Molten Metal Temperature Research Articles

Bulge-Free and Homogeneous Metal Line Jet Printing with StarJet Technology.

The technology to jet print metal lines with precise shape fidelity on diverse substrates is gaining higher interest across multiple research fields. It finds applications in additively manufactured flexible electronics, environmentally friendly and sustainable electronics, sensor devices for medical applications, and fabricating electrodes for solar cells. This paper provides an experimental investigation to deepen insights into the non-contact printing of solder lines using StarJet technology, eliminating the need for surface activation, substrate heating, curing, or post-processing. Moreover, it employs bulk metal instead of conventional inks or pastes, leading to cost-effective production and enhanced conductivity. The effect of molten metal temperature, substrate temperature, standoff distance, and printing velocity was investigated on polymer foils (i.e., PET sheets). Robust printing parameters were derived to print uniform, bulge-free, bulk metal lines suitable for additive manufacturing applications. The applicability of the derived parameters was extended to 3D-printed PLA, TPU, PA-GF, and PETG substrates having a much higher surface roughness. Additionally, a high aspect ratio of approx. 16:1 wall structure has been demonstrated by printing multiple metal lines on top of each other. While challenges persist, this study contributes to advancing additively manufactured electronic devices, highlighting the capabilities of StarJet metal jet-printing technology.

Modelling of kerf width and surface roughness using vibration signals in laser beam machining of stainless steel using design of experiments

Manufacturing industries are increasingly interested in laser beam machining as an efficient material removal process. Accordingly, there is great motivation in the modelling of the machining process to understand the physics behind the machining process in order to improve the machining efficiency. The present study made an attempt to predict surface roughness, kerf width and metal removal rate by utilizing the vibration signals measured during the laser beam machining of AISI 304 stainless steel. As per Taguchi’s L9 design of experiments, nine experiments were conducted at three levels of laser power (2.0, 1.5 and 1.0 kW), laser frequency (10, 8 and 6 kHz), cutting speed (3.0, 2.5 and 2.0 m/min) and nozzle tip distance (1.2, 1 and 0.8 mm) on 6 mm thickness of sheet metal and the vibration of sheet metal was measured using an accelerometer. It was observed that, the sheet vibration along the cutting direction increased the metal removal rate and sheet vibration perpendicular to the cutting direction caused surface roughness. Mathematical models were developed with the vibration data and predicted the surface roughness, kerf width and metal removal rate. The root mean square error of the responses was calculated as 0.615 µm, 5.44 µm and 0.259 m3/min for surface roughness, kerf width and metal removal rate respectively, demonstrating a significant correlation with experimental results. Furthermore, effect of laser power, laser frequency, cutting speed and nozzle tip distance on the surface roughness, kerf width, heat affected zone and metal removal rate was studied. The laser power and cutting speed have significant effect on these responses. Finite element modelling based simulation was carried out and studied effect of molten metal temperature on the heat affected zone. Temperature in the molten pool reached to maximum of 1773 K and the heat affected zone increased, when the laser power increased to 2.0 kW. The root mean square error between the measured and simulated heat affected zone was computed as 4.68 µm, indicating a good correlation between both.

The Effect of Aluminium Injection Parameters on the Mechanical Properties of the Material Produced by High Pressure Die-Casting

Aluminium is one of the basic materials used in many sectors, especially in automotive, defence and aviation. Generally, aluminium parts are manufactured by using injection molding methods in many sectors, such as automotive, etc. Injection presses that are used for die-casting material have a lot of parameters, affect the molded parts’ properties. In this study, the effect of injection parameters on the mechanical properties was investigated. Firstly, a test part that is shaped currently on the injection press machine in a sector was found out. An aluminum alloy, named Al〖Si〗_12 Cu (EN AC 47000), that is used widely in die-casting techniques was preferred. Three injection parameters, such as, injection velocity (m/s), time of the mold opening (s) and molten metal temperature (0C), were selected. And all works were planned with the full factorial experimental design method. Thus, the test parts were manufactured by using an injection molding machine. Moreover, many tests, such as hardness and tensile, were performed on the test parts to investigate the effect of injection parameters on the mechanical properties of the material. The tests were analysed with the full factorial and ANOVA method. As a results of the analysis, the highest hardness value was obtained as 85 HB when the molten metal temperature was 750 ℃, the injection velocity was 1.3 m/s, the mold opening time was 10 s, and the highest breaking strength was obtained as molten metal temperature 725 ℃, injection velocity 4 m/s, when the mold opening time was 12 s was found to be 264 MPa.

A novel strategy to prevent hydrogen charging via spontaneously molten-slag-covering droplet transfer mode in underwater wet FCAW

Underwater wet welding is widely used in offshore platform maintenance, oil pipeline repair and wreck salvage operations. A high diffusible hydrogen content is recognized as one of the critical reasons behind the reduction in the reliability of underwater wet welded joints. In this study, the entry route of hydrogen during underwater wet flux-cored arc welding of 304 stainless steel at a depth of 0.5 m was first confirmed experimentally using an in-situ X-ray imaging system. The hydrogen charging was deemed to dominantly occur when pendant droplets were formed due to the extremely high temperature of molten metal and the absence of slag coverage. This resulted in 13.51 mL/100 g of diffusible hydrogen remaining in the droplet and 9.42 mL/100 g in the deposited metal. To prevent hydrogen charging, an unprecedented molten-slag-covering droplet transfer mode was developed by reducing the CaF2 content and maintaining the CaF2/TiO2 to an appropriate ratio in the flux, through which the molten slag spontaneously covered the droplet, electric arc and molten pool completely during the entire welding process and the entry of hydrogen was successfully blocked and the diffusible hydrogen content was reduced to the same level as that achieved via onshore welding (3.26 mL/100 g).

Examination of a Method for Estimating Solid Fraction at Flow Cessation from Flow Velocity of Mushy Formation Molten Alloys

The purpose of this study was to experimentally estimate the solid fraction at which the cessation of the flow of a molten Al–7%Si–0.3%Mg alloy and Cu–8%Sn alloy occurs in casting. The flow cessation mechanism of two alloys is known as the “mushy” formation type, which means that the flow ceases when the solid fraction at the molten metal tip reaches a certain critical value. Therefore, the flow velocity at the molten metal tip is assumed to decrease gradually. Thus, a new method for calculating the solid fraction at flow cessation based on computer simulations was examined using experimental measurements of the flow velocity and flow length. The result of the experiment shows the experimental flow length is consistent with the simulation results, the calculated solid fraction at flow cessation. The flow velocity gradually decreased from the initial stage, but there was a region where the velocity was almost constant after the initial stage. The molten metal temperature became lower from the root side to the tip side, and the solid fraction at the time of flow cessation was calculated from the measurement results, for the Al–7%Si–0.3%Mg alloy it was 0.35–0.4 near the tip, and for the Cu–8%Sn alloy it was 0.25. Computer simulations were performed by tuning the heat transfer coefficient so that the flow length and flow velocity would match the experimental results. Computer simulations were performed by tuning the heat transfer coefficients so that the flow length and flow velocity would match the experimental results and could simulate the changes in flow velocity obtained from the experiments. The solid fraction at the tip of the molten metal was almost the same as the experimental results. These results show that it is possible to estimate the solid fraction at the flow cessation from the flow velocity at the tip.

The Effect of Temperature, Cooling Rate and Casting Speed on Quality of Continuous Cast Steel Billets

In continuous casting, the cooling rate, casting speed, and molten metal temperature significantly affect the quality of cast steel billets. Appropriate casting parameters can minimize quality problems such as surface, subsurface and interior crack, rhomboidity, oscillation mark depth, and central porosity. This research determines the relationship between defects and three significant factors temperature, cooling rate, and casting speed. The work has been performed on the two-strand continuous casting machine to investigate the billet (BS-4449 steel grade) cross-section of 150 x 150 cm2. The defects analysis through macro examination at different tundish temperatures (1510 °C to 1560 °C), varying cooling rates, and casting speeds (0.9 to 1.6 m/min). The present study provides detailed insight into the three parameters mentioned earlier, which directly affect the quality of cast steel billets.

Semisolid Casting and Die Casting of Al-4.8%Mg-2%Si Alloy

An aluminum alloy, Al–4.8%Mg–2%Si, was cast by die casting and thixocasting, and the properties of the cast specimens were investigated. When the poured molten metal temperature was lower than 640 °C during die casting, it was lower than the liquidus temperature, and the metal became a semisolid slurry in the sleeve of the die casting machine; this fulfills the conditions for rheocasting. A tension test was conducted to investigate the effects of semisolid casting on the mechanical properties of Al–4.8%Mg–2%Si. The ultimate tensile strength and elongation of the ingots cast by die casting and rheocasting were affected by the size of ingot. When the ingot had a circular base of 4.5 mm diameter, the ultimate tensile strength and elongation were excellent; however, when the cross section of the ingot was a square with a side length of 20 mm, the tensile strength and elongation were inferior. The thixocasting was conducted using square ingots with a side length of 20 mm, and the tensile strength and elongation were poor in this case as well. The results of this study demonstrate that semisolid casting cannot improve the mechanical properties of Al–4.8%Mg–2%Si ingots with a high thickness. Semisolid casting cannot produce fine-grained Mg2Si, and the mechanical properties of the material could not be improved by this casting method.

A study of process optimization of carburetor die casting process

Die-casting is a multipurpose practice for casting metallic components in high volume by pouring metal at high pressure into metal molds. In the present study, zinc based alloys having high ductility, impact strength and can be easily plated, are used to cast the carburetor. Zinc based alloys are also easy to cast, economical for small parts, good die life and low melting point. Defects arising in castings are mainly depends upon the solidification process and the intermediate temperature profiles, as the temperature gradients inside the casting will decide that a section in solidification stage has availability to necessary quantity of higher temperature molten metal. The consequences of die casting process parameters has not been deliberated widely to minimise the defects like tear out & misrun. The present work has been carried out to minimize the rejection rate due to these casting defects in die casting process of zinc alloy by adjusting parameters, molten metal temperature and time needed for solidification. During analyzing the previous data of production of castings, it was noticed that the Mixing Chamber Body of carburetors had a rejection rate of about 14–15%, but with the use of design of experiments using Taguchi method this rejection rate is reduced to 6.7%. ANOVA is used to specify the significant factors and solidification time has 92.5% contribution to minimize the defects. Confirmatory test performed at these optimal settings concluded that within 95% confidence interval casting defects were minimum. As the solidification time increases number of casting rejection rate decreases rapidly and at 6 s performed better result with lesser no. of defects and hence more effective.

Optimal design of die casting process parameters of A713 cast alloy with grain refinement by using genetic algorithm approach for automobile industries

Die casting with aluminium alloy has potential applications but often results in castings with poor properties due lagging in density, and it is mandatory to predict the nature of the output responses before manufacturing. Genetic algorithm (GA) approach prediction model helps in optimal output responses before the actual production in die casting. In this research, GA approach for optimising the theoretical and experimental density of an A713 alloy with Al-3.5Ti-1.5C and Al-3Cobalt as grain refiners is carried out. The selected die casting process parameters are molten metal temperature, Al-3.5Ti-1.5C, Al-3.0 Cobalt, die temperature and injection pressure. Theoretical and experimental densities are considered as outputs for the GA modelling. GA was performed for two cases, it was observed that the optimal prediction model for the theoretical and experimental density of A713 alloy with grain refiners have been accomplished using GA approach.

Joining light metals with polymer composites through metal overcasting

• Joining light-weight metals to fiber reinforced polymer composites without using mechanical fasteners or adhesives. • High-pressure die-casting is used to overcast molten metals (Al, Mg) on polymer composites without burning away the latter. • High cooling rates are important to prevent thermal degradation of the polymer composite. This work investigates a unique technique to join aluminum (Al) and magnesium (Mg) alloys to carbon fiber reinforced polymer (CFRP) composites without the use of adhesives or mechanical fasteners. The joints were made using an overcasting technique where the molten alloys were cast around the polymer composites using high pressure die casting method. Rapid cooling during casting allowed the composite to be embedded inside the cast metal without causing any gross damage to the former even though the molten metal temperature exceeded the melting point of the composite matrix by several 100’s of deg. C. The metal/composite interface was examined using optical and scanning electron microscopy and x-ray imaging, and the joint strength was examined through tensile testing. Although evidence of polymer melting was visible in the x-ray images and through microscopy, this melting was limited to the CFRP surface only while the bulk of the embedded section of the composite coupons retained their overall shape and integrity. Preliminary tension tests on Al/CFRP composites showed strength degradation of the CFRP and it failed a few mm outside the joint. This strength degradation in the CFRP suggests that the overcasting process needs further optimization to minimize thermal excursion in the CFRP section outside the joint. Nevertheless, the overcasting process shows great promise as a unique joining technique with application in fabricating light-weight structures for automotive and transportation industries.

Porosity formation studies in high pressure die castings of Al-9Si-3Cu alloy based on Taguchi method

PurposeNowadays, ample industries are fascinated to look for high strength and light weight materials for the development of robust parts. Because of light weight and high stiffness to weight ratio; usage of aluminum parts is growing rapidly, especially in automotive engineering. Process improvement of Al alloys and their grain structure refinement is the current area of interest in casting companies. In this research work, an investigation has been carried out to enhance the process improvement of die casting by optimization of various significant parameters and their refinement of grains by the effect of Nb-C novel grain refiner.Design/methodology/approachL27 orthogonal array (OA) has been considered to optimize the preferred casting input parameters such as molten metal temperature (°C), die temperature (°C), injection pressure (bar), Al-3.5Nb-1.5 C novel grain refiner and Ni alloying additions as key process parameters in order to increase the quality and efficiency of Al-9Si-3Cu aluminum alloy die casting by reducing the porosity formation.FindingsIt was observed that the porosity values have significantly decreased from 0.88% to 0.25% particularly at 0.1 wt.% of new grain refiner and 0.5 wt. % of Al-6Ni master alloy. As per the ANOVA results, it was observed that Al-3.5FeNb-1.5 C grain refiner (F value 2609.22), Al-6Ni alloying addition (F value 1329.13), molten metal temperature (F value 1002.43) and, injection pressure (F value 448.06) are the factors that significantly affects the porosity, whereas die temperature was found to be insignificant. The results show that new grain refiner is one the most significant factor among the other selected parameters. The contribution of the new grain refiner to the variation of mean casting porosity is around 57.74%. confidence interval (CI) has also been estimated as 0.013 for 95% consistency level to validate the predicted range of optimum casting porosity of aforesaid alloy.Originality/valueTo the best of the authors' knowledge, no study has been conducted in the past to investigate the combined effect of these die casting parameters and composition factors for the development of Al-Si robust cast parts. The paper represents original research and provides new information for the fabrication of die casting parts.

The Investigation of microstructure evolution in electron beam additive manufacturing by phase field method

The mechanical performance of the components is highly related to the microstructure characteristics in the electron beam additive manufacturing (EBAM). The solidification process with complicated behaviors during the EBAM plays a major role in the microstructure formation. This paper is focused on the dendrite evolution in the solidification process of the EBAM of Ti-6Al-4V. A phase field model coupled with macroscopic solidification of molten pool which takes the heat transfer of molten metal and transient temperature field into consideration is proposed. The microstructure evolution and solute field distribution about columnar crystal are analyzed quantitatively. The simulated results are compared with that from the analytical model and good agreement between them has been found. It is demonstrated that the evolution of microstructure is mainly determined by the temperature gradient and solidification velocity of the molten pool. The solute enrichment behavior and severe micro-segregation of columnar crystal have great effect on the morphology and growth velocity of microstructure during the EBAM. The proposed phase field model can be used to reduce the internal structure defects and select the optimal process for the desired components of the EBAM with excellent microstructure and performance.

Human reliability analysis of high-temperature molten metal operation based on fuzzy CREAM and Bayesian network.

Human errors are considered to be the main causation factors of high-temperature molten metal accidents in metallurgical enterprises. The complex working environment of high- temperature molten metal in metallurgical enterprises has an important influence on the reliability of human behavior. A review of current human reliability techniques confirms that there is a lack of quantitative analysis of human errors in high-temperature molten metal operating environments. In this paper, a model was proposed to support the human reliability analysis of high-temperature molten metal operation in the metallurgy industry based on cognitive reliability and error analysis method (CREAM), fuzzy logic theory, and Bayesian network (BN). The comprehensive rules of common performance conditions in conventional CREAM approach were provided to evaluate various conditions for high-temperature molten metal operation in the metallurgy industry. This study adopted fuzzy CREAM to consider the uncertainties and used the BN to determine the control mode and calculate human error probability (HEP). The HEP for workers involved in high-temperature melting in steelmaking production process was calculated in a case with 13 operators being engaged in different high-temperature molten metal operations. The human error probability of two operators with different control modes was compared with the calculation result of basic CREAM, and the result showed that the method proposed in this paper is validated. This paper quantified point values of human error probability in high-temperature molten metal operation for the first time, which can be used as input in the risk evaluation of metallurgical industry.

Experimental Verification of Real-Time Flow-Rate Estimations in a Tilting-Ladle-Type Automatic Pouring Machine

This paper discusses a real-time flow-rate estimation method for a tilting-ladle-type automatic pouring machine used in the casting industry. In most pouring machines, molten metal is poured into a mold by tilting the ladle. Precise pouring is required to improve productivity and ensure a safe pouring process. To achieve precise pouring, it is important to control the flow rate of the liquid outflow from the ladle. However, due to the high temperature of molten metal, directly measuring the flow rate to devise flow-rate feedback control is difficult. To solve this problem, specific flow-rate estimation methods have been developed. In the previous study by present authors, a simplified flow-rate estimation method was proposed, in which Kalman filters were decentralized to motor systems and the pouring process for implementing into the industrial controller of an automatic pouring machine used a complicatedly shaped ladle. The effectiveness of this flow rate estimation was verified in the experiment with the ideal condition. In the present study, the appropriateness of the real-time flow-rate estimation by decentralization of Kalman filters is verified by comparing it with two other types of existing real-time flow-rate estimations, i.e., time derivatives of the weight of the outflow liquid measured by the load cell and the liquid volume in the ladle measured by a visible camera. We especially confirmed the estimation errors of the candidate real-time flow-rate estimations in the experiments with the uncertainty of the model parameters. These flow-rate estimation methods were applied to a laboratory-type automatic pouring machine to verify their performance.

Casting of Al-Mg Strip Using Single Roll Caster Equipped with a Scraper

A scraper was attached to an unequal-diameter twin-roll caster without requiring large modifications. This caster was used as a 1000 mm diameter single roll caster equipped with a scraper, and its strip casting ability was tested. The effects of the scraper angle and load, the roll speed, and the pouring temperature of the molten metal on the scribed surface, thickness distribution and average strip thickness were investigated. The scribed surface characteristics were sound and the thickness distribution was flat when the scraper angle was 60° and the scraper load was in the range of 1 to 4 kg. When the scraper load was more than 1 kg, the thickness distribution was uneven. The average strip thickness decreased as the roll speed increased. The pouring temperature of the molten metal influenced the evenness of the solidified layer thickness. The solidified layer became even as the molten metal temperature was decreased. A strip cast with the determined optimal conditions was then cold rolled down to 1 mm to improve its surface quality.

Analysis and Optimisation of High Pressure Die Casting Parameters to Achieve Six Sigma Quality Product Using Numerical Simulation Approach

A numerical simulation approach is proposed to predict the optimal parameter setting during high pressure die casting. The contribution from the optimal parameters, the temperature, showed more influence on the casting quality than the other parameters. This study’s outcome was beneficial for finding the solution for casting defects that occurs due to incorrect setting of process parameters in die casting. Thus, a combination of numerical optimisation techniques and casting simulation serves as a tool to improve the casting product quality in die casting industries. This paper aims to analyse and optimise critical parameters like injection pressure, molten metal temperature, holding time, and plunger velocity, contributing to the defects. In this research paper, an effort has been made to give optimal pressure, temperature, holding time, and plunger velocity parameters using ProCAST simulation software that uses finite element analysis technology. Numerical analysis for optimising the parameters by varying the temperature of molten metal, injection pressure, holding time, and plunger velocity, concerning solidification time at hot spots, is an essential parameter for studying the defect analysis in the simulated model.

Analysis and Optimisation of High Pressure Die Casting Parameters to Achieve Six Sigma Quality Product Using Numerical Simulation Approach

A numerical simulation approach is proposed to predict the optimal parameter setting during high pressure die casting. The contribution from the optimal parameters, the temperature, showed more influence on the casting quality than the other parameters. This study’s outcome was beneficial for finding the solution for casting defects that occurs due to incorrect setting of process parameters in die casting. Thus, a combination of numerical optimisation techniques and casting simulation serves as a tool to improve the casting product quality in die casting industries. This paper aims to analyse and optimise critical parameters like injection pressure, molten metal temperature, holding time, and plunger velocity, contributing to the defects. In this research paper, an effort has been made to give optimal pressure, temperature, holding time, and plunger velocity parameters using ProCAST simulation software that uses finite element analysis technology. Numerical analysis for optimising the parameters by varying the temperature of molten metal, injection pressure, holding time, and plunger velocity, concerning solidification time at hot spots, is an essential parameter for studying the defect analysis in the simulated model.

Effects of Stirring Duration and Casting Temperature in Ultrasonic Assisted Stir Casting of Al A356 Matrix Composites

In the present study, two main parameters as stirring duration and casting temperature were taken into consideration in order to determine the effect of stirring process on mechanical properties of aluminum matrix composites. AlSi7Mg0.3 aluminum alloy and silicon carbide (SiC) particles were used as matrix and reinforcement materials to produce composite samples. Firstly, stirring processes were applied as the combination of mechanical stirring and ultrasonic vibration for the various time as 3-1, 2-2 and 1-3 minutes, respectively. To determine the effect of stirring process, tensile tests were applied to whole samples and Quality Indexes (QI) were calculated by using the results of tensile tests. According to the values of QI, the produced samples with the combination of 1 minute mechanical stirring and 3 minutes ultrasonic vibration showed the maximum mechanical properties. Afterwards, the determined stirring combination was chosen to specify the appropriate molten metal temperature. Three different casting temperatures were addressed as 700˚C, 720˚C and 740˚C. According to mechanical tests results and calculations of QI and metallographic analysis, the maximum mechanical properties were obtained with aluminum composite reinforced with 1 wt. % SiC at 720˚C molten metal temperature by applying 1 minute mechanical stirring and 3 minutes ultrasonic vibration.

Mechanical and thermal methods for reclamation of waste foundry sand

Binder material (e.g. bentonite, polymeric resins) is used for producing molds and cores in foundries. It deactivates upon exposure to the high temperature (~1400°C) of molten metal. As a result, these binders form either loosely or strongly bound deposits on the surface of sand grains, leaving them unsuitable for further use. Disposal of Waste Foundry Sand (WFS) remains to be one of the significant challenges faced by foundry industry nowadays. In order to remove these deposits from WFS, we have studied and compared two types of methods namely, mechanical and thermal reclamation. The WFS samples after being reclaimed either mechanically or thermally or by combination of both, are compared using various tests. These tests include determination of loosely bound and strongly bound clay content, compressive strength, Grain Fineness Number (GFN), Loss on Ignition (LOI), Acid Demand Value (ADV), Particle size distribution and optical microscopy. We have used the aforementioned tests to characterize the quality of foundry sand and the suitability of reclaimed sand for use in mold and core production in foundries. The results showed that neither of these treatments is sufficient to completely remove the deposits from sand grains. However, solely mechanically reclaimed sand is suitable for the mold production after maintaining 8% active clay and 10% loosely bound clay in the reclaimed sand, respectively.

Defect elimination in green sand casting using simulation techniques: A case study

The Reynolds number of molten metal flowing mold cavity causes bulk turbulence and is the main cause of defects like shrinkage porosity and sand erosion. Machined housings with shrinkage porosity at critical bearing bores and surface made the casting useless. In old gating casting areas of perimeters 290[Formula: see text]mm and 264[Formula: see text]mm of transmission housing, Reynolds numbers were observed as 16307 and 13806, respectively using simulation software. Data were collected from experiments to change casting area perimeters from 785[Formula: see text]mm and 785[Formula: see text]mm along with the addition of overlap area. New Reynolds numbers at two locations were observed as 3705 and 3393, respectively. Molten metal pressure, velocity and temperature results were related for final shrinkage results of the components on full production. The purpose of the study is to reduce shrinkage and porosity defects in green sand casting part using MAGMAS simulation software. High outcome was the reduction of casting machining rejection in transmission housing casting from 5.8% 0.7% with savings of approximately 0.13 million USD over the period of 14 months. Implications of this work include casting defects study and reduction in different grades and weight range.