Aluminium alloys milled

Multi-functional cutters offer metal removal rates in aluminium alloys of up to 10,000 litre/min owing to rigid tool body, ultra secure insert clamping and the geometry of carbide inserts

Mitsubishi Carbide said at EMO 2007 that metal removal rate is one of the key factors in determining efficiency when machining typical aerospace components such as wing ribs. Achieving the required efficiency requires a combination of several elements. as follows. * A powerful machine tool. * Rigid component clamping.

* A good coolant supply.

* A cutting tool capable of removing large volumes of material without overloading the spindle.

Mitsubishi saids that its multi-functional AXD7000 series has several features to combat the problems usually encountered when machining at such high rates.

Metal removal rates of up to 10,000 litre/min are possible when using the correct methods, said the company.

Combining features such as a rigid tool body, ultra secure insert clamping and carbide inserts with a newly designed geometry, ensures that low cutting resistance and large depths cut of are viable.

A range of cutters from 32 - 125mm diameter, including shank and arbour types, and a highly rigid monoblock style with an HSK63-A interface is readily available.

* Insert clamping - extra secure clamping of inserts on the tool body is critical and is now made possible by using two clamp screws for each insert together with Mitsubishi's AFI system to further enhance clamping and positional security.

Mitsubishi told manufacturingtalk.com that tests have shown that after cutting, tools using the double clamp and AFI mechanism have minimal insert displacement of only 6 micron, when compared to conventionally clamped inserts that moved up to 17 micron.

Mitsubishi can provide results in more detail.

However, without details such as the correct insert grade and geometry, even the most rigid of set ups wouldn't be capable of machining effectively.

The inserts for AXD are designed with th following features.

* A helical flank and a large rake angle that provide the critical element of low cutting resistance.

* A convex cutting edge ensures smooth chip flow, an essential feature during high speed cutting.

* Working in tandem with the advanced geometry, one of the two carbide grades of the insert, TF15, a non-coated micro-grain cemented carbide with a polished rake face to prevent chip welding also offers both high wear and fracture resistance.

* The alternative grade, LC15TF, with a special DLC coating offers even higher chip welding resistance and can be used in both wet and dry applications.

* Deep pocketing applications when machined by the AXD7000 type also have an advantage in the wall accuracy that is produced after several passes are made.

Conventional inserts leave an uneven surface that can present problems with excess material removal for the subsequent finishing tool said Mitsubishi.

However, the wall finish produced with the XDGX inserts leaves only minimal material deviations from step to step and consequently saves time and tool life of the finishing tool.

* Tool balancing - another essential factor that needs consideration prior to high speed milling is the balance of the tool.

Without balancing, the high revolutions would generate primary and secondary vibrations which would result in poor surface finishes and a significantly reduced tool life.

The tools are balanced to G6.3 at 10,000 rev/min according to ISO1940.