Torch Probe
Let’s discuss the “Torch Probe” button available on the main screen of Optimum CNC plasma cutting software and how it assists the operator in locating the surface of the material being worked on. We’ll cover the floating head sensor, the arc sensor, and some plasma settings options, namely ignition height and switch correction, also known as IHC correction height.
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How does the torch probe work? Essentially, the torch probe utilizes two sensors connected to the torch: the ohmic sensor and the floating head sensor. The ohmic sensor can be toggled on and off. These sensors function differently but serve the same purpose: to locate the point of contact between the torch and the working surface.
Starting with the ohmic sensor, which is usually simpler to understand, it’s directly connected to the torch. Once the torch moves down, the ohmic sensor engages as soon as the torch touches the work surface. This means there’s zero correction between the ohmic sensor and the torch itself.
The floating head sensor is the second sensor available on Optimum CNC plasma. There’s some play, meaning that once the torch goes down and touches the working surface, it requires a bit more downward motion to engage the floating head. The floating head is used when the ohmic sensor doesn’t recognize contact with the work surface, perhaps due to liquid or dirt on the material. It’s a more mechanical system, almost like a button press. This introduces a small correction value, usually set once per machine, and is configured within the IHC correction height, also called the switch correction or value B in the plasma settings.
The system moves down and detects when either the ohmic sensor or the floating head sensor is engaged. This tells the system that the current machine coordinate is the work coordinate zero. At this point, there’s no difference between the work offset, program coordinate, and machine coordinate. Once contact is made, the system recognizes that point as work zero and sets the coordinate to zero.
Next, the system moves up slightly to the ignition height. For example, if the ignition height is set to 0.06, the torch will raise to that value after zeroing. This value can be adjusted as needed.
To demonstrate, let’s run the procedure using only the ohmic sensor. We’ll toggle the sensor on and off. Raising the torch slightly and moving downward, the system detects when the torch touches the table because the ohmic sensor is on. It then raises the torch slightly after zeroing the coordinate, moving it up by the value specified in the IHC or initial height control ignition height.
Now, let’s utilize the floating head sensor. The procedure differs slightly. The torch moves downward, and at some point, the floating head sensor engages, stopping the downward motion. The torch then begins moving upward, and zeroing occurs when the floating head sensor is no longer engaged. The system adds the correction value.
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For demonstration purposes, let’s set the ignition height to zero. Although not realistic, it simplifies the demonstration. We’ll raise the torch to approximately zero and run the procedure again using the floating head sensor. As the torch moves down and engages the floating head sensor, it then moves up. Once the floating head sensor is released, the system doesn’t raise the torch higher due to the zero ignition height but adds the correction value.
Running the process again with a more dramatic correction value, say half an inch, makes it easier to observe. Although not realistic, this larger correction value helps illustrate the process. As the torch moves downward and the floating head sensor engages, the torch begins moving up. Upon releasing the floating head sensor, the system sets the work coordinate to zero and adds half an inch of correction to the machine coordinate value.
Finally, we’ll set the values back to more realistic numbers. From now on, the torch probe can be used to locate the work coordinates or program coordinates of zero on the working surface of the metal.
Definitions:
Initial Height Control (IHC): Probe sensors (floating head and ohmic sensors) and ability to find material by lowering a Torch and searching material sheet by probing
IHC Ignition Height: After contact, the torch rises to the Ignition Height and waits for the arc signal. Note that the there are two IHC speeds that can be changed in the User Settings –Probe Speed and Probe Speed (Slow). Upon approaching some distance from the material (Slow Speed Position in the Advanced User Settings), the machine will switch to the slow speed to avoid making contact too rapidly.
Switch Correction: This correction height is typically set once per machine, and signifies the correction between the IHC sensor and the actual height of the plasma torch.
Pierce Time: The pierce time specifies the amount of time, in seconds, allocated.
Torch Probe Button Location: The Torch Probe button is located in the Work Offsets panel, the second to last panel on the right side column of the software underneath the Optimum CNC logo, above the Program Controls Section.
Optimum CNC Software Screenshots: Tap on Images to Enlarge
