Joint Fabrication Session Provides Handling Tips

This morning's joint session on insulating, laminated and tempered glass during the Glass Fabrication and Glazing Educational Conference gave listeners some basic understanding of the product they handle daily, in addition to tips for proper handling.

Wayne Boor of Pittsburgh-based PPG Industries opened the joint session about 4,000 years ago, so to speak; his presentation on "Float Glass Technology" began with background on the discovery of glass. Speeding quickly through the production of sheet glass in early 20th century to plate glass to float glass in 1959, Boor moved onto discussing the technology used today to create the basic material used by each member of his audience.

One point he touched on-particularly interesting in Las Vegas with its love of color-was how to add color to glass substrates.

"We learn to make different colors everyday," Boor said, "and that is market-driven."

As Boor noted, iron, in all glass, creates the green tint. Cobalt is added to create what he described as "true blue," while selenium creates "more of a brown glass." Combinations of the latter two create shades of gray. He further explained to the audience that low-iron glass means just that, removing as much iron as possible, and to do so requires a special sand with low levels of iron.

"Low-iron glass is really becoming popular in the solar and photovoltaic industry," Boor said, adding, "they would like us to have no iron." Of course, as he notes, "I think it's impossible because you're going to have some impurities no matter what you do."

In addition to modifying the color, Boor explained, modifying the glass materials can create different properties. "You can actually make the substrate (not to the extent of a coating) somewhat spectrally selective. You do that by modifying the chemistry of the glass … [The result will allow] more light than typical glass but will block the infrared."

In addition to learning some of the basics of altering glass itself, attendees learned a little about properly "altering" glass through cutting. In a session covering "Automated Glass Cutting and Edging Techniques," Chuck Beatty of Edgeworks Inc. stressed the importance of the cutting process in glass manufacturing. Beatty went as far as saying the cutting process is what ultimately determines long-term success for glass processing companies.

"If you cut glass well, everything else is easier," he explained. "If you cut glass well, you're probably going to be successful and profitable. If you don't cut glass well? Good luck."

He offered a number of suggestions for a successful cutting process, including the importance of matching the proper cutting wheel to a particular process and product.

"I prefer to think of the cutting wheels like the tires on your car," he explained. Just as you would select a certain tire for a particular driving condition, Beatty suggests matching cutting wheels to a particular product.

Beatty also urged processors to consider the benefits of cleaning glass prior to the cutting process. Some of Beatty's customers subscribe to this method, while others do not. But the benefits, he says, make it an essential part of the process.

"The problem is most people don't wash," he says. "And the cutting environment is dusty and dirty."

Beatty says cleaning also helps maintain temperature, which he describes ad the number one enemy in glass cutting.

"Glass doesn't like to be expanded," he explained. "When you're processing glass, the greatest enemy is heat. Your ability to manage heat during the process will ensure that the end product is strong."

Jeff Haberer of Cardinal IG followed Beatty with a session on "Handling Coated Glass." He referred specially to "two different methodologies for producing coated glass: one is the pyrolitc process (hard coat) and the other is sputtered process (soft coat)."

Among the big tips Haberer offered was essentially to keep the coating protected.

"The more things you keep away from the coating, the less problems you'll have," he said. "It's commonsense."

For instance, keep individual lites from scratching one another during the handling process. Keep coated surfaces away from conveyor rollers and harp rack separators. Even, Haberer advised, keep fingers away from the coating. And when it comes to handling that glass, be sure to use some type of clean, soft glove; touch only the edges; and handle only one lite at a time.

Not that the glass won't be handled and touched. It's just a matter of doing it carefully.

"Any process, we're going to want the coating up. We rarely ever, if ever, run the coating down," Haberer said.

For washing, for example, Haberer suggested adjusting the tip of the brushes so that they are barely in contact with the glass. "Just brush off the surface, you don't want it scrubbing there … with low-E coatings you can damage if scrub too much"

There's that topic again-glass washing. Such is it's importance that Bob Lang of Billco Mfg. Inc. provided a seminar on "Understanding and Maintaining a Glass Washer."

Among the tips Lang provided was this reminder: "If the inside of the glass washer is dirty, it can't produce clean glass."

He reminded his audience that maintenance of these washing machines is critical to getting the best performance from the equipment and, by extension, the glass product going through it. "I can't stress it enough; the cleanliness of the glass coming out of washer is directly related to how well the washer is maintained."

He suggested maintenance schedule starting with the first week of operation (during which operators are recommended to tighten fasteners, grease the entire machine and perform proper motor rotations), on through weekly maintenance (such as cleaning tanks and removable screens, checking air filters, and sparingly greasing pinch roll bearings) and, ultimately, a 500 hour check-up (for inspecting brushes and rolls and cleaning all rolls, checking brush adjustment, checking belt and chain condition and adjustment, etc.).

If after all of that proper maintenance and caution taken with handling glass products an inspection turns up a mark that shouldn't be there, Lang had some suggestions for that too. First, he advised, if there are marks the washer should carefully examine what surface it is on and the direction as it relates to the conveying direction to figure out where to look for a problem. Scratches can be caused by processes prior to washing, among other things, he noted. Smudges can occur from fingerprints, leftover adhesive from a sticker that's been removed or even dirty marks on the rollers, especially during the drying process. Streaks can be the result of minerals and rinse water that has dried on the glass. Stains often occur from condensation that has formed during shipping or storage, and typically can't be removed by brushes. Likewise, defects won't be removed from the cleaning process. And "random marks" may turn out to be defects, debris that has fallen during the drying process or drops of algae that accumulated during the rinse.

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