V90 PTI - Vibration at low speeds

Hi

We have replaced a fully functional (Schneider Lexium 23M servo 1 KW) with V90 PTI 2 KW set with Incremental Encoder motor

The machine is a Low-speed Lath (NON-CNC) controlled by PLC, The 1FL motor is attached to a worm gear (1:50).

The main reason for replacement is "More Torque is required upon finishing the work-piece".

The issue is:

The normal operation requires running the motor at low speeds (25 -150 RPM).

Running at speed range 25 RPM to 100 RPM, there are vibrations that prevents correct operation of the machine.

Already made "One Time Autotune" + "Real time Autotune" many times.

Also used Manual tuning + Trace function many times.

However the vibration remains ????????

The load in our case is a 1 Ton Roller drum.

Customer never had a similar problem with the Lexium 23.

Any advises ?

Thanks