Positioning control system of CNC Machining
Time:2021-05-25
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Positioning control system
In numerical control systems, the position of the tool is defined by a set of instructions called the part program. Positioning control is handled by means of either an open-loop or a closed-loop system. In an open-loop system, communication takes place in one direction only: from the controller to the motor. In a closed-loop system, feedback is provided to the controller so that it can correct for errors in position, velocity, and acceleration, which can arise due to variations in load or temperature. Open-loop systems are generally cheaper but less accurate. Stepper motors can be used in both types of systems, while servo motors can only be used in closed systems.
Cartesian coordinates
The G & M code positions are all based on a three dimensional Cartesian coordinate system. This system is a typical plane often seen in mathematics when graphing. This system is required to map out the machine tool paths and any other kind of actions that need to happen in a specific coordinate. Absolute coordinates are what is generally used more commonly for machines and represent the (0,0,0) point on the plane. This point is set on the stock material in order to give a starting point or "home position" before starting the actual machining.