The Flying Five: 5-Axis Machining

Humans make mistakes. Machines don’t,” said Kevin O’Neil, regional sales manager for the Southwest U.S. territory at Hermle USA Inc. in Franklin, Wisconsin. O’Neil covers California, Arizona, Colorado, Utah and New Mexico.

By having a 5-axis machine to access five sides of a part in one setup, manufacturers of mission-critical aerospace components can increase part accuracy and reduce scrap by not having to re-fixture workpieces as many times as would be needed in a 3-axis machine, O’Neil explained. Fewer part setups equal less human interference. “Generally speaking, the vast majority of 5-axis work can be done on two ops as opposed to a lot of customers still doing it the old-school, 3-axis way, and having to do three or four flips.”

One of his projects, he added, involved machining a part that required 14 operations and reducing it to two. “Let’s allow the machine to do what it’s supposed to do and keep the hands out of it as much as possible.”

In addition to jet engine components, aerostructures are also produced on 5-axis machines. Image courtesy of Makino

In his territory, O’Neil estimated that 60% to 65% of the machine tool builder’s nine models of 5-axis machines are purchased by aerospace customers and at least half for the company as a whole. Vertical machining center models, or 5-axis trunnions, are more prevalent than horizontals. All models of Hermle machines are built as simultaneous 5-axis machines, but many applications only require 3+2 machining, which still allows access to five sides of a part.

Instead of 3+2 machining, Makino Inc. prefers 2+3, said Karl Lippert, manager of the 5-axis advanced technology group for the Mason, Ohio, machine builder. The first number refers to the two rotary axes for positioning the workpiece to establish the best line of sight access for a tool normal to a feature. The second number is for the three linear axes used to machine the part. “Most of the aerospace work is 2+3 in the Makino vernacular.”

Across the Horizon

A newer addition to Makino’s 5-axis line, Lippert noted, is the aZ family of horizonal machining centers: a500Z, a800Z and a900Z. The machines are based on the company’s 4-axis platform. “We turned it into a 5-axis machine by altering the pallet carrier structure providing a tilt axis on the pallet.”

The arrangement keeps the pallet work requirements for the fixture and part all at the center of gravity within the bearing arrangement on the table, “which is somewhat unique to other kinematic designs,” he said. “It allows us to be competitive from a speed standpoint but also to maintain the same or better accuracy when positioning and full 5-axis contouring.”

On the vertical side, a newer offering is the DA300P trunnion machine, Lippert said, noting that the P is for package. “We made a package machine, which allows us to fully integrate a 40-pallet magazine with a unique interface in the pallet table of the machine.”

The DA300P has a hybrid design pallet interface, he added, which is similar in nature to a Sandvik Coromant Capto trigon-style on the outside and the ability to grab like a HSK toolholder on the inside.

Lippert said Makino divides aerospace production into two types of parts: aerostructures and for the jet engine portion. The former includes wings, fuselage, cockpit area, tail section and landing gear, while the latter includes blisks, impellers, single blades and vane segments.

HMCs are more suited for aerostructure requirements, and the company’s 5-axis horizontal equipment starts at 1.5 m (59.1″) and goes up to 20 m (787.4″), he said. “The hard metals side really only goes up to 5 m, but the aluminum side goes up to 20 m in a horizontal, 5-axis configuration.”

When machining aerostructures, such as beams, bulkheads, spars and ribs, or “intercostal” parts, at most 10% of the features require full simultaneous 5-axis motion, according to Lippert. The inverse is true for engine components. “These parts require over 90% full 5-axis motion just to be able to produce the part feature content efficiently and effectively.”