Casting Equipment Research Articles

Fabrication of Gasar made from Cu-24 wt.% Mn alloy

Abstract Unidirectionally solidified porous Cu-24 wt.% Mn alloy is prepared by the Gasar process, using mold casting equipment under various conditions. The experimental process demonstrates the feasibility of fabricating a Gasar structure for alloys with a wide solidification temperature range, as well as a columnar dendritic structure. The effects of melt temperature, initial mold temperature, and partial gas pressures on the pore structure and microstructure of an alloy matrix were investigated. The growth and interruption of directional pores were analyzed based on the solidification mode to determine whether the fine-grained region atop directional pores stunted the growth of Gasar pores.

Ceramic Objects for Dispensing Molten Aluminum Alloys

Preparation of special aluminum alloys and refractories conforming to them are considered from the point of view of physicochemical processes and aluminum metallurgy mechanisms, functional capacity of melting and casting equipment and a ceramic lining, making it possible to control casting structural and chemical parameters during their preparation. Compositions and production solutions are developed for preparing shaped refractory lining objects based on cement-free ceramic concretes.

The Performance of Tungsten Carbide and High Speed Steel When Drilling Nickel–Copper

Machining of components made of materials with dissimilar properties demands the judicious selection of tooling and cutting conditions. The aim of this work is to investigate the behavior of tools with different compositions and geometries when drilling hybrid metallic (Ni–Cu) components used in continuous casting equipment. Thrust force and hole accuracy were investigated under various machining conditions and the results indicated that drill type and feed rate are the principal factors affecting thrust force. Moreover, hole diameter deviation was affected by drill type only and the influence of cutting speed was found to be negligible within the cutting range tested.

Performance of Pyroprocess Equipment of Semi-Industrial Design and Material Balance in Repeated Engineering-Scale Fuel Cycle Tests Using Simulated Oxide/Metal Fuels

Fuel cycle tests using uranium and simulants with process equipment of 1 ton HM/yr throughput were conducted to develop an equipment design for long-term and hot-cell operation with stable performance, and to investigate the influence of impurities on the behavior of sensitive materials such as molten chlorides and active metals on material mass balance during repeated engineering-scale operations. These cycle tests were performed in two phases. The first phase simulated the introduction of spent oxide fuel into the metallic fuel cycle by the sequential operations of the UO2 electroreduction, electrorefining of the reduction product, salt distillation using the electrorefining product, and injection casting of U-Zr alloy using the recovered uranium metal. The second phase, consisting of electrorefining, salt distillation, and injection casting, simulated the repeated metallic fuel cycle. The major achievements and results in these cycle tests are summarized as follows:1. Simulated metallic fuel (U-Zr alloy rods) was successfully fabricated using UO2 as the starting material.2. The electrorefining, product transfer, salt distillation, and injection casting equipment operated satisfactorily, and their performance was sufficiently high, taking the target processing rate of 5 kg/day into account.3. Regarding electroreduction, the reduction rate was approximately half the target value, and the cathodic current efficiency was also low. The reasons for the unsatisfactory result are considered to be Li2O stagnancy at the cathode, the parasitic generation of lithium and the subsequent oxidation out of the cathode, and possibly the reaction between the reduced uranium and the oxygen gas evolved at the anode. Improvement of equipment design should be continued to moderate the influence of these factors on the electroreduction performance.4. Favorable material mass balance of uranium, zirconium, and ruthenium (simulated fission products) was kept during the cycle tests, including the electrorefining, product transfer, salt distillation, and injection casting steps. No influence of three-time repetition of the fuel cycle tests was found from this viewpoint. The representativity of the anode residue and cathode product samples from the electrorefining step, which strongly influences the material mass balance evaluation, would be improved by performing anode residue treatment including metal waste consolidation and cathode processing for all the cathode products.

Design and Implementation Full Automatic Intelligent Control System Oriented to Vacuum Casting

Based on craft features analysis of vacuum casting, this paper concluded that the automation level and control precision of control system are key influencing factors for products quality of vacuum casting. So the purpose of this paper is to resolve these disadvantages of existing control system of vacuum casting equipments. This paper designed a new full automatic intelligent control system which adopts two-level distributed structure. The system is consisted of motor control subsystem, vacuum monitoring and control subsystem, and bubbles detecting and eliminating subsystem. According to the function requirement of control system, this paper described selection and configuration of hardware and function implement of software in detail. Finally, this paper designed and realized a new automatic detecting and eliminating method of bubbles based on vision sensor technology, and presented an intelligent controller model based on Wavelet Neural Network (WNN) for motors. The experimental prototype of vacuum casting has been developed and a large number of experiments have been carrying on. These new controlling algorithms have being tested. The control system integrates vision sensor, intelligent control, microcomputer interface and imaging processing technologies, so it possess high precision, efficiency and flexibility and has a good market application prospect and high economic value. It will be breakthrough for precise rapid tooling.

Controlling Nozzle Clogging by Secondary Steelmaking Without Reheating

AbstractEver since continuous casting was introduced, nozzle clogging has been a recurring subject of metallurgical research and publications. Nozzle clogging is caused by the deposition of non‐metallic inclusions – on the casting equipment – which are solid at the temperature of casting. Calcium treatment already represents a possible solution to eliminate this phenomenon, but there are special steel grades which do not allow its application either because they are price sensitive or for certain other reasons.3 Cleaning the steel melt by agitation is an alternative solution, but it has time constraints due to the cooling of the melt. Over extensive cooling can be prevented by heating the melt (in ladle), but its introduction and operational costs per heat are often too high for an individual steelmaking plant to afford. The goal of our research is to find metallurgical solution to reduce the rate of nozzle clogging in plants which do not possess a ladle furnace and the time devoted to treatment or the price of the product do not allow Ca‐treatment to be applied.

Production of forging ingots without axial shrinkage defects. Part III*

This is the third and final article on a method developed by TsNIITMASh to design forging ingots so as to prevent the formation of an axial shrinkage cavity in the body of the ingot. Theoretical and experimental results from use of the method and factory-designed casting equipment to obtain such ingots are compared together with requirements of the standard OST 108.962.02-85. It is shown that the theoretical and experimental results agree satisfactorily with one another.

Application of Fuzzy Controller with Self-Tuning Scaling Factors for the Filling System of Counter-Gravity Casting

Pressurization control system plays an important role in the process control at the stages of riser-tube filling, mold-filling, pressure-increasing and pressure maintaining in counter-gravity casting. Casting quality is affected by the precision of pressurization control system to a great extent. Input and output scaling factors of conventional fuzzy controller are static, which is hard to ensure a suitable state for various counter-gravity casting equipments. A new fuzzy controller with self-tuning scaling factors has been developed in our laboratory, which will be described in this paper. Input and output scaling factors of fuzzy controller are tuned by different error ranges. When the differential pressure error is large, output scaling factor is increased to speed up dynamic response. At the same time, input scaling factors are also increased in order to reduce steady state error. Compared to fuzzy controller and conventional PID controller, fuzzy-PID controller with self-tuning scaling factors has more steady-state precision and excellent robustness. Experimental results show that at riser-tube filling stage and mold-filling stage the gas flow is stable, and the tracking property of pressurization control system is very satisfactory.

Pressure-assisted infiltration of molten aluminium into open cell ceramic foams: Experimental observations and infiltration modelling

Partial infiltration of molten Al into three different open cell ceramic foams has been effected using pressure-assisted vacuum investment casting equipment. For the maximum pressure difference (only 0.25MPa) up to 90% of the open porosity could be filled, but since the ceramic foams were found to contain closed pores, the resulting composite densities were low. A simple modelling approach accurately predicts the infiltration behaviour and enables the processing conditions and architecture of the preforms to be optimised in respect of the maximum infiltration pressure available from the processing equipment.

Logistic Performance Evaluation of Squeeze Casting Equipments Based on Simulation

The logistic performance of a squeeze casting equipment like production cycle time and the utilization rate of components, has impacts on the production rhythm , cast quality and it's lifecycle. So it is essential to analyze the logistic performance of squeeze casting equipments during design, buying and using. This paper deals with evaluating the logistic performance of squeeze casting equipments through simulation.Flexsim software was employed to simulate squeeze casting equipments, where the simulation model of a squeeze casting machine was constructed and the utilization rate was investigated by conducting four simulation samples of different cast products.It is indicated that simulation is an easy and effective method to evaluate the utilization rate performance of squeeze casting equipments and it is concluded that the utilization rate of all component cells except squeeze mechanism is very low and decreases with the curing time of casts increase, their value is very close to the ratio of the their processing time to each total cycle time. The simulation results can also help us find the bottleneck and optimize design of the squeeze casting equipment.

Development of Engineering-scale Ingot Casting Equipment for Dendritic Uranium Deposit

The Korea Atomic Energy Research Institute (KAERI) has developed engineering-scale ingot casting equipment with a capacity of 50 kg-U/batch. This ingot casting equipment has a vibrating continuous feeder and 8 mold crucibles on a turn-table, which improves in operability such as continuous tilting. In addition, an induction heating system with a non-water cooling coil was developed to prevent a reaction with uranium by a leak of water in the hot-cell. The performance of the non-water cooling coil was tested with a cupper. When the cupper was melted at 1050oC in the furnace, the melting chamber was successfully maintained below 250oC.

비정질합금 박판 제조용 노즐 재료의 내구성평가

Erosion and thermal shock resistance of several refractory materials have been investigated, which are expected to be used as nozzles in a planar flow casting equipment for amorphous alloys. The test was conducted on five materials; graphite, boron nitride, fused silica, alumina and zirconia. Test specimens were preheated and dipped into the melt of carbon steel and amorphous alloys. Some test specimens were rotated to develop high erosion and to shorten the test periods. Fused silica and boron nitride specimens showed the excellent erosion and thermal shock resistance irrespective of the kind of melt and melting atmosphere.

Overall Design of the Forming System for Squeeze Casting

As a forming process, squeeze casting is completed in the corresponding manufacturing system. The paper deals with the overall design of the manufacturing system-the forming system for squeeze casting. To construct a practical manufacturing system for this technology, the forming control process of squeeze casting is analyzed, where the key factors are identified to determine the production quality. Then the design principles for the forming system for squeeze casting are built and its functional requirements are attained. And an overall structure for this forming system is presented including the die design system, the design and management system of process parameters and the squeeze casting equipment system. This structure decreases the difficulties and the cost of building the physical system.

Chemical reactivity of oxide materials with uranium and uranium trichloride

A graphite crucible is used for the manufacturing of uranium ingots in the uranium casting equipment of the electrorefining process. Uranium and uranium alloys are typically induction melted in graphite crucibles under a vacuum condition; however, due to the chemical reactivity of uranium and most alloying elements with carbon, a protective ceramic coating is generally applied to the graphite crucibles. To investigate the most suitable ceramic coating material for application to graphite melting crucibles used for the melting uranium in uranium casting equipment, firstly, a thermodynamic analysis using HSC software was performed to examine the chemical reactivity of ceramic oxide materials with uranium and uranium trichloride, and also, experiments concerning the reactivity of molten uranium in some ceramic coated crucibles were performed at 1,300 °C. From the results, yttria was finally selected as the most suitable ceramic coating material for application to graphite crucibles for melting the uranium.

A low-cost vacuum casting equipment for aluminium alloys

Some of the advantages inherent in the vacuum casting technique such as improved mechanical properties and elimination of shrinkage have been replicated in a low-cost design. Melting and vacuum requirements of the equipment were determined based on a furnace capacity of 15 kg of aluminium. Clay-based refractory and insulating bricks were used for furnace construction. The vacuum system was made from locally available materials and designed for efficiency required for vacuum casting. The equipment was used to melt and cast small-sized specimens using the lost-wax technique and compared with green sand and ceramic mould cast specimens. Tensile and shrinkage tests were carried out on all specimens. The results of the tensile tests were 123, 98 and 113 MPa for the vacuum cast, green sand cast and ceramic mould cast specimens, respectively. Furthermore, shrinkage defect which is common to both green sand and ceramic mould casting was eliminated in vacuum casting. The vacuum casting equipment cost an equivalent of about U.S $1000.00 (One thousand dollars) to construct and can be easily scaled-up for large-sized castings by increasing furnace capacity and the size of the moulding flask.

Hydro Casthouse Reference Centre

Since October 2006 the Hydro Casthouse Reference Centre has been operating. The centre is a full scale state of the art pilot casting centre for extrusion ingot, sheet ingot and foundry alloys, consisting of a 17Mtons furnace with a metal loop, a launder system including modular in-line melt treatment units such as ceramic foam filters (CFF) and inline melt refining units (Hycast SIR) and a casting pit with the possibility to cast full size geometries and a casting length of 5.5m. A two strand horizontal casting machine further adds the possibility of continuous casting of extrusion ingot and foundry alloy ingot. The centre has a state of the art superior control system (SCS) and a lay-out, including control room facilities, well suited for training and demonstration purposes. In addition the centre has access to state of the art software codes for simulating the casting process (Alsim) and the as cast microstructure (Alstruc). The present paper gives some examples on how the centre is operating and the support that is offered to casthouses in Hydro. This includes (i) simulation of the casting processes (hot tearing and as cast structures) applying the Alsim and Alstruc codes, (ii) pilot scale testing of casting and melt treatment equipment, (iii) testing of new parameters and procedures for melt treatment and casting (iv) production of trial orders of new alloys and (v) practical training of casthouse operators (basic for molten metal handling, emergency situations and response, casting principles and trouble shooting, etc.).

Counter-Gravity Casting Equipment and Technologies for Thin-Walled Al-Alloy Parts in Resin Sand Molds

A counter-gravity casting equipment (CGCE) has been developed, which is specially designed for the production of large-size thin-walled high-quality aluminum alloy parts with resin sand molds. In this equipment, molten metal will be pushed upward counter-gravity into the mold at predetermined rate by compressed air, and solidified at an increased pressure. The equipment uses assembled valve system developed ourselves, and has sensitive pressure-adjusting property. All of the casting parameters, including filling rate, pressure-exerting sequence, pressure hold time etc., can be closely controlled by a self-designed computer program. Up to 2 ton casting can be produced with the equipment. Compared to the castings produced under conventional gravity conditions, the castings under counter-gravity condition have generally high soundness, higher tensile strengths and ductility. The pinhole defects are also degraded obviously. The equipment and the technology have been widely adopted by several users in China for the production of large-size thin-walled aluminum alloy castings with high property requirements.

Development of pressure control system in counter gravity casting for large thin-walled A357 aluminum alloy components

Counter gravity casting equipments(CGCE) were widely used to produce large thin-walled A357 aluminum alloy components. To improve the pressure control precision of CGCE to get high quality castings, a pressure control system based on fuzzy-PID hybrid control technology and the digital assembled valve was developed. The actual pressure tracking experiment results show that the special system by applying PID controller and fuzzy controller to varied phases, is not only able to inherit the small error and good static stability of classical PID control, but also has fuzzy control's advantage of fully adapting itself to the object. The pressure control error is less than 0.3 kPa. By using this pressure control system, large complex thin-walled A357 aluminum alloy castings with high quality was successfully produced.

Quartz (SiO 2p) reinforced chilled metal matrix composite (CMMC) for automotive applications

Present investigation describes chilled aluminum-quartz particulate composite that can be cast using metallic (copper) chills much like un-reinforced aluminum using conventional aluminum casting equipments. The dispersoid (size distribution 30 to 100 μm) being added ranges from 3 to 12 vol.% in steps of 3%. The resulting composites cast using chills were tested for their mechanical and thermal properties. Microstructures and SEM photographs of fractured and worn surfaces were also taken for analysis. The materials mechanical and thermal properties particularly its improved strength, wear resistance, fracture toughness, hardness, lower coefficient to thermal expansion and thermal conductivity are discussed in some detail.

Thixo-formability of the AA6063 alloy: Conventional production processes versus electromagnetic stirring

Abstract Cold-formed AA6063 alloy has an excellent mechanical behaviour, and is used in a wide range of structural applications. In Brazil this alloy is produced in large amounts, due to wide application at low cost. The present work aims to present a new use for this material, allowing the subsequent manufacture of metal parts by thixo-forming. The objectives of this work are (a) to establish a suitable condition for the production of thixo-formable structures using electromagnetic stirring during semi-continuous casting, with and without grain refiner, and (b) to compare this to the same alloy produced by the conventional process. The alloy was supplied by Companhia Brasileira do Aluminio (CBA), and processed in a semi-continuous casting equipment at the Thixo-Forming Laboratory of Unicamp, which has a controllable electromagnetic field from 600 to 2000 W/kg of material, induced into the alloy during solidification. The final alloy structure was characterized in terms of grain size, primary particle size and shape and rheological behaviour for 45% solid fraction. Furthermore, results were compared to the chemical refining (Al–1 wt%Ti–0.5 wt%B), as well as the combination of both production methods. According to the thixo-formability evaluation protocol, the commercially produced AA6063 alloy has an excellent degree of thixo-formability, presenting a very low-apparent viscosity (105 Pa s), despite the difficulty of its processing, i.e., a very narrow semi-solid range (only 23 °C). In fact, the most important feature for thixo-formability is to have raw material presenting a very refined structure, as well as, the most globular structure. In this case, the commercial alloy presented grain size of 86 μm and rheocast quality index 0.60. For commercial processing better equipment and a better temperature control will be indispensable in the commercial development of thixo-forming operations for this type of material.