The motion of a CNC plasma cutting system will directly affect the cut quality regardless of what kind of plasma cutter you’re using. And that’s why at EZ Cut CNC one of our top “Value Components” is Z-axis motion, which is the movement of the torch lifter going up and down. When talking about Z-axis motion, there are five important areas to consider:
- Inverted Gear Rack and Pinion
- V-Groove Bearings and Guide
- Z-Axis Optical Proximity Sensor
- Finding Material Surface Using Ohmic Clip or Pressure (Secondary Lifter)
- Automatic Torch Height Control (ATHC)
The Z-axis motion is driven by the machined rack and pinion. The rack and pinion is powered by a dedicated NEMA 2-phase high-speed, high-torque drive motor. On EZ Cut CNC systems, these parts are placed in an area where they will be protected from debris when cutting (pictured below). When looking at other plasma cutting tables you might notice the use of ball and screw for Z-axis movement. The ball and screw setup is a common, inexpensive alternative and is prone to malfunction because debris can easily get in the mechanism. Although the rack and pinion is well protected, it is always recommended to do regular maintenance on your CNC plasma cutting system for the best cutting results.
The quad-capture V-Groove bearings guide the torch lifter plate up and down on the V-guide. It is ideal to have a smooth, lazy motion on the Z-axis instead of fast, abrupt movement. The V-Groove bearings not only facilitate this motion but they also help sweep away dirt and metal particles that might land in their path. In the blueprint drawing (above) of the carriage and torch lifter, notice how the V-Groove bearings are fixed to the carriage plate so that the lifter plate can easily move up and down. These bearings are also adjustable with cams so that they can be tightened or loosened to the lifter’s bearing guide.
(CLICK TO ENLARGE THE PHOTOS BELOW)
EZ Cut CNC plasma tables are built with optical proximity sensors in order to set the table boundaries. On the Z-axis, a dedicated sensor sets the boundaries for the height of the torch. Although this sensor is protected by the carriage cover, a small hole allows for the light sensor to realize when the torch has hit the limit of it’s boundaries.
Another versatile feature of our CNC plasma table is the way it finds the material surface. The system operator can choose to either use the ohmic clip or the secondary lifter. The ohmic clip is typically used for thinner material, 1/2″ or less in thickness. It is recommended to disconnect the ohmic clip and use the secondary lifter to find the surface for material 5/8″ and thicker. When cutting thicker material there is usually a lot of slag which can damage the ohmic clip wire. And, the ohmic clip isn’t really necessary since the material will not move when cutting.
When looking at the Z-axis motion of a CNC plasma table it is also important to consider if the system has Automatic Torch Height Control (ATHC). All EZ Cut CNC systems come equipped with ATHC, which is a feature that senses the arc voltage while cutting. When cutting material that may not be level, the ATHC signals the torch to move up or down to maintain a consistent voltage and distance from the material.
At EZ Cut CNC, we have hand-selected each component for our plasma cutting systems. The Z-axis motion as well as the movement on all the axis is directly affected by these components. That is why we chose the best components available to ensure top quality performance. For more information about our Value Components visit http://www.ezcutcncplasma.com/