Fixing those annoying heat spots in your KHS blow molding
Ever deal with bottles that just won’t come out right? Maybe the walls are too thin in some spots or the whole bottle looks a bit warped. Most engineers start by obsessing over the machine settings, tweaking dials for hours. But honestly? The problem is usually the lamps. If the heat isn’t hitting the preform evenly, no amount of setting-tweaking will fix it. That’s where we come in. We’ve spent a lot of time figuring out how to make high-end quartz tubes that don’t just “work”—they actually match or beat the OEM heat distribution. The secret is in the winding. Think of a quartz heater tube as more than just a wire in a glass tube. For KHS machines, the way that tungsten filament is wound determines exactly where the heat lands. If the winding is off, you get “cold spots” at the ends. We’ve calibrated the pitch of those windings to kill off those cold spots entirely. This means your PET preform gets the heat it needs across the whole length, making the plastic soft and ready to blow in all the right places. Better materials, better results. We use high-purity synthetic quartz. Why? Because when you’re pushing high wattage, cheap glass burns out. These are designed to be drop-in replacements, so you don’t have to mess around with the installation. We also tightened the tolerance on how the filament sits in the center. It sounds like a small detail, but it stops energy from leaking out and forces the infrared heat straight into the plastic. The result is a much tighter thermal footprint. You can actually turn your oven temperature down a bit and still get the same (or better) bottle quality. A few things to watch out for. Here’s the catch: these high-density tubes put out a lot of heat, which means more stress on your sockets. If you’re upgrading to higher-wattage tubes to fix those cold spots, do yourself a favor and check your wiring. Old, crusty, oxidized connectors create resistance. That leads to overheating at the base, and nobody wants that. And one last tip:replace the whole set. Don’t mix and match old tubes with new ones, or different brands together. It creates a jagged heat field, and you’ll end up right back where you started with uneven bottles. Just swap them all out and get it done right.