This was my first aluminum pour with real ingots. I now have 100 lbs of A356.2 and 100 lbs of 363 ingots. 363 is very similar to 319. I use the 363 without heat treatment and will have the 356 castings heat treated. For the crosses I used 363. Later I plan to use the 363 in permanent molds.
I had to get the ingots into the number 20 crucible. The 363 ingots had 1/3rd division marks. I placed the ingot on two boards with the mark centered between them and broke them with a sledgehammer. It broke nicely with a hard hit.
The same cross pattern I unsuccessfully attempted with iron would now be tried with aluminum. I mounted it on a match-plate for easy mould making. I also made a quick pattern for some pulley blanks. It takes longer to make a match-plate but is not very difficult or time consuming. It helps to align the sprue and make a good departure.
I made a wooden sand box to store my PetroBond sand in. I ram my molds over the box as pictured above. This is much more convenient than my old method. I loose much less sand this way. The box is made out of a single 4'x8' sheet of 3/8" plywood. I trimmed the top, bottom, and lid with 2" furring strips. It also has 4 cross supports under the bottom panel. It has 100 lbs of sand in it now. I think it will hold up to 400 lbs with no problem (strength or volume). I eventually plan to make a workbench that it will slide into.
Pouring the cross pattern.
This was on the second pour. As you can tell the crucible is much hotter. It is actually too hot which will cause hydrogen gas porosity in the aluminum. I let the furnace run with no metal in the crucible while I rammed the second molds. It melted the aluminum in about 5 minutes on the second heat. It is amazing how much a hot furnace can decrease the melt time. I do not have a pyrometer so I do not have a good way of testing the temperature of the metal. Hopefully I will be getting a thermocouple type soon when I start pouring critical projects. I poured the left over aluminum into a muffin tin. I coated the tin with a spray lubricate (like wd-40) before pouring. Powdered or spray graphite will work good to. The muffin sized ingots parted well. I had to tap with a hammer on the back of the pan to get a few of them out. They part easier the longer you let them cool.
Just poured. I ran out of sand on the pulley flask. They still turned out nice though.
The product. Not too bad for the first go. I was happy. I was amazed by how sharp the edges were. I have had not done any cleanup to the cross in the picture. Just knocked the loose sand off and cut the sprue. It does have the dark spot and a few pinholes on that end. The sprue was located on the backside of the bottom leg (near the dark spot). The spot seems to be sand that is embedded in the casting. ItItr came from the molten metal turbulence of the sprue.
Before I had problems with the corners tearing during pattern departure. Not with the PetroBond though. Nice and sharp.
Nice texture as well. At least I think so.
I actually poured two of them. Both with good results.
