Hi, for a huge volume of geometry i gave an 750mm sub surface thickness. During extrusion of the subsurface its not extruding back. Is there any limitations to give subsurface thickenss in PROAM

What do you mean by "not extruding back"? You get nothing or you get bad cells?

Is the extrusion thickness larger than the smallest cell size? At one time that created bad cells - especially regions like corners. I don't know if the the latest release still does this. But at least it would give you a surface. If you need a fine grid & large extrusion layer, you can try using intermediate surfaces & extruding in multiple steps. It's tedious but can be made to work.

Since you are doing something out of the norm (750mm is an extremely large sub-surface thickness), you may be outside the code's capability.

It's a wild guess but you could scale the model from mm to m. I believe the command is vscale. It might help. But like I said it's a wild guess.

Thanks for the suggestion. But can you tell me what you meant by "using intermediate surfaces and extruding in multiple steps"? Would appreciate if you could give me the procedure for this? Thanks a lot.

Say your surface mesh's minimum cell size is 400mm. You probably won't get a good subsurface at 750mm. So build the sub-surface in 2 steps.

First build a sub-surface at 375mm - call this SS1. Then do another sub-surface at 375mm using SS1 as your surface - call this SS2.

Proceed as normal using the original surface & SS2. SS1 has no further purpose & can be deleted.