Why Your IR Lamps are Probably Ruining Your Glass
If you’ve spent any time in a glass tempering shop, you know the frustration of “drift.” It’s a nightmare. You nail one rack perfectly, but the next one comes out bowing or stressed for no apparent reason. You start questioning everything. But here is the secret: usually, it isn’t the oven acting up. It’s the lamps.
The problem with “close enough”
When you’re using shortwave infrared preheating, tiny differences matter. If your lamps have even a 5% variance in wattage or spectral output, you’re basically baking the glass unevenly. You get cold spots, which lead to uneven thermal expansion. That’s why we obsess over the small stuff—things like how the filament is wound and the purity of the quartz. When you wire up a bank of 20 lamps, you don’t want 20 individual heaters fighting each other. You want them to behave like one single, massive, uniform heat source. That’s the only way to get a consistent result.
Power, heat, and the risk of burnout
High-wattage shortwave lamps are great because they get you up to temperature fast. But pushing that much heat into such a small space is brutal on your hardware. If your connectors and wiring aren’t up to the task, they’ll fry. We use heavy-duty contacts to stop those terminals from burning out. And a quick tip: keep an eye on your power supply. Voltage spikes are absolute killers for these lamps. One bad surge and you’re swapping tubes.
The balancing act
It’s tempting to just crank the wattage to speed up your cycle times. Sure, you can do that. But there’s a catch. If you run your lamps right at the edge of their thermal limit, the filaments are going to snap sooner. You’ll get your glass through the door faster, but you’ll spend a lot more time climbing ladders to replace dead lamps. Most of the shops we work with eventually find a “sweet spot.” They balance the rated life of the lamp against the actual surface temperature the glass needs. Once you get your lamps matched and stable, the batch variance mostly disappears. Everything just… works.