Shrinkage compensation and recommended shrinkage allowance

[jandmnik]

Hello

I have problem with shrinkage compensation. A part with material Ticona Hostaform C9021, that its shrinkage in data sheet is 2% for parallel and 1.8% for perpendicular and dimensions are 170*60*2 mm and its geometry is attached, I meshed in MD and DD and 3D. With same process setting condition, followed by molding window analysis. I ran Fill+ Pack+ Warpage for MD, DD,3D and Fill+ Pack+ Shrinkage for MD and DD. Finally, the result about shrinkage compensation was confusing.

Based on fill+ pack +warpage and applying various pack profiles, the average value of shrinkage compensation is:

	Shrinkage compensation
	X	Y	Z
MD	2.047	2.046	2.022
DD	2.062	2.3	2.084
3D	1.012	1.084	0.953

And based on fill+ pack+ shrinkage , the recommended shrinkage allowance is:

Total   =  1.97 +/- 0.11 %

	recommended shrinkage allowance
	X	Y	Z	Total
MD	Recommended	2.01	1.93	0	1.97
Single Value Validity Range (Max. -Min)	1.86:2.15	1.75:2.11	-0.00:0.00	1.82:2.11
DD	Recommended	2.01	1.92	0	1.97
Single Value Validity Range (Max. -Min)	1.86:2.15	1.74:2.11	-0.00:0.00	1.82:2.11

I have some questions:

• What’s the reason of differences in shrinkage between fill +pack +warp and fill +pack +shrinkage ?

Specially in 3D mesh and DD for Y direction, Do they have to be equal or at least close together ? 

• Witch of them has to be used for machining in mold shop and is more realistic?
• Why recommended shrinkage factor in fill+ pack+ shrinkage in Z direction is 0? We know there is shrinkage in Z direction, as it is showed in fill+ pack+ warp.
• The material is non fiber so shrinkage parallel to flow must be greater than perpendicular, but in fill +pack+ warp , is not so . what’s the reason?
• For chunky parts, MD and DD meshes are not suitable, but as upper tables show, 3D mesh didn’t gave precise estimation, sometimes we have to use only 3D mesh (because of part geometry) in such cases what is the solution?
• By comparing 2 analysis fill+ pack+ warp and fill+ pack+ shrinkage with same pack profile and process setting, results of shrinkage compensation and recommended shrinkage allowance are not same, why?
• For machining a mold, is it necessary to run both analyses fill+ pack +warp and fill+ pack+ shrinkage and deciding about shrinkage factor or just fill+ pack+ warpage is enough? And use shrinkage compensation from deflection all effects (plot properties) .

Thank you