Drilling

In our experience, any high speed steel drill can be used for drilling holes in HS 100 and HS 400. Our experience suggests that an 8% cobalt HSS-Co (m42 high speed steel) drill with a slow helix and heavy web construction can be used for HS 450 and HS 500. For production work, we recommend solid carbide or indexable carbide insert drills for a stable drilling machine. For a non-rigid machine where vibration could be a problem, we suggest cemented carbide drills. Because new drilling products are often developed, drilling charts for indexable carbide inserts, solid carbide and cemented carbide drills are best obtained from your tooling supplier or drill manufacturer.

Tapping

When tapping in HS 100 any high speed steel tap is suitable, whereas HS 400 requires a high quality HSS tap. For production work, tap life can be extended by using a coated HSS machine tap. Although it is possible to tap HS 500, this operation cannot be performed easily. We recommend a high quality tap and a top end rigid machine. Expect a shorter tap life and possible tap failure by fracture from excessive torque inside the hole. Thread milling is a more reliable operation for threading holes in HS 500. When tapping in any grade, plenty of lubrication is required. We do not recommend hand tapping for any of the above steel types. Cutting speed is machine and tap dependent. We suggest a starting speed of 3 m/min (9 sfm), with adjustments to suit your particular machine and tap combination.

Countersinking and Counterboring

Countersinking and counterboring are best performed with replaceable insert tools. Counterboring is best performed with a revolving pilot to ensure hole accuracy and tool stability. Always ensure that the workpiece is secured properly to eliminate possible vibration. Cutting data will vary slightly from machine to machine. Charts for specific countersinking and counterboring tools are best obtained from your tooling supplier. In each case, we recommend plenty of coolant. Based on our experience, we recommend the following cutting values as general recommendations for a tool with replaceable inserts:

IMPERIAL

STEEL GRADE (Drill Type) CUTTING SPEED sfm 3/16" - 3/8"
in /rev
3/8" - 3/4"
in /rev
3/4" - 1-1/8"
in /rev
1-1/8" +
in /rev
A572 - 50W
(HSS-E & HSS-co)
85 - 98 0.006 0.008 0.012 0.015
HS 100 QT
(HSS-E & HSS-co)
52 - 65 0.004 0.004 0.009 0.014
HS 400
(HSS-Co w/slow helix)
26 - 33 0.002 0.004 0.009 0.014
HS 450
(HSS-Co w/slow helix)
19 - 26 0.002 0.004 0.009 0.014
HS 500
(HSS-Co w/slow helix)
13 - 19 0.002 0.003 0.007 0.010

METRIC

STEEL GRADE (Drill Type) CUTTING SPEED m/min √∏ 5-10 mm
Feed mm/rev
√∏ 10-20 mm
Feed mm/rev
√∏ 20-30 mm
Feed mm/rev
√∏ 30 mm +
Feed mm/rev
A572 - 50W
(HSS-E & HSS-co)
26 - 30 0.15 0.20 0.30 0.40
HS 100 QT
(HSS-E & HSS-co)
16 - 20 0.10 0.10 0.23 0.35
HS 400
(HSS-Co w/slow helix)
8 - 10 0.05 0.10 0.23 0.35
HS 450
(HSS-Co w/slow helix)
6 - 8 0.05 0.10 0.23 0.35
HS 500
(HSS-Co w/slow helix)
4 - 6 0.05 0.08 0.18 0.25

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