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TECHNICAL GUIDE

PUNCHING TOOLS

Vol.21 TECHNICAL COUNSELING FAQ(1) "COUNTERMEASURES FOR GALLING"

TECHNICAL GUIDE

PUNCHING TOOLS

Vol.21 TECHNICAL COUNSELING FAQ(1) "COUNTERMEASURES FOR GALLING"

Of the questions we received from the Tool Consultation Office,
this time we will introduce “countermeasures for galling during slitting”.

COUNTERMEASURES FOR GALLING WHEN SLITTING PROCESSING

Ｑ

IThe punch and die interfered with each other during slitting, causing galling in the tool.
Is there a way to avoid galling?

Ａ

When slitting or cutting the surface of the material, as shown in Fig.1, an unbalanced load is applied to the punch, and interference between punch and die tends to cause burrs in the tool.

Fig.1 Generation of galling due to unbalanced load during slitting

A punch moved towards the space where material is absent. / Punch and die hit against each other.
A punch moved towards the space where material is absent.
Punch and die hit against each other.

As a countermeasure,

  • 1.The cutting position of during slitting, take over 70% of the punch length as a guide.
    (See Fig.2)

Fig.2 The cutting position of during slitting

70% of the cutting position is required.
he cutting position is less than 70%,possibility of galling incresed caused by uneven resistance
  • 2.Change the slitting order

Normal slitting processing order

Normal slitting processing order

Processing order with no unbalanced load

Processing order with no unbalanced load
  • 3.Use a heel tool. By providing a heel on the punch, it prevents the deviation of the punch due to the unbalanced load.
    (See Fig.3)

Fig.3 Prevention of punch misalignment with heeled tool

The heel part goes into a die before piercing.
  • 4.It is recommended that the clearance between punch and die be set slightly wider (about 0.1 mm) than normal punching (single punching).
  • 5.As for punch shear angle at the time of slitting processing,
    "Concave shear " and "Inverted-roof top shear" are more effective than "roof top shear".
    (See Fig.4)

Fig.4 Punch shear angle

Roof top

Roof top

Concave

Concave

Inverted roof top

Inverted roof top
Inverted roof top

In addition to this, there may be cases such as the occurrence of galling caused by slug pulling,
misalignment or wear of the turret, and tooling installation defects.

For details, please contact Conic Tool Desk.

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