Thesis (M.S.)--University of Wisconsin--Madison. / Typescript. eContent provider-neutral record in process. Description based on print version record.

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This thesis is about the design of the gating system and selection of proper alloy for defects free (grate bar) casting. The gating system plays an important role in casting manufacturing process. The gating system has different elements like pouring cup, sprue, well, runner, riser, and ingates. The function of the gating system is to provide molten metal to the mould cavity through different gating system elements.  Casting is a metal shaping process which is used to produce a cast component. The casting process depends upon the material, type of pattern, mould and various techniques like sand casting, investment casting, die casting, squeeze casting and lost foam casting. The sand mould casting process is used in this report. The casting process is used for making small to large cast parts, complicated shapes, and precision parts, etc. Making a casting without defects is an important requirement for its strength. The effective and efficient design of the gating system is necessary for making defects free castings. There are various defects like shrinkage cavity, porosity, pinholes, blowholes and incomplete filling that may occur in sand casting. The simulation software like Magma Soft and Nova Flow Solid are used to predict the possible defects in the casting. The uses of the simulation improve product quality and increase productivity. It also helps to reduce the rejection rate by identifying and controlling defects. This work is done at AB Bruzaholms Bruk as part of master thesis work at Jönköping University, Sweden. The company provides all the necessary data for simulation purposes. The design of the gating system is finalized as per company requirements and needs. The research questions that have been answered in this report based on the following points. 1) What does zero-defect mean? 2) Which is the best design among the ones that are prepared and simulated? 3) Which is the best alloy combination for casting parts that give defects free casting and better fluidity and filling?

Diploma thesis deals with problem of designing the gating systems for wax patterns manufacture by numerical simulation. It was created an optimum numerical simulation of wax blend injection, optimized for a simple test model and then applied to more complex pieces. Based on knowledge of plastic injection and the simulation was designed several gating systems for mass-produced pieces. These findings were subsequently applied in the design of gating systems to produce large and thin wax patterns. By comparing the various proposals were finally selected the best solution in order to verify the optimum numerical simulation in practise.

This diploma thesis deals with the optimization of gating systems of shape-complex aluminum castings produced by investment casting process. Two castings whose massive gating systems make problem with the use of liquid metal (so called yield) were chosen for optimization. Each casting is described in its own chapter. The individual subchapters deal with description of the original and newly designed gating system. Simulation, test castings, X-ray inspection and metallographic examination were performed for each variant. At the end of each chapter there is an evaluation of the results of the optimization of gating system.

The flow pattern in the uphill teeming process has been found to be closely related to the quality of ingots and further to affect the yield of ingot production, which is crucial for the steel making process. The formation of non-metallic inclusion and entrapment of mold flux has been considered to be affected by the flow pattern in the gating system and molds by many previous researchers. The aim of this study is to investigate the flow pattern of steel in the gating system and molds during the initial filling stage. In addition, to study the utilization of swirl blade implemented at the bottom of the vertical runner on the improvement of initial filling condition in the mold. A three dimensional model of two molds gating system for 6.2 ton ingots from Scana Steel was adopted in the present work. A reduced geometry model including one mold and a runner, based on the method from previous researchers, was also used for comparison with the current more extensive model. Moreover, a reduced geometry model including one swirl blade and a runner was simulated to find effects of an increased-length vertical runner on the flow pattern improvement at the vertical runner outlet. Flow pattern, hump height and wall shear stress were respectively studied. A reduced geometry with homogenous inlet conditions fails to describe the fluctuating conditions present as the steel enters the mold. However, the trends are very similar when comparing the (hump height-surface height) evolution over time. The implementation of swirl blades gives a chaotic initial filling condition with a considerable amount of droplets being created when steel enters the molds during the first couple of seconds. However, a more calm filling condition with less fluctuation is achieved at the molds after a short while. Moreover, the orientation of the swirl blades affects he flow pattern of the steel. A proper placement of a swirl blade improves the initial filling conditions. The utilization of swirl blades might initially result in larger hump height. However, it gives fewer fluctuations as the casting proceeds. In the model without swirl blades, the maximum wall shear stress fluctuates with a descending trend as the filling proceeds. An implementation of swirl blades can decrease and stabilize the wall shear stress in the gating system. A special attention should be made in choosing refractory at the center stone, the horizontal runner near center stone and the vertical runner at the elbow. This is where the wall shear stress values are highest or where the exposure times are long. / QC 20120203

The gating system transfers the iron melt from the ladle to the void in the casting mould. The gating systems dimensions and designs are crucial for the success of a casting and a poor gating system is a leading cause of scraps. The main goal of this thesis is to improve the pouring basins and sprues at Norrlandsgjuteriet, an iron foundry located in northern Sweden. The step in the offset step basin and other variables that affect the gating system is explained, investigated and simulated in MAGMASOFT. Furthermore, put to practice at Norrlandsgjuteriet. Adding a step in the offset basin fills a very important function in the system, fending off air bubbles that might enter the mould and reduce the horizontal velocity of the melt. The basin’s height and the sprue’s cross-section control the casting time and simulations conducted in this thesis show that a step can create a beneficial rounding to the flow over the step, creating a laminar flow of the melt, down the sprue contributing to a lower casting time. A narrower sprue is better, in which the melt’s surface tension is maintained, creating an oxide pipe-layer that protects the flowing melt entering the mould and from entrainment defects. The results show that replacing the offset basins used today with offset step basins, which are 30% smaller in volume, together with a tighter sprue will not only reduce the annual material consumption by 1% or 13 000 kg but more importantly increase the quality of the casting. This due to lower melt velocity, a more homogenous temperature, better flow in the basin with less air entering the mould. / Ingjutsystemet   transporterar   det   smälta   järnet   från   skänken   till   gjutformens   hålrum. Ingjutsystemets dimensioner och utformning är avgörande för en lyckad gjutning och ett dåligt utformat ingjutsystem är den främsta orsaken till kassationer. Syftet med denna rapport är att förbättra  gjutskålarna  samt nedlopp  som  Norrlandsgjuteriet,  ett  järngjuteri  i  norra  Sverige, använder. Steget i den förskjutna gjutskålen och andra variabler som påverkar ingjutsystemet förklaras, undersöks och simuleras i MAGMASOFT. Utöver detta testas det även praktiskt hos Norrlandsgjuteriet.  Att  lägga  till  ett  steg  i gjutskålen  fyller  en  väldigt  viktig  funktion  i ingjutssystemet i och med att luftbubblor avvärjs från att följa med in i formen samt minskar även  smältans horisontella  hastighet.  Gjutskålens  höjd  och  nedloppets  tvärsnittsarea  avgör gjuttiden  och  simulationer  som  genomfördes  visade  också  att  stegets rundning  i  gjutskålen skapar ett fördelaktigt flöde över steget vilket skapar ett laminärt flöde ner i nedloppet vilket samtidigt bidrar till en minskad gjuttid. Ju smalare nedlopp desto bättre upprätthålls smältans ytspänning vilket skapar ett oxidskikt som skyddar den flytande smältan, som ska fylla formen, från inblandning  av  luft  och  oxider.  Resultaten  visar  att  genom  att  byta  ut  de förskjutna gjutskålarna som används idag med förskjutna steggjutskålar, som är 30% mindre i volym, tillsammans med en smalare nedlopp så kommer inte bara den årliga materialförbrukningen att minska med 1% eller 13 000 kg men ännu viktigare att höja kvaliteten på de gjutna detaljerna. Detta på grund av lägre smälthastighet, en mer homogen temperatur, bättre flöde i gjutskålen samt mindre luft som tränger in i formen.

Diploma thesis deals with optimization of technological process casting a die cast, which is part of vacuum pump. The die cast is made from alloy AlSi9Cu3(Fe) in foundry KOVOLIT, a. s. There is a problem with inner defects at this cast. Solution of this thesis is to suggest suitable actions to minimize of incidence the defects in the cast. According to analysis of the defects in the cast these defects were classified as combination of shrinkages and gas holes. According to analysis causes of the defects are high temperature of die mould and closed air in die mould. As a result suitable actions were suggested – a change of the die mould tempering and a design adjustment of the cast. In case of implementing a new die mould in the manufacture a new gating system was designed. Suitability of the new gating system was assessed according to simulation of filling die cavity.