Turning the Hardest Materials Without Wear

The new laser turning process is being presented at AMB with the help of a holobox that illustrates what can otherwise only be observed to a limited extent. (Source: GFH)

The new laser turning process is being presented at AMB with the help of a holobox that illustrates what can otherwise only be observed to a limited extent. (Source: GFH)

Precision machining without burrs, chips and especially without tool wear – thanks to these advantages, laser systems for cutting, drilling and texturing have already established themselves in large parts of the metal industry today. GFH has now expanded this range of applications with a new technology: laser turning. Since neither mechanical forces nor relevant thermal influences act on the material here, even the smallest structures can be produced exactly and with a surface roughness of Ra < 0.1 µm. The same laser simultaneously covers all common functions so that the work piece does not have to be clamped again for subsequent machining steps. This increases production throughput, reduces costs and minimises the risk of damage.

An advantage of the system is that it can be used for cutting, drilling and texturing as well. Extensive clamping and unclamping of the work piece with the associated costs and risks is thereby eliminated. (Source: GFH)

An advantage of the system is that it can be used for cutting, drilling and texturing as well. Extensive clamping and unclamping of the work piece with the associated costs and risks is thereby eliminated. (Source: GFH)

A picosecond or femtosecond laser with a pulse duration of only 10 ps or 800 fs forms the heart of the laser turning technology. The shortness of the pulse ensures that extremely high energy acts on the work piece for a short time and the material vaporises before melting phenomena or thermal changes can occur. A perfectly rotating laser spot generated with the help of trepanning optics forms the tip of the actual cutting tool. Thanks to its low minimal diameter of 25 µm, it is capable of machining very fine contours and geometries that cannot be realised with mechanical tools. What’s more, the laser does not press against the component so that large projecting lengths are possible.

The method is suited for both roughing and finishing; the possible infeed depends on the material and the required accuracy. In order to guarantee the consistent distribution of the laser pulses notwithstanding changing diameters and therefore also different true velocities, a special laser control system makes it possible to realise pulse-on-demand regulation in relation to the path being travelled. In addition to all types of metal, this makes it possible to also process plastics and carbon as well as extremely hard materials such as ceramics or industrial diamond.

There is no tool wear with this form of turning since the laser beam works without contact. The blade geometry remains permanently sharp and dimensionally stable so that fluctuations in the cutting quality are avoided. Chips that could damage the work piece or tool are not produced during laser machining either. Since burrs do not form, there is no need for post-processing and simply cleaning the work piece is sufficient.

The GL.evo or GL.compact processing centres form the machine base for laser turning. They feature very dynamic kinematics with a high positioning accuracy of ± 1 µm and five axes with the mobility required for longitudinal, transverse and contour turning. (Source: GFH)

The GL.evo or GL.compact processing centres form the machine base for laser turning. They feature very dynamic kinematics with a high positioning accuracy of ± 1 µm and five axes with the mobility required for longitudinal, transverse and contour turning. (Source: GFH)

The GL.evo and GL.compact processing centres from GFH, which set themselves apart with their very accurate yet highly dynamic kinematics, form the machine base. Notwithstanding acceleration of up to 20 m/s², this makes it possible to position the laser on the work piece with ± 1 µm accuracy. The five axes – including two rotation axes in the work piece clamping – permit longitudinal-round, transverse-recessing and transverse-plane turning as well spherical and contour turning with a realisable precision of 1 µm in diameter with a roughness of less than 0.1 µm. Thanks to the small tool diameter, very fine recesses can also be realised.

Another advantage of these systems is that they can be used for cutting, stripping, drilling and texturing as well – without clamping the work piece again. The various process steps can be carried out immediately in sequence and with no tool changeovers, since the parameters of the ultra-short pulse laser are adjusted continuously in µm increments according to the programming. Stainless steel forceps have already been turned with a ball diameter of 0.35 mm, cut lengthwise and drilled with a 0.08 mm bore. This high level of flexibility makes the method interesting for small series production and prototyping among other things. (Source: GFH)

Link: GFH GmbH, Deggendorf, Germany

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