Hi I've been looking through the website on and off for last month, reading various posts on issues relating to crucibles applications and their performances, and thought I could be of help if anyone had any specific questions or needed to pointed in right direction on crucibles performance, application or problem solving. My background is foundry for last 40 + yrs. Working last 27 yrs for Morgan in business development, sales, technical support through Asia+Pacific, and up to recently as last 3 months held position as Global Applications role for Morgan Crucible (Morgan Molten Metal System). I've travelled extensively through Americas, Asia and parts of Europe, so seen a fair few furnaces, coal, gas, electric and induction, so they are all a little different. I'm happy to help where I can, however still working in full time position so don't pound me expecting answer within 5min Merry Xmas
Welcome bjf. Always a pleasure to have input from the pros. From a very satisifed Morgan customer..... Best, Kelly
bjf, Thanks for joining the forum and offering your considerable expertise. I melt iron in an A25 Super Salamander using diesel as my energy source. I use a typical atomizer nozzle and forced combustion air. I seem to get around twenty 90 to 100 minute melts per crucible. Is there a better crucible choice? Any tips on how to extend service of the crucible? Mine seem to thin mostly in an area from the level of molten metal to the rim with the lower portion of the crucible deteriorating significantly slower than the upper 2-3 inches. I generally melt about 60 to 65 pounds at a time as I find pouring a rim-full crucible a "hit and miss" proposition. Denis
Probably that the lower part which is immersed in the metal is protected against attack by slag. That is the reason using too much borax or other slag is detrimental for the crucible. And a rim-full crucible is an extra risk that the user spills over when moving the full crucible from the furnace to the mold.
melterskelter: excuse delay, need to turn on the push infor. button as didn't get notification of your question. can you advise how you heat the crucible up, or prepare it for melting, is the crucible preheated to required temp, and then you charge cast iron or steel and carbon/silicon to convert to iron ?. If you could post a few pic of the crucible showing top rim would be good so we are looking at the same issues, as sometimes we interpret different issues. a pic explains more If the charge is cast iron, then metal should be relatively clean, are you adding nay flux to clean, as shouldn't need it are you filling the crucible to 80% plus or running < 50% of the volume cheers Brett
Brett, No worries. I appreciate you taking the time. It's not a problem that has to be answered today though I was melting iron today finishing just before the hailstorm hit. I melt ductile iron returns but do not use magnesium to make ductile iron. The returns are very clean---bright and shiny. I simply cast the melt as grey iron. I use no flux. The brim-full capacity should be 75 pounds of iron but I typically melt 60 to 65 pounds. To begin a melt I pack the crucible with as much iron as I can get into it---usually about 34 pounds and up to 40 pounds (rarely). The crucible is then placed in my diesel-fired furnace and I start the fire running .19L/min and as hot as I can adjust the flame as guessed by appearance and experience. I think there is just a tad more fuel than the air can burn---a slightly reducing flame. After about 45 mins to 50 mins I add the rest of the charge to get to 60 to 65 pounds. A melt takes about 90 to 100 mins. I do add an ounce or so of FeSi a min or two prior to pouring. I do add some crushed charcoal and oyster shell to the empty crucible prior to the melt to ensure maximum carbon and to reduce sulfur in the iron. My iron is nice and uniformly soft with no tendency to form white iron. Here is a photo of a crucible that was pushed a long way---likely 25 melts. You can see the rim is disappearing. And you can also see about 3 inches below the rim a sort of "water mark" where the top of the iron pool usually rests. Below that level the crucible retains near full thickness but then tapers to thin at the rim above that level. As a side note, the crucible looks like it might be ready to collapse but I have never seen a hint of deformation as the wall thickness is well maintained from 3" down to the base. Your thoughts? Denis
Indeed, this picture shows clearly that the immersed part of the crucible is barely deteriorated, unlike above that. You add 1 ounce (31g) of FeSi to 65 pounds (30kg) cast iron ? That is 1:1000 which is a negligible amount. Is that correct ? Why not adding Magnesium ?
Correct ratio of FeSi as stated. Do not want or need ductile for the application if these castings. Denis
Melterskelter, excuse the delay, seems now back in the foundry industry selling Vesuvius crucibles, so been somewhat busy now being back in workforce However unbiased in approach to answering questions The Salamander crucible is great product and A25 is good alround product and reasonably priced. All crucibles are not made the same and some have different structure and physical properties A60 has high temperature capability, however has high porosity, which equates to low thermal heat transfer for high temperatures. You can get similar crucible which are denser, < 50% porosity and will transfer heat better for high temperature. These crucibles are denser and need to be heated slowly on first charge in the early stage of melting, once crucible is reddish then burner can be stepped up proportional. The fastest and best way to heat a crucible with fuel burner is to heat the crucible empty. Crucible is going to get to red heat faster if it has no charge sitting inside to act as heat sync. Once at Red heat, stop burner and charge scrap, tune burner on and way you go The top rim of the A25 has oxidised as there is no external glazes which are added to crucible to protect the crucible body from oxidation as mention the high temp and porosity doens't help the situation. The long the crucible is sitting at low temperatures < 1000 C then its being exposed to oxidation. If crucible is denser or has some of those special glazes which costs a few extra $$$ then crucible body is protected from the oxidation process and less issues with top edge thinning By heating crucible empty you will get the crucible up to temperature quickly and then should be less of any issue top edge is always coolest part of the crucible due to heat loss from surface melt loss. running insulating lid, cover can reduce heat loss. If crucible is open to atmosphere, increases change of heat loss an example of world class small furnace MMP-Miniature-Gas-Lift-Out.pdf (moltenmetalproducts.com), MMP-Lift-Out-Furnace-Gas-Oil.pdf (moltenmetalproducts.com)
Vesuvius owns Foseco globally so you can ring sales manager David Heel 02 99145500, or you can purchase the morgan salamander crucible from the distributors Skamol Asia in Melb, 03 95604477
