Wyniki wyszukiwania - BazTech

1

Impact of Sprue Base in Gating System on Quality of Filling – the Compromise Between Theory and Practice

Siodmok B., Jezierski J. R., Dorula J., Romelczyk R.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 3

167--172

EN

Foundry technologists use their own style of gating system designing. Most of their patterns are caused by experience. The designs differ from plant to plant and give better or worse results. This shows that the theory of gating systems is not brought into general use sufficiently and therefore not applied in practise very often. Hence, this paper describes the theory and practical development of one part of gating systems - sprue base for automated horizontal moulding lines used for iron castings. Different geometries of sprue bases with gating system and casting were drawn in Solid Edge ST9. The metal flow through the gating systems was then simulated with use of MAGMA Express 5.3.1.0, and the results were achieved. The quality of flow was considered in a few categories: splashes, air entrapment, vortex generation and air contact. The economical aspect (weight of runner) was also taken under consideration. After quantitative evaluation, the best shape was chosen and optimised in other simulations with special attention on its impact on filling velocity and mould erosion. This design (a sprue base with notch placed in drag and cope) is recommended to be used in mass production iron foundries to reduce oxide creation in liquid metal and especially to still metal stream to improve filtration.

2

Effects of Process Related Variations on Defect Formation in Investment Cast Components

Raza M., Silva P., Irwin M., Fagerström B., Jarfors A. E. W.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 1

103--108

EN

Castability of thin-walled castings is sensitive to variation in casting parameters. The variation in casting parameters can lead to undesired casting conditions which result in defect formation. Variation in rejection rate due to casting defect from one batch to other is common problem in foundries and the cause of this variation usually remain unknown due to complexity of the process. In this work, variation in casting parameters resulting from human involvement in the process is investigated. Casting practices of different groups of casting operators were evaluated and resulting variations in casting parameters were discussed. The effect of these variations was evaluated by comparing the rejection statistics for each group. In order to minimize process variation, optimized casting practices were implemented by developing specific process instructions for the operators. The significance of variation in casting parameters in terms of their impact on foundry rejections was evaluated by comparing the number of rejected components before and after implementation of optimized casting practices. It was concluded that variation in casting parameters due to variation in casting practices of different groups has significant impact on casting quality. Variation in mould temperature, melt temperature and pouring rate due to variation in handling time and practice resulted in varying quality of component from one batch to other. By implementing the optimized casting instruction, both quality and process reliability were improved significantly.

3

Risk Assessment of Defect Occurrences in Engine Piston Castings by FMEA Method

Piątkowski J., Kamiński P.

Archives of Foundry Engineering

|

2017

|

Vol. 17, iss. 3

107--110

EN

The FMEA (Failure Mode and Effects Analysis) method consists in analysis of failure modes and evaluation of their effects based on determination of cause-effect relationships for formation of possible product or process defects. Identified irregularities which occur during the production process of piston castings for internal combustion engines were ordered according to their failure rates, and using Pareto-Lorenz analysis, their per cent and cumulated shares were determined. The assessments of risk of defects occurrence and their causes were carried out in ten-point scale of integers, while taking three following criteria into account: significance of effects of the defect occurrence (LPZ), defect occurrence probability (LPW) and detectability of the defect found (LPO). A product of these quantities constituted the risk score index connected with a failure occurrence (a so-called “priority number,” LPR). Based on the observations of the piston casting process and on the knowledge of production supervisors, a set of corrective actions was developed and the FMEA was carried out again. It was shown that the proposed improvements reduce the risk of occurrence of process failures significantly, translating into a decrease in defects and irregularities during the production of piston castings for internal combustion engines.

4

Numerical Simulation of Directional Solidification Process of Single Crystal Ni- Based Superalloy Casting

Szeliga D., Kubiak K., Sieniawski J.

Archives of Foundry Engineering

|

2017

|

Vol. 17, iss. 2

111--118

EN

The analysis of influence of mould withdrawal rate on the solidification process of CMSX-4 single crystal castings produced by Bridgman method was presented in this paper. The predicted values of temperature gradient, solidification and cooling rate, were determined at the longitudinal section of casting blade withdrawn at rate from 1 to 6mm/min using ProCAST software. It was found that the increase of withdrawal rate of ceramic mould results in the decrease of temperature gradient and the growth of cooling rate, along blade height. Based on results of solidification parameter G/R (temperature gradient/solidification rate), maximum withdrawal rate of ceramic mould (3.5 mm/min), which ensures lower susceptibility to formation process of new grain defects in single crystal, was established. It was proved that these defects can be formed in the bottom part of casting at withdrawal rate of 4 mm/min. The increase of withdrawal rate to 5 and 6 mm/min results in additional growth of susceptibility of defects formation along the whole height of airfoil.

5

Oddziaływanie produktów cieplnego zgazowania modelu polistyrenowego na powierzchnię odlewu

Żółkiewicz Z.

Archiwum Odlewnictwa

|

2004

|

R. 4, nr 11/2

332--337

PL

W trakcie zgazowywania modelu polistyrenowego nad powierzchnią ciekłego metalu gromadzą się produkty zgazowania modelu. Stykają się one z ciekłym metalem oraz z warstwą ceramiczną oddziaływując na nią. Te trzy podstawowe czynniki tj. właściwości metalu, formy oraz właściwości fizyko-chemiczne produktów zgazowania modelu polistyrenowego wpływają na prawidłowy przebieg procesu, na możliwość wystąpienia w odlewie wad np.: niedolewy, pęcherze gazowe, wżarcia, zwiększenie zawartości gazów (wodoru) w metalu. W referacie przedstawiono wpływ procesu technologicznego zgazowywania modelu polistyrenowego na zawartość wodoru i tlenu w żeliwie szarym.

EN

During evaporation of a polystyrene pattern, the products of evaporation are accumulated above the surface of molten metal. They enter into contact with both the liquid metal and the ceramic material, affecting specially the latter one. The three main factors, i.e. the properties of metal, the properties of mould, and the physico-chemical properties of the products of polystyrene pattern evaporation, affect the correct run of the process, and inrease the risk of occurrence of casting defects, like misruns. blowholes, penetrations, and increased gas content (hydrogen) in metal. In the paper an effect of the technological process of polystyrene pattern evaporation on the content of hydrogen and oxygen in grey iron was investigated.

6

Řetízkový grafit v litině s kuličkovým grafitem (LKG)

Šustek P., Stránský K., Rusin K.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

1998

|

z. 57

135-138

7

Rozbor príčin vad v ocelích na odlitky pomocí morfologie oxidů a sulfidů

Šenberger J.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

1998

|

z. 57

125-130