Why Your IR Lamps are Probably Messing Up Your Glass
Glass annealing is all about precision. If your temperatures are off by even a tiny bit across the surface, you’re looking at warping or cracks you didn’t see coming. It’s a headache. The real culprit? Your IR lamps. If they aren’t putting out the exact same amount of heat, your batch stability just vanishes.
The “Cold Spot” Nightmare
A lot of people think of IR lamps as simple on/off switches. They aren’t. Imagine two lamps in the same bank. If one is pulling just 2% less wattage than the other, you’ve got a cold spot. In a big batch, this means the first piece of glass gets a totally different heat treatment than the tenth piece. We call this “drift.” It usually happens because the filament wasn’t centered perfectly or the quartz thickness is a bit wonky from the factory. It’s a small detail that causes a huge mess.
Getting the Specs Right
To stop that drift, you have to get obsessive about tolerances. We aim for a wattage deviation of less than ±3% across the whole array. When you hit that, the heat stays flat and uniform across the entire sheet of glass. We also use high-purity quartz. Why? Because impurities make the light shift as the lamp gets older. If you use cheap quartz, the “recipe” that worked in month one will be completely wrong by month three.
The Catch
Here is the thing: high-consistency lamps are great, but they’re picky. They need clean power. If your voltage is jumping around, it doesn’t matter how precise your lamps are—the input is “dirty,” and the results will be too. You’ve got to pair these lamps with a stabilized power supply if you actually want to see your scrap rate drop. Stop wasting your time tweaking timer settings for every single batch. That’s just treating the symptom. Fix the heat source instead. When your lamps are actually consistent, the glass just behaves. Every single time it hits the belt.