Nomex honeycomb is made of nomex paper, a form of paper made of aromatic polyamide -aramid- fibers. Nomex paper provides high electrical, mechanical and chemical integrity, moisture insensitivity, radiation and flame resistance. These unique characteristics make it the perfect solution for many applications, especially those which need to be lightweight and fire retardant.
An initial unstable expanded paper honeycomb structure is dipped into phenolic resin to produce a honeycomb core which (after cure) becomes very strong. Subsequent dipping cycles can increase strength and weight of the resulting product. Honeycomb cells can also be filled with Fibermax Composites 2 component rigid foam for greater bond area for the skins. This manufacturing technique increases the mechanical properties of the core by stabilizing the cell walls and increases thermal and acoustic insulation properties.
The behavior of the honeycomb structures is orthotropic, hence the panels react differently depending on the orientation of the structure. Therefore it is necessary to distinguish between the directions of symmetry, the so-called L or ribbon direction and W or transverse-to-ribbon direction. The shear modulus and strength in the L direction are roughly twice than this in the W direction.

The manufacturing process
Fibermax Composites honeycomb is manufactured by the expansion method which is a quite simple process. Honeycomb starts out as flat sheets of Nomex paper material. Strips of adhesive are “printed” on the Nomex paper in a staggered pattern. Next, the sheets of paper are stacked together and cured to form a “HOBE” (honeycomb before expansion) block.The HOBE is pulled apart from its sides (or “expanded”), much like an accordion, forming an expanded honeycomb block, that now incorporates the hexagon cell shapes. This initially unstable expanded paper honeycomb cell structure is dipped into phenolic resin. Once cured, the blocks are cut to the honeycomb sheets with the desired thickness.

Cell configuration
Honeycomb can be made and cut to the standard hexagonal style which is and the most common cellular configuration, or it can be over-expanded in the W direction to form the corrugated or over-expanded (OX) configuration, where the cells look rectangular. The OX process tends to increase W sheer properties and slightly reduce L shear properties compared to hexagonal honeycomb core. There are also other configurations that Fibermax Composites can design depending customers' specific needs.