manual action of inserting a tool into the machine as opposed to an Automatic Tool ChangeThere are two common reasons this is done or necessary: 1) tool life of one group of tools has expired and machining cannot continue until a new tool with sufficient tool life for the next operation is inserted (causing a tool change) 2) a tool for a given job is not available (or defined as "hand tool" meaning it needs to be inserted/changed manually at the time it is needed) and shall be provisioned.