• Journal of Technologic Dentistry
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• v.16 no.1
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• pp.5-11
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• 1994

On purpose of relative comparison of between air-vent attached pattern and non attached one, casting tests were accomplished by castability analysis unrig wax screen mesh pattern. Experimental specimens are divided Into 4groups. 1) Air-vent attached pattern with high casting pressure(coil spring type centrifugal casting machine 2.5turn). 2) Air-vent attached pattern with low casting pressure(coil spring type centrifugal casting machine 1.5turn). 3) Air vent non attached pattern with high casting pressure(coil spring type centrifugal casting machine 2.5turn). 4) Air-vent non attached pattern with low casting pressure(coil spring type centrifrgal casting machine 1.5turn). The main results are as follows : 1) The condition of high casting pressure no.1, no.3 were showed perfect castability. 2) The condition of low-casting pressure, there is a wide difference between no.2, no.4 group. Castability of no.2 group preferable to no.4 group(p<0.001). 3) Low casting pressure and complex shape cause the low-castability. So it is recommanded that use of air-vent in case of complex shaped wax pattern with low easting pressure.

• International Journal of Precision Engineering and Manufacturing
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• v.2 no.1
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• pp.56-61
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• 2001

This work is concerned with the development of a new plaster die casting process the combines pressurization and vibration for the prototyping of die-castings, and also with a plaster die-casting machine that has a structure quite similar to that of an ordinary die casting machine. The machine utilized an air cylinder for pressurization and a magnetic actuator for vibration. A rapid prototyped pattern is made by the LOM process to prepare a plaster mold. In the process, a plunger int he developed machine simultaneously pressurizes and vibrates the molten metal to fill the plaster mold completely and to facilitate the creation of nuclei in the molten metal, respectively. The developed machine produced a prototype of an end clutch cover with a remarkable improvement in mechanical properties.

• The Journal of Korean Academy of Prosthodontics
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• v.44 no.5
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• pp.654-664
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• 2006

Statement of problem: There has been a eat interest in the use of titanium for fixed and removable prostheses in recent because of its excellent biocompatibility. However, the melting temperature and chemical reactivity of titanium necessities casting system different from those used in conventional casting. The current titanium casting systems are based on an electric-arc design for melting the metal in an argon atmosphere and its exclusive investment. Despite the new development in Ti casting system, inadequate mold filling and internal porosity are frequently observed casting defects. Purpose : The purposes of this study were to compare the castibility and reaction layer of the casting titanium under the two casting machines and their investment condition. Material and method: coping and machine-milled titanium coping according to the casting methods and the marginal configurations. The total 28 specimens were used, and these are divided into 4 groups according to 2 casting machines and 2 investments. The castings were analyzed using x-ray microanalysis and microhardness testing. The reaction layer between margin of titanium casting and the investments was observed and analyzed with scanning electron microscope. Result: 1. Castabiliy of casting titanium specimen was best in the group of centrifugal casting machine and Selevest $CB^{\circledR}$ and good that of Selevest CB and pressure differential casting machine, Rematitan plus and centrifugal casting machine, Rematitan plus and pressure differential casting machine in order. 2. There was no significanct correlation in titanium castability in respect of casting machine. However ANOVA indicated that Selevest $CB^{\circledR}$ groups had significantly better castability than Rematitan $plus^{\circledR}$ groups.(p<0.05) 3. There was a significant microhardness difference between centrifugal casting machine groups and pressure differential groups.(p<0.05) Titanium castings in centifugal groups had significantly harder than those in pressure differential groups. 4. The addition of zirconia decreased interfacial reactivity. Conclusion: above result revealed that of the castability of titanium casting specimens had little correlation in casting machines and was better in magnesia-based investment contained ZrO2 groups. However in order to practice casting titanium in clininic, its castability should be improved, also there should be more research on factor of castability so that long-span prothesis and removable partial denture metla frame may be casted completly.

• Journal of Technologic Dentistry
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• v.29 no.2
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• pp.129-140
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• 2007

The purpose of this study was to evaluate the titanium castability (internal porosity) between pressure type casting machine & centrifugal casting machine with air-vent or not. Internal porosity is a well-known problem in dental titanium casting, resulting in inferior mechanical properties of dental restorations. To evaluate the castability, the square plate was chosen. 40 plate patterns($20{\times}20{\times}1.8mm$)were attached to funnel-shaped sprue. Then 20 plate patterns were attached air-vent. They were invested in titanium investment material and cast in a pressure type casting machine(20castings) and centrifugal casting machine(20castings). Each group were divided with air-vent(10castings) or not(10castings). The titanium castings were evaluated by radiographic photograph for the location of the internal porosities. The percentage porosity of each specimen was determined using standardized digital radiographs. The results were analyzed with analysis of variance and t-test for paired comparison between two groups.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.3
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• pp.122-135
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• 2014

This paper was studied on the horizontal continuous casting of Al-xSi(x=10~15%) aluminum alloy. The experiments of the horizontal continuous casting was carried out by the horizontal continuous casting machine for various casting conditions and investigated on fracture types and mechanisms. Surface defect types for the horizontal continuous casting is also investigated. And the study was carried out that the horizontal continuous casting conditions such as casting temperature, cooling rate, and drawing speed affect the hardness and primary silicon size of Al-xSi(x=10~15%) aluminum rod bar. Casting temperature within this experiment conditions don't affect on the hardness of rod bar but the higher casting temperature is the smaller primary silicon size. The higher cooling rate and drawing speed have the higher hardness and the smaller primary silicon size.

• Journal of Korea Foundry Society
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• v.41 no.6
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• pp.521-527
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• 2021

This study presents a process management method for the detection of casting defects during in high-pressure die casting based on machine learning. The model predicts the defects of the next cycle by extracting the features appearing over the previous cycles. For design of the gearbox, the proposed model detects shrinkage defects with data from three cycles in advance with 98.9% accuracy and 96.8% recall rates.

• Journal of the Korea Safety Management & Science
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• v.15 no.4
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• pp.179-184
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• 2013

An accident from machine work is often fatal to the worker. This accident is mostly preventable through perfect process jig. In case of this machine work, however, the disaster frequently occurred because of the design which is not considered the beginning of product design, post-process and mass process of production. As for sand casting method, this has the merits of the production; the product is easily produced by manual labor. On the other hand, this method has the demerits of a bigger dimensional error contrary to other mass process of production. When the sand casting product is in machine work, there are various problems such as unsafe fix and excessive cutting, product desorption and rapid life depreciation of equipment and tools. Considering the characteristics of sand casting method, it is accepted as difficulty to improve the problems. In this study, it suggests shell mold method for mold instead of the machine work after the sand casting of the circle shape container product. And the surface accomplishes the following average of surface roughness Ra$9.94{\mu}m$ of machine work with the casting of flask mold by shell mold method. In accordance with the simplification of processing process and reducing the average thickness variation by mass production of product with detailed appearance, it has a good influence on safety accident prevention caused by production and damaged product. It is confirmed that making higher degree of size precision of all machine work product is possible to increase the safety and productivity, reduce the processing process and improve environment.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.4
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• pp.386-393
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• 2015

A study is carried out on investigation on pattern costs, identification of geometric parameters for the cost, and development of cost estimation models for casting patterns. Pattern costs for machine tool structures are collected and analyzed to identify the important geometric parameters that affect the costs. The parameters are used for the development of the costing models. It is found that the geometric parameters can be easily obtained from a CAD system and then the costing models estimate a pattern cost in a minimum time. The models are verified with the structures whose pattern cost was used for this study. It is expected that this costing models can evaluate the cost of casting structures of machine tools in search of a near-optimal design based on manufacturing cost and, for example, weight at the design stage.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.27-33
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• 2011

Forensic Engineering is the area covering the investigation of products, structures that fail to perform or do not function as intended, causing personal injury or damage to property. To investigate explosion accident of the centrifugal casting machine in terms of the forensic engineering, in this paper, the computing simulation using ADINA FSI has performed to investigate that the effect of the Check-Pin fracture by the flow phenomena and molten metal weight and the mechanical properties test of the accident Check-Pin has performed using the instrumented indentation technique. Through these studies, the safety accident that may occur in centrifugal casting machine can be minimized by performing specialized and systematic investigation of the accident cause in terms of the forensic engineering.

• Journal of Technologic Dentistry
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• v.25 no.1
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• pp.81-87
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• 2003

Ti-20%Zr-X%Cr(X=0,5) based alloys not containing hamful Al and V were newly designed in order to reveal their possibility for dental casting alloys, and melted in argon-arc casting machine. The mechanical properties were evaluated by using universal testing machine. The tensile strength and %elongaton of the alloys markedly increased with Cr content. The Ti-20%Zr-5%Cr alloy showed a similar tendency with Ti-6%Al-4%V alloy in tensile strength, but surpassed in %elongation. From these results, it was concluded that new alloys for successful dental casting materials should be designed as Ti-Zr-Cr based alloys.