Drilling of self-drilling anchors can be performed with the use of rotary or rotary-percussion top hammer systems. Rotary-percussion is the preferred and the main method of installation as this is nowadays very common and also offers higher rates of production.
Top Hammer Rotary-Percussion drilling is featuring a Rotary/Impact Mechanism on the Drill Feed/Mast which is refers as Rock Drill or Drifter or Top Drive depending on the drilling machine and its manufacturer.
Drilling system can be either pneumaticly or hydraulicly powered. Generally a higher performance can be expected when using hydraulic drilling rigs. Typical drilling machines used around the world are Surface Crawlers like Geotechical Drill Rigs equipped with Drifter or a Rotary/Impact Mechanism.
Selection of the appropriate rig depends on:
• Scale of works
• Access to work site/face
• Ground conditions
• Size of self-drilling anchor and depth of drilling
Smaller sizes like R25 and up to some extend R32 with short lengths can be installed using Hand-held rock drills. This method of installation is selected for works in areas with restricted access or limited headroom application. Hand-held equipment work best when used in conjunction with an air pusher leg or within a slide frame arrangement as high operator fatigue limits production rates. Sliding frames are easily fabricated locally. The air leg is placed within the frame and normally reacts off the rear cross brace.