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  1. Cutting Tools

Two New Cutters Optimize Aerospace Machining

Aug. 11, 2011
Tooling manufacturers long-edge milling and fine-finishing cutters resolve high-speed, hard-material problems
The AeroLong shell end mill (top) and AeroFinish fine-finishing cutter (bottom) are standard tools that have been adapted for optimal machining of high-strength and heat resistant materials.

Safety, the French precision tool manufacturer, will introduce two new milling cutters at EMO Hannover 2011 next month, both of which have been designed with particular attention on aerospace machining. For critical manufacturing projects like fuselage structures and landing-gear components, Safety is offering a long-edge milling cutter, called AeroLong, and a fine-finishing cutter, called AeroFinish.

AeroLong was designed to be particularly effective at peripheral milling of high shoulders, digging and contouring, as well roughing and pre-finishing. According to Safety, thanks to its high number of cutting teeth, the shell end cutter has been highly successful at contour milling of an engine support (titanium alloy Ti6Al4V), even by comparison to full-carbide cutters. In that application, the thick, rugged four-edged inserts did not have to be replaced during the entire process.

In practice, processing times have been reduced by more than 20%, the tooling producer indicated. For conventional milling applications the AeroLong is equipped with precision-sintered indexable inserts; for pre-finishing a peripherally ground insert is offered. The new 5050 carbide grade with PVD-TiAlN coating converts the long edge mill into a universal tool for aerospace machining, for materials ranging from iron to stainless steels and titanium materials.

The optimal combination of cutting grade and tool makes it possible for manufacturers to plan service time, even for demanding conditions like pocket milling with long overhangs; insufficient workpiece clamping; or long, interrupted cuts. Long tool life is ensured even with difficult-to-machine materials thanks to the stability of the tool body. In addition, the inserts are provided with a shoulder, so in case of a fracture the milling body will remain undamaged.

The AeroLong is available in diameters from 40 to 80 mm.

The AeroFinish has a “close pitch” that, according to the developer, makes it ideal for fine-finishing tasks. The tool bodies are available in two versions: an arbor cutter and a shank cutter with Morse taper. Safety's specially developed SideLok clamping system allows for up to twice as many inserts in the tool, thus more cutting edges can process the workpiece concurrently. The table feed rate can be reliably increased up to 50%, increasing the cutting rate dramatically.

Thanks to an optimized insert, the completely ground SCKR inserts (four cutting edges) achieve geometry with large radius and finishing chamfer, and a surface quality of Ra ICP clamping system

Pocket milling is common in aerospace machining, which prompted Safety to develop its AeroLong and AeroFinish cutters.
The SideLok clamping system makes it possible to mount up to twice as many inserts in the tool, thus having more cutting edges processing the workpiece concurrently. The table feed rate can be increased up to 50% with reliability, increasing the cutting rate dramatically. Processing of titanium and Inconel materials limits cutting speed, so the key to a higher feed rate is closer pitch, according to Safety. To place even more teeth on the tool body, the supplier developed a patented insert clamping system for inserts. With SideLok, the number of teeth can be increased and more inserts can share the load. The rigid insert clamping system is more stable and offers up to twice as much space for inserts in the tool body, it said. The increased number of teeth makes it possible to raise the table feed (vf) significantly, thus increasing the feed per tooth (fz) and the number of teeth (z), which increases productivity by up to 50%.

Also, set-up times are markedly minimized by the clamping system, Safety said: Without loosening the screws completely, the ICPs are easy to index so worn inserts can be replaced quickly.

A cooling lubricant is used for targeted removal of the process heat. Using SideLok, the coolant can be passed directly through the clamp screw to the cutting edge. An internal coolant supply connects each insert to the cooling system, so that optimal cooling of the cutting edges reduces early cracking and abrasive wear on the inserts. Optimal heat dissipation also reduces crater wear.