The day had finally arrived when I had the patterns ready after a bit of fine tuning and Alumaloy Castings Inc in Toronto were going to pour some #317 aluminum alloy. A few other stars and planets had also come into alignment for some personal business that warranted the trip from Ottawa to Toronto. In testing the patterns in my own green sand, I had discovered a couple of "flaws" that I wanted to correct which also led to some delays in the final casting. In hindsight, these are "lessons learned" for my next patterns.
The master mold-maker was Marco Stabilini, one of the principles of Alumaloy. Marco's been in the aluminum business since he was knee-high to a grasshopper as his father had started the business many decades ago.
The first step was to select a flask (cope and drag) large enough to hold the two patterns. The drag was set bottom-side-up on a mold board. Alumaloy is a production facility so they have the specialized equipment for large-production green sand mold making as we shall see in the photos below.
As with any mold making, the patterns were next dusted with parting powder. The fine white talc keeps the green sand in the drag from sticking to the green sand in the cope and to the pattern. It allows us to readily separate the cope from the drag.
You can see the alignment pins in the drag in the the front of the photo below. It is these alignment pins (one on each side) that ensures that the cope will fit exactly into the correct position on the drag after the pattern has been removed from the mold.
end of this link.) The sand cores were then carefully inserted into the mold. Because of adjustments I had made when "fine-tuning" the pattern, the sand cores had to be sanded so that they had a better fit when inserted into their cavities.
The mold and casting were left for 45 minutes until the aluminum had solidified. The sand mold was then dumped into the "recycle" hopper. The hot steam from the damp sand rose up as the perfect casting (complete with sprues and risers) appeared on the scene for the first time.
The Top View:
All in all, it's been a very interesting year getting involved in this project. Starting with learning how to make patterns, experimenting with sodium silicate and CO2 to make sand cores, visiting with Marco, Paul, and Susi at Alumaloy on several occasions to see how it's done professionally, to the final steps of actually making the castings - it's been a very good educational experience for me.
Now to continue from here with trying some back-yard metal casting. But first, we gotta finish the Mikey Burner and get our foundry built.