Casting...Did you know? (part 2)
Tavia, Posted October 04, 2009
This is a continuation of the previous post about the casting process.
Step 4: Here you see the completed sprue trees, which are on rubber "buttons". These buttons aid in holding the sprue trees but also help in creating a divet area when the investment mold is created that will be used to catch the hot metal as it is poured into the mold. The picture on the right shows you the metal "flasks" that are placed onto the rubber buttons to create a container to hold the investment which will cover the waxes.
Step 5: When using a solid flask with a vacuum casting machine, it is best to create air vents that will aid the vacuum in drawing the molten metal into all the crevices that need to be filled. The image on the left shows the use of wax web to create these channels along the perimeter prior to creating the investment mold. The wax web will be melted out of the flask along with the wax models during the burn out cycle in the kiln. The image on the right shows that safety comes first. When using investment one must protect ones lungs!
Step 6: Measuring water and measuring investment (kind of like plaster). Yes, there are recipes depending upon flask size.
Step 7: Mixing the water and the investment to create an even mixture.
Step 8: After mixing the investment it is necessary to get out as much air as possible before pouring it into the flasks. The vacuum caster has one side that is used to do just that. So, covering the bowl with the bell jar and turning on the vacuum caster for a few moments will help de-bubble the investment. It is necessary to repeat this process after pouring the investment into the flasks as well. Here you also see the flasks after the investment has cured and the wax web excess is carved away. It is also important to leave some space between the top of the investment and the end of the flask when vacuum casting to once again help the vacuum caster do its job best.
...one more installment to complete the process on its way!