1
\$\begingroup\$

I have an n20 DC motor which has a gearbox with a 55mm m4 threaded shaft (see image below for visualization of the motor). I'm compressing a spring with this motor, so the motor needs to work relatively hard to compress the spring.

I am noticing that the spring compresses significantly less (3/4 the expected compression) after the 2nd or 3rd subsequent time that I try to compress the spring (I take about a 1 minute break between runs). I am noticing that the motor is slightly warm after 1 or 2 of these spring compression runs.

Is it expected to see such a large difference in spring compression?

Also, does the motor wear out over long time of use? I have been using this motor for about a month and am wondering if all of this use is causing degradation?

I've attached an image of the specs of the dc motor. The gearbox has a reduction ratio of 1/52 and I am using the 6V motor. You can see our motor's specs highlighted in red.

Could it be that the m4 motor shaft is wearing out over time and causing friction as a result? What about the m4 insert I am using (could that be causing friction over time)?

Here is the spring we are using: https://www.mcmaster.com/9657K371/

Thank you very much for the help.

n20 Motor with 55mm m4 threaded shaft

n20 dc motor with gearbox specs

\$\endgroup\$
4
  • 1
    \$\begingroup\$ You haven't said anything about what's powering the motor. \$\endgroup\$
    – Simon B
    Feb 26, 2021 at 11:09
  • 1
    \$\begingroup\$ This sounds like you're powering the motor off a small battery. In which case, measure the battery voltage and current during both first and second operations... \$\endgroup\$ Feb 26, 2021 at 13:36
  • \$\begingroup\$ Also, possible duplicate of electronics.stackexchange.com/questions/549599/… and (engineering.stackexchange.com/questions/40524/…). Is he working on the same project? \$\endgroup\$ Feb 26, 2021 at 13:39
  • \$\begingroup\$ In other words you may need to start with a proper analysis of required torque and current as in his question. \$\endgroup\$ Feb 26, 2021 at 13:44

1 Answer 1

0
\$\begingroup\$

Increased temperature of the motor windings will increase the winding resistance and reduce the maximum torque that can be produced with a given applied voltage. You could compensate by applying a higher voltage, but that may cause the motor to be damaged. You probably need a larger motor. Along with a larger motor, you should use a motor controller that will limit the motor current electronically. The current needs to be limited to a level that will produce the required torque but not damage the motor with the operation vs. rest duty cycle that you need. It may be difficult to find a motor with a published duty cycle rating.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.