FAQ Page
Category Products Capacity
Title 07. What is the most suitable range of Acc/Dec in case of using FASTECH product selection program?

In general, 20% of the in-position time is appropriate. But there is some difference between each equipment, so please try to find out the most appropriate Acc/Dec value.

Acc/Dec setting is one of the key factors to control machines. If Acc/Dec value is too short, it will impact the life cycle of machines and robots due to vibration. Also if Acc/Dec value is too long, overall productivity will be decreased due to Tack Time delay. So please try to find out the most appropriate Acc/Dec value depending on facilities.

Also load, there are friction load, inertia load and other external force(gravity) and especially inertia moment will be proportional to the ration of Acc/Dec. If inertia load goes high, will be difficult to be immediately accelerated or decelerated and also the operational capacity of the motor should be very high to shorten the time of Acc/Dec. The sudden deceleration can be a reason for over regenerative voltage error. In this case, please the loose time of deceleration.

As a result, please select an appropriate motor according to load and motion condition. And FASTECH supports customers to select the right size of the motor, especially from our website. For more details, please contact with FASTECH sales team.

( → SUPPORT → Motor Selection Guide )

General characteristic of step motor motion control can be show as curve as below and T1, T3 is item to indicate timing of Acc and Dec.

* Moving Distance S : Set total number of pulse what will be transferred by motor revolution
* Moving Velocity V : Max. Velocity where motor can reach after starting revolution
* Acc Time T1 : Time to reach Max. Velocity after Acceleration
* Dec Time T3 : Deceleration Time to reach Min. Velocity
* Velocity Offset Vo : Defined Velocity at the Initiation and End  Point of operation Declination of Acc/Dec, Rate T R  can be set by

  following formula as below.

  Acc/Dec Rate T R   =              Acc(Dec) Time (ms)              
                Operation Pulse Velocity (kHz) – Starting Pulse Velocity ( kHz)  
  If value of Acc/Dec, Rate (T R ) is big, it is slow motion of Acc/Dec,  if value is small, immediate motion of Acc/Dec. For safe motion of
​  motor, please set Acc/Dec Rate following by conditions as below.  

<General Curve of Step Motor Motion Control>

Files 200115_FAQ07_ENG.pdf