pulling during stamping process = slugs can easily pull up for
one or more of the following reasons:
die cutting edges have become worn to a bell-mouth.
being cut is very thin and light in weight.
is running with excessive lubrication and has just been sharpened.
clearance is too big or has worn off.
are not held on all sides.
can be applied to keep slugs down.
ejector into the punch, if space is permitted. ( Fig. 1 ) This method
is most effective and most common method in the market.
the cutting punch is unable to put in any ejector due to the space
constrain. A small shear angle ( slug killer ) can be ground on
the punch face as shown in Fig. 2. Slug can be held in the die profile
when slug spring back to it original shape while punch retract.
effective method is to machine a small groove ( 0.005 - 0.01 mm
) to the die profile to creates a precise amount of interference.
The grooves were machined at an angle ( 3 - 5 deg. ) to the die
surface. ( See picture below ) The slug expands into a series of
this special grooves, pressure between the slug and the die land
occurs, preventing it from pulling back through the top of the die
and onto the work zone. The
slug is then safely cleared on the next stroke from the punching
is a problem that can be prevented by proper design and correct