The THC or the torch height control is a very important aspect when you are making use of a plasma cutting machine for your cutting purposes. THC is often misused or non-functional or even sometimes missing in a plasma cutter and most often than not, the THC is usually raised up and down by the operator manually. To get the best results out of the plasma cutting operation, the THC function of the plasma cutter must be used.
There are different kinds of THCs available that have varied functions and features; however, the function of all of them is to control the position of the plasma cutter. The quality of the cut and the consumable life is determined by the torch-to-work distance or the standoff.
Elements of the Torch Height Control (THC)
The torch positioner is driven by the motor and when it gets the signals from the control panel, it helps the plasma torch to move up or down. The torch positioner consists of the screw drive, rack and pinion and the belt driven devices that produce the movements of the torch.
This is essentially the brain of the plasma cutting system, where the remote control sends the input commands, which are transmitted to the torch positioner for the output. The control console also monitors the position feedback and voltage signals.
The system interface contains the voltage divider card present in the power unit. When the plasma cutter is in operation, the voltage divider card monitors the power supply voltage and the interface divides the voltage signal and sends the lesser voltage to the control console.
This is the human-machine interface or HMI and is used by the operator to set the two vital parameters for cutting i.e. the initial height and the arc voltage. The remote control may be located in a separate box or within the control panel of the CNC.
What Is Initial Height Sensing (IHS)?
The Initial Height Sensing or IHS is an adjustable component and basically, controls the height where the plasma torch will begin the arc and cut through the material. The THC must first determine the position of the workpiece before setting the IHS. For a high-quality and accurate cut, it is very important that the plasma torch should retract to the precise piercing height after locating the position of the workpiece.
THC is a very important aspect of the plasma cutting process since the torch’s position and the pierce, both determine the success of the cutting operation. If the pierce is very low, then both the plasma torch and the consumable will get damaged. On the other hand, if the pierce is too high, then the arc will not be transferred to the material to be cut. Also, cutting at the correct height ensures that the quality of the cut is good and this will also help to minimise any expensive finishing.