FITS PEI Thermoformable panels

Currently, Nomex honeycomb with cured phenolic resin facings are applied for sandwich panels and parts for interiors of aircrafts and trains. Costly hand labor and/or time-consuming curing processes create the Nomex parts.

Generally, fillers, potting compound and metal extrusions add 20-70% weight to the original panel weight. As a result, FITS PEI parts will have a lower weight than Nomex parts.

The current aircraft manufacturing world shows increasing AC building rates. Honeycomb panels, however, lack one or more qualities really required in this aircraft interiors market: high speed, low cost processing: thermoformability, low weight (potting compound), recyclability (due to combining multiple materials), further weight reduction (at the end of Nomex’ technical capabilities).

FITS has invented the FITS PEI thermoplastic sandwich panel and its automated thermoformable application technology. FITS can achieve lower part weight and lower cost goals. It brings all elements required: new design options, enhanced part integration, significant reduced lead time, no hand labor and recyclability.

FITS PEI panels passed all relevant FAA tests. Airbus and Boeing tested FITS PEI panels. They confirm that FITS PEI panels fully comply with aviation fire, smoke and toxicity requirements. (See technical data on this site)

The FITS PEI benefits are the following:

  1. Low cost panel manufacturing technology
  2. Low weight paired with high mechanical and other properties
  3. Automated thermoformable application technology
  4. Potential applications and their weight saving

Low cost panel manufacturing technology

Thanks to the highly automated processes, FITS PEI panels cost is based on the material cost of PEI and fibers plus a modest manufacturing cost. Total manufacturing cost of FITS PEI panels is significantly below phenolic honeycombs’.

The technology and manufacturing process

FITS PEI panels are manufactured in batch in a press.

For FITS PEI, not only PEI can be used, yet also some other high temperature thermoplastics like PPSU can be applied. For the sake of convenience, we use PEI in this text for all high temperature resistant polymers.

For this process, PEI films impregnated with a physical blowing agent are placed between consolidated fiber reinforced thermoplastic PEI-facings (a pack), before the in-situ foaming takes place:

  1. In a press, a pack is heated under high pressure until a homogenous temperature is obtained to thoroughly connect the PEI in facing to the core.
  2. The pressure is released, and the press is opened allowing the blowing agent in the PEI film to create foam.
  3. The specific opening curvature ensures the creation of vertical cells for high compression strength panels.
  4. At the end of the foaming curve the FITS PEI panel is cooled to room temperature in a cooling curve.
  5. After removing the panel from the press, the Acetone is removed by a patented oven drying process.
FITS PEI

Notes:

Low weight paired with high mechanical and other properties

FITS PEI panels are low weight. The total weight of e.g. a standard 10mm panel is approximately 2.5 kg/m². The low weight is the result of:

Compared to Honeycomb panels, FITS PEI panels do have comparable mechanical properties in the area of high stiffness/strength and low weight. See also the Technical data for more information.
FITS PEI panels however, besides having the benefit of thermoformable processing, have a series of other benefits over honeycomb panels:


Automated thermoformable application technology

On average, 25% weight is added to the part weight of thermoset Nomex Honeycomb constructions through the application of potting compound, fillers, paint, decorative layers, connections, Aluminum extrusions, etc.

By contrast, with FITS thermoformable panels, only a maximum of 5% weight is added at part level. By applying heat and pressure all kinds of shapes and forms can be created in seconds by automated thermoforming machines. See the section on part manufacturing technology.

Thermoformable application technologies are for example: edge finishing, folding, reinforced corners, welding of inserts, 3D forming and 3D printing. These thermoformable technologies are much simpler, more efficient and more versatile compared to Nomex panels. They allow for automatic manufacturing instead of extensive hand labor as is common for Nomex thermoset panels.

These newly designed parts have 20-60% weight savings, up to 50% cost savings and cycle time improvements from days to minutes. The latter will not only reduce manufacturing cost, it also reduces space requirements and allows for manufacturing in high labor cost countries.

The FITS System brings the required automated part production in the aerospace, rail and ship industries. It is especially suited for large series production.

Potential applications and their weight savings

In the following table lists some aircraft interior application and related weight savings. The weight saving studies were executed with and for some potential customers to demonstrate the large potential of the FITS PEI System.


Product
Estimated
Current Weight
in gram
Estimated
FITS Weight
in gram
Twin Aisle
Weight saving
in kg
OSC without lid ¹ 5,500

5,000 40

Table aircraft seat 400
200
60
Swinging cover oxygen masks 230 45 20-25
Fixed cover oxygen system 300 65 26-35
Trolley: 20 per aircraft 16
11
100
¹ Other elements like connections, hinges, deliver a further weight saving of 0.5 kg per OSC

Of course, other parts not listed above will give significant weight savings are. They are not limited to galleys, sidewalls, toilet cabins, doors of toilets, toilet floors and (part of) seats.

Note: We cannot beat Nomex/phenolic constructions at panel weight level. FITS does beat Nomex on part level and on the part manufacturing technology.