Avoid turbulence in aerospace machining

Machinery & Manufacturing chats exclusively with Eugene Nugent, National Sales Manager at MAPAL UK, about how unique cutting tool geometry ensures smooth cutting behaviour when machining aluminium aerospace parts.

Like most applications, the machining of aluminium parts for the aerospace industry comes with its own special set of challenges. Whether it’s high-volume material removal, chip evacuation, tool versatility or noise reduction, machine shops producing aluminium aerospace components typically turn to cutting tool manufacturers for the solution.

MAPAL, a company with a strong track record in the automotive industry, has in recent years gained plenty of traction in the aerospace market. Today, cutting tool solutions for aerospace component manufacturers represent 25-30% of MAPAL’s revenue in the UK, with even more growth anticipated moving forward. The reason for these impressive gains? Innovation.

Material world
Some aerospace parts require up to 70% material removal from the raw billet, which means the number one challenge in machining operations is how to achieve this goal quickly and cost effectively.

“Based on our experience and research, the average material removal rate [MRR] in the field is around 12-14 litres per minute,” reveals Eugene Nugent, National Sales Manager at MAPAL UK. “We used this figure as benchmark to create new solutions that could push the boundaries even further.”

The result of MAPAL’s development efforts are the OptiMill-Alu-Wave solid-carbide cutter (12-25mm diameter) and the NeoMill-Alu-QBig indexable insert cutter (32-63mm diameter), which offer somewhat staggering MRRs of 21 and 18 l/min respectively.

“Our OptiMill-Alu-Wave is a next-generation evolution of the traditional ripper cutter. However, it can run a lot quicker.”

To provide some context, MAPAL field tests involving a 25mm diameter OptiMill-Alu-Wave in the machining of EN-AW50 series aluminium alloy delivered an MRR of 21 l/min. This result indicated 22% higher MRR than competitor tools.

“Aerospace OEMs and tier one/two suppliers machining wing spars/ribs/skins will see major gains,” he says. “However, the cutter is suitable for almost any kind of aluminium machining, be it wing, fuselage, chassis or even hydraulic pump applications.”

Bargaining chips
A hugely important supporting factor for the successful delivery of high MRR is chip evacuation. Here, the three-flute OptiMill-Alu-Wave has a unique offer. MAPAL’s patented knuckle design geometry aids highly effective chipping of the swarf, making it smaller and easier to evacuate. This innovation also facilitates smoother cutting behaviour, with the support of very highly polished flutes that reduce both adhesion tendencies and heat accumulation at high speeds and feeds. Further aiding heat build-up and process-reliable chip removal – as well as built-up edge – is the cutter’s central coolant channel.

“Another tooling challenge for manufacturers of aerospace parts is tool versatility, as this reduces cycle times and inventory. While a conventional ripper cutter will just rough and profile, our OptiMill-Alu-Wave can slot, profile, ramp and more.”

Of course, when removing exceptionally large volumes of material at high depths of cut, noise can also prove troublesome. To address this issue, the OptiMill-Alu-Wave features unequal spacing of its 36° helix, a design that interrupts the natural harmonics of machining to reduce vibrations within the component and, subsequently, workshop noise.

Think big
If the application demands diameters beyond the realm of standard solid-carbide tools, MAPAL can offers its new NeoMill-Alu-QBig indexable insert cutter. This monoblock tool with steel body features a fine balancing system to protect the spindle at high speeds and guard against vibration through the part for smoother and faster machining.

“Despite the larger diameters and subsequent lower surface speed of indexable insert cutters, we can still achieve a staggering 18 l/min MRR with our NeoMill-Alu-QBig,” says Eugene Nugent.

Again, chip evacuation is key, which is why the NeoMill-Alu-QBig features large chip spaces and a highly polished and very steep (positive) top rake. Internal cooling to the cutting edge of each insert also contributes to this critical ambition.

“In addition, users can take advantage of extensive tool versatility. Our new indexable insert cutter can slot, ramp, helical-mill and pocket, for example. Notably, whereas the solid-carbide OptiMill-Alu-Wave is a pure roughing cutter, our NeoMill-Alu-QBig can rough and finish, achieving Ra 0.8 µm in aluminium with the correct machining strategy.”

Due to ever tightening margins, aerospace OEMs and supply chain manufacturers are increasingly receptive to new tooling innovations that deliver competitive gain. Cutters that break new ground in terms of speed, chip evacuation and versatility deliver important cost savings. MAPAL’s OptiMill-Alu-Wave and NeoMill-Alu-QBig are set for a big future in this critical industry.