Wednesday, January 22, 2020

Motion Controller and Driver Selection Tips You Should Know

Motion Controller
The first thing that should be checked when selecting a motion controller is compatibility with other system components such as the PLC/PC, stepper driver and voltage sources.Motor speed is controlled by the pulse rate (pulses per second) supplied by the driver via the controller.Depending on the speed required, one must ensure that the motion controller can output the corresponding pulse rate to reach that speed. The motion controller must be able to output this pulse rate, and the stepper drive must be able to receive this pulse rate and send over to the SMLA. The equation for determining required pulse rate is shown in the following page.

Motion Controller and Driver Selection Tips You Should Know

• Linear speed: desired linear travel speed (in/s)
• Lead: lead screw for stepper motor travel per one full revolution of the screw (in/rev)
• Motor steps per rev: how many steps per one full revolution of the motor (steps/rev). All SMLAs are 200 steps per revolution.
• Pulses per step: pulses per step (pulse/step). SMLAs are 1 pulse per 1 step.
• Microstep: Micro-stepping resolution (micro-step/step)
After calculating the required pulse rate, it may come to light that your PLC, PC or microcontroller is capable of sending out this frequency to the stepper drive without the need of a separate motion controller.

Stepper Drive
Like a controller, the user should select a drive based on its ability to interface with all other components in the system – specifically the stepper motor and controller. For Thomson standard SMLA stepper motors, a drive must be able to allow the connection of a four-wire, bipolar motor. Electrical properties of the system must also be taken into consideration. Items such as desired output current to the motor, max input voltage from the power supply, and motor inductance will need to be reviewed.Just like a controller, required pulse rate will also need to be considered to ensure the driver is capable of driving the motor to the required speed.

There are many unique stepper motor drives out there that offer various micro-stepping resolutions. Depending on your requirement, micro-stepping may be worth considering, specifically if a smoothmotion is required. Micro-stepping essentially takes the standard 200 steps per revolution of the SMLA motor and breaks down each step to smaller increments such as from ½ step, ¼ step and even all the way to 1/256 step. Figure 7 illustrates the difference between full-stepping and micro-stepping.

Figure 7: Simple illustration comparing the motion between full stepping and micro-stepping.An important thing to note about micro-stepping is that it does not improve positional accuracy by goingto finer resolutions. A typical rotational accuracy for a stepper motor is approximately +/- 0.09 degreesregardless of micro-stepping resolution.

Final Considerations
Ultimately, experience is the best tool at one’s disposal for building a stepper motor-based system.The guidance mentioned above should only be utilized as a way of getting in the ballpark for a system build.Some experimentation with trial and error may need to be conducted to get a completely functional system. Always utilize the help of an experienced system designer and add a decent margin to system calculations when possible. When it comes to SMLA selection, Thomson can help recommend a product to get the performance you need. PLC, motion controller and drive manufacturers will also have dedicated engineers to help assist you in selecting one of their products.

Additional benefits of linear stepping motors

Additional benefits of linear stepping motors

Linear stepping motors are an excellent solution for positioning applications that require rapid acceleration and high-speed moves with low mass payloads. Mechanical simplicity and precise open-loop operation are additional features of the Compumotor microstepping linear motor systems.

Additional benefits of linear stepping motors

High Throughput – The motors are capable of speeds to 100 ips and the low mass forcer allows high acceleration.
• Mechanical Simplicity – The need for leadscrews or belts and pulleys is eliminated. The mechanical design is preengineered.
• High Reliability – Fewer moving parts and a friction-less airbearing design results in a longer, maintenance-free life.
• Long Travel – Length of travel is limited only by the length of the platen; increasing length causes no degradation in performance.
• Precise Open-Loop Operation – Unidirectional repeatability to 2.5 microns without the added expense of feedback devices.
• Small Work Envelope – A linear motor is usually smaller in all three dimensions than comparable systems where rotary motion is converted to linear.
• Easily-Achieved X-Y Motion – The assembly of X-Y gantry systems is readily accomplished.
• Multiple Motion – More than one forcer can operate on the same platen with overlapping trajectories.

Construction of a Linear Step Motor
A linear hybrid stepping motor operates on the same electromagnetic principles as a rotary hybrid stepping motor.The moving element is called a forcer. The stationary part is called the platen. The stator or platen is a passive toothed steel bar extending over the desired length of travel. All permanent magnets, electromagnets and bearings are incorporated into the armature or forcer. The forcer moves bidirectional along the platen, assuring discrete locations in response to the state of the currents in the field windings

Monday, January 20, 2020

What is the maximum speed of a stepper motor?

What is the maximum speed of a stepper motor?
Modern stepper motors can reach rotation speeds of up to 1500 RPM, taking into consideration that the motor torque curve decreases considerably with the increasing of the step frequency. If a screw of 4 mm is run at 1500 RPM, we obtain a displacement speed of 1500*4mm=6000mm/min or 6 m/min. Therefore, in practice, the stepper motors runs at max 600 RPM because the torque decrease above that values.

What is the maximum speed of a stepper motor?

14hs13-0804s or 17hm08-1204s

Related Questions:
What temperatures are stepper motors able to run at?
Most stepper motors are made with Class B insulation. This allows the stepper motor internal wiring to sustain temperatures of up to 130 degrees Celsius. With an ambient temperature of 40 Celsius, the stepper motor has a temperature rise allowance of 90 Celsius. Stepper motors can run continuously at these temperatures.
What applications would a bipolar stepper motor be used for?
A bipolar stepper motor is best used in a situation that would require high torque at low speeds.

What is the difference between a Unipolar and a Bipolar stepper motor?
The main difference between unipolar and bipolar hybrid stepper motor is the center tap connections. A unipolar motor is wound with six lead wires, each of these having a center tap. These would be used in applications needing high torque with high speed. Whereas a bipolar stepper motor has four lead wires but has no center tap connections. Bipolar stepper motors are used when you require high torque at low speeds.

What applications would a unipolar stepper motor be used for?
A unipolar stepper motor would be best used in an instance where you would require a motor with high speed and high torque.

What are the commonly used motors for CNC lathes?

1.Stepper motor Stepper motor is one of the more commonly used motors in CNC lathes. Its principle is to add electromagnetics in the column ...