TURNING: an industrial production process carried out through the removal of shavings, which is widely used in metalworking. The machinery used in this process is the lathe. Turning is defined by the rotary motion of the piece to be processed and the mainly rectilinear motion of the tool being used to refine the piece. The cutting edge of the tool penetrates the material of the piece, removing the excess material, which is called the machining allowance, and thus forming a shaving.

MILLING: a cold machining process for the removal of chips or shavings through the use of a tool that rotates around its own axis in a forward motion on the piece to be processed. In milling, the motion of the tool is rotary, rather than the rectilinear movement found in turning. In order to make the finished piece, the size of the rough piece, from which the machining allowance will be shaved, must be sufficient to encompass all the dimensions of the finished piece.

WELDING: a joining technique that creates a permanent joint between two metal pieces with or without the addition of other material (FILLER METAL) through the application of heat. FILLER METAL is distributed in a molten state between the suitably prepared (bevelled) edges of the metal pieces to be joined.
The EDGES, or borders, are the surfaces along which the welding process will be carried out on the metal pieces involved; these edges are prepared by giving them the most appropriate geometric shape, mainly according to the thickness of the material to be welded, to make the welding process easier and more effective.
The material of the pieces to be joined together is called the BASE MATERIAL.
The WELD POOL is the part of the metal which is in a liquid state during the welding process. The WELD BEAD is made up of all the metal, both base and filler, that is solidified by cooling after being melted during the welding process. The weld bead is the essential element of the welded seam and the way it is deposited on the joint determines the actual welding technique.