On Wed, 22 Jul 2020 11:29:36 -0700 Chris Albertson <albertson.ch...@gmail.com> wrote:
> I don't see any relation between max acceleration and max speed. > Acceleration is determined by (1) the mass of the table and (2) the > torque the motor can produce while speed is determined by the max RPM > of the motor. Mostly agree though as torque usually depend mostly on current there will be a resistive voltage drop at higher torque which will reduce speed at higher torque, speed reduction is usually small. For example series connected DC motors and induction motors made for direct will reduce speed so there are exceptions but do not expect these are used as servo motors anyway. Change gear ratio and use motor with same power different speed may change acceleration due to rotor inertia. > It is very easy to buy a tiny motor with low torque that spins very > fast. Or you can find powerful but slow motors. Multiplying the > speed by three to find acceleration, if it works is just a > coincidence. The factor could be 0.5 or 10. High torque motors usually need a gear box or will become heavy. This is because flux and current is multiplied to get force while there is choice between current or flux in electric motor air gap, there is an optimal choice then either air gap area or diameter need to be increased. Magnetic materials will saturate then flux get high enough while conductor losses increase with current. > There are two whys to go. A mechanical engineer would start with a > requirement for a certain speed and a certain acceleration. His boss > would give him those goals and then he would select a motor and drive. > The other way used by most amateurs is to just buy a motor that > "seems right" and then test it to see what speed and a certain > acceleration you can get from it. Not sure the boss will ask mechanical engineer about speed and a certain acceleration and then give these as a goal to the engineer. It is common boss read economics and contract but then it come to technical details odd things may happen. Nicklas SB Karlsson _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
