Which process does NOT involve the generation of chips?

The process that does not involve the generation of chips is forming. Forming processes, such as stamping or forging, manipulate the material to achieve the desired shape without removing any material in the form of chips. Instead, these processes work by deforming the material, often using pressure or heat, which changes the structure of the material but retains the overall volume.

In contrast, drilling, grinding, and milling are all subtractive machining processes that actively cut away material, resulting in chips as a byproduct. In drilling, cutting tools create holes by removing material, while grinding uses an abrasive wheel to remove material for finishing. Similarly, milling involves rotating cutting tools to remove material from a workpiece, also producing chips. This fundamental difference in how material is handled is what distinguishes forming from the other processes listed.