Draft is the difference between ejecting and excavating.
What draft actually does
Draft provides clearance between the casting surface and the die as the part shrinks onto the core during cooling. Without it, ejection drags the surface, galls the die steel, and demands ever-higher ejection force.
The needed draft depends on depth, surface finish and whether the face is formed by the cover or ejector half.
Where draft earns its keep
Deep cores and ribs need the most attention; parallel walls over any depth are the classic trouble spot. Textured surfaces need extra draft so texture detail releases cleanly.
Reviewing draft early costs a conversation; discovering it at sampling costs die rework.
FAQ
Can zero-draft walls ever work?
Only with special measures and forgiving alloys — and generally at the cost of cycle time and die maintenance. Most designs are better served by adding draft.
Does draft affect tolerances?
Yes — dimensions on drafted faces vary along the taper, so datum selection should account for it.
Which half needs more draft?
Ejector-half surfaces typically need more because shrinkage grips them as the part cools.
All figures above refer to standard product data sheets; final confirmation is subject to written quotation.