A plug can improve minimum wall thickness while creating a new imbalance elsewhere. Too much penetration may push excess material into the base and starve the upper walls. A blunt or oversized contour can trap material; a narrow plug may fail to carry enough into the cavity.
Temperature and friction alter the effective plug shape because they determine where the sheet sticks, slides, or freezes. The same physical plug can therefore distribute two materials very differently.
Optimize from measurements
Thickness should be mapped before and after plug changes. Penetration, contour, clearance, surface, temperature, and motion should be treated as separate variables. Changes should be judged by minimum thickness and distribution, not by average part weight.
A plug is not a universal solution for an excessive draw. If acceptable thickness requires unstable contact or extreme temperature, the part geometry, sheet grade, or forming method may need revision.