3+2 can be greater than 5!

February 25, 2014 7:50 am

3+2-axis milling machine is a good alternative to reduce procurement costs, ease of use, spatial requirements, energy consumption and much more
pL LEHMANN, a rotary table specialist company from Switzerland since 1970s, suggests that 3-axis vertical centres fitted with rotary axes and 5-sided processing are more economical, compact and flexible than the 5-axis machining centres.
Whether it is automobile industry or medical technology, every one consistently looks for the most productive machining concept in order to increase production in minimum time period.
In recent years, there has been a strong inclination towards use of 5-axis machining centres. “In many cases, industries use 5-axis machining centres in same manner as we use a sledgehammer to crack a nut! However, 90 per cent of works carried out by 5-axis machining centres are purely 5-sided processes, which also can be done through 3-axis vertical centres with a fitted 4th axis and, if necessary, 5th axis to attain more productive solutions. The great advantage is that 4th and 5th fitted axes can be removed as per the necessity. Hence, 3+2 is a good alternative in terms of reducing procurement costs, ease of use, spatial requirements, energy consumption and much more,” observes pL LEHMANN.
However, there are certain jobs such as milling turbine blades, impellers, forming tool or other free-form components which can only be done with a 5-axis simultaneous machining centres. Such tasks are more difficult to achieve on using 3+2-axis milling machines, due to the big component size. But for small and medium sized components, a vertical 3-axis milling centres with a 4th or 5th fitted axis offers several advantages. For example: usually 5-axis machines have 4th axis and 5th axis on the table. Thus, the length of protruding edges caused with the machining table is high which generates vibration and finally reduces the precision and accuracy of the machine and even shortens tool life. Therefore, elevated devices for the work-piece or long tools are required to add in 5-axis machines. But, if the work piece is stretched in a mounted rotary table, the protruding edges are considerably lower and short and also low-vibration tools can be used.
This is not the only advantage of 3-axis vertical milling machines with additional rotation axes; these machines also simplify multi-part or multi-side processing. Tombstones or clamping yokes can be integrated into the additional axes fitted in 3-axis vertical machine, whereas the pivoting, rotating table construction on 5-axis machines leads to a higher risk. According to pL LEHMANN, a particular plus point of the 3+2 solution is that the movement of each axis is done one after another. Hence, power consumption is also reduced in this way, whereas 5-axis machine starts working with all the axes at once which consume more electricity. Even, the floor space occupied by 3+2 is 65 per cent less in comparison to typical 5-axis machining centres. This is particularly important if the production area is limited or expensive.
The most important point of consideration is whether CNC rotary tables are available as per customer’s requirement in terms of cost, performance and quality. Hence, to meet the necessities of customers, pL LEHMANN has come up with the current 500 Series with completely new designed gear rotary table range of high and compact modular constructions.
“It is not only up to 30 per cent cheaper, but also more powerful and flexible than the previous model and comparable products in the market,” claims pL LEHMANN. 170 different varieties and combinations are available from the simple single spindle 4th axis, to a 4-spindle swivelling table construction with a 4th and 5th axis. The modular construction allows for a retrofit modification at any time and the rotary table can be expanded to adapt to new machining tasks without investing in another new rotary table. However, according to pL LEHMANN, “The most interesting thing is that the modules of the 500 series can be assembled into various combinations by representatives, machine retailers or customer themselves which again saves cost and time! Hence, 500 series CNC rotary tables can be emphasized as user-friendly in terms of their easy operations.”