Why your IR lamps are ruining your glass batches
Ever notice how the first few pieces of a run look perfect, but by the time you hit the middle or end of the batch, things start going sideways? You see internal stress or weird optical distortions, and suddenly you’re staring at a pile of scrap. It’s frustrating. And usually, it comes down to “quality drift.” Here’s the thing: it’s all about the heat. If your infrared lamps have even a tiny variance—say 5%—in their wattage or output, you’re not getting a steady soak. You’re getting hot spots and cold zones. In the world of glass, a couple of degrees of difference is the gap between a product that ships and one that goes in the bin.
Getting the heat right
We obsess over consistency because those temperature gaps are the enemy. When we talk about a “consistent” lamp, we’re really talking about the guts of the thing—how the filament is wound and how pure the quartz envelope is. If the filament winding is sloppy, the heat doesn’t flow in a straight line. You end up with “striping” on your glass. But when the radiant energy is spread evenly across the whole tube, every single piece of glass gets the same treatment. It doesn’t matter if the piece is at the front, back, or middle of the oven. It just works.
The balancing act
Now, more heat isn’t always better. If you cram too much wattage into a small space to speed up your preheating, you’re playing with fire—literally. Ramp up too aggressively and you’ll trigger thermal shock. You’ve got to find that sweet spot between the lamp’s output, how fast your conveyor is moving, and your cooling cycle. Plus, if you go for high-density lamps, just double-check that your power supplies can handle the initial surge without tripping your breakers. One last tip: keep an eye on your replacements. These lamps are built to stay stable for thousands of hours, but eventually, one will burn out. When you swap in a new one, it needs to be a perfect match for the rest of the bank. If that new lamp runs even slightly hotter than the old ones, you’ve just created a brand new hot spot in your process. And we’re right back where we started.