According to many experts, turning was the first machining operation that gave rise to a machine tool. The lathe follows very basic movements, which have helped it become one of the most used machines in machining workshops. However, these movements would not be possible without the lathe axes, which are key components for this machining.
Lathe Movements
There are multiple types of lathes available in the market. We can find automatic, parallel, vertical, and computer numerical control CNC lathes; the latter are the most famous due to the numerous benefits and functionalities they offer to the industry. Each lathe, except for the CNC, which is capable of performing all specific tasks and jobs. Thus, a lathe is capable of creating cylindrical or cone-shaped pieces, but it can also drill, cut, sand, or groove these pieces. Everything depends on the lathe, the tool used, and the movement performed.
Before talking about the lathe axes, it is important to discuss the movements performed by this machine tool since axes and movement go hand in hand in turning. The workpiece is the one that rotates, and the movement it performs is usually called “working movement.” Interestingly, although the piece rotates, it is the tool that approaches the piece to make the cut. With this system, the lathe has three movements:
- Rotation movement or cutting movement by rotation of the piece. This is the most commonly used movement. The piece is placed on an axis that rotates, making the piece itself rotate on its own axis. For chip removal machining to work, a blade must be used to allow the removal of material. If the right tool is chosen, as well as the best conditions for performing the work, the results will be very precise.
- Feed movement. In this lathe movement, it is the cutting tool that moves parallel to the piece, through a straight movement. This movement serves to define the contour of the piece to be machined.
- Penetration or depth movement. In this movement, it is the tool that enters the piece, making a cut and determining the depth of the cuts made.
Lathe Axes
In numerical control machines, the concept of axes is used to refer to the directions followed by the different displacements of the moving parts of the machine. Among these parts are the table, the cross slide, or the longitudinal slide. The lathe axes are only two: X and Z. Among these two axes, the Z performs a longitudinal movement following the main axis of the lathe; meanwhile, the X axis is responsible for making the transverse movement and perpendicular to the main axis of the lathe.
And how are the movements related to the lathe axes? Here we find that in the three types of movements described earlier (rotation, feed, and penetration), the axes play a key role. The cutting or rotation movement occurs between the surface of the piece and the tool that moves; in this movement, the piece rotates in the direction of the Z axis while the tool can move along either of the two lathe axes.
In the feed movement, the tool can also move along the two axes that make up this machine tool; if it moves along the Z axis, then a cylindrical shaping of the piece is performed; on the contrary, if it moves along the X axis, we say that a facing of the piece is performed. In the last movement, the cutting depth or penetration, the tool will always move along the X axis with the purpose of removing part of the top layer of the piece.
Three-Axis Machining
Within the realm of computer numerical control (CNC) machine tools, we find that there are three-axis lathes. These are capable of performing machining where the tools, controlled by a computer, move using three axes. The movements performed by the tools of these machines are very precise and high-speed. The movement of these axes is carried out through the support that holds the piece.
This type of lathe that operates with three axes offers multiple advantages for workshops. For example, they reduce work time since the pieces do not need to be repositioned multiple times by the operator; the finish is much better, more streamlined thanks to the tangential movements performed by the tool while the lathe is operating, and finally, it is possible to create very complex pieces.
