The THC Control Panel is located on the left side of FireControl and contains all
the settings and real-time data display for the THC module. Note: the THC Control
Panel will only display when a connection to a LS-THC module is made.
The below figure highlights the features that are contained within the THC panel.
Please refer to the subsequent sections for an explanation of these features and settings.
Live Voltage Display
The Live Voltage Display shows the real-time arc voltage of your plasma cutter
during operation when it is connected to the CNC electronics enclosure. The
voltage measuring range for the THC module is 0 - 300V.
Nominal/SMART Voltage Display
The Nominal/SMART Voltage Display shows either the programmed nominal voltage or
the SMART voltage (if enabled) when cutting. If the Nominal Voltage is set to ‘0’
in the THC settings menu, then SMART voltage is enabled (note: smart voltage is
enabled in FireControl by default). The SMART voltage feature in FireControl was
designed to take the guesswork out of cutting with a THC system by automatically
sensing the arc voltage at the height set by the Initial Height Sensing (IHS) system
and using this voltage as the nominal voltage for that cut loop. If you would prefer
to manually enter a Nominal Voltage instead of using SMART voltage, you can do this
in the THC settings menu.
To enable smart voltage, enter the THC settings menu and set the Nominal Voltage
to ‘0’ and save. The THC panel should now display ‘SMARTV’
for Nominal Voltage to reflect that smart voltage is enabled as shown in the
SMART voltage works by reading the arc voltage at the start of each cut loop and
automatically setting the nominal voltage to this value for the remainder of the
cut loop. Since we know that the IHS system sets the torch to the ideal height at
the start of each cut loop, we can measure this ideal voltage and the THC system
will work to maintain this voltage during cutting. Note: SMART voltage resets at
the end of each cut and re-calculates at the start of each new cut loop.
The SMART Voltage display box will show ‘SMARTV’ until a SMART voltage is set by
the THC system. Once a SMART voltage is set, it will be displayed in the Nominal
Voltage box along with a ‘SMART’ logo next to the box to indicate that this was
set by the SMART voltage system. Below is a screenshot of the THC panel when
SMART voltage is enabled during a cut.
SMART voltage was designed so that THC operation can be easy-to-use without having
to constantly change settings for optimal cutting performance. The only SMART
voltage settings that you may choose to adjust are ‘Offset’ and ‘Distance’. These
can be changed from the SMART Voltage sub-menu from the THC settings menu (see the
settings section below for an explanation of these settings).
The Nominal Voltage can be set manually in the THC settings menu. The Nominal
Voltage is the target plasma arc voltage value that the THC system will work to
maintain during cutting. Remember that the THC system works by automatically adjusting
the torch height (z-axis) in order to keep a fixed arc voltage (the Nominal Voltage)
throughout the cut. The Nominal Voltage can be set anywhere between 1 - 300V. NOTE:
THE MAXIMUM INPUT VOLTAGE FOR THE VIM MODULE IS 300V. DO NOT EXCEED THIS INPUT
VOLTAGE! IF YOU ARE UNSURE ABOUT THE VOLTAGE OUTPUT OF YOUR PLASMA CUTTER DURING
CUTTING, CONTACT YOUR PLASMA CUTTER MANUFACTURER FOR COMPLETE SPECIFICATIONS.
Choosing a Nominal Voltage for each cut will depend on many factors such as your
plasma cutter, material thickness, cutting amps, material type, and the cutting
feed rate. While many plasma cutter manufactures will include a table for cutting
voltages based on material type and thickness, these values are more of an idealized
condition and should not always be used absolutely. The best way to determine your
Nominal Voltage is to perform a line test and monitor the Live cutting voltage in
FireControl. We recommend cutting an 8-10” line at the desired cut speed and amperage
for a given material and then entering this voltage value as the Nominal Voltage
before cutting your part. To do this, jog your torch down to the material until
you are at the ideal cut height. Next, turn off your electronics box and unplug
the Z-axis motor from the electronics enclosure and run the line test while monitoring
the Live voltage (note: your line test cannot include an IHS loop or FireControl
will throw an alarm). The below image shows how FireControl should look when a
Nominal Voltage of 120V is entered.
Voltage Tolerance Display
This box displays the Voltage Tolerance value that was set in the THC settings
menu. The voltage tolerance value is used to establish the range of voltage values
that define an acceptable arc voltage during cutting. If your live voltage value
falls outside this tolerance range, the THC system will work to bring the voltage
reading back to within this acceptable range by moving the Z-axis accordingly. For
example, if your target voltage value is 120V and your tolerance value is set to
+/-1.5V, then the THC system will not make corrective moves if the voltage value
is between 118.5V to 121.5V.
THC Real-time Status Display
This display panel shows the current status of the THC system during cutting.
When the THC system is activated and taking control of the Z-axis, the below LEDs
indicate the current state of the THC system.
- ACTIVE - The THC system is activated and in control of the Z-axis.
- DOWN - The THC system is driving the Z-axis downward (Live Voltage > Nominal Voltage).
- OK - The Live Voltage is within the acceptable tolerance range and no Z-axis moves are being made.
- UP - The THC system is driving the Z-axis upward (Live Voltage < Nominal Voltage).
In the screenshot below, we can see that the THC system is ACTIVE and that the Z-axis
is not moving (OK). This makes sense because the live voltage reading 115.3V is within
the +/- 1.5V tolerance range of the 114.5V SMART Voltage that was set.
THC & the DRO
Note: When the THC system makes corrective up or down moves to the Z-axis torch,
these moves do not show up as positional moves on the Z-axis Digital Read-Out (DRO)
because the THC system is open-loop and does not monitor absolute position.
In other words, if THC is making corrections you will see the LEDs light up on
the Status Display and you can physically see the torch moving up and down (watch
the lead screw coupler on the Z-axis) but you will not see the Z-axis position
changing in the DRO.
Real-time Torch Speed Display
The Real-time Torch Speed Display shows the live torch speed in inches
per minute (or mm/min if metric selected) as it moves around the table
during jogging and cutting.
Program Speed Display
The Program Speed Display shows the programmed cutting speed when a cut program
is loaded into FireControl. When a program is not loaded, the Program Speed will
Torch Speed CUTOFF Setting
As seen in the previous two sections, FireControl monitors the live Torch Speed
and also stores the Programmed Cut Speed when a program is loaded. The reason that
the program speed is important for THC is because the THC system will momentarily
turn off during a cut when the live Torch Speed is less than the Torch Speed CUTOFF
threshold %. This is because as the torch speed momentarily decreases, such as around
a tight corner or a small circle, the arc voltage will increase which can cause the
torch to plunge towards the material as it tries to compensate for this sudden increase
The Torch Speed CUTOFF setting was added to the Langmuir Systems THC system to prevent
the torch from plunging towards the plate when the torch slows down (such as around
tight corners or small holes). Simply put, if the live Torch Speed falls below a
percentage of the Program Cut Speed, the THC will momentarily disable and stop making
corrective Z-axis moves until the speed increases and returns to within range. For
example, if the Torch Speed CUTOFF is set to 85% and the program cut speed is 100
in/min, then the THC will turn off whenever the live speed falls below 85 in/min.
The Torch Speed CUTOFF is set to 85% by default. It can be changed by clicking
the + or - symbol on either side of the displayed percentage. Note: For intricate
art cutting programs that involve frequent back and forth motion of the torch, it’s
possible that the torch never accelerates up to the programmed cut speed and therefore
the THC will not turn on. We suggest monitoring the live cut speed and lowering the
Torch Speed CUTOFF % if your torch is not getting up to your programmed speed.
THC On/Off Toggle
The THC On/Off Toggle button is located in the top right corner of the THC Control
Panel. This toggle can be used to turn off THC control at any time. With the THC
turned off, your CrossFire machine will function as normal with Z-axis control but
with no THC adjustments during cutting.
The THC Settings Menu can be accessed by clicking the corresponding button on the
THC Control Panel. Once clicked, the THC Settings Menu will pop up on the screen
as shown below.
THC settings can be changed in this menu and then saved by clicking the green ‘SAVE’
button in the lower right corner. The below ‘THC Settings’ section explains how these
settings affect the performance of your THC system and the allowable values for these