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USER GUIDE
GUNDRILLS

Drilling Tolerances Obtainable In Deep Hole Drilling

Deep Drilling Tolerances
Gundrill configurations when used under recommended When operating under optimal conditions,
conditions can produce holes with tolerances of IT8-IT9. even better tolerances can be achieved.

Nonferrous materials
Aluminum
Tool steel
Cast iron Machinability
High alloy steel>800N/mm 2 of
Hardened steel Metals
Low alloy steel<800N/mm 2
Carbon steel
Sintered steel
Drilling quality IT 13 12 11 10 9 8 7 6 5

Tolerance range under normal conditions Tolerance range under optimal conditions

Surface Quality
Surface quality of 0.2 Ra can be achieved when
using gundrills under recommended conditions.

N12 N11 N10 N9 N8 N7 N6 N5 N4 N3 N2 N1
Indexable Drills
Reaming
Honing
Deep drilling
Degree of roughness µ m 50 25 12.5 6.30 3.20 1.60 0.80 0.40 0.20 0.10 0.05 0.025
(Ra roughness index) µ in 2000 1000 500 250 125 63 32 16 8 4 2 1

Tolerance range under normal conditions Tolerance range under optimal conditions

Concentricity and Straightness Circularity
The resulting quality depends on different The geometric quality of bores obtained from deep
factors such as: hole drill bits is clearly higher than that obtained
• Drilling depth and diameter with the use of twist drills. It is possible to obtain
• Type of machining and cutting parameters precision with deviations of less than 4µm.
• Quality and uniformity of the workpiece material
• Machine tool conditions
• Gundrill support

Concentricity Straightness
mm
1.0 mm
0.84 0.05
0,66 0.04
0.5 0.03
0.33 0.02
0.16 0.01

500 1000 mm 250 500 750 mm
Drilling Depth Drilling Depth
Stationary workpiece – rotating tool
Rotating workpiece – stationary tool

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