The engine block cover is 470x310x105mm.The weight is about 2.4kg and the average thickness is 3.3mm.The thickness area is 26mm.The product is in complex shape and has many screw bolt hole and rib.The difference in wall thickness is quite big so the casting will has deformation, shrinkage porosity and air pore etc.
The engine block cover request good mechanical properties,density.Any kinds of crack, shrinkage porosity,air pore are not allowed.Therefore,AlSi9Cu3 is chose as material since it has nice fluidity and castability.
- Initial Tooling Design
There will be six runners in tooling as picture shown.
By simulation,it will take about 0.076s to fill up cavity.The filling speed on two side is slower than speed in the middle.Therefore,there will be some air trapped in the middle.The shrinkage porosity and air pore will happen to these area.
- Pouring system optimization
By adding two more extra runners onto the middle part,the filling speed is faster and more stable in this area,which will be useful to avoid shrinkage porosity and air pores.
- Simulation after optimization
By simulation,the filling time will be about 0.071s.It is more stable for molten alloy to fill up the cavity.The ventilation will be done smoothly.There is no air trapped during solidification.
- Spot cooling
During simulation,the thick area take more to be solidified.Therefore,spot cooling need to used onto thick area.As picture shown,there are some spot cooling added into tooling in order to improve quality of castings.
According to optimization and simulation,the trial production is made via DCC1250T die casting machine.The final product has no obvious defects.The outer surface is pretty smooth and inner hole quality is very nice.During mechanical and airtightness test,the yield rate reach 96%.