The most important thing to understand when considering using microwave energy is how the energy heats the material. A microwave is an electromagnetic sign wave at some frequency. For most residential and some commercial applications, that frequency is 2450 Mhz. This means that the wave form changes polarity (positive to negative and back) 2 billion 450 millions times per second. In the case of polar solutions like water, the molecules try to align themselves with respect to the microwave field.

Because the field is changing back and forth so many times per second the molecules create friction. This friction is dissipated in the form of heat. In materials that are not polar, microwave energy heats materials by the way of the electrons resistance to flow through the material. If the materials are very conductive such as copper or aluminum, then electrons will flow with very little resistance (Heating) conducting electrical energy.

The “Heatability” or the ability of microwave energy to heat a specific material comes from the electrons inability to flow freely. The molecular friction caused by voids in the materials conductivity cause heat. The dielectric properties graph shows the general curve of materials ability to heat. This is why it is so important to fully understand the material to be heated.

There are a number of materials that heat well in a microwave field such as ceramics, wet extrusions, laminates, alcohols, acids, silicon carbide, insulating foams, oils, carbon, etc.

The unique thing about heating materials with a microwave field is that each material couples (absorbs energy differently). Many different materials have similar abilities to absorb microwave energy.

Heating materials evenly is the science centered around how the microwave energy is applied. Many elements have to be considered when uniform heating is the objective. The ability of the material to absorb is first and for most. The second is the size of the material. The third is the desired temperature or dryness. These conditions are evaluated and fully understood before an engineering design can be applied.

The microwave fields (energy level) are normally the highest at the point where they leave the waveguide transmission path. If a material is positioned directly in front of this opening, the side facing the waveguide would heat faster than the reverse side. This is usually not the desired result. If the material to be heated was 20 ft long then applying the energy along this length evenly would be very difficult. It is obvious to see that materials come in different sizes and shapes and that to heat, dry, cure, sinter, these materials evenly takes a unique design. Contact our staff about your processing needs.