Typically rapid palatal expansion is done with a jack screw that is activated at the rate of:
High-Yield Explanation
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