Die casting is a type of metal casting in which a liquid metal is solidified in a reusable die. In such a complex process, measuring and controlling the process parameters are difficult. Conventional deterministic simulations are insufficient to completely estimate the effect of stochastic variation in the process parameters on product quality. In this research, a framework to simulate the effect of stochastic variation together with verification, validation, and uncertainty quantification (UQ) is proposed. This framework includes high-speed numerical simulations of solidification, microstructure, and mechanical properties prediction models along with experimental inputs for calibration and validation. Both experimental data and stochastic variation in process parameters with numerical modeling are employed, thus enhancing the utility of traditional numerical simulations used in die casting to have a better prediction of product quality. Although the framework is being developed and applied to die casting, it can be generalized to any manufacturing process or other engineering problems as well.

This paper presents a semi-automated grinding system for the postprocessing of metalcastings. Grinding is an important procedure in the “cleaning room” of a foundry, where the removal of gate contacts, parting line flash, surface defects, and weld-repaired areas is performed, and almost always manually. While the grinding of repetitive locations on medium to high production castings can be automated using robotics or otherwise, it is not as practical for larger castings (e.g., > 200 kg) that are typically produced in smaller production volumes. Furthermore, automation is even more challenging in that the locations of the required grinding are not a constant depending on the unique conditions and anomalies of each pouring of a component. The proposed approach is intended for a simple x−y−z positioner (gantry) device with a feedback controlled grinding head that enables automated path planning. The process begins with touch probing of the surfaces that contain the anomaly requiring grinding, and then the system automatically handles the path planning and force control to remove the anomaly. A layer-based algorithm for path planning employs a search-and-destroy technique where the surrounding geometry is interpolated across the grind-requiring surface patch. In this manner, each unique condition of the casting surface after initial torch or saw cutting can be handled cost effectively without the need for human shaping and the egregious ergonomic problems associated. Implementation of the proposed grinding control is prototyped at a lab scale to demonstrate the feasibility and versatility of this strategy. The average error for the prototype was on the order of 0.007 in (0.2 mm) with a flatness of the ground surface within 0.035 in (0.9 mm), which is within the cleaning room grinding requirements, as per ISO and ASTM dimensional and surface tolerance requirements. A significant contribution of the work is the layer-based algorithm that allows an effective automation of the process planning for grinding, avoiding robot programming or numerical control code generation altogether. This is a key to addressing the largely unknown and unpredictable conditions of, for example, the riser contact surface removal area on a metalcasting.

The Zamak 2 alloy has the best mechanical properties of the Zamak alloys with respect to the tensile strength, creep resistance, and hardness. Zamak 2 is a commercial material widely used for the manufacturing of mechanical components. The presence of Cu in this alloy (3 wt. %) improves the mechanical properties through the formation of E (CuZn 4 ) precipitates. The powder metallurgy (P/M) has an important direct advantage in the fabricated parts with respect to the finished dimensions or near net shaping due to the additional phase stabilization without heat treatment. However, there are few studies into the production of this zinc alloy via mechanical alloying and the effect of the consolidation technique in terms of the material properties; these research deficiencies led to the development of this work. The powder was analyzed during milling until achieving a steady-state, which occurred after 30 h of milling in a planetary ball mill at 400 rpm. The high-energy milling produces a Zamak 2 alloy powder with a T′ stable phase and with a greater melting point. When consolidated using hot pressing, the hardness increases compared to sintering and casting alloy.

Little work has been done on quantifying the environmental impacts and costs of sheet metal stamping. In this work, we present models that can be used to predict the energy requirements, global warming potential, human health impacts, and costs of making drawn parts using zinc (kirksite) die-sets and hydraulic or mechanical presses. The methodology presented can also be used to produce models of stamping using other die materials, such as iron, for which casting data already exists. An unprecedented study on the environmental impacts and costs of zinc die-set production was conducted at a leading Michigan die-maker. This analysis was used in conjunction with electrical energy measurements on forming presses to complete cradle-to-gate impact and cost analyses on producing small batch size hood and tailgate parts. These case studies were used to inform a generalized model that allows engineers to predict the impacts and costs of forming based on as little information as the final part material, surface area, thickness, and batch size (number of units produced). The case studies show that the press electricity is an insignificant contributor to the overall impacts and costs. The generalized models highlight that while costs for small batch production are dominated by the die-set, the environmental impacts are often dominated by the sheet metal. These findings explain the motivation behind the research into die-less forming processes such as incremental sheet forming, and emphasize the need to minimize the sheet metal scrap generation in order to reduce environmental impacts.

Due to increasing demands for faster and faster manufacturing of new complex materials, such as casting of particulate composites, the determination of pumping pressures needed for particle-laden fluids through channels is critical. In particular, the increase in viscosity as a function of the particle volume fraction can lead to system malfunction, due to an inability to deliver necessary pressures to pump the more viscous fluid through the system. This paper studies the pressure gradient needed to maintain a given flow rate, explicitly as a function of the volume fraction of particles present in the fluid. It is also crucial to control voids in the casted products, which can be traced to air-entrainment, spurious internal reactions, dewetting, etc., which can be traced to high Reynolds numbers. Accordingly, an expression for the resulting Reynolds number as a function of the particle volume fraction and flow rate is also developed. Numerical examples are provided to illustrate the practical use of the derived relations to characterize the necessary pumping pressures for process-driven, particle-laden fluid flows.

Large, complex, expensive, and long-lived equipment often operate in harsh environments, which leads to the requirements of lifecycle maintenance, repair, and overhaul (MRO). To support the continuous improvement of productivity and to reduce the cost of MRO, this paper developed a cloud-based framework for lean MRO of the equipment with the aforementioned characteristics. A concept and a model of lean MRO are proposed. Taking advantage of cloud-based design and manufacturing (CBDM) into account, an architectural framework of cloud-based MRO is proposed. A case of a lean MRO for continuous casting equipment demonstrates that the proposed cloud-based framework can achieve the goal of lean MRO of complex equipment.

To compete with other materials and/or contribute toward light-weighting of vehicles, newer grades of steel are continuously invented and experimented upon. Due to the costs and time involved in such developments, manufacture of new grades of steel at an industrial scale is difficult. We propose a method that is useful for steel manufacturers interested in producing a steel product mix with new grades of steels by predicting the required change in the operating set points of each unit operation in the manufacturing chain of products with the new grade of steel. Here, we demonstrate a method to determine the set points of one unit operation, continuous casting which is measured in terms of conflicting objectives including productivity, quality, and production costs. These parameters are sensitive to the operating set points of casting speed, superheat, mold oscillation frequency, and secondary cooling conditions. To ensure targeted performance and address the challenges of uncertainty and conflicting objectives, an integrated computational method based on surrogate models and the compromise decision support problem (cDSP) is presented. The method is used to explore the design space available for casting operations and determine operating set points to meet requirements imposed on the caster from subsequent downstream processes. This method is of value to the steel industry and enables the rapid and cost effective production of a product mix with a new grade of steel.

Polyaniline (PANi) based composites were made by electric force assisted nanocasting. The PANi matrix was mixed with thermoelectric Bi–Te alloy nanoparticles. The uniform dispersion of the nanoparticles in the polymer was achieved via electric field assisted casting. The nanoparticles can enhance the thermoelectricity, specifically increase the Seebeck coefficient. Structure analysis and Seebeck effect experiments were performed. The microstructure of the composite materials was studied by the use of electron microscopy. The preliminary results show that the nanocomposites are n-type with an average Seebeck value of 30 μV/K. The electrical resistance of the composites is about 35 MΩ.

Porous materials with well-defined pore shapes, sizes and distributions are highly desired in many emerging applications, particularly for biomedical materials and devices. However, conventional methods for processing porous materials only demonstrated limited capability in morphological control. One promising solution is the porogen templating process, where a structured porogen pattern is created first and subsequently used as a template or mold for generation of the desired porous material. Particularly, with solid freeform fabrication, porogen templates having complex internal structures can be additively fabricated, and they can then be used as molds for molding of porous materials and devices. This article attempts to offer a constructive overview on the state of the art of porogen patterning and inverse molding, with the goal of explaining the working mechanisms and providing unbiased accounts of the pros and cons of existing techniques and process variants. The article further intends to provide a fundamental understanding of the constituent elements and corresponding building blocks in porogen templating processes. An increased understanding of these elements will facilitate the development of more capable new processes.

In twin-roll continuous strip casting, casting roll is heated by molten metal, and thermal deformation is caused to change strip thickness and quality. It is imperative to understand casting roll temperature distribution and thermal deformation. In this paper, a 2D finite element (FE) model is built to analyze casting roll temperature and thermal deformation under various casting processing parameters. The influences of shrink fit of roll sleeve and shaft are taken into account and the coating was treated to be consistent to the actual situation. The results show that casting temperature fluctuates cyclically within a thin top layer in stable casting, and there is almost no temperature fluctuation near cooling water holes.

Growing interest in sustainability is driving manufacturers to improve the environmental performance of their products and processes. The production of steel and steel products consumes materials and energy resources, and creates wastes and emissions. Industry leaders and policy makers have identified iron/steel and metal casting as areas of concern from an environmental perspective. By evaluating steel product manufacturing processes commonly employed in the heavy equipment industry, environmental impacts can be mitigated during product and process design. A process modeling approach that is focused on improving the environmental performance of steel product manufacturing is developed and demonstrated. The process models focus on part production employing electric arc furnace (EAF) steelmaking and sand casting with chemical binders, and relate process energy and material inputs and outputs to product and process design characteristics. The models are based on scientific principles, as well as empirical data reported in the literature. Models of the two processes are applied to assess the production of a representative ground engaging tool (GET) component. It is found that EAF electricity use can be reduced by more than 30% and process-related CO 2 emissions by nearly 20% over initial settings. Replacing the polyurethane nobake sand mold binder with a low nitrogen furan binder is predicted to reduce casting emissions by more than 50%, and sulfur dioxide emissions by over 90%. Thus, the models are capable of estimating changes in environmental performance due to modifications in material type, part geometry, and process parameters. This process modeling approach demonstrates improvements in environmental performance for the production of a GET component, and can be extended to assess and compare other steel alloys and components.

For the development of a rotational symmetrical polyurethane part with a steel reinforcement, a requirement/constraint driven approach to process design has been taken. In this approach a scale model of the casting mold was built using fused deposition modeling rapid prototyping technique, then used to validate design, material and process parameters. After selection and testing on the scaled prototype, results were used to define a full-sized spin casting mold built using polyphenylsulfone material. This material was selected based on the process temperature and stress requirements. However, surface roughness in the as-built condition is unacceptable for demolding; this paper describes secondary processing to mitigate this effect. The result is a feasible process for manufacturing of centrifugal casting molds for polyurethane.

Visibility analysis is broadly used in milling and casting process planning and in coordinate measuring machine applications. However, standard visibility analysis (which involves determining visibility from a given viewpoint), cannot be applied directly to in-line cutting systems such as wire electrical discharge machines or hot wire foam cutters. The motivation of this paper is to accurately calculate the tangent visibility for objects represented by polygonal surfaces. In this paper we define a new type of visibility - tangent visibility. We develop an algorithm to calculate the global tangent visibility for in-line cutting systems, and several models are tested to verify its accuracy. Several polyhedral models are tested to verify the correctness of the tangent visibility algorithm; and the complexity of the algorithm is also discussed.

Today, free-form parts are made in small production volume with time consuming methods and a significant amount of material waste. These methods include computer numerical control (CNC)-machining and the layered rapid prototyping techniques stereolithography apparatus (SLA), selective layer sintering (SLS), fused deposition modeling (FDM), 3D print, etc., which are well suited for smaller parts that are rich in detail. Variable geometry molds (VGMs) offer a different approach to small production volume. A die or mold can change shape between the castings, and parts with a different geometry can be made in the same mold. VGM is used in a multitude of applications such as sheet metal forming of parts for aircrafts, trains, and cranial prostheses. The present project focuses on VGM for free-form concrete facade elements, which, in contrast to previous VGM projects, uses a liquid raw material and involves the use of only a small amount of force. The present VGM process is based on the so-called reconfigurable pin-type tooling (RPT) principle. The geometric possibilities have been examined using a proof-of-concept RPT test mold. Sixty closely packed adjustable pin-elements with hemispherical tops and a square section of 43.3 × 43.3 mm 2 create a dimpled surface that is evened out using an elastic interpolating layer. Castings with concrete and plaster are made on an elastic membrane that is sucked toward the pins using a vacuum. The shape of the cast elements and the mold surface have been measured and compared. The RPT test mold can produce a large variety of free-form geometric shapes. It is possible to make straight vertical surfaces and even horizontal surfaces with dimples of only 0.3 mm. Part details can be made down to the size of a pin with hole depths up to 65 mm and protrusions up to 19 mm. Repeatability is better than the measurement uncertainty. VGMs using the RPT principle can be used for making scale models of a range of free-form cast concrete façade elements. It is almost possible to remove the imprints from the pins by using the right interpolators, but the dimples could also be a visually attractive characteristic of the process that could be valued by architects. Large hole depths and smaller protrusions are possible.

The flow behavior of the fluid has a significant effect on the particle distribution in the solid-liquid mixing vessel. The stir casting process is generally conducted in a closed crucible, in which the flow pattern is invisible. Therefore, numerical simulation is a forceful tool to guide the experimental research. In the present study, the fluid flow in the stirred crucible during stir casting has been simulated using finite element method. The effects of some important stirring process parameters, such as the blade angle, rotating speed, the diameter of the impeller, and the stirrer geometry, on the flowing characteristics of the molten matrix have been investigated in order to achieve the effective flow pattern to uniformly disperse the ceramic particles in the molten matrix. The simulation results show that the process parameters have significant effects on the flow behavior of the fluid in the stirred crucible. The various combinations of these parameters are beneficial to generate a suitable condition for the composite casting. Further experimental investigation reveals that the present work can provide a guide for the industrial preparation of aluminum matrix composite with a uniform particle reinforcement distribution by stir casting process.

This paper describes the development of an on-line quality inspection algorithm for detecting the surface defect (“bleeds”) generated in continuous casting processes. The challenges of bleed detection in visual images lie in the low signal-to-noise ratio, the irregularity of bleed contour patterns, and significant false positives. In order to solve these problems, an engineering-driven rule-based detection (ERD) method is proposed. The ERD consists of three detection stages using the pixel features of bleeds, which are transferred from the physical features generated via engineering knowledge. The detailed strategy, ERD algorithm, parameter selection, and casting knowledge are presented. The real case study demonstrates that the developed algorithm is effective and applicable.

The service life of tooling plays an important part in the economics of the extrusion process. A number of causes are considered responsible for initiating damage to the dies before its designated life is reached. Apart from other factors such as die design and manufacturing, heat treatment, working conditions, etc, the performance of the die can directly be related to the billet quality used in the extrusion press. The purpose of this paper is to investigate the effect of Al-6063 billet source (primary or secondary) on extrusion die failure, based on microstructural investigation. A secondary (remelt) billet cast in-house at a local extrusion plant is compared with a primary (smelter) billet by applying different material characterization techniques, including optical microscopy, Vickers microhardness measurement, X-ray diffraction (XRD) analysis, and energy dispersive spectroscopy (EDS). It is observed that a secondary billet has a comparatively coarse grain structure, nonhomogeneous distribution of secondary phases, inclusions, and high hardness that can be associated with poor casting and homogenization practice. In view of present results, some suggestions during in-house billet preparation of secondary billets have been formulated for improved die service life.

A series of experimental trials was carried out to study the metallic bond produced when hypereutectic aluminum liners are cast-in hypoeutectic aluminum engine-blocks. The samples were cast in a rig that reproduces the conditions encountered during production of engine-blocks made of a type 319 aluminum alloy. The surface roughness of the liners was modified by sand blasting before casting. Some of the liners were cast after coating their surface with an amorphous carbon layer (soot) to study its effect on the metallic bond. The samples were sectioned and prepared for their examination and testing. It was found that soot does not allow the development of a metallic bond between liner and body and that the force required to remove the liners depended on such a bond; in any case, the force required to remove cast-in liners, even without bonding, was higher than that needed for removing gray iron press-in liners.

The retention of pattern voids observed in the production of expandable polystyrene patterns for lost foam casting can be traced to conditions developed during mold filling and subsequent steaming. Void formation and closure, or healing, was observed using high-speed video imaging through a clear acrylic sheet cut to match one-half of a test pattern mold. Two processing conditions, i.e., the initial bead packing density and the velocity of steam as it passes between beads, were shown to significantly impact the ability of a void to heal during steaming. A model is proposed to predict conditions where voids will heal based on three criteria that relate to a limitation of the processing window, the void size, and the ability of the bead to swell.

The rate of heat extraction during the pressure die casting process is central to both the quality and the cost of finished castings. Recent efforts to reduce the thermal resistance of dies by optimizing the effectiveness of the cooling channels have shown the potential for improvement. Reducing the thermal resistance of the coolant boundary layer means that a significant proportion of the total thermal resistance becomes attributable to the die steel. Further significant reductions in die thermal resistance can be obtained by replacing the steel with copper. This paper investigates the feasibility of using copper dies, reinforced with steel inserts and coated with a thin layer of wear resistant material, which is deposited using the thermal arc spray process. Experimental work relating to the thermal spray process has been undertaken to establish bond strengths and thermal conductivities for various process parameters. Moreover, experimental investigations have been carried out using two copper coated dies, the first of which was a pseudodie block heated by an infrared heater. The second die was tested on a die casting machine and produced zinc alloy castings at a greatly increased production rate when compared to its steel counterpart. The experimental results from the two dies are compared with those predicted by an in-house thermal-cum-stress model based on the boundary element method. Reasonable agreement between the predicted and experimental results is shown and the feasibility of copper-alloyed dies for pressure die casting is established.