From Sonic Retro
Roboticization, or robotization, is the process established in Western Sonic the Hedgehog lore of turning living organisms into robots. The idea stems from the first Sonic the Hedgehog game, in which animals are turned into Badniks by Dr. Robotnik. Sonic and friends are then meant to subsequently free the animals by destroying said Badniks.
In the Japanese manual of Sonic the Hedgehog, it is explained that Dr. Eggman (Robotnik) has imprisoned Sonic's friends in robot shells in order to track down the Chaos Emeralds. In the West, however, Robotnik is loosely established as capturing animals in order to make robots, either to destroy Sonic and mechanise the planet Mobius, or as the game's manual suggests, just because he's evil.
In most of the video games, the process of creating robots from animals is not named, however in the US television series produced by DiC (and the comic book series by Archie Comics) the process was known as "roboticization". Here, rather than just trapping animals in shells, the roboticization process causes flesh to turn into metal, essentially turning living beings into robots, robbed of their own free will and forced to serve Dr. Robotnik.
Several characters in the TV and comic book series are affected by the roboticization process, be it members of Sonic's family (such as Uncle Chuck who invented the device) or series regular Bunnie Rabbot who is partially roboticized. Much of the story involved stopping Robotnik and producing a de-roboticizer to undo the damage. Roboticization was also a focus in Sonic Underground, as well as other Western Sonic material, although Robotnik is usually depicted as more concerned with Badnik production - capturing the citizens of Mobius to use as "organic batteries" for his robot army.
In the OK K.O.! Let's Be Heroes crossover episode with Sonic the Hedgehog, titled Let's Meet Sonic, K.O. is roboticized by Lord Boxman, becoming Metal K-0. The device that transformed K.O. into this new robotic form was not called a Roboticizer but Sonic says K.O. has been roboticized in the episode.
Roboticization is not thought to have ever been an official term when it was popularised by the TV shows and comics, and many later games see Robotnik or Eggman seek other methods of achieving his aims, such as waking ancient destructive creatures or producing planet-altering weaponry. Sonic the Hedgehog CD was one of the first games to not use captured animals as motivation, as the enemies in that game run on plants, and in Chaotix and Sonic Advance 3 Badniks were powered by Rings.
Roboticization as a concept was, however, attempted by the Deadly Six in Sonic Lost World using the knowledge on how to make robots bestowed upon them by Eggman. They had intended to turn Sonic into a robot, but when Tails is captured instead, they used him for the process. However, thanks to Zavok and Zomom leaving him unattended, Tails was able to reprogram the machine he was tied to in order to merely look like he was roboticized, retaining his free will.