Microwave
With microwave curing, the heat is generated directly inside the material itself rather than starting at the surface – so thicker cross-sections cure noticeably faster and more evenly. The energy comes from magnetrons or modern solid-state technology and is coupled in differently depending on the application: the classic way is through a lid, shaft, or rod antenna, or it can be focused through a waveguide – guided-wave technology – which can even bring energy in from two opposing sides of the profile at once. Guided wave used to be internal Gerlach know-how; this is the first time it's shown publicly.
How it works
Microwaves set polar regions of the rubber's molecules into motion, and the friction that results heats the material from within – rather than the heat having to work its way in from the surface. This effect, called dielectric dissipation, usually makes heating faster and more even across the whole cross-section. The catch: how well it works depends heavily on how evenly the electromagnetic field is distributed inside the oven.
Influencing factors in detail
Diffuse vs. directed field
A diffuse field inside the oven chamber heats the profile broadly, but with some variation from spot to spot. Guided-wave technology takes a different approach: it focuses the energy through a waveguide into a tightly defined monomode zone, which makes the heating noticeably more repeatable.
Material polarity
How well microwave energy heats a compound comes down mostly to its polarity. Low-polar compounds are notoriously stubborn to heat this way – which is exactly why supplementary modules like the UHF Module 201 exist, stepping in wherever the energy wouldn't otherwise get through.
Scientific basis
- IKV HeatStraD
- The measurement device developed by Gerlach and RWTH Aachen's IKV enables, for the first time, a direct comparison of microwave, hot-air, and infrared vulcanization on the same profile — the basis for determining the most effective combination for each compound. Project lead Dr.-Ing. Florian Lemke carried this work forward in his dissertation "Vulcanization Strategies for Sulfur-Curing Rubber Profiles" (RWTH Aachen, 2022).
