SYNRAD, INC. - http://www.synrad.com  
Thursday, September 2, 2004
Issue 95



Come see us at IMTS!  September 8-15, Booth B-6258

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.

EPDM roofing gasket exhibiting permanent, easily readable mark

EPDM (Ethylene Propylene Diene Monomer) rubber has many uses where resistance to weathering, ultraviolet radiation, and heat are important factors. Commonly used for decades as a low-slope industrial roofing material, EPDM has also made substantial inroads in the automotive industry because its high heat resistance outperforms natural rubber in applications requiring durable boots and seals.

For this EPDM roofing gasket, an easily readable identification mark (with the potential to outlast the lifetime of the part) was desired. The marking setup included a Synrad sealed CO₂ laser, an FH Series marking head equipped with a 200-mm focusing lens (290 micron spot with a 5 mm depth of focus), and WinMark Pro laser marking software. We created a seven-character identification string using WinMark Pro’s built in “Simple” stroke font and set a character height of 0.3 inches (7.6 mm). In WinMark Pro, Power was set to provide 10 watts, Velocity to 15 inches per second, and Resolution to 300.

Laser interaction with the EPDM material provides an engraved mark with a metallic-like contrast. Overall cycle time is 0.36 seconds per part. Although this application involves marking rubber roofing gaskets, similar marks can be obtained on other EPDM products where identification, tracking, or part numbers must appear on the part itself.

Ablating Enameled Wire

unablated wire


wire shown after stripping


Detail of copper wire tip after varnish is stripped using 25 Watts of laser power

Enameled wire is produced by baking copper wire after it has been coated with an insulating varnish; typically a polyester, nylon, or polyamide-imide compound. The varnish provides a thin, tough, insulating coating allowing the wire to be wound for the production of electrical products including transformers, generators, and electric motors to name just a few examples.

This application involves ablating (stripping) the varnish coating from various gauges of enameled copper wire. Because copper reflects the CO₂ laser’s 10.6-micron wavelength, enough power can be applied to vaporize the varnish coating without fear of damaging the wire. Ablating the varnish produces a clean, electrically-conductive length of copper, allowing wire connections to be terminated electrically and/or mechanically as required.

Depending on wire gauge (diameter) and cycle time requirements, various combinations of power, speed, and beam delivery will accomplish the task effectively. This project called for stripping a one-half inch length from the end of each wire using 25 watts of power. Our setup scanned the beam at three inches per second (300 DPI resolution) along this length using an FH Series marking head as the wire was simultaneously rotated under the 125 mm focusing lens. At 25 W of power, cycle times ranged between 5 and 7.5 seconds depending on wire gauge.

 Integrating firestar series lasers

All firestar Keyswitch and OEM models* provide a single DB15 I/O connector that incorporates both +5 and +24 DC voltages for driving external inputs or outputs; an optoisolated PWM signal input; three optoisolated control inputs; and five optoisolated control outputs, which also mirror the state of firestar’s five status LEDs.

firestar inputs

REMOTE INTERLOCK and SHUTTER OPEN REQUEST inputs, driven by the user’s control system, enable the laser while the REMOTE RESET/START REQUEST input provide reset (Keyswitch versions) or inhibit (OEM version) functionality. The optoisolated PWM INPUT accepts pulse-width modulated signals from the user’s control system to drive laser output power.

firestar outputs

During normal operation, firestar’s LASER READY, SHUTTER OPEN, and LASER ACTIVE switched outputs close; OVER TEMPERATURE and INTERLOCK OPEN outputs remain open and only close to indicate that an overtemp or interlock fault has been detected.

Connect LASER READY and SHUTTER OPEN outputs to your control system to indicate that lasing is enabled (after a five-second delay) and firing can begin once a PWM Command signal is applied to the PWM INPUT.

Input/Output integration

The SHUTTER OPEN REQUEST input works in conjunction with the manual shutter switch on Keyswitch-equipped lasers. The SHUTTER OPEN output closes (and the Shutter LED illuminates blue) when a SHUTTER OPEN REQUEST signal is present and the shutter switch is Open. The SHUTTER OPEN output is open (Shutter LED Off) when the SHUTTER OPEN REQUEST signal is removed or the shutter switch is Closed.

On OEM lasers, the SHUTTER OPEN REQUEST input simply enables/disables the laser with corresponding changes to the SHUTTER OPEN output and Shutter LED.

Note that a five-second delay occurs between the time that the SHUTTER OPEN output closes (Shutter LED illuminates) and lasing is enabled.

The REMOTE INTERLOCK input (and the internal over temperature sensor) controls the LASER READY output and the Ready LED. The LASER READY output closes (and the Ready LED illuminates amber) when a REMOTE INTERLOCK input signal is present (Rem Int LED green) and the laser’s operating temperature (Temp LED green) is normal. The LASER READY output is open (Ready LED Off) when the REMOTE INTERLOCK signal is missing (Rem Int LED red) or an over temperature fault (Temp LED red) has occurred.

Note that a five-second delay occurs between the time that the LASER READY output closes (Ready LED illuminates) and lasing is enabled.

* with the exception of the OEM v30 laser

Browse Synrad's Applications Database

Search our online library for more applications of Synrad's sealed CO₂ laser technology. Sort by material, process, or industry.

http://www.synrad.com/search_apps/Default.htm

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