Getting IR Heating Right for Glass Screen Printing
If you’ve ever run a screen printing line for glass, you know the struggle. It’s a constant balancing act. You need enough heat to cure the ink and stop the glass from stressing out, but if you go overboard? Your edges blur, your patterns bleed, or worse—the glass warps. We use integrated IR annealing bulbs to find that “just right” spot where the lines stay sharp and the glass stays strong. The trick to the heat We stick with short-wave infrared lamps because they don’t mess around. They hit the glass surface fast. This means we can heat the ink and the layer right beneath it without baking the entire piece of glass for an eternity. Here’s the thing: if the glass sits at peak temperature for too long, the ink starts to migrate. Your crisp lines suddenly look fuzzy. By tweaking the wattage and the distance of the bulbs, we keep the heat exactly where it needs to be. Stopping the cracks Screen printing puts a lot of weird tension on glass. If you don’t anneal it properly, you’re just waiting for it to crack—either during the next step of production or, even worse, after it’s already reached the customer. That’s why we spec these bulbs to hit a precise “soak” temperature. It basically tells the molecules in the glass to relax. But you have to be careful. You need the heat to be dead-even across the whole bulb. If you get “cold spots,” you’ll leave residual stress in the corners, and that’s where the trouble starts. The trade-offs Now, high-wattage bulbs are great for speed. They get the job done fast. But there’s a catch. When you cram that much power into a small area, you risk creating hot spots. It’s a gamble. To make it work, your conveyor speed has to be perfectly synced with the lamp output. If the line slows down for a second and you haven’t throttled the power? You’ve just scorched your ink. We usually lean on a PID controller to keep things within a $\pm 5^\circ\text{C}$ window. It keeps the temperature steady so the glass doesn’t take a beating from thermal shock. It just makes the whole process feel smoother.