Accessory Pouring Basin

Discussion in 'Foundry tools and flasks' started by Melterskelter, May 15, 2020.

  1. I did ask my foundry friend about your iron finish problems, Peter said there are specific spray on coatings to apply to the runners or even the entire mould that are burnt to remove the solvents and set hard to give durable coating to the sand. He could not recall offhand the product name, just that such product exist commercially.
     
    Melterskelter likes this.
  2. Pete also added the coating residue will build up in the used sand to the point where it will need replacing after multiple casting sessions.
     
  3. Melterskelter

    Melterskelter Silver

    The other option may be to change the gating strategy. That is a lot of iron to run through a single gate over a short period of time. Much as I don’t like the idea, I may have to make up a wider flask set and use a pouring basin located on the long side of the pattern. Then run the metal parallel to the long side with multiple gates—-four to six—-so that velocity at the gates is reduced. That is not an attractive option as it involves redoing flasks, the metal bottom board and one other plywood top board used in the process of ramming up the molds not to mention widening the running gear. Uggh.

    Trying to find a commercial wash, sourcing it, testing it to find it was or was not successful, searching for another etc involves a large time investment too.

    Denis
     
  4. Is there a commercial foundry you can visit?, my local one is an hour and a half drive away and they have been very helpful with advice. I know they use some kind of wash over resin silica sand for all of their iron castings.
     
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  5. Billy Elmore

    Billy Elmore Copper

    We used weights to hold down the cope but if you can put bars across it and clamp them together with C-clamps it will keep the cope down. I will look at your gating and see if there is any suggestions I can make to help out there but there are a lot of other things that can be at play. Could be more sand related than gating. Usually making the ingates thinner and longer helps with sand inclusions and surface finish.
     
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  6. Billy Elmore

    Billy Elmore Copper

    Just curious as to whether you have tried splitting the iron into different directions from the bottom of the sprue and feed into different walls? You can split the iron into four directions in the window and feed into all four walls without changing your equipment and benefit by reducing the velocity at the entry points. Depending on the sprue size you can usually make the area of the ingates 1.7 to 2 times the area of the bottom of the sprue to get less sand wash and better surface. Sometimes it is better to have multiple ingates to accomplish a real reduction in velocity. I could not tell by the pictures that sand was washing out at the ingate but I could see lots of soft areas of the mold that could be getting wash out. Possibly add radius to the inside parts to make them easier to mold and draw and not have as much turbulence during fill. Notice the finish was rougher closer to the gating but still had some roughness where the coolest metal would have been? Could be another possibility is to add a little southern bentonite for more hot strength of the sand. Could be that adding more vents in the hottest spots of the casting to help cool the metal as it flows would help surface finish. I think you can pour this at 2480 or less with no issues...just would not go too much lower than that. There are lots and lots of possibilities that you can try but the one that is the easiest and most cost effective is usually the right one for you.
     
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  7. Melterskelter

    Melterskelter Silver

    On the last pour I tried cutting the gate about 1/8” thick and 4 to 5 inches long. The sprue is .625 dia or .3 sq inches. My hope was the the sprue opening into the splash basin would be the choke point and that would allow slower gentler flow through the gate over a wider area. I had hoped that would reduce velocity and washing. Not so much. Could the sand be rammed too softly—-maybe. I can try a more firm ramming though I thought I had that pretty well covered. I do believe it might be a skosh soft and that may be the main problem. That is the easiest fix of all. I am also going to look at misting on some sodium silicate in the area in hopes of making a slight crust without washing out pattern details.


    I am headed down to see my mentor today. He used to do large volume green sand work many years ago, but now uses resin bound sand. So, he buys and uses few products useful for green sand. He has several interesting washes for resin. I’ll take the castings and see what he has to say. The main purpose of the trip is to buy returns.

    Denis
     
  8. Melterskelter

    Melterskelter Silver

    Using a central four-gate strategy would be interesting but would require some rework of the “ceiling bolts” I am using to support the sand in the cope. Because of the pattern shape that sand will fall out in the center of the mold if not supported after I draw the pattern and as I flip the mold to close up. See the second and third posts in this thread
    http://forums.thehomefoundry.org/in...-iron-casting-completed-55-pounds.1048/page-2

    The plywood flats are now 16 ga steel but are configured otherwise similarly. Without them there is just too much unsupported sand. I could modify the middle one to have two uprights and a central hole to allow a sprue to pass.

    Denis
     
  9. DavidF

    DavidF Administrator Staff Member Banner Member

    I'm wondering if something as simple as a deeper splash well would help out??
     
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  10. Billy Elmore

    Billy Elmore Copper

    Oh yeah...Harder mold would help keep sand from falling out and help with finish detail. The looser the sand in a mold is the easier the metal will penetrate into it. Adding a sprue well like DavidF suggested would help take away some of the initial velocity at the beginning of the pour and may help stop some sand erosion at the ingate. I would also incorporate a runner with a choke at the beginning to help. If I get a chance later I will mock something up for you.
     
  11. Melterskelter

    Melterskelter Silver

    Well, I did see my mentor today at his commercial foundry where we discussed the issues I have been experiencing with sand washing. He and his foreman both think I am just trying to push too much metal through too small and area. They suggested I put in a runner along on long side with 3 or four gates and just fill the mold that way.
    The more I think about it the more that makes sense. So, tomorrow I'll get some 2X6's and make a wider and deeper flask set so that I can side feed the mold. Instead of remaking or widening the steel bottom board I think I'll just screw a wider piece of 3/4 plywood onto the steel board. The inch or so of overhang all around will no contribute to racking of the flasks as the steel will hold that in check. And I can knock together a flask set in a couple hours. So that is the direction I intend to go.

    Side notes:
    I happened to show up at my favorite time at the foundry---pouring time. So I got to see them fill their thousand pound ladle from their induction tilt-furnace and then throw in a bunch of magnesium and have the Forth of July while it burned off. Quite a show to make ductile iron.

    They did have a rarity for them---a very small run out which they quickly plugged with a hand full or two of sand and finished the pour just fine. It was instructive to see this problem and its solution. Probably not applicable to me as I am solo and could not set manage the ladle while plugging the run out in any event.

    We also talked about a plastic refractory they use to line their ladle. That stuff has to be really tough to be durable while in full contact with molten iron and burning magnesium. I'll be asking more about that in the near future. We also talked mold washes and he sent me home with samples. He uses them on resin-bound sand but felt I might be able to gun them on non-critical areas with a common spray gun. More on that when I give it a try.

    So, back to the immediate plan.
    1)Be very sure to ram up the mold good and hard and I will do it in two lifts rather than one as one fill of sand and then ramming might promote a less thorough compaction. I have been seemingly ramming well, but then I am not sure it is quite hard enough.
    2) Abandon the single gate at one end of the tilted mold and go to a level mold with 4 gates
    3)Abandon the risers which seem not to be feeding in this setting. They were put in in reaction to a single time when I experienced shrinkage near the location I placed them.
    4)Do use multiple,wide, thin gates.
    5)Try pouring not quite so hot---2475 rather than 2550.
    6)Make wider and deeper flasks to accommodate these changes. Now the whole works will weigh more like 350 pounds.

    Thanks for all of the suggestions made above. I am certainly still open to hearing more.

    Fingers (hopefully not wires) crossed...

    Denis
     
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  12. Billy Elmore

    Billy Elmore Copper

    I may not understand what you were saying about not being able to gate into the center of one of the windows, but if you can do that you would not have to increase the size of your mold. You would not need to change the sprue location or anything...just add a sprue well and a runner that runs around the inside of the window. That would give you a huge amount of ingate space to depressurize the whole system. One side note about depressurized systems...it is possible to start getting misruns or short pours if there is any interruption to the pouring and you must have a clean melt and clean mold. They do not float slag or impurities out like a pressurized system will. I will mock up something to give you a few ideas.
     
  13. Billy Elmore

    Billy Elmore Copper

    I did a quick little mock up of the casting and simulated a pour with existing gating and then a depressurized runner system. I tried uploading the wmv files but they are too large. What I saw on mock up was interesting. Because of your low head pressure and small sprue the velocity in your single ingate was not extremely high. I added the sprue well,runners and ingates and got the velocity down to laminar but added around three or four pounds of iron in the process. Not sure the effort is really worth the extra work. I would look more into the mold hardness and sand properties first. I did see lots of turbulence in the ingate area but doesn't seem to be causing you any slag issues. If you have a personal email you can pm me I will send you the wmv files for your viewing pleasure.
     
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  14. Melterskelter

    Melterskelter Silver

    Of course I would be interested in the simulation! I did send you my email in a "conversation." It will be a few hours until I will be able to view it.

    Thanks, Billy.

    Denis
     

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