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Marking Polypropylene Mugs
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Welding Electrical Contacts
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Cutting Glass-Filled Nylon Gears
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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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Marking Polypropylene Mugs
Polypropylene is a common thermoplastic that has practical applications in many different industries. It's strength, flexibility, and resistance to damage means polypropylene is an excellent material for various types of storage containers. In addition, polypropylene's ability to withstand heat makes it a good choice for food and beverage containers, such as coffee mugs, that must safely hold hot liquids.
Although there is no physical color change when laser marking polypropylene, it does vaporize cleanly so that deep engraved marks are made with good quality. Typically, there is not enough contrast to get readable barcodes; however, text and logos are easily marked with acceptable visibility.
For this application, marking polypropylene coffee mugs, we used an FH Flyer marking head, a 48-2 (25 W) laser, and a copy of our WinMark Pro laser marking software. The Flyer head was equipped with a 200 mm focal length lens that provides a 290-micron (0.011") spot size with a 5 mm (0.196") depth of field. This large depth of focus is an important factor in obtaining consistent mark quality across the curved surfaces of the mug. Too little depth of focus would result in marks that fade out along the far edges.
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This polypropylene coffee mug was laser marked using 25 watts of power and exhibits a readable, engraved mark with slight meltback.
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The mark file consisted of a TrueType Arial text logo and a coffee cup graphic imported as a .PLT file. For both mark objects, the mark Velocity was set to 152 millimeters per second (6.0 inches per second) at a power level of 25 W. The resulting engraved mark was completed in a cycle time of 7.22 seconds.
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Laser Welding Electrical Contacts
Laser welding has several advantages over conventional welding processes including reduced thermal distortion due to very small heat affected zones (HAZ), accurate control of heat input that allows welding close to heat-sensitive parts, and the ability to repeatedly direct the beam precisely to the weld point. In part, these laser welding applications are successful because the typical focused beam diameter of 100 microns (0.004") localizes HAZ around the weld area to fractions of an inch.
Unlike conventional welding techniques, laser welding is typically performed without adding filler material to the weld. This creates a homogenous junction between the two pieces without introducing foreign material in the form of filler alloys. The downside is that part fit up at the weld interface must ideally be zero to prevent undercutting of the weld joint. In actual practice, a slight gap not exceeding 10% of the thinnest piece or the actual weld depth - whichever is less - is acceptable. In addition, the conventional welding technique of creating initial spot welds at intervals along the joint helps to prevent material separation during the actual weld pass.
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A thin steel cover was welded to this electrical contact with 200 watts of power at a speed of 15 inches per minute using 3.9 CFM of argon shield gas.
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For this welding trial, we were asked to fillet weld a 0.15-mm (0.006") thick steel cover to a much thicker steel substrate to create an electrical contact. Our beam delivery setup consisted of a 63.5 mm (2.5") positive meniscus lens, which provides a 100-micron (0.004") spot size with a 1.8 mm (0.07") depth of focus. Argon shield gas, at a flow rate of 3.9 cubic feet per minute (CFM), was adjusted to flow over the processing area to prevent the molten weld pool from reacting with the surrounding atmosphere. Each weld bead measures 8.25 mm (0.325") in length and was completed in approximately 1.3 seconds using 200 watts of power at a velocity of 15 inches per minute.
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Cutting Glass-Filled Nylon Gears
Nylon gears are commonly used in many automotive, electronic, and medical applications, as well as in various industrial machines. Nylon gears offer increased service life because they wear less than metal gears (even though they require less lubrication) and reduce gear noise, which is important in consumer products. Adding a 20% to 30% glass fill to the nylon blend increases the material's stability, rigidity, and wear-resistance.
This application demonstrates the ability of a Synrad CO2 laser to precisely remove the machining hub from the center of this helical-cut gear after the last manufacturing step.
Our laser cutting setup consisted of a Firestar f201 laser delivering the beam via XY "flying optics" into a cutting head containing a 127 mm (5.0") plano-convex focusing optic. This optic produces a 203-micron (0.008") spot with a 6.3 mm (0.25") depth of focus. During the cutting process, we supplied 2.8 bars (40 PSI) of breathing-grade bottled air coaxially with the beam as gas assist.
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We cut out a 0.093" thick hub from this glass-filled nylon gear using 200 watts of power at a speed of 100 inches per minute.
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The machining hub, which measures 2.4 mm (0.093") thick, was cut from the front face of the gear by trepanning a 30.7 mm (1.21") diameter hole that matches, and is aligned to, the bore of the gear. Using 200 watts of power at a cut speed of 2.54 meters per minute (100 inches/minute), we were able to remove the hub in a cycle time of 2.3 seconds per gear. As seen in the photo, the cut edge exhibits slight charring due to the glass fill but has no effect on the finished product.
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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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