I'm looking at building a new shop for my machine tools and I've been thinking about including a lean-to style shed with a sand floor for some foundry work. I'm wondering what you guys would suggest as far as foundry layout / floorplan considerations? Eventually, I'd like room to handle fairly large iron pours - up to several hundred pounds. I'll be installing a bridge crane for my machine tools (3-4 ton capacity) and am thinking about a lighter duty gantry or bridge for the foundry side but the headroom will probably be somewhat limited. What do you guys and gals think I should be considering? I've got a few, very nebulous ideas - mostly just daydreaming but to kick off the discussion: 1) General safety considerations - fire / burns / steam explosions are obviously at the top of the list but also fumes / air quality 2) Fuel storage and conditioning area - I've got this long term scheme to try and recover waste heat from the furnace exhaust. I've got an interest in live steam and was thinking about a water-tube boiler to generate steam and use that to drive a centrifuge for cleaning waste oil. Is it practical? No probably not... but it would be a fun project! 3) Furnace - probably two furnaces, a small one with no waste heat recovery for small pours and then, later, a larger one with waste heat recovery (either water-tube boiler or maybe checker bricks for a hot blast). It would be nice to have a way of moving the large furnace outside when in-use - seems like it would be safer and maybe a more efficient use of space 4) Green sand area - Storage area of sand, maybe a sand muller at some point 5) Mold shop - Patterns could be made in a separate woodshop but probably want a bench near the sand area for actually filling flasks, making vents and runners, etc. 6) Lifting / pouring - if using a tilting furnace, maybe not as critical, but could potentially need to move and pour relatively heavy (hundreds of lbs.) crucibles, etc. Also a question of where to pour; under the lean-to means the sand floor would be dry and in-ground molding would be possible but it means pouring hot metal inside a flammable structure. Also air quality - would need to be well ventilated 7) Cleaning / finishing - Needle scaler and industrial blast cabinet shared with the fabrication / welding part of the shop Thanks for your ideas!
I do aluminum casting with an electric furnace in a heated shop and in the Winter, I melt inside next to the over head door and simply open the door, wheel out the mold, pour, walk back inside and close the door. I do lost foam casting so indoor pours isn't really an option anyway. However, if it was a fuel fired furnace, and especially iron, the furnace would be outside and I'd just make sure I had an easy means to move the mold out just before the pour. Could be on a wheeled cart with hard surface, or on rails if you want a sand pit. I know casting in a shirt sleeve environment sounds nice but it really isn't. With all the fire CO/CO2 hazards, how much of the total process time do you actually spend tending to the melt and pour? Sure, I've envisioned a nice hood with a dual wall chimney for heat recovery, but problem is, the make up air has to come from somewhere, and that's the cold outside air, so you dont gain much as far as heat recovery. As far as heat recovery, how long will you run your foundry furnace? An hour maybe? You'd be better off just making yourself a dedicated waste oil burner for heat. Way safer and more efficient. The one problem is snow and ice. So a covered pit with tarp may be necessary depending upon your climate. If you're talking very small castings like jewlery, different strory but for everything else it's just not worth all the added trouble IMO. Build your shop with ordinary materials and set yourself up to do everything except the melt and pour indoors. Make your furnace portable so it can be stored indoors if need be. Best, Kelly
Thanks Kelly - good advice as usual. To clarify, when I spoke of waste heat recovery, I wasn't thinking about heating the shop but instead using that heat to help the foundry somehow, e.g. running live steam to a fuel "processing plant" or maybe just heating the makeup air. Since I'm planning on a combustion furnace, I loose a significant amount of heat to just warming up the nitrogen in the air and it would be nice to address that problem. A long term goal is casting some metrology gear in Invar, but the initial research suggests the pouring temperature is around 3300F, which seems difficult with a typical waste oil only burner design. But you bring up a good point about short cycle times; a traditional hot blast furnace design doesn't make sense at the home-shop scale for a variety of reasons, not least of which is that it takes a while to heat up the checkers.
