Getting Your PET Blow Molding Heat Just Right
If you’re doing PET blow molding, you know the drill. You need those preforms to hit the glass transition temperature fast and—more importantly—evenly. If the heat isn’t uniform, you’re looking at a mess. That’s why we lean on halogen infrared lamps. They pack a serious punch, giving you the heat density you need to keep your cycle times tight. The power side of things Most of the setups we see use high-wattage tubes, usually somewhere between 2000W and 3000W, running on 230V or 400V. We go with these higher voltages for a reason: it keeps the current draw from getting out of control while keeping the heat exactly where it needs to be. But here’s the thing. If you’re running a 300mm or 400mm tube at full blast, the heat flux is intense. Like, really intense. Double-check that your cooling fans are actually up to the task. If they aren’t, you’re just asking for your lamp sockets to fry. Glass, coatings, and the “click” We use high-purity quartz for these lamps because it doesn’t panic when the temperature swings. You can flip them on and off rapidly and the glass won’t crack under the pressure. We also add a special coating to some of our tubes. It shifts the emission spectrum so the heat actually sinks into the plastic instead of just scorching the surface. As for the plugs, we usually stick with R7s or SK15 connectors. They’re simple, they fit right in where your old heaters were, and they stay put. Even when the machine is humming along at top speed, these won’t vibrate loose. A pro tip on maintenance Using these lamps lets you dial in your heating zones, which means fewer “cold spots” in your bottle walls and way less wasted plastic. But a word of warning: quartz is finicky. If you touch the glass with your bare hands, the oils from your skin create these tiny hot spots. Eventually, the tube will just burn out. It’s a pain, but it’s avoidable. Just grab some alcohol and wipe the tubes down before you wire them in. It takes two seconds, but it makes your lamps last a whole lot longer in a busy shop.