Transfer

The Transfer, (TV: The Dalek Invasion of Earth) also known as robotisation (PROSE: Doctor Who and the Dalek Invasion of Earth) or robotization, (PROSE: What To Do If A Dalek Attacks You!) was the Dalek operation of surgically modifying humans into servile Robomen.

The Daleks attempted to use the procedure on the First Doctor but he was rescued. They selected him for transfer after he displayed a greater intellect than those of other prisoners. (TV: The Dalek Invasion of Earth) The process was called "robotization" by the Martians, who came to know of it during the Dalek invasion of their planet. (PROSE: What To Do If A Dalek Attacks You!)

According to the Dalek Survival Guide, it was following the failure of the 2150s Dalek invasion of Earth that the Daleks started using Ogrons as shock troops; the guide suggested that the Ogrons' natural stupidity made them easier to control than humans and so eliminated the need for the time-consuming robotisation process. (PROSE: Dalek Survival Guide)

Behind the scenes
The Dalek Handbook observes that Arthur Terrall was controlled by a more advanced version of the conditioning process used on the Robomen.