Taking advantage of 5-axis machining strategies
3. A trunnion-style 5-axis machining centre is preferred for mouldmaking over a swivel head 5-axis machine
The type of mould you are manufacturing will dictate which machine is your best option, and every 5-axis machine has its own benefits (see photos previous page). The photo shows a trunnion configuration (also referred to as a table-table configuration), which has both rotary axes contained in the trunnion table itself and a stationary head. This design is a simple progression from standard 3-axis machining, so mouldmakers are typically the most comfortable with the trunnion-style 5-axis machine. The two rotary axes are often used to locate the workpiece into a desired orientation, making it easy to visualize how the machine will position and behave during machining.
Some advantages of trunnion-style 5-axis machines include:
- Larger overall usable work volume. The table tilts and locks into position, and the X, Y and Z axes are allowed their full travel range. A swivel-head machine requires that the overall work envelope be used to accommodate the length of the tool as the head tilts back and forth, and this is magnified when machining with longer tools.
- Better undercut capabilities. The table can tilt farther (at least in one direction) than the swivel-head type of machine, providing greater access to a part’s underside.
- More effective heavy metal removal. The head doesn’t articulate. The trunnion style 5-axis machine design permits the use of geared or belt-driven spindles that provide more torque at lower rpm. The stationary-head design also eliminates the possibility that the head will be pushed out of position while machining, which can occur on swivel-head machines during heavy cuts.
As mentioned previously, an articulating- or swivel-head 5-axis machine can have either a head-head configuration with all rotations completed by the head and a stationary table, or a head-table configuration with a tilting head and a rotating table (see photo previous page). Some benefits of swivel-head-style 5-axis machines include: