DC Servo motors for motion control applications.
Cost effective servo Motors
A compact and good quality servo motor that is ideal for small machines.
- 48 volts.
- 3100 RPM.
- 0.48 Newton metres stall torque.
- Integral 1000 Pulses per rev encoder.
Replacement for SEM MT22
The above motor is a a cost effective replacement for the SEM MT22, these motors are current production and ideal for new machines and replacements for milling machine servos etc.
- 60 volts.
- 4400 RPM.
- 1.7 Newton metres stall torque.
- Can be supplied with encoder and protective cover.
Motor Gearbox combinations
Motor gearbox combinations with either worm an wheel gearboxes (as shown above) and planatory gearbox.
Frequently asked questions about motors.
DC servo motors have powerful magnets around the rotating part of the machine called the “Rotor”, the rotor has coils wound into it and it uses a segmented contact block called the “commutator” the commutator has two associated carbon brushes as the rotor turns the connects the appropriate coils to the brushes allowing the motor to rotate. In brushless servo motors the coils of wire do not move and are situated around the outside of the rotor, in most cases the rotor is made using powerful magnets. If this type of motor the commutation is achieved using electronic means and there are no carbon brushes..
In most cases the answer is yes, this is because of the life of the brush gear. However, in many applications where the motor is not subject to continuous motion the life of the motor can be as long as the life of the machine. Where the motor continuously running a brushless type are better and will last longer.
In general, in many applications and if the controller can control servo motors servo motors can be used, to replace stepper motors. however it is important to remember is that motors wear and if they are badly worn it may not be in your interest to reuse old drives and motors.
In general, most modern servo motors and drives are very efficient and use considerably less than older motors. Servo motors are in general much more efficient than stepper motors, this is because most have no feedback and therefore the current setting when the motor is in position is often set at 50% of maximum, often servos will use minimal energy when they are stopped. Some older DC motors needed a fan to cool the motor and they use thyristor drives these cause noise on the electricity supply and may be illegal now. Modern spindle motors for example may save can save more 500 watts just in the cooling fan alone, in such a case it is easy to save more than 30% of the energy currently used.
Older machines often used brushed DC spindle motors (these often have a fan on the side of them), while it may be possible to reuse the motor and drive, it is not recommended. The reason that these DC motors should not be used is because they use a phase angle Thyristor based controls and they can cause serious mains disturbance that may be outside of lawful limits. Many machines use 3 phase AC motors and most of these can be used again. You may want to consider getting the motor reconditioned.
Older machines often used brushed DC spindle motors (these often have a fan on the side of them), while it may be possible to reuse the motor and drive, it is not recommended. The reason that these DC motors should not be used is because they use a phase angle Thyristor based controls and they can cause serious mains disturbance that may be outside of lawful limits. Many machines use 3 phase AC motors and most of these can be used again.
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Modern brushless motors have encoders with a much higher resolution than older motors, the better the resolution of the encoder the more stable the system tends to be! Early brushless motors did not tend to be very stable and often could be heard “singing” that is vibrating around the command position. Newer motors tend to be very stable, this is not only better for the machine it uses less energy.
TRM supplies DC servo motors up to 800 watts, du to the complexity of the brushless servo drives DC servo motors tend to be more cost effective below 800 watts. Although there are many DC servo motors over 800 Watts the cost of the power supplies reduce the cost benefits of using DC Servos over brusless motors.
There are now motors that replace standard 3 phase motors that offer better performance and that are much more efficient. These motors use a magnetic rotor and a more complex drive they are similar brushless servo motors. The main reason for the increase in efficiency is that in standard AC motors the coils around the rotor induce energy into single turn windings these produce a magnetic field this causes the motor to revolve. Motors that have a magnetic core tend to be much smaller and more efficient.
On most DC servo motors it is normally possible to fit newer encoders with a higher resolution, as long as the controller can accomodate the new resolution. However, many brushless motors are associated with a special drive and therefore changing the encoder may not be possible.
In the vast majority of cases with new DC servo motors the old servo drives will work with the new motors. While there are some generic brushless drives that can accommodate a wide range of motors, many drives are dedicated to a motor of range of motors and therefore may not work with a newer design of motor.
Brushless servo motors tend to offer the highest performance in terms of acceleration and deceleration. This is because the revolving mass of a brushless motor is usually less than other types of motors, there is also no brush gear and that allows the motor to operate under a higher current since brushes tend to limit the acceleration current.
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Servo motors, spindle motors and stepper motors
TRM can help you find the right motors for your application; we can even make mounting brackets for the new motors. TRM works with various motor manufacturers including Control Techniques, Siboni, and Estun. We part manufacture some motors and we fit encoders and make encoder covers. Likewise, we work some of the worlds best gearbox manufactures and can offer a full range of motors and gearboxes.