The 5-axis machining centre of the month: Breton Eagle

High-speed and developed to meet the needs of workshops that deal with materials such as resins, composites, aluminium and carbon, while guaranteeing dimensional accuracy. (From: Tecnologie Meccaniche)

Breton Eagle

In its history as a manufacturer of machine tools, Breton has always stood out for its care and quality in designing and manufacturing solutions for removing metal chips.

High accuracy combined with powers and torques capable of processing new materials have always been the strong points of the company from Castello di Godego (TV), to meet the needs of sectors such as aerospace, automotive and pattern making.

Breton Matrix 1000 Dynamic

For the best results, it has designed models like the Matrix machining centres, also used to process the lighter materials (aluminium, resins and composites), which still require fairly high accuracy and a good degree of chip removal.

However, Matrix is a model that, in some cases, could be overspecified for the real needs of these sectors in terms of power and accuracy and, as we know, users tend to prefer solutions that match their needs perfectly.
Often the market offers lower-performance solutions with inadequate volumetric accuracies. Eagle is Breton’s solution to meet these expectations.

A new application sector

Breton Eagle, the 5-axis machining centre of the month

Breton decided to create a product that is not in direct competition with other manufacturers, nor of course with any of the machines that it was already manufacturing, but to enter a niche that requires good accuracy without the need for large investments.

Not all customers can afford (or need) a high-power machine nor an extremely accurate one. This requirement is typical of those making aluminium moulds or carbon, composite or resin patterns and it became increasingly evident that there was a need to offer a product that could meet this demand. None of these applications requires very high accuracy, but they do need a higher accuracy than can be obtained with low-end machines.

Therefore, Eagle is a high-speed, 5-axis machining centre for milling, drilling and trimming medium and large components made of composites, sandwich structures, light alloys, resins and plastics, all with good dimensional accuracy.

This machine is conceptually simpler and more economical than a Matrix, but at the same time, it is able to guarantee an accuracy that is higher than anything available in the lightweight material machining sector.

Eagle is based on the manufacturing philosophy that has always distinguished Breton’s machines: vertical spindle, high-quality recirculating ball screws, axes drives with backlash recovery to ensure the desired accuracy, thermo-symmetric elements, symmetrical fork head and high-performance cooled motor spindles.

From an economic point of view, Eagle requires a much lower investment than buying a Matrix (about 30% less, depending on the configuration). This is a significant amount for a single machine, but often users need several machining centres dedicated to these tasks, so the economic benefit is even more apparent.

Modular construction

Eagle brings the construction philosophy of other Breton models: in fact, it is a gantry machine with high columns, balanced vertical axis and heads with a symmetrical structure so that thermal dilatation is always limited.

Not all workshops are equipped with air conditioning systems, and thermo-symmetric design reduces structural deformation and makes it easy to correct via software. Naturally, the points where heat is generated (like the head, A-axis and motor spindle) are cooled by a dedicated chiller to reduce heat transfer to other parts of the structure.

Like most of the machines manufactured by Breton, Eagle is also a highly modular design.
It is made entirely of electrowelded steel and is dimensioned using finite element analysis to reduce vibration and limit twisting. This choice allows it to meet the machine users’ need for modular dimensions, allowing Breton to customise the standard product easily to satisfy market demands.

The machine is driven by brushless motors. The bridge on which the gantry moves has racks with two motors and pinions with backlash recovery, which offers a stroke of 2 m and higher thanks to the modularity of the rack solution. Depending on the choice of model, in the Y-axis, the stroke starts from 2.5 m and can reach up to 5 m. Finally, the Z-axis stroke is 1 m for the most compact model and reaches 2.5 m for the largest one.



The streamlined structure can also reach considerable speeds and accelerations: 70 m/min on the X- and Y-axes, 50 m/min on the Z-axis (all the linear axes are equipped with encoders) with accelerations of up to 4 m/s2, 12 rpm on the A-axis and 19 on the C-axis.

The motor spindles are partly inherited from the Matrix, while others have been specially developed to meet the specific needs of users of this type of machine. Breton’s entry-level model offers a torque of 52 Nm, 16,000 rpm, 25 kW of power and is lubricated with grease. This choice was dictated by the typical field of application, namely aerospace, where lubricant leaks onto the composite or carbon parts are strictly forbidden.

Alternatively, there are other spindles developed in co-design with Breton's partners, which offer up to 40 kW and air/oil lubrication.
The machining head was developed to ensure the accuracy and performance required by this type of application sector: a solution that is compact, mechanically driven to achieve the desired performance without using the more expensive direct drive. It also has smaller pivots for improved penetration inside the workpiece, allowing it to perform all the required operations.

It is made from a cast iron block, a solution that effectively damps vibrations directly at the source. Equipped with brakes to work in 3+2 mode with locked axes, it ensures maximum rigidity even with challenging material removal.

The machine received a positive reaction from the pattern makers who make rotational moulds, which typically require heavy aluminium removal. The same goes for pattern makers who make scale Ureol parts, resin products and other prototype components.

Power and control

A requirement related to machining composite materials is that sometimes the structure contains threaded inserts to be drilled or small titanium strips.
Other solutions on the market are not able to cope with this kind of machining, which must therefore be carried out manually by an operator, with the problems of accuracy and productivity that this entails.

On the other hand, Eagle can even handle those workpieces that contain composites, aluminium and various inserts, completing the task directly in the machine.In the civil aerospace sector, Eagle is ideal for all the structural aluminium machining, interior structures, honeycomb panels, aramid fibres, aluminium and composites that required drilling and countersinking.

Obviously, Eagle is also able to machine harder materials, taking into account that its performance will be lower than that of, for example, a Matrix. The choice, therefore, will be dictated by the predominant type of machining to be performed and the materials to be used.

The accessories

Ultrasonic cutting head

In addition to the more traditional optionals, such as video cameras to monitor the machining area and tool magazines of various sizes, Breton has come up with a series of accessories dedicated to the specific application fields for which Eagle is intended.

An ultrasonic cutting head has been developed to prevent tearing or chipping the workpiece when machining composites. It can be managed like a common tool (in fact, it is housed in the magazine).

Also for composites and carbon parts, there is a countersinking control head. This is controlled automatically through simple templates in the numerical control and allows the effective hole position to be verified before countersinking. This procedure is essential, for example, with carbon aircraft doors because the carbon mould geometry is rarely exactly the same as the CAD model.
So, the system carries out a check to establish the effective hole position on the workpiece (using mechanical or laser sensing) at three points to determine its exact coordinates before counterboring. With respect to a sensing cycle, the times, and therefore the costs, are reduced significantly.

The numerical controls that can be installed on the Eagle are the Siemens 840D sl and Heidenhain 640 iTNC, both with full software options. Moreover, at the customer’s request, it is possible to develop applications, cycles and specific interfaces that run on the numerical control to improve machine utilisation.

Finally, there is an accessory with a 6th horizontal positioning axis, to perform turning that requires special workpiece positioning and complete accessibility in any situation.

Safe and productive

Depending on the specific use, the user can choose whether to machine dry or using cooling lubricants, as the machine can do both. Breton has provided for the use of evacuator belts, extraction systems or both. Where there are laminated materials, for which it is necessary to mill the carbon and then thread the aluminium inserts, the carbon dust can be handled by the extraction system and the aluminium chips by the evacuator belts.

Breton puts considerable effort into satisfying the Atex standard. When it comes to safety, especially in industrial systems, nobody wants to run into problems or “surprises”.
The machine is therefore fully closed, with top bellows to avoid dust dispersion within the workplace. There are also extraction systems on the table and spindle nose.

When machining graphite, whose dust is extremely aggressive to both mechanical and electrical parts, Breton offers IP65 cabinets for the electrical panels or, alternatively, located at an appropriate distance from the point where the dust is created.

Would you like to find out more about the Breton Eagle? 
For INFO and inquiries about this 5-axis machining centre write to mail@breton.it.

Well, that’s all for today. 
Bye-bye

Sergio Prior

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