Volume 42, Issue 6 - June 2007
Those New to Fabrication
Take in Two Packed Days of Education and Information
by Ellen Giard and Megan Headley
If you’re new to it, some aspects of the glass industry might seem a bit a confusing at first. With terms such as roll wave, quench, air space, ballistics and dual seal coming at you from all sides, you might just be wondering where to begin. And while it might be nice to travel the country seeing all of the experts for special one-on-one sessions to find out what these terms mean, that’s not really practical.
The Glass Association of North America (GANA) provides a solution. Every year, the organization offers an intense, two-day program to those new to the industry about fabrication techniques and much more. Each day begins with a general session and, in the afternoon, attendees can choose to take part in sessions specific to insulating, laminating or tempering processes.
GANA’s Glass Fabrication Conference took place this year April 16-18 at the Hyatt Regency Pittsburgh International Airport. The conference saw record attendance, with more than 170 participants in attendance.
He explained that “glass has a skin” and that the “layer of skin is protecting a layer of tension within the glass.”
If that tension is released, it will break the glass. To stop that from occurring, Beatty said it is important to support the glass when cutting and to choose the right tool for the job.
“If you choose the wrong tool, or you use one tool to do too many jobs, your [possibility of] success is questionable,” he said. It’s also important to know how much pressure to apply with the tool—as well as the correct angle to use—to create only the desired fissure and not subsurface breaks that can weaken the glass.
“For coated glass, I would choose a wheel that is 10º sharper on angle,” Beatty said.
Mitch Edwards of Guardian Industries Corp. explained that the coated surface must remain up when cutting coated glass. “About the only thing you want to touch the surface of the glass is the cutting wheel,” Edwards said. In keeping with that advice, only minimal amounts of approved cutting fluid should be used.
Handling Coated Glass
Sputtered is done completely off-line. “It’s a very thin coating and that’s why it takes a bit of special handling,” he said.
Pyrolytic coatings are applied on the float line and are rougher in comparison. Edwards said that in some cases people will rub the surface of the glass to detect a pyrolytic coating. “Sputter-coated films are not rough like pyrolytic films and cannot be felt with bare hands,” he said.
There are sophisticated tools available to detect coatings. An ohmmeter measures electrical resistance and shows a reading when the meter is placed on the coated side of a lite. It must be used near the edges of the glass and, Edwards cautioned, metal contacts may leave scratches on the coated surface. There are also commercial coating detectors available that are easy to use and won’t damage the coated surface.
Once you’ve determined that the glass is coated, the next challenge is handling it correctly. Edwards also recommended keeping the materials clean and dry and unloading glass under dry indoor conditions, and storing it out of sunlight and at least 50 feet away from glass washers, chemicals and corrosive materials. He also suggested keeping the storage area clean and well ventilated and ensuring that storage containers remain stable. Similar requirements apply for handling coated glass. Handlers should wear clean and dry gloves, and suction cups should be clean and properly aligned.
Washing Glass Washing Machines
Lang stressed that clean water is another important component. Minerals in dirty rinse water can stick to the glass and cause adhesion problems later on.
In addition to using quality water, Lang noted that many companies are looking to use less water. “In more and more areas of North America, companies are being asked to conserve water,” he said.
He suggested re-circulating rinse systems or a closed loop water filtering system to help use less water. Lang also touched on proper brush maintenance. “Adjust the brush so that no more than 1⁄32 of a bristle is touching the glass,” he said.
Tom Parseghian of Power Brushes Inc. elaborated further on brush maintenance. He began with the basics: “It’s tough to clean a brush.” He told attendees its best not to use power washers on their brushes because it can permanently bend and damage them. He also advised that brushes should be stored so that the bristles are not fully supporting the brush and that they don’t touch.
“All brush material has a memory, like carpet,” he said. If stored poorly, he suggested giving it some time and adding moisture so that it returns to its original state.
“In the glass business you deal with both tension and compression,” he said. “When you run the glass through a tempering furnace you have permanent tension.”
He explained that tension, not compression, can cause glass breakage. Tension can come from stress and cracks, he explained. There are two types of stress: permanent and temporary. At room temperature all glass has permanent stress. Temporary stress comes from heating, cooling or a combination of mechanical and thermal applied forces.
He also talked about some of the considerations that fabricators must take into account when running a tempering furnace to ensure the glass is good.
“If you’re going to cut the glass,” Maltby said, “You must have uniform temperature.” He explained that when the glass comes out of the furnace and it is easily cut very little heat is being lost in the furnace.
But the most important matter, he said, was to pay attention and to look at the glass carefully.
“You can look at the glass, look at the flaws and learn a lot about it.”
Codes & Standards
“Generally, they are specific to a building system, such as glass,” he said.
The federal code that regulates glazing is the Consumer Products Safety Commissions (CPSC) 16 CFR 1201. This sets mandatory glazing regulations for hazardous locations including swinging doors, patio doors, showers and fixed or operable panels next to a door, among others.
While building codes are enforced, a standard, on the other hand, can be a specification, a test method or a practice. Standards, Gold said, are voluntary unless they are referenced by a code. For example, the International Building Code references the ASTM E 1300 standard.
Green Building Design
“Buildings use a tremendous amount of energy, so we are looking for ways to reduce the amount used,” she said.
Glass can play a key part in this, especially in the energy and atmosphere category. Glass products not only help to reduce energy costs, but also include other energy-efficient measures such as improved glazing, daylighting and passive solar features (i.e. photovoltaics).
“What’s the best way to heat every type of glass?” he asked. “It depends on the material being heated.”
Conduction, he explained, happens when the glass is heated through direct contact. In other words, hot, ceramic rollers in a tempering oven actually touch the glass.
Convection involves blowing hot air onto the glass. “When you want more convection, you blow more air,” he said.
Radiation is when all of the hot surfaces radiate heat toward each other. The walls of the oven, for example, radiate heat toward the glass.
And going forward? McCann says we can also expect to see developments in areas such as cell-phone friendly glass and bird-friendly glass. He said birds flying into the glass is a common concern for many building owners.
“You can actually get a LEED point for innovation with bird-friendly glass,” McCann said.Ready for More?
Dates and location for the 2008 Glass Fabrication have not yet been announced. To learn more about GANA and its conferences visit www.glasswebsite.com.
the authors: Ellen Giard and Megan Headley are the editor and assistant editor, respectively, of