Scaring myself with casting cracks

[qroger]

Obviously, I need to work on my image posting skills

I think these cracks on the inside of the cast aluminum oil pan, (B-8) are from the original casting process.

[qroger]

This is more like it. Two images from inside of 1990 protege B-8.

[qroger]

And this:

[Rick the Quick]

I have seen similar cracks on aluminum castings and I agree they are part of the casting process.

[bravekozak]

They are caused by "cold shut". Any worse than that and it could leak.
That is the danger involved in filling a large cavity die for a pressure tight die casting.
As the A380 alloy aluminum fills the mold from more than one gate, the fronts collide (but not before cooling off slightly).

Oxide skins, from mold release agent, curling wave motion during the filling process, other contaminants, poor overflow locations, poor gate locations, etc. can all be possible causes for cold shut.

I think what you see in the photos is more from the deteriorated surface of the die itself.
The die has heat checks and desperately needs to be re-polished. I believe there were a lot of stickers in that diecasting tool. When they lose more time chiseling off stickers with brass chisels, and risk shutting down the assembly plant line at a cost of $30000 per hour, they will be forced to remove the die inserts and have them hand polished with polishing stones.

Molten aluminum is repeatedly shot into the tool at about 1200F.
Even H13 tool steel can't take more than about 3000 - 5000 shots before it needs some maintenance.

I estimate the cycle time for an oil pan diecasting is about 75 seconds.

[Rick the Quick]

They are caused by "cold shut". Any worse than that and it could leak.
That is the danger involved in filling a large cavity die for a pressure tight die casting.
As the A380 alloy aluminum fills the mold from more than one gate, the fronts collide (but not before cooling off slightly).

Oxide skins, from mold release agent, curling wave motion during the filling process, other contaminants, poor overflow locations, poor gate locations, etc. can all be possible causes for cold shut.

I think what you see in the photos is more from the deteriorated surface of the die itself.
The die has heat checks and desperately needs to be re-polished. I believe there were a lot of stickers in that diecasting tool. When they lose more time chiseling off stickers with brass chisels, and risk shutting down the assembly plant line at a cost of $30000 per hour, they will be forced to remove the die inserts and have them hand polished with polishing stones.

Molten aluminum is repeatedly shot into the tool at about 1200F.
Even H13 tool steel can't take more than about 3000 - 5000 shots before it needs some maintenance.

I estimate the cycle time for an oil pan diecasting is about 75 seconds.

Hello Brave, very interesting summary that you gave us. Do you work in the metallurgy field?

[bravekozak]

Yes, I was in charge of both the metallurgical lab and the foundry at a large automotive diecaster for about 6 years.
I majored in inorganic chemistry at the University of Toronto.
I can tell you stories that will make your hair curl.

[Rick the Quick]

Yes, I was in charge of both the metallurgical lab and the foundry at a large automotive diecaster for about 6 years.
I majored in inorganic chemistry at the University of Toronto.
I can tell you stories that will make your hair curl.

I doubt it, only because it's already curly.....LOL. Not so much here in New Mexico where the humidity is in the single digits at times. Ok Brave, you probably can. This will be continued until further notice.

[Twistiva]

They are caused by "cold shut". Any worse than that and it could leak.
That is the danger involved in filling a large cavity die for a pressure tight die casting.
As the A380 alloy aluminum fills the mold from more than one gate, the fronts collide (but not before cooling off slightly).

Oxide skins, from mold release agent, curling wave motion during the filling process, other contaminants, poor overflow locations, poor gate locations, etc. can all be possible causes for cold shut.

I think what you see in the photos is more from the deteriorated surface of the die itself.
The die has heat checks and desperately needs to be re-polished. I believe there were a lot of stickers in that diecasting tool. When they lose more time chiseling off stickers with brass chisels, and risk shutting down the assembly plant line at a cost of $30000 per hour, they will be forced to remove the die inserts and have them hand polished with polishing stones.

Molten aluminum is repeatedly shot into the tool at about 1200F.
Even H13 tool steel can't take more than about 3000 - 5000 shots before it needs some maintenance.

I estimate the cycle time for an oil pan diecasting is about 75 seconds.

Brave -

Your knowledge of things never ceases to amaze me, my friend! :thumbs_up: