Optimized Gating System for Steel Castings

Abstract

Computer modeling using a commercially available software package was used to explore the optimization of filling systems based on the relatively new concepts of avoiding entrainment of air bubbles and oxides by avoiding surface turbulence. The test casting was based on a pattern for a traditional top poured test bar, whose cross section was a tri-lobed clover-like shape. The study illustrates clearly that the detailed design of the filling system has a major influence on the conditions for defect generation during filling. Traditional steel casting systems using the widely popular assembly of preformed refractory tubes were found to behave poorly. Systems were demonstrated which were capable of delivering highly controlled filling behavior. The latest systems to be developed employed (1) a naturally pressurized filling system and (2) the use of filters placed flush on the top of the runner to act as bubble diverters, together with (3) terminal spin traps. These novel filling systems demonstrated excellent performance in simulation, in agreement with practical experience of the capability (of the trident gate in particular) to produce, for the first time in the history of casting, defect-free castings on a routine basis.

Numerical Simulation and Experimental Validation of Melt Flow in the Naturally Pressurized Gating System

“…The simulations and experimental casting confirmed the effectiveness of the foam filter and vortex element on the melt velocity which corresponds with previous works [19,28,29].…”

Numerical Simulation of Reoxidation Processes

“…First step of next set of experimental works was already carried out and includes a proposal for optimal gating system design based on simulations. Several publications [8] suggest to use foam filters as a mean to reduce the melt velocity, first experiments supports this claims. Figure 6 a) shows velocity evaluation by vectors, where filter (50x50x20 mm, 30 ppi) is placed as a gate above the runner in horizontal position.…”

Bifilm Defects in Ti-Inoculated Chromium White Cast Iron

“…Nevertheless, if manufacturers decide to use high inoculant levels to create crystallization underlays and hard phases to increase the wear resistance, they should consider quality casting technology. The design of a proper gating system could help to eliminate bifilm defects [ 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 ], which generate TiC agglomeration. This may improve the TiC distribution, providing more even wear properties in the entire casting.…”