Cutting of textile materials

We have designed a system for laser cutting of textile materials for a Czech manufacturer. The task is to cut polyester fabrics with high production throughput. The required parts are cut on the fly from a strip 190 mm wide, the largest part is approx. 175 mm. 2 materials were chosen for testing: 1) technical polyester (PET) fabric with a thickness of 0.45 mm 2) technical polyester (PET) fabric with a thickness of 0.16 mm.

After consultation with the customer, a laser subsystem consisting of a Coherent Diamond J3 250 W laser source with a wavelength of 10.6 μm, a scanning head with a working field of 200 x 200 mm and a 1.3x beam expander was selected for testing in our laboratory.

The Coherent Diamond J series CO2 lasers are sealed pulsed CO2 lasers offering above average power up to 1000 W in a fully integrated and compact housing. Unique pulse characteristics derived from the plate discharge design allow the Diamond J series lasers to achieve peak powers well in excess of 2800W in pulse as opposed to CW modulated lasers.

The Coherent J series lasers are available in 10.6 μm, 10.2 μm and 9.4 μm and can be operated at pulse repetition rates up to 200 kHz with fast rise and fall times. This combination of wavelength selection, high peak power, and fast rise and fall times, together with ample power and excellent beam quality, make the J Series an ideal laser for a wide range of materials processing applications. All Diamond Series lasers are built on a common platform with standardized mechanical and electrical interfaces, optical interfaces, common software and a common service and support strategy. All J-Series lasers offer proactive maintenance capabilities enabled by Coherent's integrated and comprehensive laser monitoring suite of diagnostic tools.

Key Features

• Wide operating power range
• High peak power 450 - 2800 W depending on laser type
• Pulse frequencies from single pulses up to 200 kHz
• Fast power ramp-up and ramp-down
• Excellent beam quality
• Excellent power stability
• Low cost OEM configuration
• Integrated removable RF power supply
• Compact design
• Integrated laser source status diagnostics

A test procedure was chosen to demonstrate the different processing speeds of the selected material and allow the customer to better determine the desired level of cut quality. For this reason, all samples were processed according to two different cut quality standards: 1) strict cut - no material remains in the cut, the parts are completely separated and no force is required to remove them. 2) relaxed cut - remnants of molten material remain in the cut, little force is required to remove the part.

Conclusion

• The selected laser setup with Coherent Diamond j-3 10.6 µm source was able to repeatedly cut PET fabric test sample A at Strict Cut quality at 500 mm/s and Relaxed Cut quality at 1500 mm/s.
• The selected laser assembly with the Coherent Diamond j-3 10.6 µm source was able to repeatedly cut PET fabric test sample B at Strict Cut quality at 3500 mm/s, Relaxed Cut quality at 4000 mm/s.

• In straight cuts, the cutting speed is affected by the orientation of the material relative to the direction of movement of the laser beam. In some images, it can be seen that the cut is interrupted where it intersects the weave pattern. This effect is also seen in circular cuts at higher speeds.

Notes and recommendations:

• A Coherent Diamond J-3 9.4 µm laser source would be preferable for cutting PET material. Due to the better absorption of this wavelength by the PET material, this laser may be able to achieve higher cutting speeds.
• Especially with thicker material, more smoke is produced during cutting, for this reason we recommend integrating a smoke extractor into the assembly.