Volume 43, Issue 6 - June 2008
From Silica to Siding
The Glass Fabrication and Glazing Educational Conference seminars opened to full crowds at the Monte Carlo in Las Vegas this April. The event, sponsored by the Glass Association of North America (GANA), was designed to educate individuals who have fewer than five years of experience in the industry.
As there’s always something new to learn, the conference featured two joint sessions each day that provided information on glass handling, glass production and trends in glass usage. To start in the beginning, from the trends pushing glass usage, through production and installation, read on. But if your interests are more specific, choose your own track: fabrication information is below or skip to page 76 for more on glazing education.
Give an Architect A Lite and He’s Going to Want It Coated
“We’re starting to see more floor to ceiling glass,” McCann said. And on that glass, architects are demanding high-performance coatings. He noted that more hybrid materials are being used to get the best of all performance features, from high visible light transmittance (VLT) to low U-values.
High VLT in particular has become much in demand. And, McCann said, “That’s one of the hardest things to get an architect off of.” Not to persuade architects away from letting in more light—but educating them about what high VLT really means and how a combination of coatings can create a room that has lots of visibility and is still comfortable. Laminated glass also is still growing, McCann said, for hurricane-resistant and security applications, as well as acoustics.
What’s driving these trends? Among several factors is the biggest trend of all, the focus on energy. As McCann noted, the costs of energy continue to rise. “When you start looking at building applications, buildings tend to be one of the higher consumers of electricity as well as natural gas.”
So how do glass manufacturers meet the demand for these trends? Well, glass fabricators were in attendance to learn just that—the ins and outs of handling and creating value-added glass.
Floating Through the Basics
One point he reviewed—particularly notable when surrounded by the flashiness of Las Vegas—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 noted, “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.”
Cut Down to Size
“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 said, make it an essential part of the process.“
The problem is most people don’t wash,” he said. “And the cutting environment is dusty and dirty.”
Beatty said cleaning also helps maintain temperature, which he describes as 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.”
Hands Off That Coating
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.
There’s no way to keep the glass from being handled and touched at all; it’s just a matter of doing it carefully.
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 you scrub too much.”
Cleanliness is Next to Successfulness
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 enough that the cleanliness of the glass coming out of washer is directly related to how well the washer is maintained.”
His suggested maintenance schedule starts 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 (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.).
Tensed and Shattered
Essentially, he explained, glass breaks when an applied load exceeds the strength of the glass. The real question is: when a break occurs, was the load too great or was the glass too weak?
To begin to answer that question, Barry noted, means asking how strong glass is, and that’s where the problems begin. “We don’t really know,” he said. “We know how strong it might be.”
For example, in taking 1,000 samples lites and applying force, by the time 9,000 psi was reached, eight lites still hadn’t broken. In other words, the breaking point for each lite was reached at a different point.
There are a couple of common causes of breakage, however: tensile stress (including bending, thermal stress and NiS inclusion and expansion), impact and crushing. To determine what might be the cause, fractographics can be used to examine the break—if there’s enough time and money and all the broken pieces are still available, Barry added.
When preparing the glass, Cowles said to avoid mismatched glass and when washing the glass, water temperature should be 120 to 140 degrees Fahrenheit. “Cleaning the water tank thoroughly once a week will also help the way it works to provide consistency,” he added.
The condition of the clean room also is critical. Humidity should be 20 to 35 percent and temperature should be 55 to 72 degrees Fahrenheit. “Cleanliness is imperative,” Cowles added, and suggested the use of a double-door entry to keep the factory environment out of the clean room. “Also, use tacky mats at the entry door to keep fibrous materials out of the clean room,” he said, adding that clean room clothing also needs to be considered. “You need something that won’t leave debris, lint, etc. Those are all enemies of the process.”
Troubleshooting laminated glass production was the next topic of discussion. Ron Hull from DuPont talked about how companies can improve their yields, reduce costs and improve quality and customer satisfaction through troubleshooting.
“Troubleshooting is one way to get lean,” said Hull, who cited Six Sigma as one particular troubleshooting process. “Since the economy has slowed down [there’s been more] interest in improving yields, quality, etc., as people now have time to focus on being lean.”
Hull also talked about common laminating defects and problems. One problem is PVB blocking, which occurs when the PVB sticks to itself. It’s typically caused when the storage temperature is too warm, when the rolls are wound too tightly or if the rolls are too old. To keep this from happening, Hull suggested that storage temperatures be kept cool and that the laminator has a supplier unwind and wind the roll properly. Like Cowles, Hull also recommended first-in/first-out inventory control. Finding bubbles in the laminate was another problem he discussed. The bubbles, Hull said, are actually gas pockets in the interlayer material or between the glass and the interlayer. “Basically, inadequate de-airing,” he said. Bubbles can be caused from a surface pattern that is too smooth or rough; from caliper/thickness variations; from stretching the PVB; and also if the PVB temperature is too high or too low. Other factors to consider when troubleshooting laminated glass include the measurement systems in use, machinery and equipment; materials used; and even the shifts people work and employees’ level of experience.
While the use of PVB may be the most common interlayer in use for laminated glass production, it’s not the only one available. Michael Burriss from Cytec Industries gave a presentation about ultraviolet (UV) liquid laminating. He explained that by exposing liquid resin to UV light it changes into a polymer that, in the case of laminated glass, serves as the solid interlayer. He said it takes 20 minutes for the glass to cure fully, and that the UV lights are controlled for a consistent cure. He added that the process consumed a minimal amount of energy: 7 kilowatts. In addition, Burriss said UV-cured laminated glass meets the same safety tests as PVB laminated glass (CPSC 16 CFR 1201, category I and II; and ANSI Z97.1), so the products can be used wherever safety glazing is required. The products also can be used in ballistic and bomb blast applications and offer acoustical performance as well. Decorative options, such as color and textures, can be incorporated too.
Mark Gold of Solutia covered the why, what and how of laminated glass quality control testing.
“Why test?” asked Gold, “Because we have to; it’s the right thing to do,” he explained, for regulatory and code requirements, as well as protection against liability and assurance that specifications are met. “Also, it’s just plain, good business.
”He discussed different types of tests that can be done to laminated glass, such as the boil and bake tests. When boil testing, Gold said, look for bubbles, trapped air, air penetration, de-lamination, contamination and optical distortion. With the bake test, which Gold described as a step up from the boil test, he recommended laminators get a good oven. “Have the right equipment and obtain, read and understand all of the test procedures,” he said.
“You can use it for anything,” Beneke said. She also took the crowd through a demonstration of using the 3D design tool, and left the crowd impressed with how quick and easy it can be to not only create a structure but also to change out components.
“Would you know what the tolerances that adjoining trades will be held to?” he asked. “This is a big, big problem. You need to know the tolerances of other trades or you can end up not being able to fit in the openings with glass that. “What are the packaging and hoisting requirements? This may seem like a small matter, but it’s not,” said Heinaman, as he reviewed a series of slides with checklists on them. “Do you know if the joinery seals are sufficiently detailed?” he asked. “Remember, glass doesn’t leak, aluminum doesn’t leak—but other materials do and you need to anticipate what will happen.” And speaking of details, keeping details documented was another point Heinaman stressed.
“In our business we really can’t over-document things. It’s not possible. But we have to do it on all jobs,” he said. “You can’t document well on a big job and not do it on the little ones. That’s not a wise practice. You can get sloppy. You should have policies and procedures in place on how you do things.”
Heinaman also discussed the importance of safety procedures for the company in general and on each job specifically. “Is a safety plan a requirement?” he asked rhetorically. “It sure should be. I have had very few cases where I haven’t been asked for one. If you have a large project, you should have a safety plan just for that job. This is usually accomplished by taking your standard safety program and customizing it for the job,” he said. Heinaman added that most insurance companies are willing to send a representative to the jobsite.
“It’s wise for you to have them come and inspect your job. It could reduce the likelihood of an accident, could also reduce your mod rate and increase your bottom line,” he added. “Don’t assume anything. Inspect all safety equipment. You might say ‘well, gosh, of course we would do that. But I have heard of instances where no one checked the swing stage for frayed wires and to make sure that it’s attached to something at the top of a building. You want to check it yourself. If you have to go to the edge of the building even for a moment, you must be tied off. That could be the moment you trip and over the side you go.” He also recommended doing field water tests but allowed that sometimes general contractors don’t want this. “You need to tell them up front, ‘Well, we need to do it right and we need to test.’”
Know from the start what’s expected of you,” Wirth said. “The least expensive way to correct a mistake is not at the end; it’s before it happens.”
One specific area she covered was operational training.
“Don’t be a dictator,” she advised, “but work as a team.” She reminded her audience that when they are passing the project over to the customer they need to take the time to explain to them how they need to take care of the building.
Another discussion point was having a lien waiver.
“Anything that reduces your liability is always a good thing,” said Wirth, who suggested each company have one dedicated person on-hand who understands and documents waivers that are coming in and out. On a final note, she stressed that in project closeouts documentation is critical and encouraged everyone to keep organized all of the documents related to the job, including both paper and computer files, drawings and e-mails.
Making the Code
Rob Hitchcock from Lawrence Berkeley National Laboratory followed with a discussion about COMFEN software, which is used to provide a whole building calculation. Version 1 of COMFEN, which was launched last fall, helps provide specific design guidance on commercial buildings and facades.
“The focus is on energy consumption and demand, visual and thermal comfort and CO2 emissions,” said Hitchcock, explaining that the software tool is under continual development. “We’re working on the second version and looking ahead to version three and beyond.” He said they would be looking into ways to enhance the glazing, framing and shading selections.
Mike Gainey, also of Azon USA, gave a presentation about the improvement of thermal performance in structural aluminum windows. He posed the question, “What does a thermal barrier do?” The answer: “It interrupts the heat transfer from hot to cold.” Gainey talked about the energy performance levels of using thermal barrier systems and how they can help greatly reduce energy costs and usage. He explained the window systems can be made more energy-efficient not only through the use of a thermal barrier as part of the aluminum frame, but also through the use of a warm-edge spacer in the insulating glass unit.
“The benefits are overall U-factor improvement,” Gainey said, adding that the key goal is also to minimize condensation as much as possible.
From Codes to Certification
Perilstein said it’s not that he’s opposed to the program itself. “A whole system calculation is a great design tool,” he said. “But it all goes downhill being attached to the certification and rating aspect [because of the costs involved].” He also talked much about how several individuals have been very involved in representing the unique needs of the commercial glazing industry but “despite meetings and despite their efforts they have not made the greatest of inroads.”
In addition, Perilstein talked to his audience of contract glaziers about how they specifically would be affected by the CMA program.
“You will have to pay for performance, pay for the test labs, the certification … all of this will have to go into your bids and your quotes. You will have to supply rated materials for the jobs and you will have to pay for it,” said Perilstein. “[The NFRC] does not understand what you do already.”
Perilstein said a CMA prototype will be going through testing in May and June this year, with more testing to come in October. A six-month pilot launch is planned for January 2009, with a full release scheduled for August of 2009.
In ending his presentation, Perilstein encouraged industry members to speak up and get involved. “It’s been a challenge to get people to come to the NFRC meetings,” he said.
That’s a challenge GANA certainly hasn’t faced. As executive director Bill Yanek noted, “GlassFab delivered on its goal of providing top-notch glazing education to industry newcomers and veterans alike. GANA is always striving to make its meetings better, and GlassFab 2008 was no exception.”
Applying the Glass Fab Knowledge to Today's Biggest Trend
Megan Headley is editor, Ellen Rogers is contributing editor, Drew Vass is assistant editor and Debra Levy is publisher of USGlass magazine.