Machining

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Turning

The values shown below apply to tough grades of sintered carbide, which are unavoidable for those operations where the material might be subjected to impacts, such as when turning steel with flame-cut edges.

Carbide class	Formulae:
Feed speed	= cutting speed    = workpiece diameter    = speed (rpm)    = 3.14    = feed rate    = feed rate (mm/rev)
With higher feed rate reduce cutting speed.

Countersinking and counterboring

For spot-facing and countersinking are best used tools with replaceable blades made of sintered carbide and with a rotating guiding shaft. Use cooling fluid.

Counterboring bit with replaceable blades and rotating guiding pivot	Countersinking bit with replaceable blades and rotating guiding pivot
Feed rate f (mm/rev)	Speed n (rpm)
1. if chips are breaking off, feed in 2 mm steps       2. if the machine performance is low, select cutting speed in the lower part of the value range

For WELDOX material shown in the table can be used HSS countersinking machines with three blades and a guiding pivot. It is necessary to supply enough cooling fluid.

Cutting threads

Provided you have selected the right tap, you can cut threads to any types of HARDOX and WELDOX products. We recommend to use taps with four grooves which can withstand greater torques, which are when cutting threads in hard materials unavoidable. When cutting threads in HARDOX and WELDOX, we recommend to use as a lubricant oil or thread cutting paste. For softer WELDOX 420, WELDOX 460 and WELDOX 500 steel can be also used emulsion.

In applications where the thread strength is not critical, a bigger hole than a standard size can drilled (by approx. 3%), which will reduce the tension during the thread cutting and hence prolong the thread's life. This applies particularly when cutting threads in HARDOX and WELDOX 1100 steel.

Milling

Face milling       Milling with rectangular tips       Cylindrical face milling
Roughing	Finishing	Select tool with set 90° angle	Less stable tool	Stable tool
Select tool with round tips -particularly when machining HARDOX	Select toolwith 45° angle		Select coated cylindrical face tool HSS-Co	Select cylindrical face tool CC with full-carbon blades or with inserted rotary blades

*) do not use cylindrical face tool HSS when machining flame-cut edges

When milling, the following recommendations should be followed: - Check whether the workpiece is properly clamped. - If the machine performance is low, use a milling tool with courser teeth - If possible, do not use a universal tool, as this will weaken the tool's fitting and reduce the transfer of power. - The cut width should be roughly 75 - 80% of the milling tool's diameter (see values on the right). - When the surface being milled is narrower than the milling tool's diameter, the tool should be positioned eccentrically in such a way that as many teeth as possible are cutting. - When milling flame-cut edges, the minimum cutting thickness should be 2 mm, to avoid the strengthened layer on the flame-cut edge (see the graph).

Drilling

Drilling can be done using high-speed steel or sintered carbide bits. The type of bit to be used depends on the drill available and its stability. Regardless what drilling machine is used, it is necessary to minimise vibrations.

Rotary or percussion drilling machines

In order to reduce vibrations and increase the drilling machine's life, we recommend:
- to maintain the shortest possible distance between the bit and the stand
- not to use wooden pads
- to clamp the workpiece properly and drill as close to the pads as possible
- use a short spindle and a short drill bit to allow shortest possible distance between the bit tip and the arm.
- just before the drill bit gets through the material, release for about a second the feed. Otherwise the tip of the drill bit might due to backlash and elasticity break off. When the backlash and elasticity disappear, you can resume the feed.
- Make sure that the supply of cooling fluid is adequate

Single holes can be drilled using an ordinary HSS drill bit. To guarantee rational production, we recommend to use drill bits made of micro-alloy fast-cutting steel (HSS-E) of fast-cutting steel with cobalt (HSS-Co).

Use HSS-Co drill bit (with 8% cobalt) with a gentle pitch and a robust core which will withstand high torques.

More stable machines such as for example vertical turret lathes and fixed bed milling machines: In order to increase productivity, make use of the benefits offered by sintered carbide drill bits in state-of-the-art and stable machines. You can choose from three main types of sintered carbide drill bits. The choice will depend on the machine's stability, workpiece clamping, the hole diameter and the required tolerance. Always use the shortest possible drill bit. Cooling fluid: - Use cooling fluid for drilling. - The rule for drilling with internal supply of cooling fluid: cooling fluid flow [l/min] = drill bit diameter [mm]. Full-carbide drill bit - diameter from ca 3 mm - small tolerances (high precision) - can be ground - sensitive to vibrations Drill bit with brazed carbide blades - diameter from ca 10 mm - small tolerances (high precision) - can be ground - less sensitive to vibrations as full-carbide bit Drill bit with rotating inserted blades - diameter from ca 12 mm - high productivity - bigger tolerances than the other types (lower precision) - less sensitive to vibrations as full-carbide bit