Introduction
1 Introduction
1.1 Overview
Plasma CNC cutting machine is one of the most commonly used types of CNC machine.
It’s used mostly for cutting Steel, aluminium and other conductive materials.
Like any other type of CNC machine, plasma machine has it own specifics. Machine
should be properly designed for such type of machining, considering slag, steel dust, high
temperatures, moisture, grease etc..
Plasma cutter is a great source of electromagnetic interference. So special care should be
taken into account when designing and wiring machine electronics.
Be sure to use shielded cables for motors, limit switches. External power supply for motion
controller is very recommended. Plasma cutters itself sometimes do not satisfy standards
of electromagnetic compatibility (EMC), so make sure that your plasma cutter is within
EMC regulations.
Heat emitted from plasma could deform workpiece material, usually metal sheet. In such
case plasma cutter would not cut at constant height which could result as a faulty
workpiece or could damage plasma cutter in the process. This is usually solved with THC
device. THC stands for Torch Height Control.
Torch height controller consists from torch height controller and torch height sensor device.
Torch height sensor device measures arc voltage. Bigger the distance between the plasma
torch and material higher the voltage and vice versa. So based on the measured voltage
value we can maintain constant height of plasma torch above the material.
Torch height sensor device is connected with torch height controller via optic cable. Torch
height controller then sends control signals (Up, Down, Arc OK) to motion controller which
then dynamically compensates Z axis and thus maintains constant cutting height.
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