Technical conditions of deliveries

Dear customer,

These technical delivery conditions are settled on the basis of experience, which we have gained during the deliveries of perforated materials. Please read them properly, they can be useful for understanding of some details, which are important for choice of particular material as well as for right application of particular material.

Thank You.

Perforated sheets

  • Perforated sheets are produced in accordance with the standard DIN 24041
  • Tolerances of outer dimensions are in accordance with the standard mentioned above and in accordance with dimensional standards of raw material EN10025, EN10029, EN10051, EN10131, EN10088. The raw material sheets and coils are not  pre-cut for common stock items in standard dimensions 1000 x 2000 mm, 1250 x 2500 mm and 1500 x 3000 mm. Perforated sheets can be wider and longer around 5 mm against common tolerance of the raw material. This sheet enlarging is caused by perforation process and it depends on the sizes of the holes and their density and also on the thickness and quality of raw material.

    Tailor-made sheet cutting is done with tolerance +/-3 mm up to thickness 2 mm. The sheets with bigger thickness than 2 mm are cut with tolerance +/- 5 mm.  Please state in Your order or send the technical drawing in case of request for another tolerances. There has to be bilateral agreement or approval of the sample in these cases.
  • Because we need to avoid the breaking and damages of our tools, so we use the special tools (mainly for small holes) with 2 times bigger pitches between the punches. These tools cause the uncompleted first and the last perforated rows.
  • The punch can be broken during the perforating process and it causes several missing holes. So we kindly ask You to mention in Your order,  if the perforated sheets are used for decorative purposes.
  • The burrs are caused on one side during the perforating process. These burrs can be pressed back into the holes during the flattening process. So please draw our attention in Your order if the perforated sheets must not have it because of special application.

Technical recommendations

  • Perforated sheets made from pre-galvanized steel have no layer of zinc in the inner edges of the holes. Those perforated sheets can not be used in outdoor (or in any other environment, which causes the oxidation) without any other surface treatment.
  • The surface treatment electro-galvanizing is also not suitable for outdoor environment or any other environment, which causes the oxidation. It is necessary to make the second surface treatment (powder coating etc.) to use the perforated sheets in outdoor.
  • The surface treatment hot powder coating of mild steel sheets in one layer is not suitable for outdoor environment or any other environment, which causes the oxidation. It is necessary to make previous surface treatment by galvanizing or cataphoresis or use perforated sheets made from pre-galvanized steel.
  • The surface treatment hot dip galvanizing is the most proper protection. It can be done on perforated sheets with the holes bigger than 8 mm and in steel thickness 1 mm and bigger. That surface treatment is only the protection of steel sheets and it can not be considered as decorative element. White rust, which is created by oxidation of the surface of the zinc, is not considered as the defect of the product.  Partially filled holes, diverse disparities and cuticles, which are caused by galvanizing, are not considered as the defect of the product.
  • The special oil is used during the perforation process, which contains the removable grease substances (silicon). If You need the degreased surface of the sheets, so please mention this requirement in Your order – in that case the sheets will be greased by evaporated oil, which makes a minimal clues.
  • The surface of the perforated sheets can be scratched during the perforated process thanks to twisting of the sheets in the machine. This matter can be valid for sheets with thickness more than 2 mm mainly. If You need the sheets with perfect surface without any scratches, so please mention it in Your order. The sheets will be provided by protective plastic film or the sheets will be flattened during the perforated process several times.

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