Abstract: Burn on/metal penetration is one of the surface defects of metal castings in general and steel castings in particular. A research on the effect of burn on the six ton medium carbon steel shaft for making a roller of cold rolled steel sheet produced at one of the metals industry was carried out. The shaft was cast using sand casting by pouring through riser/feeding head step by step (with time interval of pouring). As it was required to use foam casting method for better surface finish and dimensional accuracy of the cast, the pattern was prepared from polystyrene and embedded by silica sand. Physical observations, photographic analysis, visual inspection, measurement of depth of penetration and fish bone diagram were used as method of results analysis. The shaft produced has strongly affected by sand sintering (burn on/metal penetration). Many reasons may be the case for these defects, however analysis results showed that the use of poorly designed gating system led to turbulence flow, uncontrollable high temperature fused the silica sand and liquid polystyrene penetrated the poorly reclaimed and rammed sand mold as a result of which eroded sand has penetrated the liquid metal deeply and reacted with it, consequently after solidification and finishing the required 240mm diameter of the shaft has reduced un evenly to 133mm minimum and 229mm maximum mm that end in the rejection of the shaft from the product since it is below the required standard for the designed application. In addition, it was not possible to remove the adhered sand by grinding. Thus burn on is included in mechanical type burn on.
Keywords: Steel shaft, sand casting, burn on/metal penetration, lost foam casting, polystyrene, fish bone diagram, control chart
Recieved: 17.10.2013 Accepted: 5.11.2013 UDC: 65.012.7