Many machine shops may avoid taking on intricate aerospace machining work because they have already made investments in four-axis machining centers, and aerospace work mostly requires five-axis capability. "Aircraft structural and turbo machinery components very often have surfaces that are not aligned with any of the four axes," says project manager Nick Westermeyer of Makino. In addition, frequently the volume of available aerospace work does not warrant an investment in a dedicated five-axis machine.

Westermeyer adds, "Manufacturers would benefit from being able to incrementally add fifth-axis capability to a four-axis machine, and then easily remove it when they only require four-axis machining. "The fifth-axis would give them the ability to machine some geometries that are not possible with four-axis machining. In addition, they would frequently be able to machine a part in fewer setups with five-axis capability instead of four. The ability to incrementally remove the separate fifth axis ensures the equipment will still be able to machine all of the current four-axis parts.

Makino has designed a system to support the addition of the separate fifth-axis capability, utilizing a rotary table on a pallet that can be loaded into the machine via a pallet changer. The key to the system is an auto coupler designed to automatically connect a pallet-mounted rotary table to the machine and control in conjunction with the automatic pallet change itself. The system permits an operator to attach the workpiece to the add-on rotary table outside of the work cube of the machine. When the setup is completed, the add-on rotary table and associated workpiece are held in queue until the machine has completed the parts currently being machined.

The machine then automatically changes pallets, bringing in the pallet with the add-on fifth axis and coupling it with the machine and control using the auto coupler, and starting the machine in five-axis mode without operator intervention. The add-on rotary table no longer needs to be hard wired or bolted to the machine. The auto coupler system even works in conjunction with the Makino Machining Complex (MMC), enabling the customer to profit from operating the machines unattended, automatically sequencing between four-axis and five-axis mode depending upon the pallet presented by the MMC.

Buying a fifth-axis pallet mounted rotary table versus a five-axis machine depends a great deal on the machine you have, how you use it, and your volume of five-axis work. For the machine shop producing aerospace structural components and/or certain turbo–machining parts, a pallet mounted fifth-axis table and associated auto coupler is a good investment. It reduces the company's overall equipment cost, provides flexibility to run the machine in four- or five-axis mode, and provides for unattended machining capability either way when connected to an MMC.

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