Sand Foundries Research Articles

Data-Driven Process Analysis for Iron Foundries with Automatic Sand Molding Process

This paper proposes a methodological framework to develop a data-driven process control using pure industrial production data from a cast iron foundry, despite the limitation of complete casting traceability. The aim is to help sand foundries to produce good castings. A reference foundry, which produces mainly automotive and oven parts with automatic sand molding and pouring machines, was selected. Past data, where only good castings were produced, were extracted from the database to determine parameter control limits (upper and lower control limits) with the aid of statistical approach. To identify critical process parameters associated with casting defects, process data from the zero and high scrap production batches were systematically compared. This method clearly identified unstable parameters without exact synchronization between inline and part quality data. Molding sand moisture, temperature and compactability, liquidus temperature of the melt, phosphorus content, carbon equivalent and pouring temperature were found to be the critical parameters to be stabilized. Finally, a regression model for predicting and controlling of molding sand moisture and liquidus temperature of the melt was created. The determined boundaries and the models were helpful for the foundry in assisting ongoing production control and correction of process inputs to achieve target casting quality.

Mechanical Properties Improvement of Clays Using Silica Sand Waste and Dust Sand Foundry Waste

The increase of industrial waste and many road damages due to unstable subgrade invite the research on soil additives made from waste treatment as stabilizers to improve the mechanical value of clay. This study used California Bearing Ratio Test based on the ASTM standard for mechanical properties testing of clay. The soil stabilization method was carried out by mixing the clay with Silica Sand waste and Dust Sand Foundry waste in a predetermined composition. California Bearing Ratio value of 2.5 mm penetration showed a significant increase of 47.9% from the original clay in the composition of the waste 5% Silica Sand and 5% Dust Sand Foundry.

Unconfined compression strength of soil using silica sand waste and dust sand foundry as a stabilizer

The need to improve the subgrade of a highway becomes urgent when the vehicle load exceeds the carrying capacity of the soil. Industrial waste, that increase every day, was proposed in this study as an additive or stabilizer to improve the carrying capacity of the subgrade. Testing was done through laboratory experiments of the mixing original soil with Silica Sand waste and Dust Sand Foundry waste in certain compositions. To test the mechanical properties, the Unconfined Compression Strength Test based on ASTM standards was conducted. The unconfined compression strength (qu) value of the original soil was 0.289 kg/cm2. The highest qu value was shown in the composition of the soil mixture with 2.5% SS and 7.5% DSF which was 0.347 kg/cm2. The qu value increased by 20.07% from the qu value of the original soil, and showed a mechanical improvement in stabilizing soil.

Defect Reduction in Ring Blank Casting Through Design of Experiments

This research was carried out to optimize the pattern design parameters and to reduce the cold metal (CM) defect during piston ring blank casting made in high pressure green sand foundry. Design of experiments methodology was used to minimize the defect level in gating system of the pattern design. Multiple input factors are considered and controlled simultaneously to ensure that the effects on the output responses are causal and statistically significant. Metal feeding system parameters like runner diameter, choke thickness and pouring basin weight with different level were taken as input factors for this study. A full factorial design was used to design the experiment and the established variable relationships and studies on interaction effects were discussed in this study. Experimental data were statistically analyzed and optimized by using Yates method of computing factorial effects.

Competitiveness of South African Foundries – A Review and Comparison of Sand, Permanent Mould and Investment Foundries

South African Foundries have promptly been met with challenges from international competition due in part to trade “liberalisation” of South African foreign trade. To objectively evaluate the challenge, data from selected local foundries were analysed together with and compared to international data from selected countries from industry and specific foundry macro level. The review seeks to evaluate the impact of resource use efficiency and resource specific cost on the local foundry and compare the challenges and opportunities available specifically to the local foundry industry. A simplified financial model was used to output an income statement type result containing the major cost elements, to arrive at levels of profitability, which was used to evaluate and compare the competitiveness of the local to international foundry industry. From these results, some macro suggestions for the local foundry industry to achieve sustainable cost competiveness improvements become apparent. Index Terms: South African Foundries, Sand, Investment, Die, Gravity, High Pressure, Benchmarking, Resource efficiency, Resource usage, Resource costs, International comparison.

Measurement of Elastic Modulus of PUNB Bonded Sand as a Function of Temperature

The stiffness of molds and cores has a large effect on casting quality in sand foundries. Measurements of the elastic modulus of PUNB bonded silica sand are performed from room temperature to 500C (932F). The measurements are taken almost instantaneously during the heating to capture the changes in the elastic modulus throughout the temperature range. The effect of the heating rate is investigated in detail. For an intermediate heating rate of 8C/min (14.4F/min), the elastic modulus decreases steeply from a room temperature value of about 3,900 MPa to 600 MPa at 125C (257F). Above 250C (482F), it increases to 1,200 MPa at 280C (536F) and then decreases again to 900 MPa at 325C (617F). Above 350C (662F), the elastic modulus increases almost linearly with temperature until it reaches 2,400 MPa at 500C (932F). At approximately 500C (932F), the strength of the bonded sand vanishes. At elevated temperatures, the elastic modulus is found to be a strong function of the heating rate and time. For example, while holding a specimen at a constant temperature of 200C (392F) for 30 min, the elastic modulus can increase from 600 MPa to 2,000 MPa. Only the steady-state values of the elastic modulus are in agreement with previous measurements. Upon cooling to room temperature, the bonded sand regains its full stiffness only for holding temperatures below about 275C (527F). These variations in the elastic modulus with temperature correlate well with the physical and chemical changes the binder undergoes during heating. Additional experiments are needed to investigate the elastic modulus variation for higher heating rates and other binder systems.

Comparison of Hydroxyl Radical Generation for Various Advanced Oxidation Combinations as Applied to Foundries

The authors monitored hydrogen peroxide (H2O2), ozone (O3), and apparent hydroxyl radical (OH·) concentrations in the liquid phase, along with gas phase ozone when operating an advanced oxidation (AO) system that included H2O2, O3, sonication, and underwater plasma (UWAP). The OH· radical converted non-fluorescent terephthalic acid to fluorescent hydroxyterephthalic acid (HTA). As determined from HTA formation, when a 500 ppm H2O2 dose in tap water was combined with O3 and sonication, nearly twice as much OH· (0.72 ppm) accumulated than with H2O2 alone. When UWAP accompanied H2O2, O3, and sonication, these together generated 15–35% more OH· than when UWAP was excluded. When ozone was introduced into this AO system, the AO system decomposed almost all the O3. This research has been conducted as a part of a study that has appraised this advanced oxidation system (Sonoperoxone) in green sand foundries, where it has diminished volatile organic compound (VOC) and hazardous air pollutant (HAP) emissions by 20–75%; and clay and coal consumption by 20–35%.

Characterization of Hydrocarbon Emissions from Green Sand Foundry Core Binders by Analytical Pyrolysis

Analytical pyrolysis was conducted to study a relative comparison of the hydrocarbon and greenhouse gas emissions of three foundry sand binders as follows: (a) conventional phenolic urethane resin, (b) biodiesel phenolic urethane resin, and (c) collagen-based binder. These binders are used in the metal casting industry for making cores that are used to create internal cavities within castings. In this study, the core samples were flash pyrolyzed in a Curie-point pyrolyzer at 920 degrees C with a heating rate of about 3000 degrees C/sec. This simulated some key features of the fast heating conditions that the core binders would experience at the metal-core interface when molten metal is poured into green sand molds. The core samples were also pyrolyzed in a thermogravimetric analyzer (TGA) from ambient temperature to 1000 degrees C with a heating rate of 30 degrees C/min, and this simulated key features of the slow heating conditions that the core binders would experience at distances that are further away from the metal-core interface during casting cooling. Hydrocarbon emissions from flash pyrolysis were analyzed with a gas chromatography-flame ionization detector, while hydrocarbon and greenhouse gas (CO and CO2) emissions from TGA pyrolysis were monitored with mass spectrometry. The prominent hazardous air pollutant emissions during pyrolysis of the three binders were phenol, cresols, benzene, and toluene for the conventional phenolic urethane resin and biodiesel resin, and they were benzene and toluene for the collagen-based binder. It was also found that volatile organic compound and polycyclic aromatic hydrocarbon emissions considerably decreased in order from conventional phenolic urethane resin to biodiesel resin to collagen-based binder. These results have shown some similarity with those for stack emission testing conducted at demonstration scale and/or full-scale foundries, and the similar trends in the two sets of results offered promise that bench-scale analytical pyrolysis techniques could be a useful screening tool for the foundries to compare the relative emissions of alternative core binders and to choose proper materials in order to comply with air-emission regulations.

Pyrolysis of carbonaceous foundry sand additives: Seacoal and gilsonite

Seacoal and gilsonite are used by the foundry industry as carbonaceous additives in green molding sands. In this study, pyrolysis was used to simulate the heating conditions that the carbonaceous additives would experience during metal casting. Gas chromatography–mass spectrometry was used to tentatively identify major organic products generated during their pyrolysis at 500, 750, and 1000 °C. A number of compounds of environmental concern were identified during the pyrolysis of seacoal and gilsonite, including substituted benzenes, phenolics, and polycyclic aromatic hydrocarbons (PAHs). These thermal decomposition products, and especially PAHs, were generated at each pyrolysis temperature in all foundry sands containing seacoal. In gilsonite-amended sand, however, mainly alkanes and alkenes were identified at 500 and 750 °C and PAHs at 1000 °C. Compared to seacoal, the most intense peaks occurred during the pyrolysis of sand containing gilsonite. The greatest loss of pyrolyzable material also occurred during heating of gilsonite-amended sand from ambient temperature to 1000 °C in a thermogravimetric analyzer. The results obtained from this study will be useful to green sand foundries looking to reduce volatile hydrocarbon emissions.

Evaluation of Volatile Hydrocarbon Emission Characteristics of Carbonaceous Additives in Green Sand Foundries

This research studied a relative comparison of the hydrocarbon emissions during pyrolysis of four carbonaceous additives that can be used in green sand foundries. These included a highly volatile bituminous coal, anthracite, lignite, and cellulose. Analytic pyrolysis was conducted to simulate the heating conditions that the carbonaceous additives would experience during metal pouring. Specifically, the samples were flash pyrolyzed in a Curie-point pyrolyzer at 920 degrees C with a heating rate of about 3000 degrees C/sec. This simulated some key features of the fast heating conditions that the carbonaceous additives would experience at the metal-mold interface when molten metal is poured into green sand molds. The samples were also pyrolyzed in a thermogravimetric analyzer (TGA) from ambient temperature to 1000 degrees C with a heating rate of 20 degrees C/min; and this simulated key features of the slow heating conditions that the carbonaceous additives would experience within the bulk of green sand molds that is further away from the metal-mold interface. Hydrocarbon emissions from flash pyrolysis were analyzed with GC-FID, while those from TGA pyrolysis were monitored with mass spectroscopy and GC-FID. The anthracite exhibited very low volatile hydrocarbons during both flash pyrolysis and TGA pyrolysis. The cellulose released less hydrocarbons than bituminous coal or lignite in TGA pyrolysis, but more hydrocarbons than those two during flash pyrolysis. This means that cellulose can release sufficient volatile hydrocarbons at the intensely heated molten metal-mold interface where they are most desired for ensuring casting quality, but much less within the bulk of the mold where they are undesirable. This characteristic of cellulose offers an important opportunity for green sand foundries to diminish their hazardous air pollutant (HAP) emissions.

Epidemiological adaptation of quartz exposure modeling in Swedish aluminum foundries: nested case-control study on lung cancer.

In a recent cohort study in aluminum foundries and remelting plants an unexpectedly high risk of lung cancer was found in workers in sand foundries. On the basis of present and historical measurement data, we developed a statistical model for exposure to total dust and crystalline quartz for different jobs and time periods. Cumulative dose estimates of total dust and crystalline quartz were calculated and used in a nested case-control study in the cohort. From the cohort of foundry workers (n = 5016), 46 cases of lung cancer were identified. The final analysis was performed on 31 cases and 233 controls with one year or more of employment. Historical measurement data from the 1960s and onward were collected, totaling 203 total dust and 103 crystalline quartz exposure observations. Regression models, using the determinants of job title, time period, type of foundry, and size of production, were developed for assessing historical total dust and crystalline quartz air concentrations. These estimates were used to calculate individual cumulative exposure in the case-control study. In the multiple linear regression analysis, the determinants explained much of the variations in dust level (r(2) = 0.58). The explained variation in crystalline quartz was much lower (r(2) = 0.13). The regression coefficients for the type of foundry, time period, and size of production were statistically significant for total dust. On the basis of the regression analysis, the final models were used to calculate individual cumulative exposures. The calculated cumulative dust and quartz exposures averaged 33 mg/m(3) * year and 0.42 mg/m(3) * year, respectively. The odds ratios (ORs) were not significant, but showed dose-response trends for both dust and crystalline quartz.

Gating and risering in vertical green sand moulds

The high number of successful green sand foundries working with vertical moulding equipment is the best proof of the advantages of this technology. It provides high productivity and accurate positioning of cores. It offers the freedom to design and produce with optimal functioning gating systems to secure good casting quality.The aim of the paper is to look into new ways of improving this successful casting technology. First a short introduction to the advantages of vertical moulding will be presented.The next subject is the advantages of utilising casting process simulation to optimise casting layout, gating and risering. Focus is on castings produced in the conventional way as well as on castings that are produced using the newly developed active feeding and active bottom filling technique.The last subject is to investigate if this new active feeding technique could be used for iron castings too. Experimental casting trials, as well as numerical simulation results, indicate that it is also functioning for iron castings; so the limiting factor will be the availability of robust equipment, which can keep up with the very fast vertical moulding machines.

Exposure to chemical agents in Swedish aluminum foundries and aluminum remelting plants--a comprehensive survey.

Secondary aluminum melting is mainly performed in sand, die, and static die-casting foundries and remelting plants. In seven Swedish foundries and two remelting plants, the exposure and area concentrations of total dust, metals, organic gases, and vapors were determined mainly as daily, time-weighted averages (TWAs). For most combinations of jobs and agents, the exposure levels were well below the current threshold limits suggested by the American Conference of Governmental Industrial Hygienists (ACGIH). However, high exposure levels of mineral oil mist (geometric mean [GM] = 0.6 mg/m3) were observed in the die-casting process, with a maximum of 4 mg/m3. The findings were similar for total dust (GM = 5.1 mg/m3) and crystalline quartz (GM = 0.05 mg/m3) during molding operations in the sand foundries, maximum air concentrations being 31 mg/m3 and 0.22 mg/m3, respectively. Other agents which occasionally reached high exposure levels included furfuryl alcohol (up to 23 mg/m3 during furan binder use in sand foundries), aniline (up to 2.6 mg/m3 during thermal degradation of cold-box binders), and dimethylethylamine (up to 9 mg/m3) in the cold-box process used in static die-casting and sand foundries. The average aluminum exposure levels (GM = 0.043 mg/m3) were low in all foundries, individual values not exceeding 0.94 mg/m3. The exposures to metals were below 10 percent of their threshold limits. Similarly low levels were detected of polyaromatic hydrocarbons, phenol, formaldehyde, methylenebisphenyl diisocyanate, and phenylisocyanate. In the aluminum remelting plants, a few high exposure levels of total dust (GM = 1.4 mg/m3) up to 8 mg/m3 were detected in furnace workers. Aluminum and other metals were well below 10 percent of their threshold limits, with the exception of a few high concentrations of manganese, up to 0.14 mg/m3. The between-worker variability (GSDB) in the foundries for total dust, aluminum, and oil mist were on the order of 3-4. The heterogenicity of secondary aluminum melting requires assessment of a wide variety of chemical agents. For certain exposures, technical and medical monitoring programs are still needed.

Multi-agent approach and stochastic optimization: random events in manufacturing systems

We propose a method to solve industrial problems and to take into account random events. It is called the triple coupling. It is based on stochastic algorithms, a simulation model and the multi-agents model of artificial intelligence. The method we propose is easy to use and allows us to take into account most of the constraints found in manufacturing systems. Experts look for solutions to increasing the capacity of production. But the production can be disturbed by random events experienced by the system. Industrial experts need schedules which prevent the consequences of random events. Minimizing such consequences is very important to increasing system delivery. Capital investment is often very high in factories and the cost of the investment goes on regardless of whether the resources are running or not. The multi-agent approach is used to determine schedules for which the consequences of random events are low, and a stochastic algorithm is proposed which permits us to optimize a random variable. We prove that this algorithm finds, with probability one, the schedule of the production for which the consequences of random events are the lowest. We propose to measure the consequences of random events using an influence ratio. Our approach has been used to study the consequences of random events in Peugeot sand foundries of Sept-Fons (France). A benchmark test is presented to prove the efficiency of our solution. For the Peugeot sand foundry of Sept-Fond, random events increase the production time by about 20% compared with the production time without any random events occurring. We have determined schedules of production for which the consequences of random events are about 0.5%.

Modeling of the behavior of an integrated industrial system during a catastrophe

Lines and groups of equipment including robots are recognized as the basic level of the Integrated Industrial System, IIS. The management system is considered as a high level of the IIS which is controlled with a Hierarchical Numerical Control, system HNC. Metallurgical objects, in particular sand foundries are taken into consideration. The evaluation criterion of a catastrophe course is the speed of the decrease in the IIS reliability (R) in the crash time period ( τ cr): V R = dR/dτ cr . If failures appear, then V R≈0 and the system structures tolerates the failures. If the failures increase, the threshold tolerance is crossed, and V R will increase as well. V R assumes low values for the soft degradation of the IIS system, while V R → ∞for the crash degradation. The course of catastrophe can be simulated by testing the IIS system model. Simulating testing of the IIS takes into consideration the transformation of reliability structure under the influence of load changes. This process determines the behavior of the system during a catastrophe. The basis for determining the transformation is the construction of a formula for a generalized reliability connection. The generalized reliability connection is characteristic for reactions of the soft degradation type. During a catastrophe caused by system load growth and decreasing reserves, there occurs an IIS structure transformation in the following sequence: • -parallel multibranch reserving with multiple reserve, • -parallel singlebranch reserving with full reserve, • -parallel with partial reserve, • -series. If one element is damaged after the final stage transformation (for the series structure), the IIS system will be crashed. Evaluation of the course of a catastrophe of the IIS system allows: (1) the correct decisions for the prevention of the catastrophe, (2) the design of the fault tolerance system architecture when V R ≈0.

Titanium Casting with Sand Foundry Techniques

The ability to produce a east titanium configuration has a history of approximately 10 years. It is presently being done in the United States by six companies. Casting of titanium is no simple task when one considers the thousands of foundries in existence producing cast parts from other metals. The difficulties are that titanium must be handled more carefully because molten titanium is very reactive to liquids, gases, and solids. At present, consumable vacuum arc melting offers the only suitable commercial method of producing titanium castings. The rapid contamination of titanium at elevated temperature by oxygen and nitrogen and the severe damage to ductility by small percentages of such contaminants requires that melting of titanium be done in the absence of air. Because liquid titanium is an extremely effective solvent, problems of containing the molten metal within a crucible during the melting operation are encountered. A water-cooled copper crucible is used to extract heat so rapidly from the liquid metal that it solidifies before its solvent reaction can take effect. This provides a thin film of solid titanium between the molten titanium and the copper crucible. This is referred to as skull melting. The liquidus to solidus range of titanium is quite narrow and problems of fluidity exist. When enough molten titanium is accumulated in the crucible, the power is cut, the electrode is rapidly withdrawn, and the pot is tilted, all within a few seconds or the pool will solidify. A centrifuge is used within the furnace vacuum chamber during the pouring of the melt. The high g forces during the casting operation help overcome the lack of fluidity. The centrifuge action assists in filling mold cavities with metal densities vastly superior to those from conventional sand foundry static casting. Conventional materials such as sand, shell, or ceramic molds are unsatisfactory for titanium since titanium above or near its melting point will violently react with these materials. A water soluble, expendable graphite mold system is a relatively new development in titanium casting and configurations with close tolerances and excellent surface finish are obtainable. New information related to the production of titanium castings with the latest applied technology was presented.