I'm attempting to make a re-usable ingot mold with a curing refractory mixture. The pattern is a mix of ABS and PLA. I'm wondering how to remove the pattern from the cured mix without damaging it. Any advice? They are in there pretty good rapping doesn't do much to them. The shape is pretty important as the volume is calculated to be a hair over 1lb after pouring.
You could try drilling and tapping the pattern so you can insert draw spikes to lift it out. Worst case the pattern may be stuck fast to the refractory and may need to be burnt out. Pete
Success! Let's fire this baby and see if we get a reusable mold. Hoping to get 10 1lb brass ingots out of it
What did you use for parting compound and what kind of refractory? Some refractories are formulated for metal contact, some not and metal can adhere to varying degrees. Some graphite or soot from and acetylene torch might be advisable before each ingot. Is that going to be an open face or closed mold? I see the rectangular ingot but what it the little wing/gate and hole? Best, Kelly
Yes I had already put in some spikes but it wasn't budging. After a lot of rapping I put a screwdriver through the eye holes and used it as a lever to get it loose. 1000° no cracks! I think it's gonna work starting the brass melt...
I didn't use any parting compound. The refractory is a mixture of plaster, refined silica sand, ash and some grog. It's an open face mold so the little gate is flush with the top of the ingot and once it's full will spill into the overflow reservoir so I know to stop pouring and have a bit of wiggle room if I pour too much.
I suppose it goes without saying but I presume you are going to fire that thoroughly before use. Seems like bronze can pretty tenaciously adhere to such when used as mold material so prior comments about graphite, soot may increase odds or reuse if it can survive the thermal shock. Best, Kelly
Yes I brought it slowly to 1000C and soaked for a bit. Plaster is a minor component of the mix, only to have it set faster so the other components don’t settle out. It’t something like 30% PoP, 50% sand and 20% ash. I’ll be pouring with the mold at about 700C
Luckily I have a few worn out pure graphite crucibles that provide ample graphite powder to sprinkle the mold with!
Well the mold worked, but it fell apart pulling the ingot out. Ah well. I was just hoping to have a way to make many ingots without using sand and ramming up flasks, or buying a cast iron mold in the exact dimensions I want. Shiny ingot! 1.03 lb
Sawdust or charcoal powder might do the trick. Copper and bronze stick very aggressively to my crucible walls as well as my furnace refractory. Pete
I am a bit out of my depth here as I have not done any brass casting. So take this with a grain... Why not cut to the graphite chase and just buy a block of graphite and mill out a couple molds? Here is a 4" x 4" block for 30 bucks. https://www.amazon.com/OTOOLWORLD-G...6&sr=1-3-ab57425f-010b-46ba-9b54-4c012bcb0387 I have a few tapered end mills that would be sweet for milling pocket with proper draft. Denis
Truth! If you need an ingot mold, a wood pattern cut from a block of of old 4x4. We would not use a refractory ingot mold. A quality issue is about the refractory eroding over time and getting into the metal. In a home metal cast environment, low volume etcetera. I cannot see it being an issue. I gotto be bored outta my mind to be answering a thread whose part was finished 1 1/2 years ago. Think I'll go ride my bike
