GlossaryKind of term: Manufacturing termSimultaneous 5-axis milling
What is simultaneous 5-axis milling?
In simultaneous 5-axis milling the rotary axes move together with the linear axes during the cut, so the tool axis can follow the surface.
In simultaneous 5-axis milling the rotary axes change position while the cutter is cutting, at the same time as X, Y and Z. That lets the tool axis hold a chosen angle to a surface that keeps changing direction. It is used for free-form shapes such as impellers, blades and mould cavities, for flank milling, where the side of the cutter machines a wall whose angle changes along the contour, and for tilting a shorter tool along the walls of a deep cavity. Work in which the rotary axes only position is called 3+2.
What does simultaneous 5-axis milling ask of control and machine?
The control has to keep the tool tip on the path while the rotary axes turn. This is usually done with a tool centre point control function, often abbreviated RTCP or TCP; without it, the postprocessor calculates the axis positions for one fixed arrangement of machine, tool and part. The achievable feed depends on the dynamics of the rotary axes and the control, and can drop well below the programmed value in tight curves. Collisions with holder, spindle head, table and workholding are checked in a simulation of the whole machine. Accuracy also depends on the kinematic calibration of the rotary axes.
How does simultaneous 5-axis milling work in practice?
Most of the extra time comes before the machine runs: programming with collision checking, simulation, a postprocessor proven on that machine, and a first piece proved out at reduced feed. A 5-axis machine usually carries a higher hourly rate than a 3-axis machine. A machining time from the CAM simulation is a prediction, not a measurement; the real time depends on how the machine executes the moves. In many shops a 5-axis machine runs 3+2 most of the time, and simultaneous only where the surface calls for it.
What is simultaneous 5-axis milling often confused with?
Simultaneous 5-axis is not 3+2: in 3+2 the rotary axes stand still during the cut. And a 5-axis machine in the machine park does not by itself mean simultaneous work; that depends on control, postprocessor, CAM and experience.
How do you see simultaneous 5-axis milling in Blake?
Programming is its own line in Blake, next to setup and machining, for milling up to 5-axis. Hourly rate and axis count come from the machine in your machine park. If a free-form part needs more programming time than the estimate, you correct the line with a reason; the previous value is kept. More on milling.
Frequently asked questions
When do you need 3+2 and when simultaneous 5-axis?
Simultaneous when the surface demands it: free-form shapes, flank milling of walls whose angle changes along the contour, or a deep cavity only reachable with a short tilted tool. Prismatic parts with faces on several sides are usually 3+2 work, with a simpler program.
Why does simultaneous 5-axis take so much programming time?
The programmer steers the tool orientation along the whole path and checks it for collisions with holder, spindle head and workholding. That takes a machine simulation, a proven postprocessor and a careful prove-out of the first piece. The time varies with the shape.