This is only my second time pouring iron after finishing the new furnace. Using K-bond (petrobond) sand. This has happened both times. The metal never makes it past the gates into the mold, but it's hot enough to mostly pour into the ingot mold after the third mold. Best I can figure, I'm pouring too cold. The iron is liquid and appears to boil, and just started throwing a few sparks. Color is somewhere in the yellow range. Don't have a pyrometer to know where the temp is though. What indications do you look for to know when you're ready to pour?
I had a similar problem due to actually pinching off the runner flow to nothing just before entering the casting. Carving the sand runner into the object to be cast a bit will cure the problem but leave an extra bit on the casting to be ground off. Also a small amount of ferrosilicon can deoxidize the iron which increases fluidity for a minute or so after addition. It's hard to tell but it also looks like you have a thin section casting and adding some thickness to the pattern will increase your chances of success.
I appreciate the responses. Yes, all the same plaque pattern. I've been watching your videos for years but haven't noticed your techniques for measuring temperature. How do you know when you're hot enough, and what do you look for? I don't have a thermocouple that's rated that high.
I do have a thermocouple that can measure high temperatures but it is a pain to use. My furnace always takes 55 minutes to melt 14 kgs of iron so when the last piece of scrap has been added at 45 minutes, 10 minutes is all I need to get the iron hot enough to pour. If I am pouring really thin castings 15 minutes is enough to make the iron really fluid. Also when iron is hot enough to pour the surface becomes shiny and reflective. I have poured a plaque that was 2.8 mm in thickness and filled up but if you are new to iron 6 mm is about as thin as I would go to have a minimum of rejects.
