Cant tell the difference between a pseudo-five-axis and a genuine five-axis? Whats the difference compared to a three-axis?

As the automotive industry booms, five-axis simultaneous machining center CNC machines are becoming increasingly prevalent. However, in the current market, there are few genuine five-axis machines (with RTCP function) and many pseudo-five-axis machines (with only indexing function). What is a genuine five-axis machine, what is a pseudo-five-axis machine, and how do they differ from three-axis machines? The following is an explanation.

A genuine five-axis machine has RTCP (Rotary Tool Center Point) function. It can automatically convert based on the swing length of the spindle and the mechanical coordinates of the rotary table. When programming, only the coordinates of the workpiece need to be considered, without regard for the swing length of the spindle or the position of the rotary table. Whether a machine is a genuine five-axis machine is not determined by whether the five axes move in unison; a pseudo-five-axis machine can also have five-axis simultaneous movement. The key to a genuine five-axis machine with RTCP is that it uses a specific algorithm for indexing operations. With RTCP, only one coordinate system needs to be set, and only one tool setting is required. In contrast, a pseudo-five-axis machine is much more cumbersome.

(Image 22.png) A CNC system with RTCP function allows programming directly using the tool tip, without considering the distance from the center of the rotary axis. When RTCP mode is applied, five-axis machining can be programmed directly for the tool tip rather than the center of the rotating spindle head, making programming much simpler and more efficient.

(Image 23.png) As we can see from the diagram, for a pseudo-five-axis machine with dual rotary tables, multiple coordinates need to be set to achieve indexing operations. However, if it is a swivel-head five-axis machine, indexing operations cannot be completed because when processing downwards, it is not a pure Z movement but a combination of Z and X or Y movements. In this case, programming for a pseudo-five-axis machine becomes very cumbersome, debugging is even more difficult, and the G51 offset function of a three-axis machine cannot be used.

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