Design guidelines MD Expanded metal
If you are considering using MD Expanded metal in your project, here are some design guidelines that might help you with your plans.
These terms indicate the different mesh sizes available:
- Long way (LD)
- Short way (CD)
- Strand width (w)
- Material thickness (t)
For example, a specification using MD Coliseum 02008024 means:
200 x 75 (80) – 24 x 1.5
LD CD (CD) w t
The size between the brackets is the actual mesh height when you stand in front of the MD Expanded metal sheet. The LD size without brackets is the stretch size of the stretching machine.
The diagram below explains the terms when applied to MD Expanded metal:
As well as the fixed mesh dimensions, we can also work with variable meshes. The mesh size varies within a panel. This allows us to create varied effects, for example more open or more closed.
For some applications it is necessary to increase the opening size of MD Expanded metal panels, for example where naturally ventilated spaces are required. View the front openings of MD Expanded metal patterns.
We can supply MD Expanded metal in any of the following materials:
Thicknesses range from 1.5 to 3 mm, partly depending on the type of MD Expanded metal. Other considerations for material choice are the desired appearance of the material, weight and strength required.
The following surface treatments are available for MD Expanded metal:
- Thermal galvanizing (steel)
- Powder coating (steel and aluminum)
- Anodizing (aluminum)
The choice of surface treatment depends on the desired appearance (colour, shine) and the material type (for example corrosion protection in steel). But the mode of detail also affects the surface treatment to be chosen.
The production process creates two sides of the material with a different appearance: an A- and B-side. In most cases, we use the A-side as the outer side.
The production process also causes differences in transparency in that the material is more or less open epending on the direction the MD Expanded metal is viewed from. This allows the designer to obscure some aspects of the structure behind the facade, or provide a proper view through it. For example, MD Expanded metal is widely used to hide installations on a roof construction.
In these cases, we apply the MD Expanded metal to the face the surface is to be viewed from. As a frontal facade, it is often desirable to keep the view open from inside to outside. In these cases the viewing direction is applied downward. Finally, MD Expanded metal can also be used where the viewing direction is intended to be from the left or the right.
Downward viewing direction:
Upward viewing direction:
The average tolerances of MD Expanded metal are:
- In the direction of the mesh width: 5 mm. A seam between two panels must, therefore, be at least 5 mm to accommodate this tolerance.
- In the direction of the cutting height: 1/2 CD per 1500 mm.
These factors affect the tolerances:
- The roughness of the mesh: the coarser the mesh, the wider the tolerance.
- The thickness of the expanded metal: MD Expanded metal made from aluminum with a thickness of 3 mm has a lower tolerance than the same product of 1.5 mm.
- The mounting method: tolerances can be minimized by welding MD Expanded metal into a frame.
- For MD Expanded metal with variable openings, other tolerances apply.
Mesh on the edge of the panels can show slight deviations in shape and/or size. Given the many factors that can affect tolerances, we recommend that you ask us about tolerances specific to your project.
When using patterns with a mesh width of 100 mm or more, the meshes at the edges can slightly deform when stretching. Because the material is not fixed and these are the meshes at the end of the panel, the material can stretch unevenly along the edges. On assembly the transition between the two panels becomes even more visible, because the pattern is disrupted.
To prevent this, MD Expanded metal can be produced with a half mesh extra on each side before cutting the material to size.
The best effect is obtained when the panels are measured on whole meshes, similar to layer sizes in brickwork. This applies both to the height and width of the panel. To set a tie, you must also take into account clearance between the panels to allow room and tolerances. This section depends on the mounting method of the panels, the tolerance of the MD Expanded metal and the roughness of the mesh. This varies between about 5 and 20 mm.
With the type MD Coliseum 02008024, the long way is 200 mm. The desired panel size is approximately 1350 mm, and the panel is screwed onto a framework at the rear.
1350 divided by 200, is 6.75. You should then round this up to 7 meshes: 7 × 200 mm = 1400 mm. MD Coliseum is quite coarse and also has wider tolerances. A screwed attachment requires relatively little clearance. The clearance between the panels is 10 mm, therefore the pattern becomes 1410 mm.
The maximum width size (long way) of MD Expanded metal is 1500 mm, with some types up to 3000 mm. The maximum current height (mesh height) is 3000 mm but can also be larger if required.
The most advantageous width size (long way) of MD Expanded metal panels is 1000, 1250 or 1500 mm. The height of the panel is up to you, but panels of up to 3000 mm are the most advantageous as far as handling and transport are concerned. The more panels with the same size you choose, the better the price.
The following modifications are possible with MD Expanded metal:
- Welded framework behind the MD Expanded metal;
- Sloping panels;
- Panels with a radius;
- Rolled panels;
- Converted panels. In a vertical conversion in models with a mesh width of 100 mm or more, the setting is in the middle of the mesh. Horizontal alignment is set between two meshes;
- 3D shapes;
- Panels with a recess;
- Variable short way apertures within a panel.