Newsletter 143: Degating Cell Phone Components, Cutting Foam, Marking Aluminum Tags

SYNRAD, INC. - http://www.synrad.com
Thursday, August 10, 2006
Issue 143


Degating Cell Phone Components	Cutting Self-Adhesive Foam	Marking Painted Aluminum Tags

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.

Degating Cell Phone Components

The traditional injection molding process creates parts where the gate or sprue is still attached to one or more pieces in each shot. The sprue must be removed before assembly and ideally it is removed at or near the injection mold so that the plastic material can be reground, remelted, and reused. Although hand trimming by workers using sharp razor knifes is common, the production volume and complexity of today’s consumer products dictates a faster, more precise trimming solution. To support high-throughput speeds, the best solution is the installation of a Firestar sealed CO₂ laser from SYNRAD. Beam delivery to the part surface is accomplished through fixed or flying optics, by moving the laser, by moving the part, or by galvanometer beam steering. The result is a perfect cut every time on every part.

The polycarbonate sprue inside the cell phone
case above was precisely cut at three different
points in a cycle time of only 0.3 seconds per part.

The accompanying photograph shows before and after views of a polycarbonate cell phone case where the task was to trim the sprue from each part at three different attachment points. Our setup consisted of a Firestar 100 watt laser connected to an FH Series marking head and 125 mm high-power optic that provides a 180-micron (0.007”) focused spot with a 3 mm (0.118”) depth of focus. The maximum width of each sprue attachment was 5.1 mm (0.2”), so we created a mark file with three lines measuring 5.1 mm (0.20”) in length and used WinMark Pro’s precise positioning capabilities to place each line accurately within 0.0025 mm (0.0001”). To cut through the 1-mm thick (0.04”) polycarbonate case, we set a Power (duty cycle percentage) corresponding to 100 watts and set a cutting Velocity of 50.8 mm per second (2 inches/sec) at a Resolution of 300. Using these parameters, we successfully trimmed each case in a cycle time of only 0.3 seconds per part. The cut edge is clean with no residue and just a slight amount of melt back.

Cutting Self-Adhesive Foam Tape

Double-coated foam tapes are lengths of closed cell polyethylene foam coated with either rubber or acrylic adhesive on both sides. Ranging in thickness from 0.8 mm (0.0312”) to 3.2 mm (0.125”), these tapes are used for adhering various plastics or metals in bonding, gasketing and sealing applications where conformability, vibration dampening, or cushioning properties are required.

For this application test, we were asked to cut sections of 65-mil (1.6 mm) tape covered with a 5-mil (0.13 mm) liner on one side. Our motion system consisted of a large-area XY table and a cutting head carrying a 63.5 mm (2.5”) positive meniscus focusing optic. This particular optic provides a 100-micron (0.004”) focused spot with a 1.8 mm (0.07”) depth of focus. Our laser of choice was a Firestar 200 W laser because of the customer’s cut speed requirement.

This section of double-coated polyethylene foam
tape and paper liner, with an overall thickness of
70 mils (0.070”), was cleanly cut using 200 watts
at speeds of 850 inches per minute.

At a power of 200 watts, we achieved cut speeds of 21.6 meters per minute (850 inches/minute) using 1.4 bars (20 PSI) of air assist. The adhesive-coated foam and its paper backing exhibit clean edges with no charring.

Marking Painted Aluminum Tags

Although bare aluminum is reflective at carbon dioxide’s 10.6-micron wavelength, anodized or painted aluminum products are perfectly suited to CO₂ laser marking. The CO₂ beam easily removes the pigment from anodize coatings or ablates paint, to consistently create a highly legible mark on aluminum surfaces.

This stamped aluminum ID tag, featuring a painted surface, illustrates how fast and easy the laser marking process really is. We setup a Series 48 (25 watt) laser and an FH Series marking head equipped with a 125 mm focusing lens. This lens provides a 180-micron (0.007”) spot over a maximum mark area measuring 85 mm by 105 mm (3.4” × 4.2”).

This painted aluminum tag exhibits a high contrast laser mark. The 40-character text string was
marked in only 1.09 seconds using 25 watts of
power at a speed of 12.5 inches per second.

In our WinMark Pro laser marking software, we created and positioned a text object and then entered three lines of text. Using WinMark Pro, we could have just as easily created an ID tag with imported artwork, such as a company logo, or added a 1D or 2D barcode.

For this example, our 40-character text string was created using the Simple stroke font with a Text Height value of 4 mm (0.16“). On the Marking tab, we set a Power (duty cycle percentage) corresponding to 25 watts and a Velocity of 317.5 mm per second (12.5 inches/sec). At these settings, we marked each ID tag in a cycle time of 1.09 seconds per tag.

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

Contact Us:

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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