
Publication date: 16 October 2019

Abubakar Abubakar Umar, Ismail Mohd Saaid, Rashidah Mohd Pilus, Aliyu Adebayor Sulaimon, Berihun Mamo Negash and Nurul Suhana Abd Rahim

This paper aims to examine the effect of wax, calcites and clay on the stability of petroleum emulsions. It proposes a proxy model that takes into cognizance the presence…

Abstract

Purpose

This paper aims to examine the effect of wax, calcites and clay on the stability of petroleum emulsions. It proposes a proxy model that takes into cognizance the presence of solids other than asphaltene and resin. This study aims to investigate the combined effects of these solids on the stability of emulsions and show their relevance or otherwise in the creation of petroleum emulsions.

Design/methodology/approach

This paper used synthetic emulsions based on a response surface methodology using different weight concentrations of wax, calcites and clay. A Box–Behnken design model was adopted and the effects of the different variables on emulsion stability were analyzed. The conventional visual observation (batch testing) was augmented with a more robust technique of studying emulsion stability (Turbiscan) based on light backscattering or transmission. Analysis of variance and other statistics were used to analyze the results.

Findings

The paper makes an available proxy model that can predict the stability of petroleum emulsions in the presence of wax, calcites and clays. The findings suggest that in the presence of significant amount of wax (0.3 Wt.%), the presence of relatively lower concentration of clay (0.1 Wt.%) produces very stable petroleum emulsions. The results show that the most stable emulsion is obtained when significant amount of wax exists in the continuous phase and that a concentration of calcites more than wax (in a ratio of at least 2:1) produces an emulsion that separates very fast, indicating low stability.

Research limitations/implications

Due to the variations in the amount of asphaltene and resins in crude oils, the proxy model cannot generally predict the stability of every emulsion that forms in the presence of these solids. To have a more general model, it should include asphaltene/resin. This can be tested further.

Practical implications

This paper provides useful information to the oil industry, especially where formation of severely stable emulsion is a problem. It also establishes the relationship that exists between solids in emulsion stabilization.

Originality/value

This paper satisfies a demand on the effects of other surface-active materials in addition to asphaltene/resin in stabilizing petroleum emulsions.

Details

World Journal of Engineering, vol. 16 no. 6
Type: Research Article
ISSN: 1708-5284

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Article
Publication date: 2 August 2011

Munish Chhabra and Rupinder Singh

This paper seeks to review the industrial applications of state‐of‐the‐art additive manufacturing (AM) techniques in metal casting technology. An extensive survey of…

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3585

Abstract

Purpose

This paper seeks to review the industrial applications of state‐of‐the‐art additive manufacturing (AM) techniques in metal casting technology. An extensive survey of concepts, techniques, approaches and suitability of various commercialised rapid casting (RC) solutions with traditional casting methods is presented.

Design/methodology/approach

The tooling required for producing metal casting such as fabrication of patterns, cores and moulds with RC directly by using different approaches are presented and evaluated. Relevant case studies and examples explaining the suitability and problems of using RC solutions by various manufacturers and researchers are also presented.

Findings

Latest research to optimize the current RC solutions, and new inventions in processing techniques and materials in RC performed by researchers worldwide are also discussed. The discussion regarding the benefits of RC solutions to foundrymen, and challenges to produce accurate and cost‐effective RC amongst AM manufacturers concludes this paper.

Research limitations/implications

The research related to this survey is limited to the applicability of RC solutions to sand casting and investment casting processes. There is practically no implication in industrial application of RC technology.

Originality/value

This review presents the information regarding potential AM application – RC, which facilitates the fabrication of patterns, cores and moulds directly using the computer‐aided design data. The information available in this paper serves the purpose of researchers and academicians to explore the new options in the field of RC and especially users, manufacturers and service industries to produce casting in relatively much shorter time and at low cost and even to cast complex design components which otherwise was impossible by using traditional casting processes and CNC technology.

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Article
Publication date: 1 May 2006

K. Dotchev and S. Soe

The main objective of this paper is to analyse all stages of the CastForm™ polystyrene (CF) pattern fabrication process, identify the reasons leading to inferior quality…

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1561

Abstract

Purpose

The main objective of this paper is to analyse all stages of the CastForm™ polystyrene (CF) pattern fabrication process, identify the reasons leading to inferior quality, and outline techniques for its improvement and reduction of failures.

Design/methodology/approach

This paper describes rapid manufacturing of patterns for shell or flask investment casting using the laser sintering (LS) technique with CF material. The process involves data preparation, LS fabrication of a “green” part, cleaning, and wax infiltration. All process stages are equally important for successful project completion in terms of pattern quality and delivery time. A failure at any stage requires a part or pattern to be produced again, which would incur additional time and cost.

Findings

The conducted experiments show how the CF material strength varies at different process stages and temperatures. Cleaning and wax infiltration are considered the main reasons for part distortion and breakage.

Originality/value

The paper proposes a new approach for wax infiltration. Deformation and breaking of unsupported features could be reduced or eliminated by introducing a supporting structure under these features.

Details

Rapid Prototyping Journal, vol. 12 no. 3
Type: Research Article
ISSN: 1355-2546

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