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Why use a 4-axis turning solution?
One of our customers recently replaced a 2-axis lathe with a 4-axis lathe for a family of shafts. The cycle time on one of these shafts was reduced from 17 minutes to 10 minutes or a 42% savings. Throughput was increased and it allowed for additional capacity within the cell. Cycle time reduction is the main reason most people choose a 4-axis process over a 2-axis lathe but there are other important reasons as well. By having 2 opposing tools in the cut at the same time, part stability is increased and the chance of chatter is reduced. The benefit is a reduction in set up time trying to work around a chatter issue. Speeds and feeds can be optimized for the cutting tools resulting in greater tool life and reduced cycle times. The lower turret on a 4-axis machine is not limited to just cutting tools. A steady rest can be mounted to this turret as well. While this does reduce the number of usable cutting tool stations, it adds capability to the machine for turning long shafts. The customer in the example above also utilized this benefit. The steady rest allows their long parts to be supported, increasing part stability and reducing the chance of chatter. Parts that were historically difficult to set up and run are now completed predictably. Cycle time, repeatability, and quality all improved as well.
A 4-axis lathe increases the tooling capacity of the machine. This customer was able to load most of the tools needed for the family of parts into the machine. Only a few insert and holder changes were needed to complete the part family setup. This eliminated tool change setup time for the main part runs in the family. As we see with the examples given above, it is not just a reduction in cycle time that can be realized with a 4-axis solution. We also see increases in machine capability, increases in part capacity, and a reduction in set up times. |
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Of course the answer is that you can have 2 tools working on the part at the same time, thereby reducing cycle time. A 4 axis process can see cycle time reductions of up to 40%.
By mounting the steady rest to the lower turret, part-to-part set up time is completely eliminated. Positioning is handled by programming. It can be programmed for multiple positions in any combination that the programmer chooses or the set up requires. It can also be used as a follower rest behind the cutting tool.Now you can get accuracies within .014 microns in all 5 axis on a Millac 800VH machine! The R-Direction is within .024 microns in all 5 Axis also. |
