Newsletter 117: Marking Wiper Blades, Marking SMT Capacitors, Cutting Polyester

SYNRAD, INC. - http://www.synrad.com
Thursday, July 28, 2005
Issue 117


Marking Wiper Blades	Marking Ceramic SMT Capacitors	Cutting Polyester Ribbon Cable

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.

Marking Wiper Blades

Rubber, in both natural and synthetic forms, is a material that is easily cut, marked, and drilled by CO₂ lasers. Typical items manufactured from rubber include gaskets and gasket material, floor mats, flapper valves, weatherstripping, and wiper blades. When laser cutting, edge quality is related to the grade of rubber and the amount of carbon added to the formulation.

When marking rubber, the mark is created either by engraving or by discoloration depending on the power density applied to the substrate. The rubber wiper material shown in the photograph exhibits a slightly contrasting mark due to a heat-induced color change.

In this application, slightly contrasting marks were achieved on wiper blade material using an FH Series marking head and 60 watts of power.

To produce the eight-character product code, we set up an FH Series marking head with a 200 mm focusing lens. This lens provides a 290-micron (0.011”) spot with a 5 mm (0.196”) depth of focus over a 134 mm × 165 mm (5.3” × 6.5”) mark field. Using 60 watts of power and a velocity of 35 inches per second, we created the mark in 0.13 seconds. In Tracking applications where this string is reproduced every 114 mm along the length of the blade material, an FH Tracker head using the parameters described above, could mark at line speeds of approximately 150 feet per minute.

Marking Ceramic SMT Capacitors

The change from discrete electronic components to Surface Mount Technology (SMT) devices was a revolution for device and board manufacturers alike. In many cases, SMT devices are several times smaller than their discrete counterparts and their leadless package design helps to reduce, if not eliminate, lead trimming and thru-hole drilling operations.

The problem for manufacturers is how to mark or label individual components when they typically measure only a few millimeters in length and/or width. As a case in point, the surface mount capacitor in the accompanying photograph measures only 2.6 mm by 3.2 mm (0.102” × 0.125”). The solution to miniature part identification is CO₂ laser marking. Because the laser’s output can be precisely controlled, heat input into the part is limited to just enough energy to affect a visible change in the part surface and the laser’s small beam diameter creates legible characters with Text Height values only four to six times the focused spot size.

Text measuring only 0.61mm high was marked
on this ceramic capacitor using 7 watts of power.

To create this CO₂ mark on a ceramic SMT capacitor, we fitted an 80 mm lens to an FH Index marking head. The 80 mm lens provides a 116-micron (0.005”) focused spot with a 0.8 mm (0.032”) depth of focus. Using one of WinMark Pro’s twelve built-in stroke fonts, we created a four-digit part code that measures only 0.61 mm (0.024”) high. In WinMark Pro, we set a Power value corresponding to 7 watts and a Velocity of 9 inches per second. With these settings, the resulting cycle time for each part mark is 0.07 seconds.

Cutting Polyester Ribbon Cable

For years, ribbon cable has been used in the computer and electronics industry as a method to transmit multiple bits of data in parallel between other cards or peripheral devices. Today, you will find ribbon cables in products ranging from appliances to automobiles as manufacturers integrate an ever expanding array of computerized controls and sensors in an effort to increase reliability, safety, and performance.

One example of ribbon cable is this section showing conductors encased between two sheets of one mil thick polyester film. Polyester film (also known as Mylar®) has excellent dielectric properties and is an effective insulator in electrical applications.

Using 10 watts of laser power and an assist gas
of 20-PSI air, clean lengthwise cuts were achieved
on the polyester ribbon cable shown above.

Depending on the width of the data bus required (8, 16, or 32 bit) this ribbon cable, with an assembled thickness of 0.44 mm (0.0175”), is cut to create one or more groups of eight conductors. The beam delivery setup consists of a cutting head equipped with a 2.5” positive meniscus lens that provides a 100-micron (0.004”) spot with a 1.8 mm (0.07”) depth of focus. Using 10 watts of laser power and a 20-PSI air assist, we made lengthwise cuts between groups of conductors at a line speed of 500 inches per minute. The resulting cut edge is exceptionally smooth with no dross or burrs present.

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