Today's KNOWLEDGE Share:Mold Deformation

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Today's KNOWLEDGE Share

Do you realize how deformable your mold can be ?

Years ago I measured the mold plate deflection under a packing pressure of 80 MPa (that is 800 bar or less than 12000 psi) , for a simple two plate, robust, stainless steel plate mold. We found that the bending accounted for 20 microns equivalent increase in cavity thickness. Over the original 2mm cavity thickness, this is a whole 1 %, more than the typical shrinkage of a nicely packed PC. But the amazing finding, based on FEA computations of the mold metal structure itself, is that about 1/3 of this increase was due to steel compressibility !

So, even in the remote (actually impossible) case your mold would be very very stiff, the cavity would still grow bigger during pack because of STEEL COMPRESSIBILITY !


source:Vito leo

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