In the current economic climate that we are in it becomes more and more necessary to save where we can. Consumables is a very important part of the cutting process and increasing the life of them can save a lot of money in the long run.
What is consumables?
Consumables is a term used in the industry for all the parts (nozzles, seals, shields electrode etc) of the cutting head of a plasma, oxyfuel or laser machine. The term consumables is used because these parts have limited life span and therefore must be replaced regularly. The consumables have a limited life span due to the heat generated during the cutting process. A key factor in limiting the life span of consumables is the pierce through the material which causes flashbacks back into the cutting head. If one can reduce the number of pierces, that would significantly increase the life of consumables.
How do you decrease the number of pierces?
If you have the Advanced NC Profiling module in your SigmaNEST then there are a couple of options available to decrease the number of pierces. The Advanced NC Profiling module is standard if you have a Maximiser license of SigmaNEST. iPierce, Chain cutting and Bridge cutting are the options that are available inside SigmaNEST to decrease the number of pierces.
iPierce
iPierce is a function of SigmaNEST that cuts a small loop when cutting out a part. The cutting path is altered, when cutting around the first part, to cut a small loop when the distance between the two parts is close enough to the user specified distance, before continuing to finish the cut of the first part. The loop insures that the adjacent part does not need a pierce to start cutting from because there is already a hole created for the cut to start from. SigmaNEST then ignores the specified lead in for the second part and begins the cut for the second part with a “edge start” inside the hole created by the first cut.
Bridge Cutting
Bridge cutting is a function of SigmaNEST where, instead of cutting and finishing the one part and then cutting and finishing the next part, the cutting path is changed to cut from one part to the next part. The cut starts with a pierce on the first part and then goes along the contour of the first part until it gets close enough to the second part. The cutting path is then interrupted, and it cuts towards the second part and then follows the contour of the second part. As the cutting path surrounds the contour of the second part it returns to the bridge. The cutting path is then interrupted once more as the bridge cuts back to the first part and then continues with cutting and finishing the contour of the first part.
The above description is described only for two parts but, one can cut the entire nest with only one pierce. The bridge gap size can also be specified by the user. If the bridge gap is larger than the kerf diameter then all the parts will be attached to each other. If the bridge gap is smaller than the kerf diameter then the parts will be loose from each other and also from the skeleton of the sheet.
Chain Cutting
Chain cutting is a function of SigmaNEST where SigmaNEST changes the cutting path in such a way that, instead of switching the flame off when finishing the cut on one part, it continues cutting to the lead in of the adjacent part. In the above picture the machine pierces the bottom left part and then cuts around the contour of the first part. The cut then continues to the next part (right bottom part) without switching off the flame and when the cut around the second part is complete it continues to the third part (right top part) and then to the fourth part. The result is that four parts is cut with only one pierce.
Pierce height and cut height
Other parameters to look out for to improve the life span of consumables is the cutting height and pierce height. If the pierce height and cutting height is too low, then “flashbacks” from the material to the cutting head will occur resulting in too much heat inside the cutting head that will significantly reduce the lifespan of consumables. These correct cutting height and pierce height parameters can then be added to the SigmaNEST tech table to automate the output of these parameters.
Conclusion
In the current economic climate that we are in, it will be very useful to increase the lifespan of consumables. SigmaNEST has the right tools to help to improve the cutting path and cutting process to aid with improving the lifespan of consumables.]]>
