Matt (Staff) (04/07/2012)

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Hi Lisanty,

There are very many different types of core materials that you can use in a composite laminate ('sandwich' composites), we stock some of the more popular or easy to use core materials and so given the wide range available I'll only summerise the ones we stock.

The idea of all core materials is to increase the thickness of a panel without increasing its weight, cost or layup time (depending on the core material and the production priorities) as much as solid reinforcement would. Because in a panel under load it's really the innermost and outermost skins that do the majority of the work and because increasing the thickness of a panel increases its stiffness significantly, low density core materials can be very effective in creating stiff, light panels.

COREMAT
The simplest core material of all. Really only used in wet-layup of conventional GRP parts. Lower density than solid glass but still with quite a high resin uptake so more of a time and cost saver than a weight saver.

LANTOR SORIC
Like an infusion grade version of coremat but with a much more sophisticated honeycomb-like cell structure. Soric will act as an internal flow media for resin during infusion (meaning resin flows through it easily and in fact Soric can function as the only resin flow facilitator in an infusion project). Soric has a medium resin uptake meaning that there are lower density core materials out there but almost none that are as easy to use. No special processing is required, just lay the soft, flexible honeycomb-like mat into your laminate before infusion. We sell this is 2mm and 3mm.

Matt

Could you comment on nomex honeycomb please. 

Thanks

Fred

CLOSED CELL PVC FOAM
Lower density than Soric, easy to work with foam core material. Closed cell foam has good compressive strength, bonds well to resin systems (particularly epoxy resin) and needs no special processing. Being a 'closed cell' material means that it have virtually zero resin uptake and so it remains a low density core even after infusion. Suitable for wet-lay, vacuum bagging, resin infusion and pre-preg (depending on processing temperature). For co-infusion, the core MUST be drilled to allow resin to flow from the top skin to the bottom skin. Alternatively, upper and lower skins can be made in advance and then bonded together around the core.

ALUMINIUM HONEYCOMB
The highest performance (in terms of mechanical strength vs. density) of all core materials but certainly the most complicated to work with. Generally, when working with aluminium honeycombs (or even other honeycomb materials), it is necessary to make the two skins separately first and then bond in the honeycomb using a liquid honeycomb bonding adhesive or an adhesive film (such as Hexel's Redux 609). Aluminium honeycomb has excellent shear strength and good compressive strength and used correctly will result in the highest performance (hence its widespread use in aerospace and F1). Aluminium honeycomb is not suitable for infusion (because the cells would simply fill with resin) and so, as with other laminating methods, it is necessary to make both skins separately first.

I hope this gives you a good insight into these different core materials and what they can do for you. For further information, take a look at the product pages for the respective products where you'll find mechanical and process data (such as resin uptake, density, compressive and shear strength) which would be helpful when making comparisons.