Page 168 - Demo

A clean cut depends on several factors.%u25cf AMPERAGEStandard rule of thumb is the thicker the material the more amperage required. On thick material, set the machine to full output and vary your travel speed. On thinner material, you need to turn down the amperage and change to a lower-amperage tip to maintain a narrow kerf. The kerf is the width of the cut material that is removed during cutting.%u25cf SPEEDAmperage and speed are critical to producing a good quality cut. The faster you move (especially on aluminium), the cleaner your cut will be. To determine if you're going too fast or too slow, visually follow the arc that is coming from the bottom of the cut. The arc should exit the material at a slight angle away from the direction of travel. If it's going straight down, that means you're going too slow, and you'll have an unnecessary buildup of dross or slag. If you go too fast, it will start spraying back onto the surface of the material without cutting all the way through. Because the arc trails at an angle, at the end of a cut, slow your cutting speed and angle the torch in to cut through the last bit of metal.%u25cf DIRECTIONIt is easier to pull the torch towards you than push it. The plasma stream swirls as it exits the tip, biting one side and finishing off on the other leaving a bevelled edge and a straight edge. The bevel cut effect is more noticeable on thicker material and needs to taken into consideration before starting your cut as you want the straight side of the cut to be on the finished piece you keep.%u25cf TORCH TIP HEIGHT & POSITIONThe distance and position of the plasma torch cutting tip has an affect on the quality of the cut and the extent of the bevel of the cut.The easiest way to reduce bevel is by cutting at the proper speed and height for the material and amperage that is being cut.%u25cf TIP SIZE AND CONDITIONThe tip orifices focus the plasma stream to the work piece. It is important to use the correct size tip for the amperage being used, for ex-ample a tip with a 1,2mm orifice is good for 0-40 amps whereas a 1,6mm orifice is better for 40-80 amps. The low-amp tip has a smaller orifice which maintains a narrow plasma stream at lower settings for use on thin-gauge material. Using a 25 amp tip at an 60 amp setting will blow out and distort the tip orifice and require replacement. Conversely, using an 80-amp tip on the lower settings will not allow you to focus the plasma stream as well and creates a wide kerf. The condition of the tip orifice is critical to the quality of the cut result, a worn or damaged tip orifice will produce a distorted plasma stream resulting in a poor cut quality.%u25cf ELECTRODE CONDITIONA fixed gap is established between the electrode and the inside of the cutting tip. Electrons arc across the gap, ionizing and super heating the air creating the plasma stream. The electrode contains an insert in the end made of a highly conductive material called hafnium. This insert erodes with use and develops a pit in the end of the electrode, when the pit becomes too much poor quality cuts will result and necessitate replacement of the electrode.%u25cf TECHNIQUE TIPS%u2022 It is easier to pull the torch through the cut than to push it.%u2022 To cut thin material reduce the amperage until you get the best quality cut.%u2022 Use the correct size tip orifice for the amperage being used.%u2022 For Straight cuts use a straight edge or cutting buggy as a guide. For circles, use a template or circle cutting attachment.%u2022 Check that the front end consumable parts of the plasma cutting torch are in good condition.CUT QUALITYCorrect torch height andsquare to the material.Minimum bevel & equal bevel.Longest consumable life.Torch angled to the material.Unequal bevel, one side may be excessively beveled.Torch height too high.Excessive bevel, plasmastream may not cut all the way through the materialTorch height too low.Reverse bevel. Tip may contact the work and short out or damage the tip.