Hello, complete casting noobie here so very much appreciate any advice. I'd like to cast some compression molds plates in aluminium to make a surfboard from recycled plastic. I've created the top of the initial mold in plaster and split into two to make it easier to cast. The dimensions of each half are 90 x 60 x 8cm with a thickness of approx 5mm. Is this kind of shape possible to cast in sand? My worries are the thin walls, convex shape and open end (where the two molds will be joined) see photos below. Many thanks!
That is a long way to run the metal with such a thin wall. I am not an aluminum guy but I think with the proper mold and gating it could be done....but I will let guys more familiar with aluminum look at it and see what they think. I know we could do it in cast iron but aluminum has much different pouring properties and I could see the metal getting pretty cold on the leading edge.
Thanks Billy, that's my concern too. I could potentially make the mold thicker but don't want to make the final piece too heavy. I wonder if there's a ratio for length to thickness as a guide for casting?
Is that the mold in the pictures or is it the pattern? I'm assuming it's the pattern. It might just be the way I'm seeing the pictures but the parts look thicker than 5mm.
Here is the Math, it is doable, if poured corectly https://www.mrt-castings.co.uk/casting-thickness-tolerances Probably upright on it's side , But dude, thats a HUGE sand mold , like 30 X40 inch, not a hobbiest project you will need a 4 man crew, or a really good crane to flip the Mold , the bigest I have done hobbiest is under half that size, V/r HT1
Thanks for the replies. Perhaps I'm biting off more than I can chew. Yes sorry that's the pattern, not the mold (bit like moldception!) Might look more than 5mm as there's a lip on the joining side. I thought casting box size and weight could be an issue too. I though about building a box a similar shape just an inch or two bigger rather than a rectangle to reduce the weight and sand of the whole thing.
OK stop with the Math!!! your part is 35.4 X23.6 x 3.15 Inch realistically you gotta use a flask 38 X26 with a 4 inch drag/ 3 inch cope ( cope drag are interchangable, but the thickness is required) depending on your sand system 3 inch and even 4 inch thick will require ALOT of support So 38X26X7=6916 so you are lookin g at 6916 in3 of sand at .055556 Lbs/in3 so 385 Lbs of sand , add flasks and lots of supports 400Lbs or 182 Kilos , even if you get really froggy on the custom Flask I doubt you can loose more then 1/3 of that weight. This is a big two man project V/r HT1 P.S I assumed Silicia sand. I know Zircon is significantly heavier, olivine is the same or a little heavier then silica
Thanks for your help HT1! Definately some rethinking to be done. I've split the pattern into two already, I guess there's nothing stopping me splitting it into 4 to make each piece more managable and bolt it all together at the end.
