Outstanding milling

[article by Edoardo Oldrati, original source: "Tecnologie Meccaniche" Magazine, June 2017]

The German mould maker, WFT Werkzeug- und Frästechnik, has invested in Breton milling solutions. Specifically, in the recent Flymill HD for machining superalloy, steel and aluminium parts with complex three-dimensional shapes.

Founded in 1997, but the heir of an entrepreneurial history that started in 1919, WFT Werkzeug- und Frästechnik is a German company that manufactures matrices and moulds for punching, foaming and compression moulding of all kinds for the automotive, aerospace, medical and renewable energy industries. 

“State-of-the-art technology and many years of know-how”, explain Frank Elzener and Stefan Lühr, managing director and owner of the company respectively, “allow us to provide our customers with everything they need for each process phase, from design and manufacture to assembly and testing, giving them a single source procurement service”.

In the Coppengrave plant in Lower Saxony, more than 50 employees use modern production systems to machine blanks. The CNC machines have up to a maximum of 5 programmable axes and can machine workpieces up to 8 metres long and weighing up to 46 tonnes.

One of the strengths of WFT is precisely this advanced fleet of machines, which takes up four halls with an overall surface area of 3 thousand square metres. For the past three years, WFT has relied on machines supplied by Breton. Currently the company's plant houses a Breton Matrix 1000, with axis travel of 2200 x 2500 x 1000 mm, and a new Flymill HD with head change and an axis travel of 8000 x 3500 x 1300 mm.

Flymill HD in action

HIGH MILLING PERFORMANCE

A company like WFT must be able to rely on milling machines that can combine high material removal capacity with high accuracy. Precisely for this reason, a partnership was started with the Italian manufacturer Breton, which has supplied two machines in recent years.
The most recent one is the high-speed, high-performance milling machine with 5 continuous interpolated axes, the Flymill HD. It is ideal for machining superalloy, steel and aluminium parts with complex three-dimensional shapes that must be made accurately.

A sample worked by WFT with the Breton Flymill 1300 milling machine

To ensure high performance, the Flymill is equipped with sturdy shoulders made using the exclusive Metalquartz® technology, which provides high structural rigidity and a high degree of vibration damping to guarantee improved surface finish and increased cutting tool life.

The large work table size, the strength of the structure and the large operating travels make this high-speed milling machine suitable for use in a single work area or in pendulum mode, with a milling speed of up to 40 m/min for the linear axes, reaching up to 60 m/min in rapid mode. The bi-rotary heads (with continuous C-axis rotation, A-axis rotation up to 135°, power of 85 kW and rotation speeds of up to 100 rpm) allow the machine to rapidly perform even the most complex machining, working simultaneously in all three dimensions with very simple programming. In fact, considering that the A-axis can rotate up to 135°, it is easy to perform difficult undercuts without repositioning the workpiece. 

The machine model installed at the German company has an axis travel of 8000 x 3500 x 1300 mm. There are electrospindles for the Flymill HD heads that can guarantee high performance through their bilateral fork structure made of cast iron, which gives them structural strength and vibration damping ability. The Breton Flymill is equipped with the Tornado HD head, which can take a 75 kW (S1), 14,000 rpm spindle for rough machining and finishing.
Also noteworthy is the compact structure that meets the increasingly widespread demand for small-footprint systems. 

Furthermore, the Breton machine previously installed in WFT, a Matrix 1000 with an axis travel of 2200 x 2500 x 1000 mm, features high machining speed and high material removal rate.

It is a high-speed, high-precision machining centre for milling parts with complex three-dimensional shapes, ideal for applications in the aerospace, automotive, mould making and design industries. In fact, thanks to the speed of its linear axes, which can reach 60 m/min, and its Direct Drive head with a continuous C-axis rotation speed of 100 rpm, the Matrix can perform uncommon high-precision and dynamic machining of complex profiles with 5 continuous axis.

Matrix 1000 Dynamic

The bi-rotary continuous head with direct drive can be positioned at any angle within its operating range, thanks to powerful hydraulic brakes. This makes it possible to use spindles with continuous powers of up to 40 kW and 28,000 rpm, giving the machine a considerable material removal capacity.
It is also worth noting that it can easily handle high-speed machining and milling of both light alloys and other special alloys that are often used in the aerospace industry.

The completely enclosed structure with mechanisms at the top of the machine offer maximum operator safety with maximum machining reliability and precision. Its machining quality and precision are also achieved through the thermo-symmetry of the structure and the a thermal stabilisation system in the Z-axis lead screws and bearings and the axis drives, which keeps the temperature of these parts aligned with that of the machine structure during operation. 

This stabilisation system makes the machine practically immune to deformation caused by the thermal dilatation of the structure that is induced by continuous daily use for high-speed machining. Sophisticated finite element method (FEM) dimensioning integrated with global dynamic simulation has made it possible to obtain strong structural elements that combine stable geometric precision with dynamic high acceleration of the operating units.

THE KEY TO SUCCESS

WFT manufactures prototype moulds, pilot moulds and production moulds for a wide range of plastic machining technologies. Depending on the geometry of the workpiece, the number of components and the customer's needs, WFT can offer the optimal mould concept from both the technical and economic points of view, providing its customers with recognised know-how as well as intelligent and highly technological solutions. 

In addition to its versatility, another element behind the success of WFT is its ability to follow the whole implementation cycle of moulds and customised machines, from design to production. “Our personnel create the three-dimensional model of the component to be made on CAD/CAM workstations. The design department is connected with customers around the world, allowing them to see the data on line and to perfect the design through direct consultation”.

The target industries for the moulds made by the German company impose high quality standards.

“Quality is our watchword”, confirms the technical department, “and many years of experience and the constant training given to our engineers and experts guarantee the highest quality combined with reduced production times. To ensure excellent quality, every aspect of all moulds and machines is tested before being delivered to the customer. Moreover, visual inspection is an effective method, but it is not enough to meet the current requirements imposed by the manufacturers of components for the automotive and aerospace industry. 

For this reason, we reply on complete control systems and we manufacture measurement devices and test equipment from aluminium, steel or light material, to guarantee accurate measurement of every product. Here, the distinctive feature lies in making the measurement: in fact, the test and measuring devices provide assessment, documentation and display. We can also build custom test devices to meet customer requirements”.

The ability to innovate is also essential, not only by investing in a fleet of state-of-the-art machines, as we have seen, but also by developing new technologies. An example of this approach is the innovative joint technology for plastic products that WFT uses in its plant. 

To make products such as trims for doors or bumpers, dashboards or fuel tanks, packaging components or medical items, plastic components are applied to various objects. In these cases, WFT uses latest generation joining technology to integrate metal elements into the plastic, fold laminated materials or securely fasten thermoplastics by welding or riveting.

For more information please write to mail@breton.it.

Thank you for the attention and best regards.

Bye-bye

Sergio Prior

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breton flymill, flymill hd, Matrix 1000 Dynamic, WFT

Matrix 1000 Dynamic - Machining centre with moving bridge

Machining accuracy and speed, these are the strong points of the Matrix 1000 Dynamic, the Breton gantry-type machining centre. The solutions adopted to assure high performance and strength include the use of high power, high torque electrospindles, and a hybrid structure (Metalquartz®) in electro-welded steel and a quartz-polymer matrix composite material.

When machining medium-large size parts it is essential to be able to rely on a machine tool offering excellent structural rigidity. The concept of "broad shoulders" encapsulates the core construction philosophy of the Breton Matrix 1000 Dynamic.

The company, based in Castello di Godego (TV), uses the experience gained in fifty years in the industry to produce gantry-type machines with moving bridge supported on shoulders that are large (for milling of large size parts) and extremely sturdy (to guarantee high chip removal volumes without any negative effects).

For all materials

This 5-axes gantry-type machining centre with moving bridge was designed by Breton to meet new requirements associated with high speed machining of large, complex parts for the aerospace and automotive, die-manufacturing and design industries. The Matrix 1.000 Dynamic has a 2,200 mm X-axis travel, 1,000 mm Z-axis travel, and a Y-axis travel that ranges from 2,500 to 6,000 mm.
In addition to the generous working range, one of the characteristic features of this machine is its ability to mill parts made of various materials, namely steel, aluminium, resin and composites.

This machine in fact can be fitted with a vast range of electrospindles with continuous power outputs of up to 40 kW and torque outputs of up to 137 Nm, which combined with a rotation speed of 28,000 rpm offers a notable milling capacity. The software-controlled compensation of the electrospindle’s natural thermal expansion, and its thermal stabilization guarantee high precision machining.

These spindles are housed in the cast iron dual fork head, which guarantees high structural rigidity and an excellent vibration damping capacity. The direct drive twist head, positionable at any angle of its operating field thanks to powerful hydraulic brakes, makes it possible to use spindles with a continuous power output of up to 40 kW and torque of 51 Nm or 100 Nm and is able to reach speeds of up to 18,000 rpm, to the benefit of the chip removal capacity and surface finish quality, also on complex profiles.

Alternatively, the electrospindle with 20 kW power output and continuous torque of 38 Nm in S1 is the best choice for high speed milling of steel and lightweight alloys, from roughing to precision finishing, thanks to the maximum speed of 28,000 rpm.

Innovative structure

An interesting feature of Breton machines and of the Matrix 1000 Dynamic in particular, is represented by the strong shoulders produced using innovative Metalquartz® technology: a sandwich structure made of stabilized arc welded steel, with ribbing embedded in a quartz polymer matrix composites. This exclusive technology ensures a very high structural rigidity and vibration damping, which guarantees a better surface finish and a longer service life of the cutting tools and parts subject to wear. In addition, this composite material has the same thermal expansion coefficient as the steel parts of the structure, thus preventing dimensional changes in the structure.

The face of the bridge is equipped with a rigid guideways-holder  carriage composed of an electrowelded and normalized steel structure. The carriage travels transversely across the bridge on recirculating ball shoes moved by a system with a ground ball screw with double preloaded ball nut, driven by a brushless motor. To guarantee the highest accuracy, the position of the carriage is read directly by an ultra-high precision, micrometric resolution Heidenhain pressurized linear encoders.
The guideways are balanced by two cylinders permanently charged with inert gas and positioned symmetrically at the side of the structure. A system with emergency load-holding brake mounted on the vertical ways ensures the highest safety in the event of a power loss or loss of the cylinders' gas supply.

The head structure is equipped with a three-axis accelerometer that is invaluable for tool balancing control and essential to monitor possible collisions and reduce potential damage in the event of accidental impact, also during manual operations. The plant is supplied complete with software to establish monitoring and trip thresholds.
The quality and precision of the machining work are achieved also thanks to the thermal symmetry of the structure and to the action of the temperature stabilization system for the Z axis ball nuts and bearings and the axis drives, which keeps the temperature of these parts aligned with that of the machine structures.

The carriage and beam travel on properly dimensioned recirculating roller guideways to ensure machining accuracy and stability. Linear axis speed can reach 60 m/min thanks to the digital drives with brushless servomotors and the ground ball screw and double preloaded ball nut assembly. To guarantee the highest accuracy, the position of the beam and carriage is read by optical scales.
For the maximum safety, the machine is enclosed by steel framed guarding that is openable at the front thanks to the presence of a series of manually operated sliding doors equipped with large inspection windows. During machine operation the doors are secured in the closed position by electric safety locks.

Customization

Performance at a dynamic level, offering high power and precision, are not the only advantages, and the machine can be customized with a series of accessories to meet the customer's specific requirements. In this context Breton offers tool magazines with a rapid tool changer to reduce tool change times. These magazines are installed outside the work area so they can't come into contact with milling dust or residues, and can be fitted with a system for the automatic encoding of tool data and a chip reader for an even higher level of plant automation.

The standard tool magazine has 30 locations designed to accommodate tools with a maximum diameter of 140 mm and length of 300 mm. The total weight that can be handled, including the tool holder, is 10 kg.
Matrix 1000 Dynamic can also be equipped with a laser probe for tool presetting and a radiofrequency touch probe to acquire the workpiece coordinates and dimensions.
On the basis of the milling operations to be performed, the tool cooling system may use compressed air, a spray mist system, or coolant sprayed inside and outside the spindle at an internal pressure of up to 70 bar.
For customers machining composites and resins we can supply dust extraction systems to install on the spindle nose, in addition to top-roof bellows to isolate the work area from the surrounding environment, protecting the operator from any noxious or harmful elements. The fact that all the kinematic mechanisms have been located at the top of the machine is proof of the focus on operator safety. Finally, to meet every possible application requirement, the Breton Matrix 1000 Dynamic can be configured for pendular machining in two work areas.

The numerical control is the Siemens 840D Solution Line unit: this model, which is an evolution of its 840D predecessor, incorporates a series of functions designed to reduce total energy consumption of the machine without limiting power output or performance. The numerical control also incorporates the remote assistance package, software for management of the Blum laser tools presetting system and the workpiece touch probe management software.

The machine is equipped with a control console at the front, with function pushbuttons, LCD display and the numerical control keypad. In addition to the main control panel, the machine is supplied with a remote handheld control unit incorporating control buttons to select axis movements, spindle stop/start buttons and a handwheel to move the axes. The handheld control unit, which is cable-connected to the CNC unit, can be brought to any position in the working area by the operator, thus simplifying procedures for positioning and zero setting of the workpiece.

Demanding applications

Matrix 1000 Dynamic is a gantry-type machining centre with travelling bridge, designed and built in particular to meet demands for high speed milling for the production of die tools and design parts, and hence for complex and large size workpieces.
The carriage and beam travel on properly dimensioned recirculating roller guideways to ensure machining accuracy and stability. Linear axis speed can reach 60 m/min thanks to the digital drives with brushless servomotors and the ground ball screw and double preloaded ball nut assembly.

Properly sized structure

An interesting feature of Breton machines, and of the Matrix 1000 Dynamic in particular, is represented by the strong shoulders produced using innovative Metalquartz technology: a sandwich structure made of stabilized arc welded steel, with ribbing  embedded in a quartz polymer matrix composites.
This exclusive technology ensures a very high structural rigidity and vibration damping, which guarantees a better surface finish and a longer service life of the cutting tools. In addition, this composite material has the same thermal expansion coefficient as the steel parts of the structure, thus preventing dimensional changes in the structure.

Power and torque

The spindles installed on the Matrix 1000 Dynamic are mounted on a cast iron dual fork head that guarantees high structural rigidity and excellent vibration damping capacity.
The direct drive twist head, positionable at any angle of its operating field thanks to powerful hydraulic brakes, makes it possible to use spindles with a continuous power output of up to 40 kW and torque of 51 Nm (28,000 rpm) or 100 Nm (18,000 rpm), to the benefit of the chip removal capacity and surface finish quality, also on complex profiles.

Identity card

Name: Matrix 1000 Dynamic

Occupation: 5-axes machining centre with moving bridge
Manufacturer:
Breton Spa
Via Garibaldi, 27
31030 Castello di Godego (TV) – Italy
Tel. +39 0423 7691
Fax +39 0423 769600
E-mail: mail@breton.it
www.breton.it

Technical specifications:

Work area
X” axis travel	2,200 mm
Y” axis travel	2,500...6,000 mm
Z” axis travel	1,000 mm
Table surface area	2,000x4,500 mm
Table load capacity	15 tons/m2
Spindle
Power	40 kW
Maximum torque	100 Nm
Maximum spindle speed	28,000 rpm
Spindle taper	HSK - A63
Ram travel	1,000 mm
Ram section	400x400 mm
Axes performance data
Linear axes feedrate (work)	30 m/min
Linear axes feedrate (rapid)	60 m/min
Tool magazine
Number of magazine tool locations	30
Max. tool diameter	140 mm
Max. tool length	300 mm
Max. permissible weight (tool + tool holder)	10 kg
Numerical control
CNC	Siemens 840D solution line
Dimensions and Weights
Footprint	50 m2
Dimensions (LxWxH)	6,800x5,700x5,000 mm
Machine weight	58 tons

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gantry machining center, Matrix 1000 Dynamic, pendular machining