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Sheet metal Z bending and N bending

Definition: Z bend implies zigzag bend. Average bend procedure supposes Z-bend highness >V-groove apothegm + density. The least processing sizes depend on the models being applied, whereas the utmost processing sizes are dependent on the device table shapes.

Z bending

 Make an L bend. Then bend the lateral sides of L bend to make a Z bend.

Rules on Placing Work Pieces to Make a Z Bend

  1. Comfortable, reliable durability
  2. There are some similarities to L-bend
  3. The work piece appears smooth with the bottom die when placed for the second time.
  4. L bend angles must be maximum precise, commonly 89.5-90 degrees.
  5. Make the necessary rear gauge setting to avoid deforming the work piece. 

 Common Processing Techniques To Make Z Bend

  • Processing must be realized in the given order as depicted. Point 1 must be bent the first, then pass to point 2.
  • L bend must be bent the first, and then go on to bend the Z form (as there exists some interference with the work table, it is convenient to receive a big angle, later process the second point and then point 1).
  • Make use of two sharp angles in order to bend Z form. The right angle should be bent first, after it comes 2, which is followed by 1.

In case of interference point 1 should be bent first to gain a big angle and after bending point 2 press 1. Otherwise, while realizing a common Z bend process, point 1 gets bent first and point 2 follows it.

Special Z Bend Technique 

  • Process the bottom die decenter.
  • Process a little V-groove.
  • Bend to gain a big angle and go on to press.
  • Select a grinding bottom die.

Alternative Techniques   

  • Make use of offset dies for processing.
  • Use transformable dies to accomplish processing.

N Bending               

   Accomplish double processing over the surface to gain an N bend.

Precautionary Tips on N Bend Processing

  • The first bend angle must be no more than 90 degrees.
  • The second bend rear gauge depends on the processing face.

N Bend Special Techniques 

In case Y sizes N bending in the aftermath of the interference with upper punch, realize smoothing through the hem die. In case the interference with upper punch appears severe, after positioning A, C and B points form shapes through hem dies and padding.

Process through shape punches and dies.

Arch processing 

This implies two types: all round cut with bend models, all round cut through arch knives.

Arch knives can be of two kinds: static and rod.


While processing through a bottom die of 90 degrees, the result might be insufficient and pushing the molds with hands or applying a bottom die of 88 degrees is preferable.

 Assure the work piece final sizes by making use the detecting device.

While machining arch of 90 degrees, the bottom die must be decided on 2(R+T).  

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