In deep drawing, a punch pulls a flat blank into a die cavity while a blank holder controls how freely the flange feeds in. Almost every defect traces back to that balance: too little restraint and the metal buckles; too much and it tears. Reading the part tells you which way to move.
Wrinkles in the flange or wall are compressive buckling: the metal has more material than the geometry needs and nowhere to go, so it folds. It is most common on shallow blank-holder pressure, large unsupported flanges, and thin stock.
Fixes, in order of preference: increase blank-holder force; add or deepen draw beads to raise restraint locally; reduce the blank size so there is less excess; and improve flatness of the binder surfaces. Raise pressure gradually — overshoot turns wrinkling into tearing.
Splits, usually near the punch radius or up the wall, mean the wall stress exceeded the material’s strength. Causes are excessive blank-holder force, too small a punch or die radius, poor lubrication, or simply attempting too deep a draw in one stage.
Fixes: reduce blank-holder force; enlarge the punch and die radii; improve lubrication on the flange and die; and — critically — check the draw reduction ratio. If a single stage exceeds the limiting draw ratio for the material, split it into draw and redraw stages.
Ears are wavy peaks and valleys around the rim of a drawn cup. They come from planar anisotropy — directional differences in the sheet’s properties inherited from rolling — not from the die. You manage earing by selecting material with lower anisotropy and by orienting the blank, then trimming the cup to the lowest valley.
Start with the cheapest, most reversible lever: lubrication. Then adjust blank-holder force in small steps, watching whether wrinkles or splits respond. Only then change tooling radii or blank size, and reserve adding draw stages for when the reduction ratio is genuinely out of range. Our Draw Troubleshooter walks this decision tree defect-by-defect.