An Experimental Examination on Ice Pattern for Casting Process

The casting process has come to wide range of use in manufacturing process. Wooden, aluminum and wax are mostly used materials for pattern in the casting. However, it contains some limitations such as expansion of wax pattern, cracks in ceramic, complexity limitation in wooden pattern and removal of wooden pattern from sand mold etc., in the light of this, the work attempts to use ice pattern for mold making and sublimating ice pattern to create cavity in the mold for pouring. Ice pattern can be produced with aid of rapid freeze prototyping (RFP) or by traditional ice mold method. Integration of RFP/Traditional ice mold method with sublimated ice in casting process allows the quick creation of complex metal parts. Here, mold is produced by ice pattern and then ice pattern is removed by sublimation process (sublimation is the process of direct conversion of solid phase to vapor phase of matters) to create cavity. The advantages of no parts geometric complexity problems , No need of parting line design, less complex limitation, sound casting, clean and less cost of process operation, and better performance. This paper will present our creation study on sublimation of ice pattern in greensand for mold making for casting, and results of the cast piece obtained from sand casting process.

Development of Modeling Process in Rapid Freeze Prototyping

Through rapid prototyping [1,2] it can be achieved both conceptual models: the final prototypes and functional parts in less time than with conventional technologies. The author of this paper shows the dependence of the diameter of liquid nitrogen spray nozzles according to the diameters of the water spray nozzle, a factor that is important in determining the amount of liquid nitrogen required to freeze the drop of water. Regarding the deposited layer thickness estimation, the author presented two theoretical models of contact between water droplets, which depend on the step between two consecutive drops of water.

Designing a Cold Plate Used in Rapid Freeze Prototyping Technology

The rapid prototyping with ice is a new manufacturing technology that can generate three-dimensional objects from ice by depositing and rapidly freezing water layer by layer. In order to freeze the water droplets, the plate must meet certain conditions, among those it is worth to be mentioned, the surface temperature, which should not surpass 0°C. The equipment presented in the paper is a part of rapid freeze prototyping equipment, designed and built by the authors. The authors analysed various freezing systems and they discovered that the classical cooling systems are not appropriate to be used in rapid freeze prototyping technology. The unique solution is the utilisation of thermoelectric cells, generic named as Peltier cells. The modern technology can be used in obtaining Peltier cells, with a high degree of reliability, electrical consumption and yield. This can be successfully used as heat pumps in industry. The author developed an original system that permitted to implement the Peltier cells. The cold plate was designed by using CAD software. In addition, the cold plate was produced and tested. The equipment obtained, has a greater power in comparison with the classical ones, even if it has smaller dimensions. The electrical power supply has to be well filtered in order to generate a higher efficiency. Through the main advantages of the Peltier cells can be mentioned: no maintenance have to be performed as this type of cells have no moving parts, thus having a major advantage; no CFC or other consumables parts have to be used, thus proving to be more economical than other systems; the heat regulation can be performed easier compared with the classical systems offering a better control and precision; it can be used in severe environments where conventional cooling systems can fail, being successfully used in the presence of liquid nitrogen; it can perform in various positions and is reversible similar to heat pumps. The main drawback of this system is that it uses a great amount of electrical energy, consequently can have a low yield.

Trajectory Control for an Innovative Rapid Freeze Prototyping System

The subject of this paper is trajectory control for an Adept Cobra 600 robot, which has been retrofitted for additive ice construction. Since this application is quite different from typical SCARA applications, considerable development is needed for trajectory control and data flow. We first outline the trajectory control system requirements, as well as the limitations of the robot hardware. Different control options are proposed and their merits and demerits are discussed; the most suitable scheme is judged to be custom programming in Adept’s V+ programming language, with trajectories expressed in the Cobra 600 joint space. With this control scheme, all system requirements are met, data manipulation is most efficient, and the system is readily adaptable for planned modifications. A specific data format is needed in order to implement this control scheme; we describe how trajectory data produced with our part-slicing algorithm is converted to the format required for the V+ programs.

Predictive Modeling and Experimental Verification of Temperature and Concentration in Rapid Freeze Prototyping With Support Material

Rapid freeze prototyping is a solid freeform fabrication method that uses water freezing into ice as the build material. Each layer of geometry is deposited and allowed to freeze before the next layer is added in order to additively create a three-dimensional ice part. A sacrificial support material is needed for the fabrication of complex ice parts. Identifying a suitable support material and understanding the interaction between the build and support materials is the motivation behind this study. A temperature prediction model and a concentration prediction model are presented. Experimental results have been obtained to validate these models.

Finite Element Analysis of Solidification in Rapid Freeze Prototyping

Rapid freeze prototyping (RFP) can generate three-dimensional ice patterns from computer-aided design (CAD) models by depositing and solidifying water droplets layer by layer. One important issue of the RFP process is how to fabricate the ice pattern to desired accuracy in an acceptable short time. The waiting time between two successive layers is a critical factor. A waiting time that is too short will lead to unacceptable part accuracy, while a waiting time that is too long will lead to an excessive build time. Finite element analysis is employed in this study to predict the solidification time of a newly deposited water layer and to develop a better understanding of heat transfer during the RFP process. ANSYS Parametric Development Language (APDL) is utilized to develop software for the prediction of solidification time. The result is used to investigate the effect of various process parameters on the solidification time of an ice column and a vertical ice wall. These parameters include environment temperature, heat convection coefficient, initial water droplet temperature, layer thickness, and waiting time between two successive layers. Experiments are conducted and the measured results are shown to agree well with simulation results.