Hi,
I've seen on some cylinder head castings a mesh or crosshatch pattern, with lines about 5mm appart about 2mm high. It's too small to be structural or for heat dissipation. Can anyone tell me why the grid is there.

Cheers
Splint

Couple differanrt possiable reasons.
One is in the mold we sometimes Have a HOT spot that just does not cool quick enough and there for creates a porosity area. To solve this we need to cool this area. we will sometimes add a CHILL to this area, It can be a steel block or a differant piece of material that will aid in solidification.
Sometimes we add this cross hatch patern to the block we are adding and sometimes to the mold itsself and put water cooling in the mold.
Hope this answers your question It is mainly for solidification of the part. Usually.