Drilling methods

1. Hammer drilling:

   • The material is removed mainly by the high impact energy of the hammer drill machine. The rotation of the drill bit has a supporting function only.
   • This method is recommended for concrete.

2. Impact drilling:

   • The material is removed by the rotation of the drill bis, which is supported by the slight axial impacts (vibration) of the impact drilling machine.
   • This method is recommended for massive masonry.

3. Rotating drilling:

   • The material is removed only by the rotation of the drill bit, while the axial impact of the machine is de-activated.
   • This method is recommended for hollow masonry.

4. Diamond drilling:

   • The material is removed like grinding by diamond grains, which are fixed at a hollow drill bit by nickel coating or by sintering.
   • This method can be used for all materials.
   • Diamond drilling makes less noise only and can be used in sensitive areas like hospitals.
   • The surface of boreholes manufactured with diamond drills is quite smooth, Therefore, such boreholes can be used for anchor installations only if diamond drilling is explicetly allowed by the respective ETA.
   • Some ETAs foresee the use of a special tool to roughen the surface of the borehole before anchor installation.
   • Currently, there are no common tolerances for diamond drill bit diameters. To avoid a proliferation of different tolerances by the single anchor manufacturers, PGM recommends to use the same tolerances as defined for drill bits with carbide tips also for diamond drill bits.