Proper ejection force for damage-free part removal
F_eject = P x A x (cos a x sin a + mu x cos^2 a). P = shrinkage pressure (MPa), A = contact area (mm^2), a = draft angle (deg), mu = friction coefficient.
Polished steel vs PP: 0.3. vs ABS: 0.4. vs PA: 0.5. vs PC: 0.45. Mirror finish reduces friction by 30-50%.