FAQs

The increasing replacement of conventional metal structures with composites, and particularly carbon fiber reinforced plastic (CFRP), has been an ongoing trend in airplane and helicopter engineering for years. In the area of high-performance fiber composites, sandwich structures are the preferred choice for light yet stiff designs. The selection of the optimal sandwich structure is usually based on the different conditions associated with load-bearing capacity, production, and component design. The aerospace industry has long made use of ROHACELL® as a lightweight, structural core material that also reduces the cost of sandwich materials because of its processing reliability.

The creep compression resistance behaviour can be improved by drying Rohacell.

We recommend drying all grades at 125+5°C. The drying time depends on the thicknesss of the sheet: 5h for 24mm and less, up to 12h for 100mm and higher. Please request drying guideline documents via email.

Machining doesn’t necessarily require drying. But if Rohacell has to be dried, it should be dried pior to machining. Drying after machining can lead to a distortion of the shaped part due to internal stresses. The curing process conditions determine how long the foam can be exposed to environmental moisture before it shows excessive creep. Evonik recommend avoiding the foam absorbing moisture for more than a day. Ideally machined parts should be stored in moisture-proof bags.

As above, this depends on their curing process and also the relative surface of the part (the more surface per volume,the faster the foam will pick up moisture). The environmental conditions also play a role, with the foam picking up more moisture at higher relative humidity and temperature. Rohacell can generally be left for up to a day.

Primarily HT customers are in the aircraft industry. The main benefit is the higher creep resistance in the process, i.e. the foam can be cured at higher temperatures and pressures without collapsing. Curing it at 180°C requires HT (Manual aircraft resins have to be cured at 180°C).

For manufacturing procedures with curing temperatures between 125°C to 175°C, it is possible to heat treat IG-F. However, IG-F is intended for industrial applications that don’t require very high curing temperatures. Evonik have not heat treated this product and therefore have not produced a heat treated properties sheet.

Yes, it does. Imagine HT as an extreme drying process. If exposed to moisture from the environment, molecules will absorb moisture over time and lose the HT properties.

TEMPERATURE, YET CAN ONLY WITHSTAND LOWER TEMPERATURES? For many grades, Evonik use the same copolymer recipe to form different densities. In this case Evonik determine the final foam density by foaming temperature: the higher the temperature, the more the blowing agent expands and the lower the density. Foaming temperature and thermoforming temperature are related to some extent, the higher the foaming temperature, the higher the thermoforming temperature.

If it is at room temperature: excessive mechanical loads. If the compressive strength limits are surpassed, cell walls will start crushing and the integrity of the foam will be lost. If it is at high temperatures: moisture.

The choice of adhesive depends on the required temperature resistance and the size of the area to be bonded. However, most adhesives are suited for Rohacell. The only concern is that the adhesive doesn’t bond by evapourating a solvent. Rohacell foam is nearly impermeable and it would take very long for the adhesive to cure.
– For small areas we recommend a 2 component Epoxy resin.
– For larger areas we recommend an Epoxy resin film.

Evonik recommend a 2 component Epoxy resin for small joining surfaces and a thermoplastic or thermoset film adhesive for a larger area.

A company that cut wings for F1 cars told us that their machine on the SD grade 400mm per min @115° allows them to hot wire large pieces of Rohacell.

A company that cut wings for F1 cars told us that their machine on the SD grade 400mm per min @115° allows them to hot wire large pieces of Rohacell.

Our cutting plants include a Horizontal Bandsaw, a Circular Saw and a Laser Machine.

If an order is placed in the morning we will endeavour to arrange a same day delivery through our couriers, however please note this does implement a higher carriage cost than normal. If for whatever reason we cannot do same day delivery, it will be with you the following day.

Our laser machine has the capability to cut Rohacell into tiles, strips and complex 2D shapes.