Expanded metal terminology

Expanded metal

  • Expanded metal is a material with cuts on its whole surface.
  • Those cuts are done by mutual staggered slitting without waste of material and cuts are formed by expanding.
  • Expanded metal is made from steel sheets or coils.
  • Expanded metal meshes are not formed by knitting or welding.
  • Therefore expanded metal can be cut to any required dimensions without loss of its solidity.

 

Expanded metal production scheme

Mesh

  • The basic element of expanded metal is mesh.
  • Mesh is made up opening, which is surrounded by nodal points.
  • The mesh size is determined by its length and width.

Mesh

Mesh length and width

  • Mesh length is the distance from center nodal point to center nodal point toward the long diagonal.
  • Mesh width is the distance from upper edge nodal point to upper edge nodal point toward the short diagonal.

Mesh length and width

Mesh opening

  • Four strands form the sides of the expanded metal opening.

Mesh opening

Width and thickness of strand

  • Strand width is the width of the material remaining between the openings.
  • Strand thickness is the thickness of the used material.

Width and thickness of strand

Bond

  • Crossover of two adjacent strands.

Bond

Length and width of bond

  • Bond length is the distance between two diagonals.
  • Bond width is approximately doubled strand width.

Length and width of bond

Length, width and thickness of expanded metal

  • Length of expanded metal is total length measured in the direction of shorter mesh diagonal.
  • Width of expanded metal is total width measured in the direction of longer mesh diagonal.
  • Thickness is the measurement from the top surface to the bottom surface of the expanded piece.

Length, width and thickness of expanded metal

Type of cut sheets

If the shearing sheet are cut from the expanded metal, so it is necessary to keep special conditions due to particular shearing types. (symmetrical with open or closed mesh). For this reason the following five types were determined:

Bs.

Symetrical cut in the width (with same bond projection).

Bg.

In the width with closed mesh cut. Only possible if the width measure is approximate a multiple of the mesh length.

BLs.

It is cut symmetrically in the width and length.

BLg.

The material is cut on or near the center of the bond, which eliminates prongs or jagged edges. Bond shearing is only possible if the dimensions fall directly between bonds.

BLo.

After given measures in the width and length without consideration of the symetry of the mesh can be cut-to-size.

 

Tolerance

  • A) Normal sheet
    Width tolerance: ± 5%
    Length tolerance: ± 10%

  • B) Cut sheets
    Width tolerance: ± 5%
    Length tolerance: ± 10%

    Tolerance Group I
    Width tolerance: ± 5%
    Length tolerance: ± 10%

    Tolerance Group II - up to max. thickness 2 mm
    Up to width and length 600 mm: ± 1 mm
    Up to width and length 1000 mm: ± 1,5 mm
    Over width and length 1000 mm: ± 2 mm

    Tolerance Group II - Nad tloušťku 2mm
    Up to width and length 600 mm: ± 2 mm
    Up to width and length 1000 mm: ± 3 mm
    Over width and length 1000 mm: ± 5 mm

Mesh types - indication

  • TR - rhombic mesh
  • TQ - square mesh
  • TE - round mesh
  • TH - hexagonal mesh
  • TD - decorative mesh

Example

Expanded metal from mild steel,
Rhombic mesh 22/12 mm TR 22

 

Flattening

  • Expanded metal can be rolled up to width 1400 mm.
  • Flattening is indicated by letter F after size of mesh.

Flattening

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