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    Advantages of CNC Plasma Torch Height Control (THC)

    Advantages of CNC Plasma Torch Height Control (THC)

    The role of a torch height control system for mechanized cutting systems is often understated. A good THC (Torch Height Control) is absolutely critical to good cut quality. It is a known fact that by far the best possible control method is by sensing the cutting voltage. The cutting voltage is directly proportional to the height between the torch and the workpiece; higher the distance, higher the voltage and vice-versa. So one can easily take the cutting voltage as a control parameter and use the same for controlling the stand-off distance. This method of control is frequently referred to as AVC (arc voltage sensing). Sensing the arc voltage is not devoid of challenges. The torch is subjected to a high frequency pilot arc, which creates plasma. This HF can easily traverse back to the sensitive voltage measuring circuitry and damage/cause malfunctioning of the system. It is absolutely essential to isolate the measuring circuitry from the plasma HF and yet be able to measure the voltage accurately. Highly sensitive arc voltage control circuitry can detect voltage variations less than 0.5V. Accurate measurements as well as isolation can be achieved through use of Hall sensors.

    Here are 3 main advantages:
    1. Allows for automatic control of the 3 necessary modes of height for excellent consumable life and cut quality.
    Pierce height being correct is absolutely critical to the life and long-term cut quality of the torch nozzle (tip). One pierce too close will permanently affect cut edge angularity, dross, and overall edge quality. Finds the surface of the material and then retracts to the proper pierce height.

    2. Once the pierce height is located accurately, the torch then moves down (after pierce delay timer times-out, allowing for a full pierce) to the proper cut height.
    Cut height is critical to cut edge angularity, dross and warpage. Too low will cause plate collisions, too high will widen the kerf, increase edge angularity, and cause dross and warpage.

    3. Once the X- and Y- motion get up to speed (after the height control delay timer times out) the arc voltage feedback control takes over to maintain the proper torch to work distance, controlled by the arc voltage setting.

    A properly functioning height control will allow you to program and nest hundreds of parts and walk away from the machine while it is cutting. This is what CNC machines are supposed to do!

    If you are cutting one part at a time and don’t mind babysitting the machine continuously during cutting, and can adjust the pierce height for every pierce, stop, then adjust the cut height, then you can get along without height control. Many do. However, the height controller makes these machines truly automated and pay for themselves much more quickly. There are no industrial grade machines available on the market without height control.

    If anything we can help with CNC Plasma and CNC spare parts, welcome to contact us, we will do our best to support.