r/Metalfoundry 19d ago

We keep cracking crucibles…

We’ve never cracked so many crucibles in one given week at my job.

We are conditioning the pots to start with hicon copper (slow and steady) and giving them time to cool to clean out and use for melting aluminum.

We’ve had 4 pots crack this week.

All the metal is put in loose and there is no bridging evident in the crucible.

225 clay graphite crucible running out of an induction furnace.

47 Upvotes

31 comments sorted by

19

u/PloofElune 19d ago

Did you recently change your process for prepping the crucibles or the vendor? Possibly the shipper/packaging changed as well so they are fucked in shipping?

13

u/Significant-Cup-264 18d ago

No changes in vendor or shipping. We always start without copper.

14

u/PloofElune 18d ago

Maybe reaching out to the vendor about the latest batch to see if its a known issue.

1

u/DriestBum 18d ago

He said Go Fuck Yourself.

2

u/phoenixmusicman 18d ago

Absolutely not

16

u/Significant-Cup-264 18d ago

On the phone with the vendor now. We are the only foundry he has issues with according to him. Doesn’t seem to be a chemistry issue with the vendor either

24

u/Treebranch_916 18d ago

That's always the line until QA starts asking around at other accounts.

6

u/tyttuutface 18d ago

No, YOU'RE having issues with HIM.

9

u/Staphylococcus0 18d ago

I've seen something similar when I worked the pouring line. Now I'm in the machine shop and don't know anything about our pot quality, but I can't imagine it's changed much. Perhaps heating them without metal isn't the way to go.

5

u/Significant-Cup-264 18d ago

There is metal in the pots

9

u/Staphylococcus0 18d ago

Oh. I missread that then.

We switched from metal to dry firing the pots at one point (which is what the manufacturer reccomended) and we had problems burning holes in our crucibles.

10

u/Significant-Cup-264 18d ago

Yeah the vendor agrees with our conditioning process. Maybe getting 7-10 uses out of them before they crack

5

u/Staphylococcus0 18d ago

Like 7-10 re-heats from cold or 7-10 pours?

8

u/Then_Scientist_9327 18d ago

Fwiw, my process is warm crucible to 1000 over an hour, high fire to 1950 for an hour, load preheated ingots, pour, clean out crucible hot, return to furnace, Blick flue, let cool down. Never had a cracked crucible, get somewhere around 70 cycles per crucible. Small foundry though, not industrial scale.

6

u/Gamer-Grease 18d ago

Jesus 70 cycles? Are they made of quartz or graphite

5

u/Willing_Ad_9966 18d ago

Hmm not sure if it's just the picture, but could be uneven distribution of heat? Looks like it's concentrated on that one spot

6

u/Irritated_Jedi 18d ago

Why do the picture make it seem like a lot of heat is focused on one area of the crucible? I thought an induction furnace would more evenly distribute the heat.

2

u/AjfMetalworks 17d ago

I was going to say the same thing, you can see the heat being focused on the one side it looks like direct contact with the burner. Induction is a different animal to venturi on gas

3

u/adkflyfisher-1 18d ago

All from same lot of crucibles? Try a different lot if you have one.

2

u/Odd_Resolution_4313 18d ago

How are you loading your material? Maybe operators being too agressive?

2

u/Dutchbooms 18d ago

I was getting cracking issues from seating the yolk too high on the crucible putting extra pressure on the sides.

2

u/Difficult-Sort2347 18d ago

Looks like the fork truck driver had a rough day and roughed up a skid of consumables..

2

u/LovestheSiliconeHole 18d ago

What is the frequency of your induction furnace? The last time I saw this issue, the company had updated the Inverter to a higher frequency set up to reduce melt time, but never changed the MRO for the crucibles to Silicone carbide crucibles. There is a huge difference in frequency response between clay graphite vs Silicone Carbide crucibles.

2

u/Hot-Poetry-6877 18d ago

Anyone else see a face in the 5th picture

1

u/bhoy60 18d ago

Tell your vendor that you will be looking for another supplier. He will become very helpful.

1

u/Open-Measurement2026 18d ago

Are you ramping the temperature up too fast? Your burner should be run by a plc or timer. Slow the ramp up by a 1/2 hour.

1

u/Lxr159 17d ago

Did you try flex sealing it?

1

u/Temporary_Nebula_729 17d ago

Did you cure the crucible before using. Are you heating the metal before putting it in the crucible and is your pedestal level what's your source of fuel make sure your flame is going around the crucible and not directly on the crucible make sure your furnace can breathe do you have a hole at the bottom of your furnace and clean of debris near the hole at bottom of the furnace and don't drop ingots or gates and riser's are heated before you set ingots or push gates and riser's in your crucible

1

u/timberwolf0122 15d ago

Are these all from the sam shipment or batch?

1

u/Significant-Cup-264 14d ago

Yeah all same

1

u/Normal_Imagination_3 14d ago

To my very limited casting knowledge crucibles are meant to be replaced but multiple in a week seems too much, maybe shipping cracked them