JEC COMPOSITES MAGAZINE - Issue #105 - June 2016 - 49

To overcome the limitations of peel-ply and mechanical abrading techniques, lasers have been considered as an effective tool
for the pre-treatment of CFRP parts for cleaning and texturing
the surface. Lasers are known to provide a dry, non-contact,
precisely controlled high-speed process. Research shows
that parts pretreated using UV and near-infrared (IR) lasers
can achieve a lap shear strength similar to that of an abraded
part [9]. However, the high absorption of UV laser radiation
inside the matrix material compared to near IR laser is useful
to avoid possible material damage by delamination. Also, the
process window for UV laser is wider compared to near IR
laser. Using the Quasar 355-60 UV laser, an area cleaning and
surface texturing rate of 80 mm2/min was demonstrated without any visible damage to the fibre.
In collaboration with the Institute of Joining and Welding
(TU Braunschweig), Germany, Spectra-Physics conducted the
standard DIN EN 1465 lap shear strength test on 2-mm-thick
aerospace-grade unidirectional CFRP samples. At a pull speed
of 5 mm/min using the 150-µm-thick AF 163 adhesive from
3M Corporation, Quasar UV laser cleaned and textured parts
showed about the same strength as mechanically abraded
parts. Data also showed that untreated parts had a lower
strength than cleaned and textured parts. A high percentage of
undesirable adhesive failure modes was observed for untreated
parts, indicating very poor adhesion. The strength test was
repeated after ageing the samples for 1000 hours in a 70°C,
100% humidity chamber. The shear strength of all the aged
parts decreased as expected, due to the degradation occurring in the adhesive. However, the advantage of cleaning and
texturing parts is evident from the data since the drop in shear
strength of untreated parts is higher compared to cleaned and
treated parts. The laser treated samples had the smallest drop
in lap shear strength, as shown in figure 4.

Conclusion
Pulsed UV nanosecond lasers are a promising tool for CFRP
processing. With the >60 W UV Quasar laser, the high power
and programmable pulse width/shape result in both high
quality and speed for CFRP processing, including cutting,
drilling, surface texturing and cleaning. With this high-power
UV laser, a low HAZ can be achieved at fast processing speeds

ranck Glowacz holds Master's Degrees in Fundamental
Physics, Composite Materials, and Business Management.
As a writer for JEC Composites Magazine since 2007, he
has been in a very good position to observe the composites
market over the years.
-

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without damaging the carbon fibres. Also, UV laser cleaning
and texturing of CFRP parts provides stronger joints. Further
work is actively being pursued to extend to other process
configurations and thicker materials and to further study the
effects of laser parameters on CFRP machining. n
References
[1] http://www.compositesworld.com/articles/
the-markets-automotive-2015
[2] http://machinedesign.com/contributing-technical-experts/
will-carbon-fiber-find-widespread-use-automotive-industry
[3] Herzog, D., Schmidt-Lehr, M., Canisius, M., Oberlander,
M., Tasche, J. P., Emmelmann, C. (2014) Laser cutting of CFRP
using a 30 kW fiber laser, in proceedings of the International
Congress on Applications of Lasers & Electro-Optics (ICALEO),
San Diego, CA, USA.
[4] Hira, H., Tsuboi, A. (2011) Study on cutting of CFRP plate by
fiber laser, in the proceedings of the 18th International Conference on Composite Materials (ICCM), Jeju Island, Korea.
[5] Schneider, F., Wolf, N., Petring, D. (2013) High power laser
cutting of fiber reinforced thermoplastic polymers with cwand pulsed lasers, Physics Procedia 41, 415-420.
[6] Wolynski, A., Herrmann, T., Mucha, P., Haloui, H., L'huillier,
J. (2011) Laser Ablation of CFRP using picosecond laser pulses
at different wavelengths from UV to IR, Physics Procedia 12,
292-301.
[7] Weber, R., Freitag, C., Hafner, M., Onuseit, V., Berger, P.,
Graf, T. (2012) Heat accumulation in short-pulse laser processing of CFRP, in proceedings of the International Congress on
Applications of Lasers & Electro-Optics (ICALEO), Anaheim, CA,
USA.
[8] Kim, Y.C., Kim, O., Kim, S.W, Kim, H.D. (2014) Laser cutting
of carbon fiber reinforced plastics (CFRP) by using femtosecond
laser, in proceedings of the 15th International Symposium on
Laser Precision Manufacturing (LPM), Vilnius, Lithuania.
[9] F. Fischer, S. Kreling, K. Dilger, Surface pre-treatment of
CFRP by using laser radiation, Proc. of 19th ICCM, 2013, pp
4792-4801.
More information:
www.spectra-physics.com

Carbon fibres: history, players

and forecast to 2020 by Franck Glowacz, JEC Group
The study includes:
- Extensive description of the major players
- Data on main markets for a deep understanding
- Carbon fibre manufacturing explanation with
equipment manufacturers
- Listing of nearly all commercially available fibers

No105 June 2016 /

- Global demand forecast until 2020
- New development trends
- Demand on carbon fibres by sector:
Aerospace, Sport & Leisure, Wind
Energy, Automotive...

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jec composites magazine 49

http://www.compositesworld.com/articles/the-markets-automotive-2015 http://machinedesign.com/contributing-technical-experts/will-carbon-fiber-find-widespread-use-automotive-industry http://www.spectra-physics.com http://www.wwwjeccomposites.com

Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #105 - June 2016