Assessment of the suitability of a gate design modification compared to the change in pressing velocity considering the distribution of gases in the casting volume

The qualitative properties of high pressure die castings are closely correlated with their internal structure, which is directly conditioned by the gas entrapment in the melt volume during the casting cycle. It is known that the gas entrapment in the volume of the melt and their subsequent distribution into the cast can be reduced by changing the technological parameters of the casting cycle or by the modification of the gating system design. The contribution addresses the issue of which variant of the gas content reduction is more efficient regarding the gas entrapment and the nature of the melt flow in the runners. The experiments are based on a real casting process. The established design solution of the gating system and the technological parameters setting are considered as a referential. Different gating system modifications were designed where the design modification is connected with the cross-section of a gate, in which the final acceleration of the melt flow occurs. The observed melt velocity in the gate is considered as a correlation factor, based on which the modification in the piston velocity is determined. The assessed parameter is the gas entrapment in the cast volume at the end of the filling phase. Assessment of the casting cycle and evaluation of experiments is performed using simulation program Magmasoft. Based on the performed analyses, it can be stated that the gate design modification will affect the filling regime of the die cavity by changing the melt velocity in gate, but the nature of the melt flow in runners remains unchanged. Modification of the piston velocity affects the filling regime of the die cavity, and also the nature of the melt flow as it passes through the runners, thereby promoting the gas entrapment in the melt volume. Therefore, it is necessary to pay an increased attention to the design of the gating system and only after debugging the design to proceed to the optimization of technological parameters.

Research and Evaluation of the Influence of the Construction of the Gate and the Influence of the Piston Velocity on the Distribution of Gases into the Volume of the Casting

Distribution of gasses to the cast volume and volume of pores can be maintained within the acceptable limits by means of correct setting of technological parameters of casting and by selection of suitable structure and gating system arrangement. The main idea of this paper solves the issue of suitability of die casting adjustment—i.e., change of technological parameters or change of structural solution of the gating system—with regards to inner soundness of casts produced in die casting process. Parameters which were compared included height of a gate and velocity of a piston. The melt velocity in the gate was used as a correlating factor between the gate height and piston velocity. The evaluated parameter was gas entrapment in the cast at the end of the filling phase of die casting cycle and at the same time percentage of porosity in the samples taken from the main runner. On the basis of the performed experiments it was proved that the change of technological parameters, particularly of pressing velocity of the piston, directly influences distribution of gasses to the cast volume.

Shrinkage Porosity in Steel Sand Castings: Formation, Classification and Inspection

In this Chapter, shrinkage porosity defects in steel castings are analysed, particularly for low carbon, high alloyed steels, which have applications in critical engineering components. It begins with the mechanisms for porosity formation within the solidification contraction phase of the casting cycle, highlighting the importance of feeder design. This is followed by characterisation of the solidification phase of steel alloys, including the evolution of phases, which is important in distinguishing between microstructure and porosity in microscopy analysis. A more detailed discussion of interdendritic feeding and mechanisms for shrinkage micro-porosity is then provided. This leads to the well-established interdendritic flow model and commonly-used thermal criteria for shrinkage porosity prediction. The discussions are then consolidated through the classification of shrinkage porosity in terms of formation mechanisms and morphology, and its causes relating to composition, design and process conditions. Finally, engineering standards for classification and inspection of porosity types and severity levels in steel castings are discussed. Throughout, basic design and process improvement approaches for improving melt feeding during solidification contraction is given, with emphasis on providing practical solutions for prediction and evaluation of shrinkage porosity defects in castings.

MINIMALISASI BIAYA PENYEDIAAN FRAME SCAFFOLDING DENGAN METODE LINEAR PROGRAMMING PADA PROYEK X

ABSTRACTIn the process of casting, we need a temporary structure that functions as a support or called scaffolding. Scaffolding frame is one type of modern scaffolding that is very commonly used today in high rise building construction. The amount of frame scaffolding needs on a project is not small so the amount of supply of frame scaffolding material can affect cost control on a project. In this study, the linear programming method is used to minimize the cost of providing frame scaffolding material in Project X. The study uses various combinations of frame scaffolding component sizes in casting beams and floor slabs with constraints or problem constraints such as storage of frame scaffolding components, load capacity the maximum that can be held by frame scaffolding, the supply of material quantities, and the casting cycle. By using the linear programming method, a cost savings of 4.3% can be made from the total cost of providing frame scaffolding in Project X if frame scaffolding material is provided with a volume of 3 floors, then 20.23% if frame scaffolding material is provided as much volume 2.5 floor, and 28.7% if frame scaffolding material is provided as much as the minimum floor volume.ABSTRAKDalam proses pengecoran, dibutuhkan struktur sementara yang berfungsi sebagai penyangga atau yang disebut perancah. Saat ini, frame scaffolding merupakan salah satu jenis perancah modern yang sangat umum digunakan pada konstruksi gedung bertingkat. Jumlah kebutuhan frame scaffolding pada suatu proyek tidaklah sedikit sehingga jumlah penyediaan material frame scaffolding ini dapat mempengaruhi pengendalian biaya pada suatu proyek. Pada penelitian ini, digunakan metode linear programming untuk dapat meminimalisasi biaya penyediaan material frame scaffolding pada Proyek X. Penelitian menggunakan berbagai kombinasi ukuran komponen frame scaffolding pada pengecoran balok dan pelat lantai dengan kendala berupa tempat penyimpanan komponen frame scaffolding, kapasitas beban maksimum yang dapat ditahan oleh frame scaffolding, penyediaan jumlah material, dan siklus pengecoran. Dengan menggunakan metode linear programming, dapat dilakukan penghematan biaya sebesar 4,3% dari total biaya penyediaan frame scaffolding pada Proyek X jika material frame scaffolding disediakan sebanyak volume 3 (tiga) lantai, dapat dilakukan penghematan sebesar 20,23% jika material frame scaffolding disediakan sebanyak volume 2,5 (dua setengah lantai), dan sebesar 28,7% jika material frame scaffolding disediakan sebanyak volume lantai yang paling minimal. Selain itu, dengan menggunakan metode linear programming dapat diketahui jumlah material frame scaffolding yang paling baik sesuai dengan kondisi-kondisi di lapangan.

The Influence of the Tablet Height and Plunger Pressing Velocity on the Final Porosity of Die Casting

With a pressure die casting process, one of the important factors affecting the quality of castings represented by porosity is plunger pressing velocity determines the regime die cavity filling and correct determination of dose mass of a molten metal required for one casting cycle. The mass is given by a total of the net mass of a casting, overflows, a gate system and a metal rest inside a filling chamber (the tablet height). As a rule, the tablet height represents the largest mass ratio regarding the waste metal. A correct determination of the tablet height is important from both economical and qualitative aspect of a pressure die casting process.

Highlights methodology of time characteristics optimization for plastic products production

Basic elements of casting process and its main stages are considered. Features of time characteristics for production of plastic products are investigated. The main stages in the methodology of time optimization characteristics for the production of plastic products are given. The proposed methodology allows to increase productivity and optimize the time characteristics of the process of production of plastic products, taking into account the preservation of the quality of plastic products which is achieved by reducing the casting cycle. At the same time the considered methodology considers plunger time forward and backward, the "course" of the nozzle time, the time of extraction of the product from the matrix during the production of plastic products.

Assessment of Suitability of the Design of Gating System with the Use of Simulation Software

The quality of thin wall castings produced by metal die-casting depends on the coherence and consistency of various aspects influencing the process of casting cycle. The qualitative properties of castings should already be considered in the design phase of construction of the gating system. The simulation software is an effective facility for the initial revealing of defects of the design phase. The assessment of casting cycle by the means of simulation predicts an incidence of defects of the casting core in the design phase and therefore reduces both the incidence of defects in the production and the costs while the production efficiency is increased. The article deals with the assessment of the design of the gating system for a particular casting type. The filling of mould cavity, casting solidification and time course of temperature changes occurring in the selected locations of gating system were defined as parameters indicating the assumptions of design accuracy. Simulation tests were carried out in the NovaFlow&Solid program. The tests resulted in a conclusion evaluating and describing the adequacy of structural design of the gating system.

Dynamics of Treatment Device for Die Casting of Metals

The aforementioned proves that the grease flow in mould treatment equipment can be regarded as a regulation system with the input quantity by medium pressure p1 above the grease level and with the output quantity by the grease flow speed.The utilization of treatment equipment for die casting of metal enhances both the working environment and work culture during die casting of metals. Application of grease flow regulation results in better repeatability of die casting cycle which positively influences the quality of castings.

Cooling Thin Parts of Pressure Casting Moulds by Means of Liquid CO2

To ensure optimal temperature conditions during casting cycle the pressure casting moulds are equipped with cooling systems. These days the cooling systems used in the most of Czech foundry plants enable pre-heating of pressure casting moulds to the working temperature before start-up of production and during casting operation to keep optimal temperature balance among the casting and the mould. Pressure casting mould temperature balance is provided by system of mutually connected channels which are mostly parallel with parting line and inside those the heat transfer medium flows. However such a system allows removal only limited heat amount from the most overheated places of the casting mould and does not allow heat removal from cores of small diameters. This inhomogeneous heat removal causes porosity of the casting in certain areas and also lifetime of the pressure casting mould is dramatically reduced. Cooling by means of liquid CO2 was developed as one of the new cooling possibilities for such places in the pressure casting mould where the heat is concentrated and for standard cooling systems it is too complicated to fully control the heat processes there. The paper deals with the behaviour monitoring of the new cooling system utilizing the potential of liquid CO2. This system was applied into pressure casting mould core and its final impact on the casting quality in the close surrounding was observed.