Why Your Glass is Cracking During Annealing
Ever wonder why your glass just snaps during annealing? It usually comes down to a fight between the surface and the core. If the outside gets way hotter than the inside, the material hits a breaking point. In an annealing lehr, this happens when your IR heating profile is a mess. You get these “hot spots” where the glass expands too quickly in one area. Then, as soon as it cools down unevenly—snap. There goes your yield.
The Problem With “Generic” Lamps
I see this all the time. An operator grabs some generic lamps that don’t actually match the machine’s specs, thinking they’re saving a few bucks. But here’s the thing: if the wattage is too high for the length of the tube, you’re basically slamming the glass with more energy than it can handle. The heat hits the surface like a hammer, but it can’t soak into the center fast enough. You end up with a massive temperature gap. That’s why we don’t guess. We calculate the exact wattage-per-centimeter. It’s the only way to make sure the heat actually penetrates the glass without scorching the top layer.
Short-Wave vs. Medium-Wave
The type of IR you choose changes everything. Short-wave lamps are aggressive. They hit hard and fast. If you’re working with thin sheets, that’s a recipe for disaster. We often use coated quartz tubes to bounce that heat back toward the glass or dial back the output. It stops that annoying “striping” effect—those little lines of stress that eventually turn into full-blown cracks.
When the Line Stops (The 7-Day Fix)
There is nothing worse than your line grinding to a halt because an OEM part is backordered for months. It’s a nightmare. We handle those emergencies in about a week. But we don’t just look at the label on the old lamp and copy it. That’s how mistakes happen. We map out your actual voltage and footprint and verify the electrical load. A replacement has to match the original resistance perfectly. If the voltage drifts or a connector is even slightly loose, you get arcing. And arcing creates instant heat spikes. One spark, one spike, and your glass is in pieces.