Document Type : Research Paper
In this research, the effect of friction between the liquid metal and the sand mould wall and the effect of passage of liquid through a vertical bend and through a ceramic filter on the fluid flow and the melt velocity has been studied by measuring the velocity of the melt and direct observation of the liquid flow through the different parts of a naturally-pressurized running system. The friction factor was calculated using the experimental results and it was shown that the friction had a significant effect on the reduction of the melt velocity. The effect of passage of liquid through a vertical bend was measured to be 20% and a filter was estimated to reduce the liquid metal velocity by half (almost half of the effect that was stated in the literature). The design of the running system was slightly altered considering the obtained effect of filter on the melt velocity. The comparison of reliability of the castings obtained by different running systems, using a Weibull statistical method, showed that the altered naturally-pressurized running system produced the most reliable castings and that the effect of the new method of running system design was greater than that of the use of a ceramic filter in the common unpressurized running system.