Science Fair Project Encyclopedia
Holes can be punched through a variety of materials for a variety of purposes. One of the most common uses of punched holes is for filing papers. When done on a large scale the holes are usually drilled.
The most commonly used system for punching filing holes into paper is defined in International Standard ISO 838. Two holes with a diameter of 6±0.5 mm are punched into the paper. The centers of these holes are 80±0.5 mm apart and have a distance of 12±1 mm to the nearest edge of the paper. The holes are located symmetrically in relation to the axis of the sheet or document. Any paper format that is at least 100 mm high (e.g., ISO A7 and larger) can be filed using this system.
Not specified in ISO 838, but also widely used, is an upwards compatible four-hole system. In it, the two middle holes correspond to those defined by ISO 838, plus there are two additional holes located 80 mm above and below these, to provide for more stability. Sheets punched with the four holes of this system can also be filed in ISO 838 two-hole binders.
The left margin of a printed document should be 20-25 mm wide, to accommodate for the ISO 838 punchholes.
In the United States (and in part also in Canada and Mexico), a different system with three filing holes is widely used, which is incompatible with the International Standard. There, the hole centers are 108 mm apart, while diameter and distance to the paper edge vary. This system is only usable for paper formats that are at least 240 mm high.
Other uses for punched holes in paper
- Ticket validation and cancellation
- Punched cards
- Punched paper tape
- Punched card voting machines (see also hanging chad)
- Orienteering checkpoints
- Perforations for tearing along
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