Q: I have an application for a syringe pump and I need to know what the minimum speed of your DRL Compact Linear Actuators are I see the maximum speed is shown in the catalog and on your webpage, however I want to know the slowest that I can make it operate.
A: The lowest frequency setting for the DRL series product with a built-in controller type driver is 1 Hz. The frequency setting in Hz is the same as steps per second. This setting will be for the operating speed of the motor, however you also have to take into consideration your acceleration and deceleration rates. The acceleration time, operating time, and deceleration time all factor in to the motion profile
We offer several types of leads for the DRL actuators. We offer both Rolled Ball Screw and Ground Ball Screw. Depending on which actuator you select, the resolution of the actuator may be different. If we take the DRL20G-02B1P-KD package as an example, then the resolution will be 0.002 mm (0.000079 in) per step. Therefore, at a frequency setting of 1 Hz, the actuator would move 0.002 mm (0.000079 in) per second. You can change the resolution of the motor on the DRL series by microstepping the driver. In order to microstep the driver, we need to change the step division. Below is the step angle adjustment section of the DRL manual:
When changing the step division, you are changing the amount of steps needed to be taken per 1 full revolution of the motor; or in the case of resolution setting, the distance traveled by the actuator. This change does not affect the Hz value which you have selected, however it will affect the overall speed of the motor. You are still traveling the same amount of steps per second, however now the amount of steps to move the same distance as the previous setting has changed. Therefore, your speed will be divided by your selected number of divisions.
For a linear actuator: linear speed in mm/sec (or inches/sec) = resolution *frequency.
Therefore, dividing the resolution by 2 (Number of divisions is set to 2) will half the linear speed.
The slowest speed can be achieved by using the DRL20/28 actuator at the largest microstep division of 250x. This will yield a resolution of 0.000008 mm/step (0.00000031 in/step). Therefore, at 1 Hz, the speed would be 0.000008 mm/sec (0.00000031 in/sec).
A 1 Hz setting is still a low setting of frequency. Therefore, it would be recommended to adjust the resolution of the motor via microstepping so that a larger Hz value could be used. Using a larger frequency value will achieve a smoother operation of the actuator. It should also be noted that you want to avoid the resonance frequency of the motor. The resonance frequency is usually around 200 Hz, but can be anywhere between 150 and 300 Hz.
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