Carbon fibre monocoque chassis machined by Breton “MATRIX” vertical machining centre

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Breton MAXIMA - Multitasking vertical machining centre (part 1)

Specifically designed and developed for demanding markets, Maxima performs to its best in terms of precision and productivity combining 5axis milling with turning. Thanks to a design that offers interesting possibilities to users, first of all pendulum machining while carrying out turning and milling operations.

Maxima is a machine developed from the experience gained by Breton with other models, from which it has taken the best that they could offer. Breton engineers have started from a heavy structure gantry machine, then adding a turning table and a head change system able to manage both the milling and the turning process at best.

It is really a machine with double possibilities because, besides relying on a modern milling machine, thanks to the head change it is possible to carry out also turning operations (even heavy) without stressing the components exclusively designed for milling.

Solid and stable

Starting from the structure, electrowelded steel,  coupling the steel with an optimized geometry it is possible to obtain the correct sizing of each component of Maxima.

But not only: the inside of each module is filled by an engineered granite patented by Breton, MetalQuartz, which offers interesting properties. First of all, it contributes in the vibration dampening, consequently increasing the stability and the quality of machined surfaces. Besides, this composite silicon-quartz material owns the same thermal expansion coefficient as the structure steel.

Milling and turning

Maxima is sold in different versions and configurations. The most evident element is the Y axis travel that, as above mentioned, can vary depending on the purchaser’s requirements simply adding other modules during its manufacturing.

Another value that characterizes each machine consists in the turning table diameter: we start from the smallest, with 1,200 mm diameter, up to 3,000 mm of Maxima 2500, passing through the 1,600 mm version.

The smallest tables are operated by direct drive, while with bigger diameters traditional motors in dual drive configuration are used. In this way it is possible to reach different speeds, torque and powers, suitable for specific uses.

The version with 3,000 mm diameter guarantees the maximum power of 100 kW, 116 kW in S6 at 40%, and a torque of 20,000 Nm (24,600 Nm in S6). With such characteristics, the 230 rpm that the motor/transmission group can offer is more than eough to machine with high peripheral speeds and heavy stock removals, like a real vertical lathe.

Besides, when it performs a turning operation the Gantry axis and the Z axis are kept in position by a set of hydraulic brakes, ideal for assuring the best statics of the structure without putting engines under strain.

 

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5 axis machining centers, aerospace machining, breton cnc 5 axis, CNC turning and milling center, high speed vertical machining centre, Maxima

Breton MAXIMA - multitasking vertical machining (part 2)

Heads and tools

The machine uses different tools for multitasking operations.

While the head used in turning is relatively simple, a model with Capto C8 taper, the milling one is certainly more complex.

The coupling with the ram is guaranteed  by a Hirth crown assuring the correct and constant positioning of heads and removing the risk that the efforts – especially in turning – are concentrated on the components dedicated to milling. Machines of this type are expected to machine for several years without needing extraordinary overhauls determined, for instance, by excessive stresses on parts not designed to bear them.

 

Maxima 2500 HD is characterized by the innovative head Tornado HD. This name hides a head with torque motor on the C axis that eliminates backlashes, permitting to achieve precisions in the volume of few hundreds on the five axes and enabling to reach 100 rpm. The flexibility is guaranteed by the fork-shaped configuration with non-coaxial spindle and big roughing power. Besides, the high-frequency electrospindle permits to operate effectively in milling (roughing and finishing) on steel, light alloys and alloys resistant to heat (used in some of the outlet application sectors of this machine, such as aerospace and military).

The change system provides for apposite niches in the structure where replacement heads are housed.

A further option offers the possibility of replacing the spindle cartridge only: in this way a single head can house, for instance, a motor suitable for roughing and a high-speed electrospindle for finishing.

Tornado HD 300/14 is the standard head proposed on Maxima: with a maximum power of 75 kW and a spindle torque of 300 Nm, it is proposed as solution able to meet successfully most requirements expressed by customers. It can reach in fact 14,000 rpm and house tools with HSK-100A taper.

 

Tools are housed in a wheel-type magazine that, in the change phase, is introduced into the machining field through an apposite panel. A variable number of tools, ranging from 20 to 30, can be housed, depending on their size. As an alternative, a rack with 60, 100 or 150 pockets can be installed, with a shuttle for the tool recovery and an arm that physically carries out the exchange. In both cases, the machining area is perfectly free and completely available for the piece positioning, allowing the movement of the head in the space without constraining it with the presence of tools or tool/head change equipment.

 

The secret of precision

Maxima has been conceived to satisfy very exacting demands in terms of productivity and precision. We have mentioned the capability of reaching a volumetric precision within 5 hundredths but it was not easy to attain these results.

 

The stable and stiff structure certainly contributes in essential way but it was necessary to do more: besides the air pressured optical scales, equipping both sides of the machine and the Z axis, and the encoders on rotary axes, the machine is provided with a balancing system for the compensation of the head and ram weight.

In this way, the only forces that affect the structures are the machining ones, widely within design parameters.

The “universal” mission of Maxima guarantees the possibility of machining a big number of materials, such as steel, aluminium, resins, titanium and carbon fibre. For the latter, in particular, they have studied suitable solutions for assuring the constant operation of the machine. First of all the upper part can be closed with bellows that do not limit the possibility of loading pieces with the crane but that, in presence of carbon fibre dust, isolate the machining area and do not allow the removed particles to go out. Moreover, all sliding and supporting surfaces are protected by a standard pressurization system.

Thanks to TM - Tecnologie Meccaniche

(Mr. Andrea Pagani)

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5 axis machining centers, aerospace machining, breton cnc 5 axis, CNC turning and milling center, high speed vertical machining centre, Maxima