![dynatorch plasma table cuts crooked dynatorch plasma table cuts crooked](https://www.practicalmachinist.com/vb/attachments/f30/12298d1240959839-cnc-plasma-table-ideas-img_2363.jpg)
Torch height has the greatest affect on bevel angle of the plasma cut piece. It adjusts the torch up or down to maintain that target voltage.Įach voltage setting corresponds to a specific height that optimizes the arc characteristics for a clean, straight cut. Once the cutting begins, the THC starts sampling arc voltage from the power supply and comparing it to the target voltage set by the operator. This voltage setting is usually between 100 and 200 VDC.Īfter the torch height control has completed initial height sensing and the torch has pierced the plate, motion of the cutting machine is enabled and the torch begins to move. The operator sets the arc voltage on the remote control according to the cut charts in the plasma system's operations manual. This allows the system to maintain proper torch height regardless of variations in the material, or flatness of the cutting bed. The torch height control uses arc voltage to maintain a consistent distance from the plate while the torch is cutting. When the torch to work distance increases the voltage goes up when the torch-to-work decreases the voltage goes down. The resistance in the arc is a function of the distance. Voltage is directly proportional to resistance (Ohms Law states that V=I*R).
![dynatorch plasma table cuts crooked dynatorch plasma table cuts crooked](https://cdn.thefabricator.com/a/improving-plasma-cut-quality-plasma-cutting-components.jpg)
Plasma power supplies are a current source-they generate a very steady operating current when the torch is cutting.Voltage, on the other hand, varies depending on the distance between the cathode (the electrode in the torch) and the anode (the material being cut). Note that arc voltage is the same thing as power supply output voltage. Torch to work distance distance, or standoff, during the cutting process is adjusted by monitoring and controlling the arc voltage. The rule of thumb is to pierce at 150-200 percent of the cut height. If it attempts to pierce too high, the arc will not transfer, causing a misfire. This is the number one cause of premature parts and torch failures (see Fig. If the torch pierces too low the consumable parts will be damaged. Regardless of the method used, the most important thing is that the torch finds the plate and accurately retracts to the proper pierce height, whether on thick plate or thin, rusty plate or clean, above water or below.Ĭorrect pierce height is essential. A variety of schemes are used for sensing the plate from simple mechanical devices, to motor stall technology, proximity sensors, and electrical circuits that sense nozzle or shield contact. In order to set the initial height (also called retract distance) the THC must first find the position of the plate. IHS is an adjustable parameter that determines the height at which the torch will fire and begin piercing through the plate. The difference between IHS (initial height sensing) and voltage setting is very important to understand and is often confused. It may be located inside the CNC control or in a separate remote box. This is where the operator sets two critical cutting parameters: initial height and arc voltage. The remote control is the HMI, or human machine interface. It "divides" the voltage signal and sends a smaller signal voltage to the control console. The voltage divider card monitors power supply voltage during cutting. This device usually consists of a voltage divider card that is mounted inside the plasma power supply. It receives input commands from the remote control, sends output commands to the torch positioner, and monitors position feedback and voltage signals.
![dynatorch plasma table cuts crooked dynatorch plasma table cuts crooked](https://www.picclickimg.com/d/l400/pict/303678740165_/5-x-10-CNC-Plasma-Table-Package.jpg)
Screw drive, rack and pinion, and belt driven mechanisms are used to translate motion. This device moves the torch up and down in response to signals from the control console. This "torch to work" distance or "standoff" is critical to both cut quality and parts life. But all use the same basic elements to control position of the torch relative to the material being cut. Each of these automatic THCs has a variety of functions and features. There are a variety of torch height controls, or "standoff controls," on the market. In either case the shop is not getting the most out of its cutting operation.
#Dynatorch plasma table cuts crooked how to#
The THC is either not working properly or the operator has not been trained on how to use the equipment. In many fabrication shops you will see the torch operator manually driving the torch up and down while cutting-his eye on the torch and his thumb on a toggle switch. But it is also the piece of equipment on the cutting machine most likely to be misused, nonfunctional, or even missing. The automatic torch height control (THC) is one of the most important elements of the mechanized shape cutter.