Author Topic: No blowholes in this casting  (Read 4024 times)

Offline ironman

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No blowholes in this casting
« on: July 26, 2013, 03:06:43 AM »
This was the leftover iron, I  poured it into a billet mold in the big crucible video.

This sand was made seven years ago so I rammed it lightly to keep the porosity high.

Two test cuts were made, no blowholes.

 After that pour I decided to get rid of that sand before blowholes begin to develop.

One last word on bubbles. Have you ever noticed what happens when water is poured into a clear glass? There is a lot of turbulence and air bubbles. This billet mold was poured the same way, no blowholes.

I have read the foundry books where you must keep the sprue full at all times otherwise you will get blowholes because of all the turbulence. I never bother to keep the sprue full and I don't get blowholes in my castings.

Pat you can't believe everything you read.




MetalCaster

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Re: No blowholes in this casting
« Reply #1 on: July 29, 2013, 12:23:03 AM »

Pat you can't believe everything you read.


I don't believe that. 

Sorry, I couldn't resist.  :)

Yes, you are right.
I have not had blowhole problems either, so I don't know, I can only guess.

MetalCaster

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Re: No blowholes in this casting
« Reply #2 on: July 29, 2013, 12:52:57 AM »
I glanced at the Navy Foundry Manual.

None of the foundry books completely agree with each other on all details, but the trick is to find a method that works with the setup and metals that you are using.
It is not really a right or wrong thing since conditions can vary so much with furnace types, metal types, sand types, etc.

The only photos they had with metal with holes in them were labeled "gassy metal", don't ask me what gassy metal is, and sand too damp.
Both photos show holes, the sand holes being smaller and closer to the surface, and the gassy metal holes being larger and uniform throughout the piece.

Another photo shows a similar defect from a "damp ladel".

You could always pour the metal into a steel ingot mould and see what you get.
That would rule out or verify a sand moisture problem.


Offline ironman

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Re: No blowholes in this casting
« Reply #3 on: July 30, 2013, 08:18:52 PM »
I always pour leftover iron into a ingot mold and never have blowholes. The sand molds do have blowholes which proves my point.