Fixing those annoying heat spots in KHS Blow Molding
Ever pull a batch of PET bottles off the line and see that weird, cloudy pearlescence? Or maybe the walls are thick in one spot and paper-thin in another. It’s frustrating. Usually, it comes down to one thing: your heating isn’t uniform. Either your lamps are losing their punch, or the heat field just isn’t hitting the preform where it needs to. The good news is you don’t always need to overspend on OEM parts to fix it. High-spec domestic lamps can often knock those hot spots right out.
The deal with SBO6 lamps
Here is how it works. The SBO6 lamps have to balance power and length perfectly. If the PET doesn’t hit that “sweet spot” temperature (the glass transition point), you’re in trouble. Too cold and it won’t blow; too hot and you’re burning the plastic. We build our tubes to match the KHS oven’s voltage and wattage exactly. Now, if you cram high wattage into a short tube, you get a really dense heat zone. It heats up fast. Really fast. But just a heads-up: that extra intensity puts a bit more stress on the ends of the lamp.
Quartz and the “Drop-in” fit
We use high-purity quartz glass because it can take a beating from thermal shock without cracking. We also use a halogen cycle. This stops the tungsten filament from evaporating and gunking up the inside of the glass. It keeps the light clear. For thousands of hours. And nobody wants to spend their Saturday rewiring a machine. That’s why we use standard R7s or SK15 connectors. You just pop them in. No modifying brackets, no messing with the wiring. It just works.
What happens in the real world
These lamps lean heavily into short-wave infrared. Why does that matter? Because it sinks deeper into the PET plastic and does it faster than long-wave heat. If you’re working with thicker preforms, this is how you kill that “cold core” problem. But there is a trade-off. If you crank up the heat density to get your uniformity back, your oven’s ventilation has to work harder. If you’re pushing more wattage than the original spec to save a failing heating zone,**clean your cooling fans.**If they’re clogged, the oven shell can overheat, and that’s a headache you don’t want.