Foundry Industry Research Articles

Evaluation of Physical and Chemical Properties of South African Waste Foundry Sand (WFS) for Concrete Use

The foundry industry in South Africa forms one of the greatest industries in the manufacturing sector. It produces waste foundry sand (WFS) that ends up in landfill sites. Around 80% of the WFS could be utilized as a substitute for sand in concrete. The utilization of WFS will benefit the industry, as raw materials (natural sand alternative) and energy are conserved, while costs of disposal are lowered. Soil pollution, as well as water and air resources, will be minimized and the foundries’ competitiveness will be improved. In this study, the physical and chemical properties of five WFSs (two clays and three chemically bonded molding sands) from Gauteng, South Africa were analyzed. The samples were investigated with a view to determine their conformity with applicable engineering criteria when used as a replacement, to various extents, of the fine aggregate. The main properties investigated included physical properties (particle gradation, moisture content, un-compacted bulk density, specific gravity, loss on ignition, clay content, and fineness modulus) and the chemical properties (X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), pH). The sands generally did not meet the standards pertaining to grading requirements. However, the chemical test results showed the composition of these sands to be comparable with results from other investigations and suitable for use as a natural sand replacement in concrete.

Optimization and Predictive Modeling of Green Sand Casting Process to Minimize Persisting Defects in GI Components

Quality of castings produced by a sand casting process have always been the result of proper control over an enormous number of parameters involved in the process, while some of the defects are persisting. In the work presented in this paper, the primary focus is on the investigation of the essential parameters of the green sand casting process for effective understanding of most influential parameters which affects the persisting defects in gray cast iron components. The study applies the Taguchi's 'design of experiments' approach for determining the optimal level of parameters to minimise the persisting defects in the foundry industry producing cast components required in the automotive, factory situated in central India. Besides, a mathematical model has been developed using multiple regression analysis for an individual defect. The outcomes of this study assure that the approach used in this work is useful to foundry industries to minimise the casting defects.

Effect of Silica Fume and Foundry waste sand on strength characteristics of Geogrid and Ferro cement panel

The present study has made an emphasis for comparing the strength characteristics of ferrocement panels with panels made with HDPE geogrids. Also, an attempt has been made to replace cement partially by silica fume; which is a by-product obtained from the production of silicon and ferrosilicon alloys in the electric arc furnaces. The rise in the cost of river sand used as fine aggregate in concrete has increased the cost of construction significantly in the past few decades. Foundry Sand, which is obtained from the Foundry Industries are treated as waste materials that have the recycling capability in concrete and it is been proposed for partially replacing sand in this study. Different mix proportions using the above materials have been made and panels were prepared for optimum proportion based on the compressive and tensile strength of cube and cylinder specimens. Panels with two layers of steel mesh and geogrid mesh were cast. A comparative study on strength characteristics has been made and failure patterns of the panels have been studied. It was shown that strength of geogrid panels was on par with ferrocement panels and are advantageous to ferrocement panels in corrosion resistance and elasticity

Waste Foundry Sand/Bauxite Residue for Enhanced NO<italic>x</italic> Reduction in Diesel Exhaust Pretreated With Plasma/O3 Injection

The increased usage of diesel fuel of late has led the researchers to pay more attention toward abatement of increased emission of oxides of nitrogen (NOx) in the engine exhaust. The focus is, therefore, lies in providing a technique that is economical, feasible, and long lasting. The combination of electric discharge plasma with adsorbent/catalyst derived out of solid waste can be one such possible technique. In this paper, waste foundry sand from foundry industry and red mud or bauxite residue from aluminum industry have been used. Diesel engine exhaust under dry condition was exposed to an oxidizing discharge plasma environment. The plasma-treated exhaust was subjected to either adsorption over waste foundry sand or catalysis over red mud. Studies were carried out in the laboratory environment with 20% loading of diesel generator. The oxidizing plasma environment was either with direct plasma or with indirect plasma in which case ozone injection into the exhaust was accomplished. The ozone-adsorbent cascading system has resulted in about 87% NOx reduction in the dry exhaust case. The effect of O3:NO ratio was discussed from the point of NO/NO2.

Process knowledge for improving quality in sand casting foundries: A literature review

Foundry operation has many interlinked and complex processes that require skill and caution to ensure good quality of castings. The complex production processes and variables in the foundry industry also imposes quality limitation for final castings. Due to this, defect reduction still remains the main objective in sand casting foundries. In this regard, process knowledge is important in foundries to increase productivity by reducing sand casting defects. Process knowledge is defined as the identification of process variables. This includes the gathering approach, conceptualisation system and analysis to determine the varying process variables that are associated with product characterisation for final products. The paper presents a literature review on process knowledge in manufacturing focusing in sand casting method. It then explores possible application of this methodology specifically to the metal casting industry with the main aim of making it more competitive.

Experimental Study on Gas Evolution Process of Binders in Foundry Industry based on TG-MS

The gas evolution performance of the mold is a very important index, which is directly related to the quality of casting. As the gas generation of sand is much smaller than that of binder, the gas evolution process of binders plays a decisive role in the formation of defects such as pores during casting. Therefore, it is of great significance to study the gas evolution process of binders in foundry. In this study, TG-MS analysis will be introduced into the study of the gas evolution process of binders in foundry. Three kinds of resins in foundry and one kind of sodium silicate will be selected, and the binders will be tested by TG-MS after being hardened to find and analyze the types and temperatures of gassing in the heating process. This study helps to find out the regular pattern of gas evolution process of binders in foundry and to provide theoretical and practical guidance for the study of casting defects such as pores.

The influence of temperature conditions of melting on changes in interplanar distances in quartzite

The reliability of the operation of an induction crucible furnace of industrial frequency (IFC) used in the foundry industry depends on the durability of its lining. For this reason, a lot of research work is devoted to quartzite, as the cheapest material of the acidic lining, both in our country and abroad. The goal of the research is to develop the technology for the manufacture and operation of acid lining, which is used for smelting alloys at operating melting temperatures above 1450 ° C. The effect of melting temperature regimes on changes in interplanar distances in the structure of quartzite, affecting the stability of the furnace lining, is considered.Ill.4. Ref. 14.

Recycling of shards of quartz ceramic shells from investment casting

The use of quartz for its low-temperature modification creates additional risks in the manufacture of molds in the part of their reduced crack resistance due to polymorphous transformations and in practice it often leads to cracking and even destruction of individual layers of the shell wall or the mold as a whole. Preliminary calcination of the covering material practiced in many foundries can somewhat reduce the negative consequence of dangerous polymorphic transformations of quartz. But at the same time, smooth heating of the molds to reduce the likelihood of their cracking, which is carried out in the support filler, contributes to an increase in duration of the technological process and in additional energy costs. Among the options for reducing the likelihood of cracking and the destruction of RP during their calcination, the most popular is replacement of pulverized quartz sand, as filler, with dispersed quartz sand of a polyfraction composition, disten-sillimanite, pulverized aluminosilicate, spherical corundum or fused quartz. However, all of them are quite expensive and do not meet modern challenges and resource saving requirements in foundry and metallurgical industries. In this connection, attention is drawn to the ceramic shards of shells of steel and aluminum investment casting on silica-based models. At present, the shards of spent ceramic shell molds for investment models is not used for recycling. This material is sent to the dump or used as a supporting filler of the flasks when the shells are formed therein. The conducted component chemical and phase analysis of the material has shown that in shards of ceramic shells formed after knocking out steel and aluminum castings from molds, in addition to quartz in the high-temperature phases of tridymite and cristobalite (base), there are up to 5 - 10 % of iron and iron scale and 3 - 5 % of aluminum and its oxides. The use of ceramic shell shards as a covering material excludes the repeated polymorphic quartz transformations during calcination and pouring of shapes that determine the change in volume, density, and change in types of material crystal lattices, which makes it possible to increase the fracture toughness and strength of the shells and to minimize discard of the resulting castings. Residual iron, aluminum and their oxides contribute to improving the processability of the mold. Experimental testing of the proposed recycling option in the conditions of current production has confirmed its effectiveness.

Effects of heat and cyclic reuse on the properties of bentonite-bonded sand

Bentonite-bonded quartz sand is the most common mould material used in foundry industry. During casting, however, the moulding sand undergoes alterations, which deteriorate its properties. Aim of this work, therefore, was to gain accurate insights into the relation between smectite alteration and property change. To this end, the wet tensile strengths of heat pre-treated and cyclically reused sands were related to the kinematics of water within the sand as measured by in-situ neutron radiography and neutron diffraction. Sands subjected to 22 cycles of drying (T = 120 °C) and remoistening (3 wt%) revealed modifications of the d values of the basal reflections of smectites. No significant change of tensile strength, however, was associated with these modifications. Contrarily, sands pre-treated with temperatures as low as 225 °C revealed a reduction of tensile strength, which was neither correlated to the loss of tightly bound water nor to dehydroxylation. For temperatures above 300 °C a correlation between the reduction of tensile strength and the loss of tightly bound water or early dehydroxylation was evident. With completing dehydroxylation of the smectites above 670 °C, total loss of wet tensile strength of the pre-heated sands was observed. The results showed that cyclic use of moulding sand had little impact on the sand quality as long as the temperature of the sand remained low. For the practice in foundry, the results imply that a rigorous separation of heat-exposed sand is advantageous.

Impact of Quality of Work Life on Employees of Foundry Industries in Belagavi

Impact of Quality of Work Life on Employees of Foundry Industries in Belagavi

OBTAINING OF LOCALLY OPTIMAL SOLUTIONS BY COMBINING PROPERTIES OF MIXTURES FOR FOUNDRY MANUFACTURE

The aim of research is establishment of the relationship between the various properties of the mixture with liquid glass and hardener for the foundry industry – survivability, compressive strength and crumbling. Such an interrelation in the form of an adequate functional dependence makes it possible to assess the quality of the mixture for its compliance with the specified requirements, without resorting to additional laboratory measurements. It is very important to evaluate its suitability for the manufacture of rods, in particular, to meet the stringent requirements of production. Using the combined procedure of active and passive experiments, a regression equation was obtained describing the dependence of the mixture survivability on compressive strength and crumbling. It has been established that compressive strength is a more significant factor influencing survivability compared to crumbling, and it is almost 3 times (а1=0.36>а2=0.13). Analysis of the resulting regression equation shows that both of these factors have a positive effect on the survivability of the mixture – with an increase in compressive strength and crumbling, the survivability increases. In part, this conclusion requires confirmation in relation to crumbling, since the fact of a positive effect on survivability may be in doubt. By applying the procedure of comb analysis to the obtained regression equation, in order to describe the response surface, locally optimal solutions are established in the form of a ridge line. This line represents the optimal combination of compressive strength and shedding in the sense of ensuring the maximum survivability of the mixture. The corresponding ratios can be used as a nomogram, which allows to evaluate the ratios of the desired properties of the mixture, if it is fundamentally important to assess its quality by a set of properties.

Manufacturing feature-based cost estimation of cast parts

Seventy percent of new product cost is committed in the design phase. Therefore, the cost needs to be minimized. Incorporating accurate cost estimation capabilities into manufacturing processes can help industries to minimize the cost and optimize the design. The casting process has been employed as a key process to manufacture parts having the advantage of low cost and customized products in foundry industry. This paper presents a cost estimation system for the casting process based on the design features, which incorporates the casting information at the design stage of castings. It aims to deliver the best cost-effective choice for casting design features of a product. Two kinds of knowledge, namely economical knowledge (describing the relation between the casting design considerations and the cost) and technical knowledge (involving the material of the casting features) were structured in this research work. On the basis of the minimum product cost, casting material selection can be carried out in detail. The developed system has been validated through an industrial case study.

MATHEMATICAL MODELING OF METAL FLOW IN CRYSTALLIZER AT ITS SUPPLY FROM SUBMERSIBLE NOZZLE WITH ECCENTRIC HOLES

Flow of liquid melt in the crystallizer is a little-studied process. Analytical solutions of melt flow in general case refer to complex mathematical problems, therefore numerical methods are used to model it. The purpose of this work is to use numerical method proposed by Professor V.I. Odinokov, based on finite-difference representation of the initial system of equations. This method has been successfully used in mechanics of continuous media, in foundry industry in mathematical modeling of strained deformed state of shell molds on investment models,as well as in other technological works, which indicates its universality. In the present study, the object of research is hydrodynamic flows of liquid metal during steel casting into a rectangular section mold when fed from a submerged nozzle with eccentric holes, and the result is a spatial mathematical model describing the flows of liquid metal in the crystallizer. To simulate the processes occurring in the crystallizer, the software complex “Odyssey” was used. The theoretical calculation is based on fundamental equations of hydrodynamics and approved numericalmethod. Solution of differential equations system formulatedin the work was carried out numerically. Investigated area was divided into elements of finite dimensions, for each element the resulting system of equations was written in the difference form. The result of the solution is velocity field of metal flow in crystallizer volume. To solve the system of algebraic equations obtained, a numerical scheme and a calculation algorithm were developed. Based on developed numerical scheme and algorithm, a computation program was compiled in Fortran-4. Mathematical model makes it possible to vary geometric dimensions of the crystallizer and cross-section of metal exit openings from the immersion nozzle, and it can also help to understand the flow pattern of the cast metal that affects heat dissipation of crystallizer walls and to find the optimal parameters for liquid metal outlet from the gravy glass at various casting modes. As an example it is given calculation of steel casting into a rectangular mold with a height of 100 cm and a section of 2000×40 (cm) in plan. Casting was carried out from immersion nozzle eccentrically in both sides in a horizontal plane. The calculation results are presented in graphical form. The movement of liquid metal flows is shown, their magnitudes and intensity are determined.

Rapid casting of complex impeller based on 3D printing wax pattern and simulation optimization

Rapid casting is the product of digital, information, and optimization of casting technology. It mainly includes rapid prototyping and virtual manufacturing. In order to shorten the production cycle of a stainless steel closed impeller casting, the wax pattern was made by high impact polystyrene (HIPS) with a selective laser sintering and photosensitive resin with stereolithography (SL). In order to prevent the formation of shrinkage defects, different gating systems designed to examine the molten metal flow and solidification behavior during the pouring and solidification process. The results show that pouring temperature is 1550 °C and pouring speed is 0.75 m/s, which is favorable for filling impeller castings, and can avoid casting defects. The optimized gating system prevented surface shrinkage and interior defects. The optimized gating systems have been verified by experiment, and the rapid casting has been realized based on 3D printing wax pattern and simulation optimization. This rapid casting can reduce processing time and costs, and enhance casting quality in the foundry industry.

Furfuryl alcohol-aldehyde plywood adhesive resins

ABSTRACT Furfuryl alcohol, a biosourced material, is widely used in the foundry industry, and also as additive or modifier in the adhesives field. However, furanic resins have not been reported as being used alone as wood panel adhesives. In the present work furfuryl alcohol-aldehyde resins were prepared by reacting furfuryl alcohol with three different aldehydes, namely formaldehyde, glyoxal and glutaraldehyde. p-Toluene sulfonic acid and an acid self-neutralizing system were used as resin hardeners to prepare plywood and evaluate their bonding performances. Matrix assisted laser desorption ionization time of flight (MALDI-TOF), Fourier transform infrared (FTIR), nuclear magnetic resonance (13C-NMR) and thermomechanical analysis (TMA) were used to analyze the thermomechanical properties of the resins and the structure of the oligomers formed. The results showed that formaldehyde and glyoxal can react with furfurly alcohol to obtain resins of excellent performance. However, the reaction of glutaraldehyde with furfuryl alcohol appeared to be difficult, the self-condensation of furfuryl alcohol instead predominating. The acidity of the curing agent has a great influence on the bonding performance of the resin. The furfurly alcohol-glyoxal (FAG) resin showed also a good bonding strength and water resistance, higher than the standard requirements (≥ 0.7MPa), even when using an acid self-neutralizing system as hardener. The FAG resin was particularly good considering that no formaldehyde was used.

Effect of waste foundry sand addition on strength, permeability and microstructure of ambient cured geopolymer concrete

Increasing urbanization and industrialization is raising burden on existing natural resources used in construction industry which is leading to severe environmental issues. Using industrial waste materials in construction can be one alternative to curb this problem. Geopolymer concrete (GPC), known as the next generation of concrete, is more durable and environment friendly as compared to conventional concrete. The current investigation presents the effect of waste foundry sand (WFS), a by-product of foundry industries; on low-calcium fly ash based GPC. The WFS was replaced by natural sand in the range of 0% to 100%. Tests on hardened concretes, such as, compressive strength, split tensile strength and sorptivity were conducted to evaluate the strength as well as permeability of ambient cured geopolymer concrete. Results indicate consistent decrease in workability of concrete with increase in WFS content but its inclusion improved the strength as well as decreased the sorptivity of concrete upto 60% replacement level of WFS. Maximum enhancement of approximate 43% in compressive strength was achieved in the GPC with 60% replacement by WFS. The results are validated by conducting SEM study.

Analysis on the hazard factor of occupational eye disease on foundry industry

Through process analysis of foundry industry, the hazard factor of occupational eye disease on foundry industry were indentified and they included infrared ray, ultraviolet ray, X-ray, and dust. The occupational eye disease on foundry industry can be prevent by strengthen engineering protection, personal protection and enhance the management of occupational health. Key words: Foundry industry; Occupational eye disease; Hazard; Protection

Determination and Prediction of Respirable Dust and Crystalline-Free Silica in the Taiwanese Foundry Industry.

Background: Respirable crystalline silica (RCS) has been recognized as a human carcinogen; however, the measurement and analysis of RCS in small-scale foundries is rare and difficult. This study aimed to measure respirable dust and RCS levels among 236 foundry workers in Taiwan and used these data to establish predictive models for personal exposure. Methods: Personal sampling of various production processes were measured gravimetrically and analyzed using the X-ray diffraction method. Multiple linear regression was used to establish predictive models. Results: Foundry workers were exposed to geometric means and geometric standard deviations of 0.52 ± 4.0 mg/m3 and 0.027 ± 15 mg/m3 for respirable dust and RCS, respectively. The highest exposure levels were observed among workers in the sand blasting process, with geometric means of 1.6 mg/m3 and 0.099 mg/m3 for respirable dust and RCS, respectively. The predictive exposure model for respirable dust fitted the data well (R2 = 0.75; adjusted R2 = 0.64), and the predictive capacity for RCS was higher (R2 = 0.89; adjusted R2 = 0.84). Conclusions: Foundry workers in the sand blasting process may be exposed to the highest levels of respirable dust and RCS. The developed models can be applied to predict respirable dust and RCS levels adequately in small-scale foundry workers for epidemiological studies.

Manufacturing Refractory Bricks Using Exhaust Dust from Foundry Industries

The exhaust dust is an industrial waste that results from the sand molded casting process in the foundry sector. The metal casting industry plays an important role in the reduction of the environmental impact by recycling industrial waste. The idea of manufacturing thermally resistant refractory bricks made of exhaust dust from the foundry industry has motivated managers and researchers. The purpose of this study is to analyze the manufacturing process of refractory bricks made of 10, 20 and 30% exhaust dust and their properties. The dust was analyzed by using the SEM/EDX and XRD techniques. Results show that the specimens used in this study did not meet the required water absorption specifications. However, the 10% and 20% samples presented a desirable porosity. The manufactured bricks were classified as dense, insulating and semi-insulated, respectively. In relation to compression resistance the rupture stress proved to be lower than the level of stress detected in commercial bricks. The temperature test showed that bricks made of exhaust dust cannot be considered refractory for commercial purposes. Although the exhaust dust does have some refractory properties it still cannot be used as raw material in the manufacturing of refractory bricks since it does not meet all the necessary specifications as proposed by this study.

Failure analysis of a railway brake disc with the use of casting process simulation

Abstract Software for modelling of industry processes is an integral part of production involving many segments of industry. The use of simulation software in foundry industry is perceived as a tool for visualization of ongoing processes in casting production. These tools eliminate defects and imperfections within the process before the production even begins which has a subsequent positive effect on quality increase and reduction of financial costs in product manufacturing. The paper deals with a solution of formation and occurrence of foundry defects such as shrinkage in the casting produced from ductile iron with the use of simulation software. The casting of railway brake disc and its 3D model were used in the experiments. The goal of the study was evaluation of simulation results with regard to casting quality increase and decrease of shrinkage formation, as well as decrease in manufacturing costs during casting production. The paper focuses on a possibility of improving the utilization of liquid metal in the solidification of castings with the help of simulation that compares basic as well as adjusted parameters of casting. Computer simulation of casting uncovered the gating system elements' adjustments and technological modifications effect on the entire casting and on reduction or elimination of shrinkages incidence along with the increase of liquid metal utilization during casting. These imply the reduction of financial costs and increased efficiency in production of castings. The paper presents the results of the simulation casting of the railway brake disc. Based on the results of these simulations, the shape of gating system and position of casting in mould was modified and the number of feeders has been reduced from 6 to 1. This technology modification saves the liquid metal and the casting has been without shrinkages.