Blind hole
In manufacturing technology, a blind hole is a hole that does not completely penetrate the workpiece like a through hole , i.e. has a certain depth. Blind holes are made when
- the material thickness of the workpiece is very large and drilling is not necessary (then the depth is usually of minor importance) or
- drilling through is not wanted for structural reasons ( sealing , stability , operational reliability , appearance ). Then the intended depth must be adhered to exactly.
Blind holes are mostly used to fasten or lock other parts using screws or pins . They can be provided with a thread (so-called blind hole thread ), made conical or cylindrical and reamed with a reamer to produce a fit .
Blind holes are also made in wood with the help of Forstner bits.
If the requirements for accuracy are not too high, blind holes can be incorporated in cast parts and in modern materials such as plastics , sintered materials , etc. directly during production by casting or pressing . If necessary, reworking by drilling, reaming or thread cutting is then necessary.
To z. B. To remove iron filings that remain in the blind hole through the hole in metal workpieces, a blind hole magnet is used. Alternatively, the chips can be blown out with compressed air.
In the field of the production of multilayer circuit boards ( multilayer ) in electrical engineering, blind holes are used to connect an outer layer with an inner layer . B. establish contact between the first and second wiring level. Since the layers underneath are then not affected by a drilled hole, conductor tracks can still run there, in contrast to fully drilled holes (complete vias).
