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TECHNICAL GUIDE

PUNCHING TOOLS

Vol.24 TECHNICAL COUNSELING FAQ(4) "SHEAR OPTIONS"

TECHNICAL GUIDE

PUNCHING TOOLS

Vol.24 TECHNICAL COUNSELING FAQ(4) "SHEAR OPTIONS"

This time, we will introduce “Shear Angle” from the questions we have contacted the Tool Consultation.

SHEAR OPTIONS ON PUNCH

Ｑ
When should the shear angle be applied? Also,
please tell us the type and selection criteria of the shear angle.
Ａ

The shear angle is obtained by processing the punch edge surface into a “convex” or “concave” shape, and is effective in

  • 1.Reduce tonnage
  • 2.Slug pulling
  • 3.Reduce noise

Popular shear shapes are bellows.

Fig.1 Type of shear angle

Roof top shear

Roof top shear

Concave shear

Concave shear

Inverted shear

Inverted shear

4way inverted

4way inverted

4way concave

Concave shear
Flat punch = No shear angle

SHEAR ANGLE TYPES AND SELECTION CRITERIA

ROOF TOP SHEAR
  • 1.The most common shear angle.
  • 2.At Conic, shear angles are standard at 2 degree and 5 degree.
  • 3.It is relatively easy for customers to perform regrinding.

Fig.2 Resistant direction to the punch tip

In case of roof top shear

In case of roof top shear

In case of concave shear

In case of concave shear
CONCAVE SHEAR, INVERTED SHEAR
  • 1.This shear angle is suitable for slitting processing.
  • 2.Since force is applied outward to the cutting edge during punching (See Fig. 2),
    when processing a thick plate with a narrow punch, cracks may occur from the bottom.
    In the case of urethane kicker, it may be damaged early.
  • 3.It is difficult for customers to regrind without dedicated jigs.
4 WAY CONCAVE SHEAR, 4 WAY INVERTED SHEAR
  • 1.This shear angle is suitable for slitting with a square shape in both X and Y directions.
FLAT (NO SHEAR)
  • 1.In general, small diameter punches do not have a shear angle because the removal load is small.
    However, when processing thick plates,
    it may be added as a measure to prevent slug pilling.
  • 2.There is no shear angle for the blank type (if the slug is a product) because the blank is deformed.

ADVICE ON ONE POINT：Calculating formula of tonnage with shear

Tonnage with shear = tonnage without shear x shear coefficient

  • ■When the material thickness is thinner than the shear angle height.
    Shear angle coefficient = 0.5
  • ■When the material thickness is thicker than the shear angle height.
If the height of shear is higher than sheet thickness
Calculating formura of tonnage with shear
  • ※For calculation of tonnage without shear angle, refer to Technical Information Vol.13
    “Calculation formula frequently used in sheet metal”.

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Vol.24 TECHNICAL COUNSELING FAQ(4) "SHEAR OPTIONS"(470KB)

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