Introduction

Strenx performance steel and Hardox wear plate are steel grades that can be machined with high speed steel (HSS) or cemented carbide (CC) tools. This brochure includes our suggestions for cutting data (feeds and speeds) and the selection of tools. Other factors that should be taken into account in machining operations are also discussed. The proposals have been drawn up following our own tests on tools of various makes and in consultation with leading tool manufacturers.

TYPICAL PROPERTIES FOR HARDOX AND STRENX

Drilling recommendations

HSS-DRILL

Use only HSS drills when you have unstable machine conditions. HSS drills are only suitable up to 500 Brinell. If the machine conditions are good you have several choices of solid cemented carbide drills with exchangeable heads or indexable insert drills.

ADVICE FOR REDUCING VIBRATIONS AND INCREASING THE LIFETIME OF THE DRILL

• Minimize the distance to the column and between the drill tip and the workpiece
• Don’t use longer drill than necessary
• Always use metal supports and clamp the workpiece securely
• Solid and firm table
• Always use coolant
• Coolant mix 8-10%
• Just before the drill breaks through, disengage the feed rate for about a second, play/springback can otherwise snap the drill tip, re-engage the feed rate when the play/springback has ceased

FORMULAS AND DEFINITIONS

ADVICE FOR DRILLING IN THIN PLATE BELOW 8 MM

1. Important to have good support under the plate to avoid deflection.
2. Indexable drill is recommended, because it begins cutting at the periphery, and does not build up the high pressure a solid carbide drill would do.
3. With a drill diameter over Ø 10 mm and a point angle of 118-140° it is very important to support the plate that is drilled. If the drill tip breaks through the bottom surface without a supporting plate to guide the tip, it may result in an oval and undersized hole (see picture).
4. Reduce feed rate and increase cutting speed Vc, especially when using an indexable drill.

INDEXABLE INSERT DRILL

For stable machine conditions and with internal coolant

DRILLS WITH EXCHANGEABLE DRILL HEADS

For stable machine conditions and with internal coolant

COUNTERSINKING AND COUNTERBORING RECOMMENDATIONS

Countersinking/boring is best performed using tools with replaceable inserts from the tool supplier Granlund. Always use a revolving pilot and use coolant. See table below for screw and article number for the tool.

Reduce the cutting data with about 30% for countersinking

TAPPING RECOMMENDATIONS

With correct tools and tool holders we recommend tapping up to 500 Brinell with four-flute taps that can withstand the very high torque occurring during tapping in hard materials. If diameter is not critical, the drilled hole can be 3% larger than standard (see table below). This will increase the lifetime of the tap.

MILLING RECOMMENDATIONS

MILLING ADVICE

• Position the cutter off-center (to the left) to achieve a thicker chip at the entry and to avoid thick chip at the exit.
• Avoid cutting through the center line of the cutter, as this could generate vibration.
• Always use down milling (climb milling).
• The recommendation is that the width of the cut (ae) is 25 or 75-80% of the diameter.
• Use rolling into cut method.
• Dry milling is recommended if insert is used.
• If the machine power is low use a coarse pitch cutter.
• Always use wise or good clamping equipment.
• The depth of cut with milling gas-cut edges should be at least 2 mm,
• to avoid the hard surface layer of the cut edge.

Formulas & definitions

If you enter the workpiece with the rolling into cut method the chip thickness on the exit is always zero, and it will help to give a longer tool life.

INSERTS GRADES FOR MILLING

WORKPIECE MATERIAL

The last 2 numbers in the insert grade indicate the position of the insert in this scale, if the insert has wear or toughness resistance.

INSERT GEOMETRY

The macro geometry affects many parameters in the cutting process. An insert with strong cutting edge can work at higher loads, but it will also generate higher cutting forces, consume more power and generate more heat.

Parameter	L	M	H
Edge strength
Cutting forces
Power consumption
Max chip thickness
Heat generated

• 
  
• Use inserts grade P30-50 with light cutting geometry and a coarse-pitch cutter if the machine power is low and with unstable machine conditions.

FACE MILLING RECOMMENDATION WITH A 45° SETTING ANGLE

In very stable machine conditions and with rigid set-up the insert grade P10 would be more suitable in all milling operations with inserts, especially in Hardox 600 and Extreme. Then the cutting speed can be increased by approximately 80-100%.

Recommendation for average machine conditions

FACE MILLING RECOMMENDATION WITH ROUND INSERTS

Round inserts have strong cutting edges and are good to use when the surface has holes and cavities etc.

Recommendation for average machine conditions

SHOULDER MILLING RECOMMENDATION WITH A 90° SETTING ANGLE

Recommendation for average machine conditions

HOLE MAKING WITH HIGH FEED MILLING (CIRCULAR RAMPING)

Circular ramping (also called helical interpolation, spiral interpolation, can be an alternative to drilling). It is a simultaneous movement in a circular path (X and Y) together with an axial feed (Z) with a defined pitch (P). To manage circular ramping a CNC machine is necessary.

Advice

• Use compressed air to remove metal chips.
• Always down-milling/climb milling.
• P = pitch mm/rev.
• Max pitch with insert size 09 is 1,2 mm.
• Max pitch with insert size 14 is 2,0 mm.

Circular ramping

END MILLING RECOMMENDATION FOR SOLID CEMENTED CARBIDE TOOL

Slot milling recommendation

Slot milling advice

Ap (depth of cut)
max 0.5x D

SHOULDER MILLING RECOMMENDATION

ap (use the whole
cutting lenght)

ae (radial depth of cut)
max 0.1 x D

TROUBLESHOUTING FOR DRILLING AND MILLING

DRILLING

Short lifetime of cemented carbide tool
Short lifetime of HSS tool
Vibrations
Wear on the cuttiing edge/margin
Wear on the chisel edge/drill center
Asymmetrical holes
Small chipping on the cutting edges
Chip build-up in the drill flutes
Chipping on the corner of the cutting edges
Holes oversize/undersize
	Choose a tougher cemented carbide grade.	Increase the coolant flow rate and clean the coolant holes of the drill.	Check that the right HSS or cemented carbide grade is used.	Check the guideline for the cutting data.	Check the toolholders and the total indicated run-out.	Improve the set-up of the workpiece /reduce long tool set-up.	Increase the cutting speed.	Reduce the cutting speed.	Increase the feed rate.	Reduce the feed rate.

TURNING RECOMMENDATIONS

The cutting data recommendations below are applicable for tough cemented carbide grades. These grades are necessary for operations in which impact may occur, such as when turning plate with gas-cut edges.

FORMULAS AND DEFINITIONS

RESULTS FROM OUR OWN TESTS

MACHINES USED DURING THE TESTS

VMC FADAL 4020 HT modell 1997

• Spindle type ISO 40 taper
• Through spindle coolant
• Spindle speed max 10,000 rpm
• Effect spindle motor 16,8 kW
• Torque 303Nm

CSEPEL RF 50 modell 1970

• (Radialdrilling machine)
• Spindle type morse taper 4
• Spindle speed 45-2000
• Effect on the spindle motor 4 kW

TOOL RECOMMENDATIONS FOR HARDOX AND STRENX

DRILLING IN HARDOX AND STRENX

High speed steel drill alloyed with 8% cobalt (HSS-Co 8%)
Supplier: Alpen-MayKestag, Austria
www.alpenmaykestag.com

High speed steel drill alloyed with 8% cobalt (HSS-Co 8%)
Supplier: Witec, Germany
www.witec-tools.de

High speed steel drill alloyed with 8% cobalt (HSS-Co 8%)
Supplier: Somta, South Africa
www.somta.co.za

High speed steel drill alloyed with cobalt
(DRILL BIT COBALT”S”+X-ALCR DIN1897N HARDOX STUB)
Supplier: Izar, Spain
www.izartool.com

Solid cemented carbide drill
For hardness grade 450 Brinell and below, otherwise M-geometri.
Supplier: Seco, Sweden
www.secotools.com

Solid cemented carbide drill
Supplier: WNT, Germany
www.wnt.com

Solid cemented carbide drill
Supplier: Hoffmann-Group, Germany
www.hoffmann-group.com

Drill with exchangeable drill heads
Drillheads grade: IDI SG IC908
Supplier: Iscar, Israel
www.iscar.com

Drill with exchangeable drill heads
Drillheads grade: ICP IC 908
Supplier: Iscar, Israel
www.iscar.com

Countersinking in Hardox and Strenx
Use countersink with indexable inserts and the inserts grade should always end with H.
Supplier: Granlund Tool, Sweden
www.granlund.com

Tapping in Hardox and Strenx
Tap for through holes
HSSE-PM tap with TiCN coating
Supplier: Manigley, Switzerland
www.manigley.ch

Tap for blind holes
HSSE-PM tap with TiCN coating
Supplier: Manigley, Switzerland
www.manigley.ch

Tap for through holes
HSS-E-PM with CoolTop coating
Supplier: Sandvik Coromant, Sweden
www.sandvik.coromant.com

Tap for through holes
HSSE-PM with TiAlN coating
Supplier: Hoffmann-Group, Germany
www.hoffmann-group.com

Face milling with Coromill 300
(Round inserts)
Supplier: Sandvik Coromant, Sweden
www.sandvik.coromant.com

Shoulder/face milling with Coromill 490
Supplier: Sandvik Coromant, Sweden
www.sandvik.coromant.com

Holemaking with high feed milling
Supplier: Sandvik Coromant, Sweden
www.sandvik.coromant.com

Insert grade in Hardox and Strenx
Use insert grade P1030 for average machine conditions. In very stable machines and with a rigid set-up the insert grade P1010 would be more suitable, especially over 500 Brinell.
Supplier: Sandvik Coromant, Sweden
www.sandvik.coromant.com

The contents of this brochure represent general suggestions. SSAB accepts no responsibility for their suitability in individual cases. The user is therefore responsible to make the necessary adaptations to the conditions in each individual case.

SSAB is a Nordic and US-based steel company. SSAB offers value added products and services developed in close cooperation with its customers to create a stronger, lighter and more sustainable world. SSAB has employees in over 50 countries. SSAB has production facilities in Sweden, Finland and the US. SSAB is listed on the Nasdaq OMX Nordic Exchange in Stockholm and has a secondary listing on the Nasdaq OMX in Helsinki.