As parts requiring five-axis machining have risen in demand, especially in the aerospace and medical industries, manufacturers are faced with the challenge of justifying a dedicated five-axis machine for a limited number of parts or parts series.
Shops can now achieve five-axis capabilities with high precision without incurring the cost-prohibitive financial commitment of a dedicated machine.
Accurus Aerospace has been machining complex aerospace parts at its Tulsa, Oklahoma facility since 1974. The company has worked on major programs for customers such as Boeing, Spirit AeroSystems, and the Triumph Group. When looking for a 5-axis solution, they selected Okuma HMCs with Tsudakoma rotary tables from Koma Precision Inc.
The company specializes in hard metal, 5-axis machining in titanium and steel. The sheer power of high-torque spindles on their Okuma MA-600HII and MB-8000H machines and the addition of a 5th axis via a double-sided rotary table set the stage for success. Accurus is able to cut 4-axis parts on one side and 5-axis parts on the other side.
In explaining the choice, Senior Engineering Specialist Don Moody said adding a rotary table costs much less than a dedicated 5-axis machine. “It also allows us to get to the center of the part easier.”
The spindle utilization of an HMC can often be more than twice as much as that of a vertical machining center. Unlike a full 5-axis, trunnion-style machine, an HMC plus a rotary table allows for setting up parts on the pallet outside the machining area while parts loaded on a second pallet are being machined. This drastically reduces downtime caused by stopping the machine to set up the fixture.
“Having two pallets on the HMC increases our efficiency and time management,” Moody said. “The operator is more flexible as to when he can load/unload the part. Plus, the machine is not waiting on the load/unload.”
“We have applied this same concept on the different size Okuma MA machines in our facility. The Okuma design is so powerful that we are able to cut and surface the part in one pass with a custom, slotted cutter,” stated Larry Johnson, VP of Operations.
To maintain the automatic pallet changing capabilities of the HMC, Koma installed a cable management system on-site. It allows the rotary table to remain connected throughout the pallet change while keeping all the cabling out of the way of fixtures and metal chips. Furthermore, if there are hydraulics or air-sensing lines involved, this system can monitor and actuate automatic fixturing.
When machining high-quality aerospace parts, high rigidity and positioning repeatability are key. In this case, Tsudakoma’s hydraulic dual-disc clamping system was the ideal choice. It maintains the fixture and part positioning while the machining center is taking its cuts. The machine is only as accurate as the rotary table, so positioning repeatability throughout the entire production run is critical to making good parts.
Johnson confirmed the benefits of a rotary table setup. “We have many Okuma machines with Tsudakoma rotary tables. We run them day in and day out, 24/7, and they all provide, highly-accurate, steady machining.”
This modular approach enables manufacturers to generate high-precision five-axis parts without investing in a dedicated five-axis machining center. Despite the seeming complexity of the system, the entire five-axis modification is said to be easily removable from the machine table and stored for later use.
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