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Welding Polyethylene Film
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Marking Powder-Coated Steel
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Cutting Synthetic Leather
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SYNRAD's sealed CO2 lasers are used in a variety of industrial processes including cutting, welding, drilling, and marking. This news brief showcases some of the interesting materials and products that are processed daily by Synrad's line of CO2 lasers and marking heads.
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Welding Polyethylene Film
Polyethylene films are commonly used in the bagging and packaging industries where high-speed sealing operations are needed for large volume production runs of finished products. Hermetically sealed weld lines are often critical to the quality and repeatability requirements of the application.
Many traditional low-volume sealing methods include some type of heating element; however, the actual heat output of these elements may vary during operation, depending on the physical surface properties of the element and the amount of time it has been on. This can lead to inconsistent results over large production runs. Because CO2 lasers have very consistent output power and the heating process is always non-contact, laser-formed seals will remain very consistent over hours of operation.
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These two layers of polyethylene film were welded together using 50 W of power at a
speed of 12.7 meters/min (500 in/min).
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For this particular application, which required sealing 0.05 mm (0.002" or 2 Mil) thick polyethylene film, a Synrad 50 W laser was used in conjunction with an XY table and a cutting head outfitted with a 63.5 mm (2.5") focal length lens. This lens typically provides a 0.1 mm (0.004") focused spot size; however, for laser sealing operations, a larger spot size is often preferred. A larger spot size yields lower overall power density and leads to increased melting and less vaporization of thin films. The larger spot size also increases the weld line width, providing better weld strength. For these reasons, the lens was unfocused slightly by increasing the standoff distance to around 5 mm (0.2") between the surface of the film and the tip of the cutting head, to obtain a 0.5 mm (0.020") wide weld line on the plastic film. The cutting head traversed two layers of the film at a speed of 12.7 meters per minute (500 inches/minute) to produce the final finished seal. The resulting seal is consistent in strength across its entire length.
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Marking Powder-Coated Steel
Although Synrad CO2 lasers successfully mark bare steel and stainless steel using powers around 80-100 watts of power, our lower power lasers work very well when the part surface is painted or coated. An example of low-power metal marking is this 25 W application for marking powder-coated steel parts. As shown in the photograph, a very high-contrast mark is created by ablating the coating.
In this application, the marking setup consisted of an FH Series marking head equipped with a 200 mm lens that creates a 290-micron (0.011") diameter spot with a 5 mm (0.197") depth of focus. In WinMark Pro laser marking software, we created a 20-character alphanumeric part number measuring 98.8 mm (3.89") long with a Text Height of 8.95 mm (0.35") followed by a filled ellipse measuring 2.54 mm by 7.62 mm (0.10" x 0.30").
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This high-contrast mark on a powder-coated steel surface was made using 25 W at a speed of 20 inches per second.
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For both objects, we set a marking Velocity of 508 mm per second (20 inches/sec) at a Power (duty cycle percentage) equivalent to 25 watts. We then chose a marking Resolution of 300 for the stroke text object and 150 for the filled ellipse. At these settings, we achieved overall cycle times of 0.94 seconds to mark both the 20-character part identifier and the filled ellipse.
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Cutting Synthetic Leather
Within the garment industry, synthetic leather, or "pleather", made from polyurethane film, has increased in popularity over time due to its inexpensive price and ease of care compared to genuine leather products. This material breathes easily due to the porous nature of polyurethane, and can be lined with, or laminated to, other fabrics that provide additional comfort or insulating properties.
Like many other fabrics cut with CO2 lasers, synthetic leather provides a clean, sealed edge and exhibits little or no discoloration. In this application, a foam backing was laminated to the substrate, giving an overall material thickness of 0.115 inches (2.9 mm).
Using an XY table for motion control and a 2.5" positive meniscus lens (0.004" spot size / 0.07" depth of focus) for beam delivery, we cut this composite fabric using 100 watts of power at a speed of 400 inches per minute (IPM). Nitrogen at 20 PSI provided the gas assist.
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Foam backing, when welded to the synthetic leather substrate, provides a clean, sealed edge.
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FH Flyer / Fenix Flyer Technical Updates
Synrad Technical Updates keep you informed of recent developments related to FH Flyer Marking Head or Fenix Flyer Laser Marker products. Sign up to receive these bulletins automatically via email at http://www.synrad.com/FH_Flyer/flyersupport_subscribe.htm
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Contact Us:
Please do not reply directly to this newsletter. E-mail questions or comments to synrad@synrad.com
Synrad, Inc.
4600 Campus Place
Mukilteo, WA 98275
Tel: 1-425-349-3500
Fax: 1-425-349-3667
E-mail: synrad@synrad.com
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Copyright ©2009 SYNRAD, Inc. All rights reserved.
SYNRAD and Synrad product names are trademarks or registered trademarks of SYNRAD, Inc. All other trademarks or registered trademarks are the property of their respective owners.
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