METAPOR® – Air Permeable Materials

By John Shpack, Process Specialist, CMT Materials

What is METAPOR®?

METAPOR® is a composite, air permeable material made of pulverized aluminum granules and epoxy resin. It provides thermoformers with an alternative to vented aluminum prototype or production tools. In contrast to sintered metals, the pores do not close off after machining allowing for excellent definition and surface quality.

Who uses METAPOR®?

Thermoformers, toolmakers and machine shops all use METAPOR® for a variety of different applications. A thermoformer or toolmaker might use it to build a shallow-draw mold because the final part appearance cannot have vacuum holes. A machine shop will typically use it in a fixturing application where clamping cannot be used due to difficult geometries. The primary benefits that users see are reduced set-up times and lower labor costs.

Are there different grades of METAPOR®?

METAPOR® is available in 3 different grades: BF 100, HD 100, HD 210.

– BF100: standard grade that is used with most commonly thermoformed polymers such as PS, ABS, PVC, PET and PE. The upper operating temperature is 212°F (100°C).

– HD 100: high-density grade recommended for use in applications where the surface characteristics of the finished part are critical. It is specially formulated to have a smooth surface yielding better transparency on clear or translucent parts.

– HD 210: high-temperature, high-density grade recommended for more challenging applications such as polycarbonates and acrylics. The upper operating temperature is 410°F (210°C).

Can I machine it on my equipment or are there special considerations?

METAPOR® has excellent machining qualities. It must be machined dry and should not be in contact with any cooling fluids. In order to avoid any closure of pores, sharp tools made of HSS or carbide with edge angles must be used. It is recommended to use dust extraction. Avoid contact with grease, solvents or other fluids. Grinding and polishing of the machined surfaces can be done by hand or with a vibrating grinder. Use corundum paper with grains of 400 / 600 / 1200 in ascending order. METAPOR® must be polished dry without any polishing paste.

What else should I know?

METAPOR is offered in 4 standard sizes: 19.7″ x 19.7″ (500mm x 500mm) squares with 0.6″ / 0.8 / 1.2 / 2.4 thicknesses (15mm / 20 / 30 / 60). After the cutting process, the air permeability of the slab surface is reduced due to partial closure of the pores. It is essential to mill both surfaces of the slab by cutting off ~0.5mm (0.02”) to provide complete air permeability. You can download more details here.