C-Axis Stepping motor - MAXcomputer GmbH - www.max-computer.de
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C-Axis Stepping motor
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BAE50 Machining unit with stepper motor
When you mount a milling spindle to the Z-table, this is not yet an axis in the sense of the CNC-norm. Only if this spindle is programmable in its rotating angle, rotating direction and angle feed, it becomes another CNC-axis. As it rotates around the Z-axis, it is called "C-axis". This programmability requires the use of a stepping motor with relating axis controller as a drive. The advantages of this technology are enormous:
very low noise when working
drilling with low speed
milling with high speed
thread cutting with normal thread cutters
angle positioning of tools
angle positioning of workpieces
See the technical data below.
Notes on the use of the C-axis 
(in German)
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Stepping motors are particularly low, they have no powertransmission to the rotor (no collector with brushes and the like required) and they need no air cooling (no ventilator). They can be easily controlled, quickly stopped and are available in a big range of technical data. By integrating them into the Multi-Controller MCS and into the software nccad vast new ranges of applications are possible
The stepping motor becomes a machining unit, resp. C-axis, when it is connected to a spindle via power transmission and when it is mounted to the Z-table (see picture above). This is the type series BAE5x. It always consists of the following components:
Spindle with double bearing
Holder in different versions
Clamp with clamping nut
Motorplate with covering hood
2-phase-stepping motor
Gear wheel set with tooth belt
Encoder for supervision and positioning
Connection cable and plug
Axis controller fof C-axis
Software-support inside nccad since version 7.5
The integrated encoder provides information about speed, standstill, or zero-position to the relating axis controller and allows intelligent error-analysis.
The C-Axis can be integrated into all machines with Multi-Controll MCS.
Older machines of the type KOSY2 can be retrofitted under certain conditions: they must be equipped with the electronics for the U-Axis, still, the software-support remains limited (e.g. no speed supervision).
BAE 50
- Gear ratio approx. 1:2,2
- Torque max. 0,5 Nm
- Speed approx. 20 .....3000 rpm
- Noise level (without machining) 50...70 dB
- Weight approx. 2,5 kg
- Collet ER16, DIN 6499 B, 426E
- recommended max 6mm
- Speed control
- Reference run 0° for angle positioning
- C-AxisController must be integrated into control
BAE 51
Customer specific, on demand
Different operating modes can be differenciated by now:
- Mode "drilling/milling spindle"
- Run up spindle with/without ramp
- feedback when target speed has been reached
- rotation supervision with hard stop in case of error
- after switch off, fast ramp for stopping
- rotating direction to be selected/programmed
- support of direct manual operation (picture)
Mode "C-Axis"
- drive spindle to angle position with/without ramp
- rotating direction to be selected/programmed
Mode "multi-axes operation"
- coordinated travel with other axes e.g. together with Z-axis for thread cutting
Separation between spindle and motor has many advantages:
the motor can be selected from a big range of versions and can be placed to the bottom,
it does not protrude the machine top.
The range of refs and the angle resolution can be varied through variable gear combinations.
Disadvantage: The tooth belt must be exchanged every now and then.