Newsletter 127: Marking Stainless Steel, Cutting Interior Trim Panels, Machining Alumina Ceramic

SYNRAD, INC. - http://www.synrad.com
Thursday, December 15, 2005
Issue 127


Marking Stainless Steel Parts	Cutting Interior Trim Panels	Machining Fired Alumina Ceramic

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 Stainless Steel Parts

Manufacturers specify stainless steel for a variety of consumer and industrial products because of its corrosion resistance, durability, and aesthetic appeal. Stainless steel performs well in both high- and low-temperature environments and the ease with which stainless is cleaned and sanitized makes it the ideal choice in the health care, pharmaceutical, and food processing industries.

When it comes to marking stainless steels, Firestar t-Series lasers are an excellent choice due to their fast rise/fall times. With rise/fall times less than 75 microseconds (< 0.000075 seconds), our t-Series lasers provide a greater depth of modulation for a given marking frequency. This means that a larger percentage of peak energy is applied during each “laser on” pulse.

We marked this nicely contrasting 10-character
code on 316 stainless steel with 60 watts of
power in a cycle time of only 0.22 seconds.

To mark this right-angle connector, stamped from 316 stainless steel, we setup an FH Series marking head with an 80 mm lens to achieve a 116-micron (0.005”) spot over a 33 mm by 41 mm (1.3” x 1.6”) mark field. In WinMark Pro, we created two text objects and typed a fixed part number for the first part of the code. The second half of the date is a Julian date code (DDDY format) that is set to increment automatically based on the mark computer’s system clock. We chose a stroke font (Simple), set a Text Height of 2.3 mm (0.09”), and added 0.25 mm (0.01”) of Extra Character Spacing. At a Power percentage corresponding to 60 watts and a mark Velocity of 6.5 inches per second, we marked this 10-character text string in a cycle time of 0.22 seconds.

Cutting Interior Trim Panels

In the automotive industry, uptime is paramount. The key to increased throughput is to reduce the time required for “makereadys” or equipment changeovers as the production line is reconfigured to produce another component. Whether for trimming fabrics or degating molded parts, lasers are a key factor—instead of mechanically changing and aligning an entire die, the laser’s motion controller is simply reprogrammed by loading the appropriate cutting file. The laser’s ability to make precision cuts piece after piece allows you to layout cutting files to minimize waste and produce the maximum number of pieces per unit of material. The laser’s fine power control means that output power can ramp down proportionally in the event that one or more motion axes slows down while executing a tight contour.

As the photo shows, the laser-cut fabric edge is clean and sealed, which eliminates fraying, while
the fiberboard backing exhibits very light charring.

For this cutting trial, we were asked to cut a 5.3 mm (0.210”) thick automotive interior panel consisting of a 0.5 mm (0.020”) thick woven fabric that was stretched over 2.8 mm (0.110”) foam padding and glued to a 2 mm (0.080”) fiberboard backing. To demonstrate feasibility, we setup the cutting head on our XY gantry system with a 63.5 mm (2.5”) positive meniscus focusing lens to achieve a 100-micron (0.004”) focused spot with a 1.8 mm (0.07”) depth of focus and then we selected clean, dry air at 40 PSI as the assist gas.

In this situation, the Firestar f-Series laser is the CO₂ laser of choice. With the RF power supply integrated into the laser chassis, f-Series lasers are easily mounted on moving gantries or robotic arms without the need to accommodate RF cables. At a power level of 100 watts, we trimmed the panel to size at cut speeds of 3.18 meters per minute (125 inches/minute). As the photo shows, the laser-cut fabric edge is clean and sealed, which eliminates fraying, while the fiberboard backing exhibits very light charring. Because of its lower melting point, the central foam padding is undercut by approximately 0.5 mm (0.20”) and the outer edge is melted, however this melting extends only 0.025 mm to 0.050 mm (0.001” to 0.002”) into the foam and does not affect its resiliency.

Machining Fired
Alumina Ceramic

The use of alumina ceramic materials in the biomedical and electronics fields is becoming commonplace due to the superior wear and corrosion-resistance properties of ceramic. Orthopedic joint implants now feature ceramic components and alumina acts as a substrate for many thin-film electronic devices. In industrial environments, alumina ceramic is frequently used to manufacture nozzles, dies, seals, and wear plates.

There are two methods for manufacturing alumina ceramic components. The first is to shape ceramic powders and binders into a “green body” and then create any holes or openings in the part before it is fired at temperatures ranging between 700 °C and 1500 °C. The second manufacturing method is to machine—cut, scribe, grind, or drill—the fired alumina. Although difficult to accomplish, machining fired alumina is often necessary for tight tolerance parts due to subtle variations in part-to-part shrinkage during the firing process.

The part layout consists of 16 individual pieces
on a sheet of 0.5 mm (0.02”) thick alumina.

This application illustrates the quality and ease of machining thin-sheet fired alumina using a Synrad sealed CO₂ laser. As shown in the photo, the part layout consists of 16 individual pieces on a sheet of 0.5 mm (0.02”) thick alumina. With a power level of 100 watts, the four thru holes and rectangle on each part were cut out at a speed of 0.15 meters per minute (6 inches/minute) using a pulse duration of 2 ms at a frequency of 143 Hertz. After cutting, the area between each part was laser-scribed to create a “perforated” line so that pieces are easily separated from each other by snapping along the score line.

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The next Applications Newsletter will be e-mailed
Thursday, January 5, 2006.

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