Plasma cutting is essential in fabrication. However, cut quality problems are common. Even with the right equipment and consumables, you may encounter issues such as bottom dross, surface finish, and angularity. Fear not, as we’ve got you covered. In this article, we’ll provide solutions to these common problems to help you achieve precise and smooth cuts. You’ll want to carefully look for this when selecting the best CNC plasma table for small business. So, let’s dive in and learn how to deal with the most common cut quality issues in plasma cutting.
1. Dross
Dross is caused by cutting at incorrect speeds, either too slow or too fast. When cutting too slowly, the plasma arc widens the kerf, and the high-velocity portion of the plasma jet stops blowing the molten metal away. The result? Metal starts accumulating at the bottom of the plate. Cutting too fast results in high-speed bottom dross, which is harder to remove.
To find the dross-free window, make speed adjustments from the set point in your cut chart. Increase and decrease the speed in 10 percent increments from the set point to find the optimal speed. If dross appears along the top edge of the cut, adjust the standoff and amperage from the plate (since cutting at a too-high amperage or too-low standoff can also result in low-speed dross.
2. Warped Material
Warping of material and parts is another factor that may affect the quality of your cuts with your plasma table. First, you’ll want to create cut paths that enable sections to cool down before moving on to adjacent parts. This is especially helpful when cutting very thin material. Program your CAM software in a way that creates these paths for your specific project.
Additionally, it’s best to go with the lowest possible amperage but choose the fastest possible cut speed for the corresponding consumables. This approach helps to control the heat input and prevent warping.
If you plan on using a water table, keep the water in contact with the material to help prevent warping. But keep in mind that the water may impact the edge smoothness and hardness of certain materials.
3. Interrupted Cuts
To prevent interrupted cuts during a nesting program, make sure that the consumables used on the torch are in good condition. Worn parts on the torch can cause half-cuts in the middle of the program.
Additionally, ensure that the size of your part or nesting program matches the size of your plate to prevent the torch from running off the plate while cutting. If the cut is interrupted, most CNC plasma cutters will allow you to resume the cut when the cycle is paused or stopped.
4. Poor Hole Quality
Another issue often encountered in plasma cutting is low-quality holes. If you don’t have access to True Hole technology, you can still achieve better hole quality by following some general rules.
First, slow down the torch speed for holes to at least half the speed of perimeter cuts. This allows the bottom half of the plasma arc to catch up with the top half, minimizing lag and taper of the hole.
Second, lock the torch in place for holes under one inch. This is crucial because torch height control systems become less stable with lower cut speeds. Freezing the height control axis at the recommended height for all holes under one inch ensures greater uniformity in the cylindricity of your holes and minimizes the chance of collisions between the torch and the material.
5. Dimensional Inaccuracy
To achieve better dimensional accuracy in your cutting, start by checking the alignment of your torch to ensure it’s at a perfect 90-degree angle to the plate. If the torch is aligned properly, examine the slats on your cutting table. If there’s excessive slag, the plate may not sit level, causing angled cuts. After ruling out these two issues, you can move on to the cut height.
Factors like gas velocity and energy density influence the plasma arc geometry, which can be visualized as a tapered candle flame. If the torch is too close or too far from the plate, the arc won’t hit the plate at the widest point, resulting in angled cuts. Use the cut height indicated in the cut charts and made small incremental adjustments from there to achieve better results.
Keep in mind that there may be other factors specific to your machine that can impact your results, but starting with these basic principles will put you on the path to success. Plus, always check your consumables, use the appropriate cut height, slow down for holes, and pay attention to your lead-in and lead-out. By taking these steps, you can achieve optimal results and take your plasma cutting to the next level.
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