Five-Axis Performance from a Four-Axis Machine

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, saving hours and enhancing cycle time. You do not have to set the fixture more than twice under normal circumstances. 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.”

Auto Coupler Makes the Difference

Makino has designed a system to support the addition of a 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 the 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.

Five-Axis Challenges

One downside of adding a fifth-axis rotary table, according to Westermeyer, is “that the fifth axis will simply reduce the available work envelope on a machine. The maximum part height allowable by the machine will be reduced because of the application of the auto coupler. However, the five-axis table is a flexible and an adaptable piece of equipment essential for extending the life of existing equipment in many machine shops. When comparing one of Makino’s A-Series horizontal machines with a five-axis table, a five-axis trunion-style machine is definitely more expensive.”

“One of the nice things about the fifth-axis rotary table is that it is applicable to older machines,” adds Westermeyer. “Prior to the fifth-axis table being developed, a machine shop would have to either re-fixture a machine or move a project on to a totally different type of machine. If you have an A-Series horizontal machine sitting in your shop, and you have a chance to do some five-axis parts that you cannot produce any other way, you can add the table and become cost effective in that type of work.”

Considerations of Choice

Buying a fifth-axis 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. Additionally, there are several important factors relative to properly selecting a table option, according to Westermeyer.

“Once you install a fifth-axis table, you also have to power it, which means that you have to have cables that hang in and out. These tables are servo-driven, so you will need air and power and control cables for fifth-axis rotary table integration and operation. This installation can be done permanently, but this prohibits easily removing it from the machine or pallet. You have to leave it in place on one machine, which limits the flexibility and adaptability of the table.”

Unfortunately, the “plug and play” type of five-axis table is not an applicable choice for a Makino Machining Complex (MMC) machine or a module system where you have multiple pallets with multiple machines that are going through a work setting station. You would have to manually initialize them once installed in order for them to properly operate on an MMC series.

The biggest advantage to choosing the technology is work scheduling. If a fifth axis could be automatically integrated in and out of a machine, this would allow you to utilize the finer points of the MMC. Multiple fixtures and workpieces can be staged in a repeatable system where operations on five-axis parts can be efficiently machined. Otherwise an operation would require having to call an operator, connect the table, initialize it and then machine the part...and then calling back the operator to disconnect it…every time you wish to operate your machine.

A Good Investment

For the machine shop producing aerospace structural components and/or certain turbo-machining parts, a fifth-axis table 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. With a fifth-axis table properly engaged with the auto coupler, a company can simply increase its productivity, achieve better return-on-investment (ROI) and life cycle costing to get profitable unattended machining hours.

Having fifth-axis capability can eliminate two standard machine processes. This means you also save spindle time because of the elimination of change times and human delays in prioritization. Furthermore, you simply get better spindle utilization, especially with the auto coupler.

The type of material that you work with is also not a factor with a fifth-axis table. “There are no limitations regarding the types of metal you can use,” says Westermeyer. “Mostly, we have seen it used on aluminum, but it is not metal-sensitive. It could be used on any material...magnesium, inconnel, titanium or aluminum. It is more shape-sensitive than anything else.”

Makino produces both horizontal and vertical trunnion style five-axis machines that can give a customer all the benefits of five-axis machining capabilities. Makino also produces a large variety of four-axis horizontal machines that accommodate the addition of a fifth-axis rotary table option. However, when weighing in the cost of all available five-axis options, including five-axis machines, utilization and flexibility remain the key elements to making the right choice.