Why we preheat glass before cutting it
Cutting glass is basically just a fancy way of breaking it on purpose. But if you try to score a sheet at room temperature, things often go sideways. You get those annoying chips or corner breakouts that make the whole piece look amateur. That’s where infrared (IR) preheating comes in. It changes the way the glass reacts when the wheel hits it.
The “Why” behind the heat
Think of it this way: heating the surface relaxes the glass. It lets go of that internal tension. When the glass is warm, it takes way less energy to start the crack, which means the break actually follows your score line. If you skip this, the crack can jump or wander. Then you’re stuck with jagged edges and a lot of wasted time spent grinding them down. Nobody wants that.
Getting the gear right
We usually go with short-wave IR lamps. Why? Because they hit the surface fast. You don’t need to bake the entire sheet of glass; you just need the top layer ready to go. If your conveyor is moving quickly, you need a lot of heat hitting the glass in a very short window. The trick is all in the positioning. Too far away and you get cold spots. Too close and you risk thermal shock. You’re aiming for a sweet spot—usually between 60°C and 120°C—right as the cutting head moves in.
The real-world catches
Now, this isn’t some magic wand that works for everything. It’s great for float glass, but be careful with ultra-thin sheets or heavy coatings. Those can overheat in a heartbeat. You’ll want to spend some time dialing in your PID controllers. Here’s the thing: if your conveyor slows down but your lamps are still cranking at 100%, you’re going to warp the glass. Plus, make sure your cooling zone is big enough. You need that residual heat gone before the glass hits the stacking area, or you’re just asking for trouble.