The Vulcanalia backyard foundery!
Okay, it took almost 5 years of research and development, but now it runs! Bronze and copper can be cast for art en engineering projects. Spectacular!
Doorknocker 'Hugo de Groot' (lost wax, bronze)
'Head of a girl' by H. W. (lost wax, bronze)
Flange for distillation kettle (sandcasting, copper)
Filling cap for distillation kettle (lost wax, copper):
Left: As it came from the plaster. Right: After cutting and sandpaper treatment
Current topic of research:
Augustus 2010: Finite Element Analysis with Comsol, 2D transient analysis
Plaster mold: Specific heat: 840 J/Kg K Conduction: 1.3 W/m K Density 2300 Kg/m3 Dimensions 10*10cm
Air Hot Chamber: Specific heat: 1006 J/Kg K Conduction: 0.025 W/m K Density 1.205 Kg/m3 Dimensions 30*30cm Airflow 1 m/s Temperature 673K (400 degrees C)
In this analysis the plaster mold is situated in an upgoing airstream of 400 Celsius. The airflow is 1 m/s. For a square mold with length of 10cm it takes around 3 hours to heat up completely.
From wikipedia i learned that plaster (calcium sulfate) has several stadia in which water is debonding from the plaster. The last stage occurs at 250 degrees C. It is clear that this transformation will impose a stresshold in the temperature distribution. This effect is neglected in this analysis and will be determined experimentally.
Finite element model. (1) Plaster mold (2) Airflow
The temperature distribution after roughly 3 hours:
The temperature in the middle of the mold. Time is in seconds.