Pinhole pattern
In addition to a deformation zone, punched perforated sheets have a cylindrical cutting zone and a conical breaking zone towards the bottom. The hole diameter is measured in the cutting zone. It should be noted that punched perforated sheets generally have a slightly conical hole pattern.
Burr formation
Like any other punching and cutting process, perforating causes a more or less pronounced punching burr on the punch exit side of the sheet to be perforated. The strength of the burr formation varies depending on the material and the sharpness of the tool and cannot be generalised. A burr-free surface can only be achieved by post-treatment. There is also a correlation between burr formation and the formation of surface stresses. To avoid major stresses, the burr should be minimised as much as possible.
Perforated sheets - lightly greased or degreased by machine,
Oil is used when perforating perforated sheets. At the customer's request, the sheets can be degreased afterwards. This is an additional work step that is offered on request. Degreasing can be a possible pre-treatment of steel and stainless steel sheets for further processing such as welding. Degreasing therefore removes oil from the surface.
Lightly greased:
Without specific instructions from the customer, our perforated sheets are shipped lightly greased. This means that they may have a tangible and visible film of oil or grease on delivery. This film serves to protect the surface during transport and storage, particularly in the case of perforated steel sheets.
Machine degreasing:
For applications where a grease-free surface is essential, we recommend machine degreasing. In this process, the perforated sheets are chemically degreased. This guarantees that no grease or oil residue remains on the surface or in the holes. The result is a completely degreased surface, ready for your specific requirements.
Unperforated zones and edges
The edge is an unperforated area between the outer edge of the panel and the perforated edge of the first row of holes. A distinction is made between longitudinal edges and end edges. Standard perforated sheets are usually supplied with a narrow circumferential edge. Another variant of standard perforated sheets are perforated sheets with narrow longitudinal edges and cut perforations at the end edges.
Sheets and cut-to-size sheets can be manufactured with freely defined edges or without unperforated edges. As a rule, the variant without unperforated edges is the more favourable.
Incomplete hole field start
Punching tools with several rows of punches are required to produce a perforated sheet quickly and cost-effectively. This means that the rows of holes are not complete until the second or third punching stroke. This is referred to as an incomplete hole field start and end.
Different hole field starts can be taken into account:
Running and screening direction
The specified running direction indicates the direction of the manufacturing process during punching. The screening direction, on the other hand, refers to the direction in which the material to be screened would always hit a hole.
In the case of staggered perforation, the running and screening directions are usually rotated by 90° to each other. The screen direction must always be specified for an offset perforation if the perforated plate is to be used as a screen plate.
Ripple, flatness and elongation of the perforated sheets
Perforated sheets are straightened after punching. During levelling, they pass through a cassette with up to 21 levelling rollers and are literally rolled through. As a rule, levelling produces a satisfactory result in terms of flatness.
Due to the raw material quality, small perforations, narrow pitches or punching burrs, a residual waviness often remains despite careful levelling. Unperforated zones or very wide edges can also lead to ripples. This can then often no longer be eliminated.
In accordance with the DIN required flatness tolerances, the sheet metal is generally only straightened once by machine.
Standard dimensions
Perforated sheets are available in the following 3 sizes according to European standards:
Small size (small format): Length 2000 mm, width 1000 mm
Medium size (medium format): Length 2500 mm, width 1250 mm
Large size (GF): length 3000 mm, width 1500 mm
You can find standard products in our FACO Lagerware Shop
MANUFACTURING OPTIONS FOR PERFORATED SHEETS
There are various manufacturing processes for the production of perforated sheets. As there are a large number of different perforated sheet applications in the various branches of industry and trade, different processes are used to ensure the most cost-effective production method for the respective product. The members of our sales team are available to help you identify the most cost-effective process.
PUNCH-NIBBLING
Punch-nibbling or punch-laser machines are mainly used to produce perforated sheets with different hole diameters or complex contours. The batch sizes can vary between individual and series production. The advantage of punch-nibbling machines lies in the variability of the perforations. There are various tool stations that can be equipped with a wide variety of punching or forming tools.
- The maximum dimensions of the sheets are 1500 x 3000 mm
- Sheet thicknesses from 0.5 mm to 6.0 mm are processed.
- Material quality: steel, stainless steel, non-ferrous metals, heat-resistant qualities
WIDE PRESS PRODUCTION
We produce small, medium and large series from coil on wide presses.
- The maximum punchable dimension is 1500 mm.
- After perforation, the perforated coil can be cut to the desired length using a cut-to-length line or the strip can be wound back into the perforated coil.
- Sheet thickness 0.5 mm to 5.0 mm depending on perforation and coil width
- Material quality: steel, stainless steel, non-ferrous metals, heat-resistant grades
STRIP PRESSES
Auf Streifenpressen fertigen wir kleine bis mittlere Stückzahlen von Lochblechen aus Formattafeln oder Zuschnitten.
- Maximum punchable format is 2000 x 5000 mm.
- Sheet thicknesses from 0.8 to 15.0 mm
- Perforations: Round, square, slotted, special perforations
- Material quality: Steel, partly also in wear-resistant, stainless steel, also in heat-resistant qualities, aluminium and other non-ferrous metals
HOLE PATTERN GEOMETRY
Hole width: The hole width refers to the hole size (depending on the geometry).
Hole pitch: The hole pitch refers to the centre-to-centre distance (centre-to-centre distance) between two adjacent holes.
Web width: The web width indicates the smallest unperforated space between two neighbouring holes.
The ratio of web width to panel thickness should not be too small, depending on the perforation, material and manufacturing process. Otherwise there is a risk of the webs breaking between the holes.
