Stubborn gas defect

[Kipara12]

I am having trouble resolving a gas defect on my product produced in a grey iron sand casting process. The gas defect occurs opposite the gates on the cope side. Most affected cavities are furthest away from the sprue any ideas to resolve issue are welcome

 

[IRstuff]

where, and in what direction is the sprue relative to the defect? Can you add sprues?

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[Kipara12]

Unfortunately i cannot share sprue runner and gating design due to confidentiality constraints but i can share that the sprue is 135 degrees clockwise from the defect, the ingate is 180 degrees to defect location. Pattern is 5 on so long runners to go around center cavity.

 

[EdStainless]

Are there vents in mold?
Looks like you need to add some.

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P.E. Metallurgy, consulting work welcomed

 

[Kipara12]

Yes the mold has vents. So far i have tried to contain turbulence by controlling the shock transferred to the mold flasks as they shuttle down the pourline. This reduced the scrap rate from 16% to current 8%. Any ideas on other factors i should look into?

 

[EdStainless]

What about inlet turbulence in the pour?
Can the cup and sprue be altered to help that?

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P.E. Metallurgy, consulting work welcomed

 

[Kipara12]

Ran a trial with a wider pour cup in an attempt to control pour times and head pressure with minimal to no effect. Planning thinner cross sectional area ingate trial based on EdStainless suggestion. Hope to see some improvement. I believe @ EdStainless your rational is a less turbulance into the cavity faster freeze time for the gates with a smaller cross section, correct?