Page 120 - HOLE MAKING CATALOG p185-310

GUNDRILLS USER GUIDE

Drilling Tolerances Obtainable In Deep Hole Drilling

Deep Drilling Tolerances

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

Nonferrous materials

Aluminum

Tool steel

Cast iron Machinability
High alloy steel>800N/mm2 of Metals
Hardened steel

Low alloy steel<800N/mm2

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 μ m 50 25 12.5 6.30 3.20 1.60 0.80 0.40 0.20 0.10 0.05 0.025
Reaming μ in 2000 1000 500 250 125
Honing 63 32 16 8 4 2 1
Deep drilling Tolerance range under normal conditions

Degree of roughness
(Ra roughness index)

Tolerance range under optimal conditions

Concentricity and Straightness Circularity
The resulting quality depends on different factors such as: The geometric quality of bores obtained from deep
• Drilling depth and diameter hole drill bits is clearly higher than that obtained
• Type of machining and cutting parameters with the use of twist drills. It is possible to obtain
• Quality and uniformity of the workpiece material precision with deviations of less than 4 µm.
• Machine tool conditions
• Gundrill support mm
0.05
mm 0.04
1.0 0.03
0.02
0.84 0.01

0,66 250 500 750 mm
Drilling Depth
0.5

0.33

0.16

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

304 ISCAR