Thankyou, You are a true expert with very good attention to detail. Casting is a lost art and you are doing a fine job of analyzing problems just like they did years ago. I have been involved in casting commercially, engine components. and as an apprentice. Defects were a common problem. Holes, lime and coke were common inclusions. Plenty and son. we made filters for the oil industry, and I was usually machining the lids. from 3" to about a foot in diameter. Wonderful days and fantastically knowledgeable people. We had our own foundry and pattern shop.
Interesting video! At first sight it seems the problem could be reduced by pouring through a gate, but after your final comments, I wonder if it has to do with the sand itself. Maybe you could return to this, with a few more details. Thanks!
Interesting stuff lucky. Thanks for sharing. I'm not sure I understand completely about the sand ramming too hard vs soft. If pouring a billet directly into the sand mold, you are saying ram it soft? Won't that cause problems when the metal hits the bottom of the sand mold, potentially intruding into the sand or breaking some off?
I would like to know as well it be a cool colab vid video if you two would explain it for example lucky Gen from a experience / arithmetic of view and yourself from a practical point of view
I think the bubbles would not go very deep in the first place as cast iron's density is huge compared to water. The bubbles near the skin could be the last ones which didn't have time to float out as the skin froze first. I once did this with aluminium and the resulting bar was very very porous. I poured it into a metal pipe with a bit of sand packed to the bottom to seal it. But some of the sand broke loose and floated on top which contributed to the porosity. A bottom gate would probably improve it a lot but it is difficult to mold.
Ah, the age old problem of the battle between how fast the bubbles rise and how fast the metal solidifies and thus perhaps traps the bubbles. BUT we need to remember that the bubbles do damage on the way through - not perhaps here so much where we are dealing with cast iron - God's gift to the foundryman. With more reactive metals like aluminium the bubbles will leave a trail of aluminium oxide behind - usually so thin as to be invisible but highly damaging to metal properties. Of course large parallel sprues cause the same problems particularly if unnecessarily high. I wonder if some of that subsurface porosity is due to the extra quick solidification of the near surface trapping bubbles that would escape further in where solidification is a lot slower? It looks a bit too random and there almost does not seem to be enough of it to convince me of its origins solely from mould gasses. Perhaps worth repeating the experiment with aluminum, a better machined finish, and a caustic etch - maybe even with soft and hard rammed moulds (that should keep you busy fort a while! 😊).... Martin
I have poured these billets before without these defects but were rammed very softly. The only problem was I would get swelling and made it hard to grip in the chuck. If you have a look at 1:15 in the video there are pinholes starting to form on the surface. This must of happened when cast iron becomes sluggish so the bubbles do not penetrate too far under the skin. I will try it with aluminium in a future video.
I suspect that the bubbles under the skin were loose high density contaminants from the sand or slag which were trapped and vapourised when the iron was semi liquid and re-solidified after cooling. It would be interesting to view the bubbles under very high magnification and also do spectrometry on samples from the walls of the bubbles and compare them to the rest of the casting.
6:15 maybe some moisture in the sand pushes steam inward.......... or maybe like in your glass demo bubbles happen and most are pushed out by displacement but, bubbles might stick to the sand and THEN the moisture of sand and the start of the initial bubble steam a cavity pressure spot into the casting? do you think poking vent holes into the casting from the sides would help?
There are many types of porosity.. in order to correctly diagnose the issue first you must determine the type of porosity.. there are 3 main types.. inclusion porosity, gaseous porosity, and shrinkage porosity. Each type has it's own causes. The porosity in the top part of the casting looks like inclusions because they are angular and not round in shape like a gaseous bubble is. Perhaps use sodium silicate to harden your mold and use a clean crucible.
Cast iron and water are both liquid. I think the main reasons why no air bubbles formed inside the rod are. The viscosity and the density: if a liquid is poured at the same mold and speed, but different viscosity and density, then the thicker and denser the liquid, the less air bubbles there will be pour will form.. The temperature: During the casting of gray cast iron process a high-temperature air layer forms above the melt, which prevents the air bubbles from penetrating into gray cast iron, thus hardly any turbulence is formed within the melt. If you have poured with different pouring speeds and pouring points, then the result looks completely different with many air bubbles in the core.
Hi ironman. I think 90 weight oil in a glass might be closer to what happens with iron re. bubbles. Iron is even more viscous and much denser than oil.
Hi. Thanks for the videos. All very interesting. I would like to see you try pouring a mould that is slightly tilted, at first, but then allowed to come upright as the pour is completed. The metal would run down the side of the filling hole, rather than falling, slowing it down a bit. Then the metal should pool together as the filling progresses. This would keep the heat together, rather than letting the metal wander randomly and chilling hap hazardly. The filling hole would need to be placed at the lowest part of the mould for this to work. Think of filling a glass with a beer. You have probably done that a few times. Reduces turbulence and keeps gasses contained in the liquid. The tilting could be done by a foot operated mechanism. Your own weight could be used to hold the tilt on the flask until you want it to come upright by lifting your foot. I don’t do foundry myself, but have watched a lot of videos about it. Just some thoughts. Good luck. All the best. Stephen NZ
Reducing hight of the pour may help. Having a chambered gate would help to, but lower your rendered part. Forging can take care of bubble and improve other properties. But the slag ... Yeah, "sand problem", too wet you get steam and sand pop'n off. Forging wouldn't help with impurities. But with forging you'd get an idea if it's pure iron or "feet of clay", to quote king Nebuchadnezzar. Perhaps increase talcum powder for the bottom of the column, or a disc of metal for a floor to stop the kickup (a washer or cut cross section from your existing piece)? Be careful it doesn't turn into a piston. Sure hate adding a gate if it really isn't needed. Sorry, that's the best I can remember. It's been 30 years since I worked in a pattern shop and foundry....
Hey man I'm interested to know what brand of lathe do you have it looks like a Reed Prentice because of the way the chuck is attached and the general figure is fairly indicative but correct me if I'm wrong
I’m interested in how and what is the best iron for making a home style anvil. Can you please explain what makes one anvil different from another and how to make the best anvil.
I made my anvil out of mild steel and simply hard face the top imo for a DIY approach that is the most economical way to do it in terms of time and resources
Green sand vs Petro bond vs a phenolic bonded sand (like AlpHaset), If I could afford it I would throw my Petro bond out and use only AlpHaset or equivalent. IMHO the chill affect from water would be most pronounced followed by oil. and of course, the AlpHaset has no moisture. check out my trailing truck or tilting furnace video. that 50-pound part is basically 1/4-inch walls both vertical and horizonal and I found no porosity.
Thankyou, You are a true expert with very good attention to detail. Casting is a lost art and you are doing a fine job of analyzing problems just like they did years ago. I have been involved in casting commercially, engine components. and as an apprentice. Defects were a common problem. Holes, lime and coke were common inclusions. Plenty and son. we made filters for the oil industry, and I was usually machining the lids. from 3" to about a foot in diameter. Wonderful days and fantastically knowledgeable people. We had our own foundry and pattern shop.
Interesting video! At first sight it seems the problem could be reduced by pouring through a gate, but after your final comments, I wonder if it has to do with the sand itself. Maybe you could return to this, with a few more details. Thanks!
Interesting stuff lucky. Thanks for sharing. I'm not sure I understand completely about the sand ramming too hard vs soft. If pouring a billet directly into the sand mold, you are saying ram it soft? Won't that cause problems when the metal hits the bottom of the sand mold, potentially intruding into the sand or breaking some off?
I would like to know as well it be a cool colab vid video if you two would explain it for example lucky Gen from a experience / arithmetic of view and yourself from a practical point of view
I think the bubbles would not go very deep in the first place as cast iron's density is huge compared to water. The bubbles near the skin could be the last ones which didn't have time to float out as the skin froze first. I once did this with aluminium and the resulting bar was very very porous. I poured it into a metal pipe with a bit of sand packed to the bottom to seal it. But some of the sand broke loose and floated on top which contributed to the porosity. A bottom gate would probably improve it a lot but it is difficult to mold.
Ah, the age old problem of the battle between how fast the bubbles rise and how fast the metal solidifies and thus perhaps traps the bubbles. BUT we need to remember that the bubbles do damage on the way through - not perhaps here so much where we are dealing with cast iron - God's gift to the foundryman. With more reactive metals like aluminium the bubbles will leave a trail of aluminium oxide behind - usually so thin as to be invisible but highly damaging to metal properties. Of course large parallel sprues cause the same problems particularly if unnecessarily high. I wonder if some of that subsurface porosity is due to the extra quick solidification of the near surface trapping bubbles that would escape further in where solidification is a lot slower? It looks a bit too random and there almost does not seem to be enough of it to convince me of its origins solely from mould gasses. Perhaps worth repeating the experiment with aluminum, a better machined finish, and a caustic etch - maybe even with soft and hard rammed moulds (that should keep you busy fort a while! 😊).... Martin
I have poured these billets before without these defects but were rammed very softly. The only problem was I would get swelling and made it hard to grip in the chuck. If you have a look at 1:15 in the video there are pinholes starting to form on the surface. This must of happened when cast iron becomes sluggish so the bubbles do not penetrate too far under the skin. I will try it with aluminium in a future video.
I suspect that the bubbles under the skin were loose high density contaminants from the sand or slag which were trapped and vapourised when the iron was semi liquid and re-solidified after cooling.
It would be interesting to view the bubbles under very high magnification and also do spectrometry on samples from the walls of the bubbles and compare them to the rest of the casting.
6:15 maybe some moisture in the sand pushes steam inward.......... or maybe like in your glass demo bubbles happen and most are pushed out by displacement but, bubbles might stick to the sand and THEN the moisture of sand and the start of the initial bubble steam a cavity pressure spot into the casting? do you think poking vent holes into the casting from the sides would help?
There are many types of porosity.. in order to correctly diagnose the issue first you must determine the type of porosity.. there are 3 main types.. inclusion porosity, gaseous porosity, and shrinkage porosity. Each type has it's own causes. The porosity in the top part of the casting looks like inclusions because they are angular and not round in shape like a gaseous bubble is. Perhaps use sodium silicate to harden your mold and use a clean crucible.
Cast iron and water are both liquid. I think the main reasons why no air bubbles formed inside the rod are. The viscosity and the density: if a liquid is poured at the same mold and speed, but different viscosity and density, then the thicker and denser the liquid, the less air bubbles there will be pour will form.. The temperature: During the casting of gray cast iron process a high-temperature air layer forms above the melt, which prevents the air bubbles from penetrating into gray cast iron, thus hardly any turbulence is formed within the melt. If you have poured with different pouring speeds and pouring points, then the result looks completely different with many air bubbles in the core.
Hi ironman. I think 90 weight oil in a glass might be closer to what happens with iron re. bubbles. Iron is even more viscous and much denser than oil.
Hi. Thanks for the videos. All very interesting. I would like to see you try pouring a mould that is slightly tilted, at first, but then allowed to come upright as the pour is completed. The metal would run down the side of the filling hole, rather than falling, slowing it down a bit. Then the metal should pool together as the filling progresses. This would keep the heat together, rather than letting the metal wander randomly and chilling hap hazardly. The filling hole would need to be placed at the lowest part of the mould for this to work. Think of filling a glass with a beer. You have probably done that a few times. Reduces turbulence and keeps gasses contained in the liquid. The tilting could be done by a foot operated mechanism. Your own weight could be used to hold the tilt on the flask until you want it to come upright by lifting your foot. I don’t do foundry myself, but have watched a lot of videos about it. Just some thoughts. Good luck. All the best. Stephen NZ
I have found that the porosity will be far worse in aluminum if you do the same method!
I could guess that the density of the metal being much higher than water forces the air up and out much faster.
The viscosity, density and surface tension of the two are very different, so it won’t behave the same.
Great info, I would be very satisfied with that casting.
Reducing hight of the pour may help. Having a chambered gate would help to, but lower your rendered part.
Forging can take care of bubble and improve other properties. But the slag ... Yeah, "sand problem", too wet you get steam and sand pop'n off. Forging wouldn't help with impurities. But with forging you'd get an idea if it's pure iron or "feet of clay", to quote king Nebuchadnezzar.
Perhaps increase talcum powder for the bottom of the column, or a disc of metal for a floor to stop the kickup (a washer or cut cross section from your existing piece)? Be careful it doesn't turn into a piston.
Sure hate adding a gate if it really isn't needed.
Sorry, that's the best I can remember. It's been 30 years since I worked in a pattern shop and foundry....
Hey man I'm interested to know what brand of lathe do you have it looks like a Reed Prentice because of the way the chuck is attached and the general figure is fairly indicative but correct me if I'm wrong
I’m interested in how and what is the best iron for making a home style anvil. Can you please explain what makes one anvil different from another and how to make the best anvil.
I made my anvil out of mild steel and simply hard face the top imo for a DIY approach that is the most economical way to do it in terms of time and resources
Very interesting! 👍
Sounds like pouring like a beer from tap, trying to reduce the head is the way to go!
Ok looks like only necessary if you can’t machine off that outer skin, very interesting
The Chinese don't seem bothered about a few "air bubbles and inclusions"
🇬🇧☹️
Very interesting
Green sand vs Petro bond vs a phenolic bonded sand (like AlpHaset), If I could afford it I would throw my Petro bond out and use only AlpHaset or equivalent. IMHO the chill affect from water would be most pronounced followed by oil. and of course, the AlpHaset has no moisture. check out my trailing truck or tilting furnace video. that 50-pound part is basically 1/4-inch walls both vertical and horizonal and I found no porosity.
That is a big casting. What gauge is the track for that casting? Building a big boy that big would keep you busy pouring castings for a long time.
@@luckygen1001 it's 7/1/2 inch, lots of casting using many different methods. getting ready for some 4140 steel castings.