Stop the Chipping: Why IR Preheating Actually Works
Cutting cold glass is a bit of a gamble. You’re dealing with internal stress you can’t see, and when that diamond wheel or carbide cutter hits the surface, the crack doesn’t always behave. It wanders. That’s how you end up with those annoying chips and corner breaks that ruin a perfectly good sheet. To fix this, we use infrared (IR) preheating. Basically, we warm up the glass just enough to soften things up before the cut ever happens. The “Why” Behind the Heat Here’s the thing: glass is terrible at conducting heat. If you try to warm it up slowly, you just create a temperature gap that adds more stress to the material. That’s why we use short-wave IR lamps. They punch through the surface fast. By getting the cutting zone warm, the glass becomes a little less stubborn. The score line follows a straight path, the break is clean, and you stop seeing those jagged edges. Getting it Right on the Line You can’t just throw any lamp on there. You need high-wattage quartz lamps that can get the glass up to temp in the few seconds it spends gliding across the conveyor. Timing is everything. If your lamps take too long to ramp up, the first few sheets coming down the line are going to be under-heated. And that means they’re going to chip. You also have to watch out for cold spots. If there are gaps between your lamps, you’re asking for trouble. Those gaps are exactly where your corner breaks happen. The whole array has to be perfectly aligned so the edge is hit with consistent heat before the cutting head even touches the glass. The Trade-offs Now, this isn’t some magic button. If you push too much heat too quickly, you’ll hit “thermal shock.” That’s when the glass cracks on its own before you even start cutting. It’s a balancing act between how hot the lamps are and how fast your line is moving. Plus, these lamps get incredibly hot. You’ll want to spend some extra time on your cooling fans and shielding. Trust me—you don’t want to find out the hard way that your conveyor belts can melt or warp under all that radiant heat.