Fixing those annoying “cold spots” in your annealing lehr
If you’re working with glassware that has a weird shape—maybe a really narrow neck or a deep, heavy base—you’ve probably dealt with “temperature dead zones.” It’s a nightmare. The heat just doesn’t reach every nook and cranny, internal stress builds up, and then… snap. Your piece cracks. We fix this by using targeted short-wave IR lamps to plug those gaps.
Why air isn’t enough
Most standard heating relies on moving air. But air is lazy. If the shape of your glass blocks the flow, the heat just skips over the hard-to-reach parts. IR lamps are different. They don’t wait for the air to move; they send radiation straight into the glass. By setting these lamps up in a multi-angle array, you can basically “bounce” the heat into those recessed areas. It means the whole piece hits the annealing point at the exact same time. No more guessing.
The nitty-gritty on hardware
We use high-purity quartz envelopes for these lamps. Why? Because they can handle the constant heating and cooling of a lehr without giving up. Depending on what your power grid looks like, you can wire these for 230V or 400V. Now, if you go with high-wattage tubes, you’ll get a much faster ramp-up, which is great. But keep an eye on your control panels. If you’re pushing 2000W+ per tube, your contactors and wiring need to be beefy enough to handle that current, or you’re asking for trouble. As for the install, we stick with R7s or Sk15 connectors. They’re simple. When a tube eventually burns out, you just pop it out and put a new one in. No need to rewire the whole rack or stop production for half a day. Just swap and go.
The catch
IR heating is fast. It’s precise. But it only works if the lamp can actually “see” the glass. If you crowd your conveyor and stack your glassware too densely, the lamps will only hit the outer layers. The stuff in the middle stays cold. You’ve got to find that sweet spot between how much you’re loading and where your lamps are placed. Get that balance right, and the cold spots disappear.