WZG – Threading tools
Here you can find a wide range of carbide thread milling cutters and HSS-E taps and fluteless taps
Carbide thread milling cutters
- For cutting threads in materials up to 54 HRC at low torque
- Thread milling cutters with low cutting pressure, for materials up to 63 HRC
- Thread milling cutters for metric and BSP threads
- One threading tool for different thread sizes with the same pitch
- For right-and left-handed threads
HSS-E taps and fluteless taps
- Standard HSS-E taps with TIN coating
- Taps for hardened materials up to 63 HRC
- Taps for metric and BSP threads
- Fluteless taps for the chipless forming of metric and BSP threads
Thread milling process and technology
As the thread milling cutters are designed for right hand cutting, the direction of rotation is generally clockwise. By altering the axial direction of feed through reverse rotation or synchronous milling, all thread combinations can be produced.
For thread milling, synchronous milling should be applied whenever possible, in order to achieve lower cutting forces, improved chip formation, longer tool life and better surface quality.
Pressure angle and feed ratio
If the milling cutter diameter to the nominal thread diameter ratio of 70% is adhered to, a profile distortion, irrespective of the profile depth of the thread, should not occur. This factor is well proven.
The diameter of the thread milling cutter and the profile depth determine the pressure angle to the thread diameter.
The feed at the cutting edge of the thread milling cutter is calculated by the cutting speed (revolutions) and the feed rate per tooth. With linear movement, the feed rate at the cutting edge is identical to that at the tool‘s centre. However, the helical interpolation follows the path of a circle in the plane. As the machine tool always calculates to the tool‘s centre, a command must be programmed for converting the cutting speed (contour related program). If such a command does not exist or the program is centre-related, the feed rate must be converted first.
The interactive control at the control panel indicates the speed at the centre point of the tool. When running with no load this is simple to check. If disregarded, the milling cutter runs at a speed many times faster than the feed which generally leads to tool breakages.
Thread milling cutter entry cycles
90° Quarter circle entry cycle (WZG 17223)
With an entry cycle of 90° and a small difference in diameter between the tool and the thread, a large part of the total chip volume is removed during the linear section of the entry cycle. This method is therefore only recommended for relatively large differences in diameter between hole size and thread milling cutter. The advantages presented by this entry method are simple programming and a quite short entry path.
180° Semicircle entry cycle (WZG 17123)
With a 180° entry cycle, the loading on the tool is the lowest when plunging, as the angle of contact is relatively small during the complete entry cycle.
Helical interpolation (cyl. thread)
Helical interpolation is the overlaying of circular and linear movement. Different threads can be produced by the form of overlaying the direction of pitch and the direction of rotation of the circular movement.
Helical interpolation (conical thread)
In order to produce a perfectly round thread with a thread milling cutter, it is necessary to consider the taper when doing the NC progamming. In contrast to cylindrical threads, the machining path is not a 360º circle but four segments of a circle. With every one of the four segments the taper is corrected inwards.
Radial cutting index