On a high-speed blow molder, the heating tunnel is where the whole cycle lives or dies. Preforms hit the tunnel cold, and the window to get them stretched evenly is measured in seconds. If the IR output drifts even a little, or lamp-to-preform distance is off by a few millimeters, you’re staring down uneven wall thickness, crystallized necks, and line stops. We built our NIR heating lamps to keep that tunnel stable at speed—on Sidel, Krones, SIPA, Husky, SACMI, and Nissei ASB machines.
What matters, technically
Near-infrared (NIR) makes more sense for PET than conventional medium-wave because it penetrates the preform wall faster, heating from the inside out. That shortens heating time and keeps the surface from getting scorched. The emitter uses a high-purity quartz tube with a tungsten filament, tuned to a tight 0.9–1.2 μm band. Specs are matched to OEM heating zones: 2400–3600 W, 230/400 V, 115–230 mm active length, and R7s or custom ceramic connectors. Reflector geometry is fixed to the original focal line, so you keep the same lamp-to-preform distance and a repeatable heat profile.
Why it works in stretch blow molding
Stretch blow molding demands heat exactly where the material stretches—and it needs that heat fast. NIR delivers rapid energy transfer, so the preform hits set temperature with less dwell. You can run higher cycles without burning the surface. The payoff is fewer rejects, better control of grams per bottle, and less energy per part because the emitter only runs when it needs to and cools quickly. Swapping it in is a direct fit: same mounting, same wiring, same control logic.
The details that keep it honest
NIR lamps are tightly focused—powerful, but they require discipline. Keep reflectors clean, verify lamp alignment, and make sure the preform path stays inside the focal window. Match the power supply and control to the lamp’s cold-start behavior; get that wrong and you shorten lamp life and invite temperature drift. After install, run the line for 24 hours and log temperature stability. If the curve flattens out, you’ve got the match dialed in.