Die Clearance

What is Die Clearance?

Die clearance is equal to the space between punch and pie when the punch enters the die opening.


Regardless of material thickness, the recommended penetration of the punch into a Mate SlugFree® die is 0.118(3.00)

Proper Clearance


Clearance Too Small


The Importance of Proper Die Clearance

The slug is essentially a mirror image of the hole with the same parts in reverse order. By examining your slugs you can tell if punch-to-die clearance is correct, if tool angularity is correct, or if tooling is dull.


An idea slug is created when the fracture planes coming from the top and bottom of the material have the same angle and form in alignment with each other. This keeps punching force to a minimum and forms a clean hole with little burr. When clearance is proper, tool life is extended.

If the clearance is too large, the slug will show a rough fracture plane (C) and a small burnish zone (B). The larger the clearance, the greater the angle between the fracture plane (C) and the burnish zone (B). Excess clearance makes a hole with large rollover (A) and fracture (C) so that the profile is somewhat pointed with a thin burr (D). When clearance is too large, tool life is reduced.

If the clearance is too small, the slug will show a fracture plane (C) with little angle, and a large burnish zone (B). Inadequate clearance make a hole with small rollover (A) and steep fracture (C) so that the profile is more or less perpendicular to the surface of the material. When clearance is too small, tool life is reduced.