Tavia, Posted October 05, 2009
This is the final installment about the casting process. Watch all the magic!
Step 9: So here are the flasks that are placed into the kiln with the rubber buttons removed (don't want to melt those!) I use a 14 hour burn out cycle to go through the steps of melting all the wax and curing the investment for casting. Also, you see, once again, that safety is important when preparing to cast. Those flames can be bright, so be nice to your eyes and where glasses!
Step 10: Heating the metal in the crucible.
Step 11: Still heating the metal. After it becomes liquid it is time to sprinkle in some flux and use a stirring rod to clean the metal of any impurities.
Step 12: When the metal is ready, the flask is taken out of the kiln and placed onto the casting side of the vacuum caster with the "button" side up (where the divet was created by the rubber button). Here I am pouring the molten metal into the flask after it is placed onto the vacuum caster and the caster is turned on, thus aiding in drawing the air out of the flask and the metal into all the crevices. After all the metal is poured into the flask, you see a metal "button" in place of the rubber button that was used to create the sprue tree.
Final Step: Quenching. After casting and waiting about 5 minutes or so, it is time to quench the hot flask into a bucket of water to break away the investment mold and reveal the cast metal pieces. On the left you see the engagement ring, that I had carved in wax and cast in 14k white gold, after quenching. On the right you can see all of the sprue trees which are now metal trees that have been cast and are ready to be cut apart into individual pieces and made into jewelry.
Hope you enjoyed my photo diary of lost wax casting! Hopefully you learned a little something new!
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!
Tavia, Posted October 02, 2009
This is a little insight into the lost wax casting process. I thought it would be fun to document my last casting and share it with you through a photo diary of sorts. There will be three installments. Enjoy!
Step 1: If your design requires a rubber mold to create multiples, or to make a wax copy because the material of your original is not conducive to the lost wax casting process, then this would be your first step-creating a rubber mold. There are many different kinds of molds out there, I use a silicone rubber mold. These are two examples. The one on the left shows a mold of 7 toy car wheels (plastic isn't the best material to burn out in a kiln), and the mold on the right is a pendant from my limited edition series.
Step 2: After cutting open the mold and removing the original item(s), the opening of the mold is pressed against the nozzle of the wax injector and liquid wax fills the mold at which point you let it cool before removing the wax item from the mold. Here you see the wax injector nozzle and a filled mold.
Step 3: On the left you can see the collection of waxes I have created that need to be cast (I think there were around 40 pieces!). On the right, you can see the beginning of building the sprue tree that consists of a main wax channel with all of the waxes attached by small wax channels. These channels are called sprues. I am using an electic wax pen to heat the end of each sprue and melt it onto the main sprue.
Step 3 continued: Here is a close up of a sprue tree in progress consisting of pieces from my limited edition line to be cast in sterling silver. Also, on the right, you see a carved wax of an engagement ring to be cast in 14k white gold, which has to be cast separately as it is a different metal. Injection wax is a softer more maleable wax and blue carving wax is more durable to withstand carving, filing and sanding to create the design.
Hope that was enough to whet your appetite...casting story to be continued!!!