Typically rapid palatal expansion is done with a jack screw that is activated at the rate of:
Every turn of the screw opens the appliance by 0.25 mm. 
Each turn involves 90° activation. 
With rapid maxillary expansion at a rate of 0.5–1 mm/day, a 10 mm expansion is achieved in 2–3 weeks.

Textbook of ORTHODONTICS Sridhar Premkumar
1.0 to 2.0 mm/week
1.0 to 2.0 mm/day
0.5 to 1.0 mm/week
0.5 to 1.0 mm/day