All calculators provides theoretical data and are only provided to give an estimation of the settings for best drilling practice.
roto percussion drilling RPM calculator
To determine what rotations you should have we need to know 3 things.
- Hammer frequency in BMP (If you only have the Hz of you hammer times that with 60 to get BPM) (B)
- Drill bit OD in mm (π x d)
- Gauge button OD in mm (Dd)
Formula: N = B x Dd / π x d
If a hammer have the frequency of 2220 BPM (at DTH hammer running pressure) and a drill bit with 115 mm OD with a gauge button of 14.5 mm it would give you a RPM at 89*.
BPM = Beats per minute
RPM = Revolutions per minute (N)
OD = Outside diameter
RPM calculation for core drilling
To help find the right RPM for core drilling, depending on what size and kind of core bit is used
V1 is the lower speed of the drill bit (m/min)
V2 is the higher speed of the drill bit (m/min)
D is the outside diameter of your coring bit (mm)
To drill 101T2 with a impregnated diamond bit.
- Find the drilling speed of the impregnated diamond (in this case No5 under guidelines, 150 m/min to 270 m/min).
- Put the lower number in V1 and the higher number in V2.
- Then you add the outside diameter of the core bit in value D (in this case 101 mm)
Outside diameter sizes:
This calculation is for all core drilling tools but here is only the messurements for Terracore range from TerraRoc.
|T2 Series||Outside diameter||T6 Series||Outside diameter||S Geobor||Outside diameter|
|46T2||46 mm||76T6||76 mm||S||146 mm|
|56T2||56 mm||86T6||86 mm||S Oversize||152 mm|
|66T2||66 mm||101T6||101 mm|
|76T2||76 mm||116T6||116 mm|
|86T2||86 mm||131T6||131 mm|
|101T2||101 mm||146T6||146 mm|
Guidelines (margins depending on conditions)
This is just guidelines and ground conditions, medium and WOB can change parameters
- TCI bits, PDC bits Diapax(DPX), Saw tooth Tripax (TRX) 23 to 51 m/min
- Corborit (crushed tungsten carbite) 36 to 70 m/min
- Tripax bits (TRX) (small pdc inserts) 60 to 108 m/min
- Surface set bits (SS) (diamond grains) 108 to 150 m/min
- Impregnated bits 150 to 270 m/min