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High productivity thanks to high machine dynamic

FOOKE ENDURA® Gantry Milling Machines for Tools and Model Making
Nowadays, in many cases, heavy 5-axis machines for 5-side finish machining of workpieces made of cast iron, steel and alloyed steel are used. As known by experience, milling tools with big diameters are often used for roughing process that representing approx. 20 to 30% of the total machining time. Therefore, the machining unit is equipped with a drive milling spindle that normally has high torque (800 Nm and more).

During machining processes, powerful forces and/or process forces affect on the bearing, drives, guiding systems and the structure elements of the machine. Therefore, it is designed to be very robust and stiff. Probably for tradition reasons, those machines are often clearly overdimensioned in term of their dynamic mass, that means, the mass of machine elements that is moving.

It is only natural that smaller and small tools diameter are used for approaching and achieving finished workpiece geometry, that means for pre-finish and finish. If the same machine should be used therefore, the milling device will be exchanged. A high frequency milling spindle with higher number of revolutions (20,000 min-1and more) will be used. The process forces that are reacting on the machine and their structural elements are now significantly less. For the working steps that have to occur, actually representing approx. 70 to 80% of the total machining time, the dynamical mass of the machine is developing considerably to the disadvantage.

ENDURA_704LINEAR_Werkzeugbau

Innovative companies go nowadays more and more for optimised milling strategies: therefore, the contour is realised by using smaller and mid-sized tool diameter (until approx. 63 mm) and quite slight cutting depth. There is no need to use any drive milling spindle. Moreover, the clearly low force allows use of highly dynamical machines.

The company FOOKE GmbH located in the Münsterland region manufactures such machines since many years. During the development of the ENDURA® machines, it was consequently considered that right by using smaller tool diameters; the process forces are significantly lower. The tools‘wrap angle and/or wrap distance exert elementary influence.

FOOKE ENDURA® gantry milling machines have a machine structure designed with intelligence. In this context, intelligent means that structural elements are dimensioned to fit together, they are manufactured with suitable materials and unite the decisive features for good milling results that are: STIFFNESS, MASS and DAMPING in an optimal ratio.

The process forces on one side and the dynamic stiffness of the machine structures‘elements on the other side are significantly responsible for the milling result, that means: for the quality of the surface and the accuracy. The harmonious ratio of the structures‘elements is decisive for the productivity of the machine that is based on the best use of suitable materials and suitable mass.

FOOKE machines of the construction series ENDURA® 700LINEAR and ENDURA® 900LINEAR are designed that way. Combined with linear motors in all linear motors and as far as it is wished and/or technically reasonable – with torque motors in the round axes, beside their dimensions, these machines stand out for their excellent quality of motion control: best surface quality and accuracy, produced in shortest machining time.

As milling unit, exclusively efficient high frequency milling spindles (e.g. HSK63A, 42 kW, 24.000 U/min, 67 Nm or HSK100A, 63 kW, 15.000 U/min, 300 Nm) are used.

Particularly the high machine dynamic of an ENDURA® machine makes potentials useful at pre-finishing and finishing machining. Compared to machines that have conventional feed drives and high dynamic mass, the high accelerating values and rate of feed of an ENDURA® machine effect an overall clearly higher speed level, a higher productivity.

One more advantage of linear and/or torque motors: integrated in a suitable machine structure, a direct drive functions quite as a sensor and can be used as a process monitoring device. Power superelevation from milling processes, collisions as well as settlement effect of the foundation that can lead to geometrical changes within the tool machine structure can be clearly and quickly identified and notified. Collision energy can be reduced.

Compared to a conventional feed drive that always includes a cinematic chain of reactions, the feed drive of a linear motor has a clearly shorter reaction time. In case of conventional feed drives, mechanical transmission elements such as gear rack pinion, ball screw drive, drives and bearings are used.

On the other hand, the cinematic reaction chain of a linear motor feed drive „only“ consists of the track of permanent magnets, the so-called „secondary component”, and the real motor, the primary component. The feed motion is realised through the electromagnetic field. The electromagnetic field between the primary and the secondary components is regulated in the current control loop in thousands of a second.

FOOKE’s ENDURA® machines with linear motor drives are used worldwide already since 2004. Particularly, lack of mechanical transmission elements in the linear and round axes reduces maintenance needs significantly. The diagnostic possibilities e.g. for changes in geometry and wear and the “sensor properties” represent a significant added value and clearly reduce the machine down time.

Another aspect: purchase costs of such tool machine systems have to be described as throughout „moderate“ by considering the clearly better properties.

The properties of an ENDURA® machine and its advantages in key terms:

  • High machine dynamic
  • High rate of feed
  • High path contour accuracy along the programmed path
  • High productivity
  • Low process forces, low reaction forces on the machine and its structure elements
  • Less wear
  • Moderate purchase costs

We are showing a compact milling machine ENDURA® 704LINEAR at the EMO 2013 in Hannover at our booth A14 in hall 13. This ultra-modern linear motor milling machine in gantry construction with 5 CNC controlled simultaneous axes is particularly suitable for rational 5-side machining of work pieces made of aluminium, cast-iron and steel.