Taking advantage of 5-axis machining strategies
Simultaneous 5-axis machining uses all five axes at one time. This process is commonly used for manufacturing turbines, impellers, plastic moulds and port surfaces. In 5-sided machining (or 3+2 machining), a 3-axis milling program is executed with the cutting tool locked in a tilted position using the two rotational axes of the 5-axis machine. In this way, the two additional rotary axes are used to position the part at some designated angular orientation. Four Common Myths:
1. You lose rigidity with 5-axis machining
This concern usually involves the swivel-head or articulating-head 5-axis machine, of which there are two types: a head-head configuration with all rotations completed by the head while the table is stationary, and a head-table configuration with a tilting head and a rotating table.
Concern about rigidity is simply due to machine design and the possibility of inadequate clamping to hold the additional two axes in position. In actuality, the B axis will be the least rigid on a swivel-head machine, and this should be a consideration when machining any heavy metal. The trunnion configuration is a more solid design and is preferred for heavy-metal removal.
2. Full 5-axis machining is better than 3+2 machining
For simplicity and increased rigidity, you should use 3+2 machining (also known as 5-sided or positioning) and you will achieve faster cycle times compared to full 5-axis machining (also known as simultaneous 5-axis). With full 5-axis machining, the machine’s movement is limited by the speed of the slowest rotary axis. This isn’t the case with 5-sided or 3+2 machining, because the additional two axes are used for positioning only, which means the linear axes are free to cut at the fastest maximum feed rate allowed by the control.
However, even when you’re using 3-axis toolpath technology, you can still take advantage of the obvious reduction in multiple setups and benefit from many other characteristics associated with 5-axis machining. For example, when using the rotary axes solely to position the part for machining, nothing dictates that the tool axis angle must be perpendicular to the surface being machined. Positioning in a non-perpendicular orientation allows you to cut on the corner radius of a ball- or bull-nose end mill, achieving the desired surface finish and chip load control.