As a reamer (also reamer or reamer ) is defined as a tool that is used for fine machining of holes (especially in metal parts ) by the so-called " rubbing ". Be improved while both the surface quality and the shape and dimensional accuracy.


First, a hole is drilled with a twist drill, which (usually 0.1-0.2 mm) is a few tenths of a Millimeteres smaller than the nominal size. Possibly may be necessary for the drilling of this hole pre-drilling. After drilling / reaming the hole is suitably countersunk with a 60 ° countersink so that the reamer touches on better. In many cases, the incision of the reamer has a forward angle of 60 °. Then the hole using the reamer is brought to the nominal size. Thus, required tolerances, for example, H7, manufactured. The achievable tolerance is normally at IT7. In special cases, or even IT6 IT5 is possible. With what accuracy is also higher accuracies to the shape tolerances are maintained. The rubbing improves the roundness and cylindricity.


A reamer is similar to a Wendelnutbohrer for metal. The cutting edges are located at the periphery, however, only in exceptional cases, at the gate. The cutting edges and flutes are either straight and run accordingly along the axis of the reamer (ie in purely axial direction) or helically like a Wendelnutbohrer.

In normal through-holes to provide helically extending blades with a link slope. Due to the left slope of the resulting chips are discharged when rubbed forward so that scratching the bore surface is prevented by clamped chips between the bore wall and edge of the reamer. Reamers with right slope ( as in the conventional twist drills ) are used for the blind holes, so that the chips are transported out of the bore. The reamer with helical flutes are particularly indispensable for frictions with interrupted cut.

Proven mainly reamers with straight teeth number have ( since the diameter can better measure ) and unequal tooth pitch (which reduces the chattering ). Typical diameters are between 1 mm and 50 mm. Adjustable reamers as a special form of the reamer are not intended for a specific dimension of fit, but can be set for the production of individual diameter.

Another special type of reamer is the reamer, which creates no cylindrical fit, but in accordance with the conicity of a conical reamer.


Cutting materials for reamers can be:

  • HSS,
  • Carbide, either in solid carbide, carbide cutters with brazed onto a steel body and equipped with replaceable inserts
  • Cermet
  • Polycrystalline diamond
  • Boron nitride


It also distinguishes between machine and hand reamers.

  • Have reamers for better guidance of a long -angle of about 1 /4 of the cutting length and a longer guide part. At the shank end is a square to accommodate the wind iron.
  • Machine reamers have, since the guidance is a short gate and guide member through the machine spindle. Due to the short gate itself reamers are more suitable for short blind holes ( blind holes ).