Continuous Production of Thermoplastic Honeycomb

Sandwich Components for Automotive Interiors.

Low Weight – Low Cost Technology

Tomasz Czarnecki, EconCore

SPE, Novi, 7 – 9 September 2016

Introduction: Sandwich construction by nature

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The efficient use of material and energy is a fundamental principle of nature.

Nature set the examples – let’s save resources

Section of a bird wing

Section of an iris leaf Honeybee comb Section of a human skull

Sandwich in Construction and Transportation

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Stephenson 1830

Sandwich frame in locomotive by Stephenson

Important historical examples of sandwich construction in transportation

Bi-plane wing construction by Chanute

Chanute 1894, 1903 (Wright flyer)

Fairbairn 1845

Tubular Bridge design by Stephenson and Fairbain Sandwich metal wing design by Junkers

Junkers 1915

Sandwich construction today

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AerospaceTrains

Trucks

Cars

Building

Sandwich constructions are composed of

• Two thin facings (skins, liners)

• One thick low density core

• Bonding layers (adhesive)

Adhesive

Core material

Adhesive

Sandwich applications

Lower skin

Upper skin

Packaging

Recreational vehicles

Potential of Sandwich Construction

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Effect of the sandwich thickness:

• Geometrical definitions(symmetrical sandwich materials)

t

t

h

Economic advantage depends on low core material cost and low production cost

82.3 % weight saving

82.3 % cost saving

Core material types

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… but high manufacturing costs

Sandwich core materials

Homogeneous support of the

skins

Foam cores

Structured (non-homogeneous) support of the skins

Punctualsupport

Textile/pin cores

Regional support

Cup shaped cores

Bi-directional support

Honeycomb cores

Unidirectional support

Corrugated cores

Core types

Best material properties

Conventional honeycomb production processes

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Thermoplastic honeycomb production by extrusion

Tubular honeycombs

Out-of-plane extruded honeycombs

Extrusion of single tubes

Collecting the tubes Cutting to a honeycomb

Welding to a block

Extrusion small honeycomb blocks

Extruder

Extruder

saw

saw

Welding to a bigger block and cutting to a honeycomb

• require the production of blocks and the cutting from blocks

• result in a low degree of automation and in relatively high costs

Both processes

Continuous production process

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Aerospace Packaging Industry

Internal structure

and mechanical

properties

Production concept

and machinery

• Honeycomb cores from a continuous film through a step-by-step in-line process

⇒ Automatic production⇒ Low production costs

⇒ Best mechanical properties⇒ Major cost reduction

New Honeycomb Cores

ThermHexThermoplastic Honeycomb

• Automated in-line production leading to very low production costs

• Direct lamination of skins allows in-line production of panels

EconCore Technology - ThermHex

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Continuous production of ThermHex honeycomb panels

...or by direct polymer film extrusion

from rolls of thermoplastic films...

Value chain

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rawmaterials

(for coreand skins)

Core material producer

Sandwich panel producer

Assembly plant

In-line core Sandwich material In-line post

preparation producer processing

End user

Partproducer

sandwich constituents (core, skin and bonding layer)

sandwich panel(sandwich material)

sandwichpart

sandwichstructure

bonding /

laminationforming assembling

core

production

Sandwich production value chain

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Thermoformability of “folded honeycomb” sandwich panels

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Honeycomb - Properties

Thermal insulation e.g. for wall or inner cladding

skinsThermHex

PP skin strip

Thin PP cell walls Still air entrapped in the cells(more than 95% volume fraction)

Heat flow

A thermal barrier against conduction created by still air and PPAir movements suppressed or rather eliminated – air entrapped in the cells Radiative effects limited – conductive skins separated

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Honeycomb - Properties

Acoustic absorption e.g. for wall cladding, separation walls

Steel skins

Air filled, one side open ThermHex cells

Sound waves

damping of the noise (acoustic vibrations are transferred to the opposite skin – panel stiffness driven)

Tests proved good sound absorption ability of the ThermHex core

Dissipation of the sound waves in the one side open honeycomb structure

One or two (for separation walls) side perforated skins

Air filled, one side open ThermHex cells

Sound waves

Improved damping of the noise – sound absorption(energy dissipated in the core structure)

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Automotive trunk trims

Sandwich composition: PP honeycomb core - PP/wood flour composite skins

Thermoplastic honeycomb panels – application examples

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Vibration damping with honeycomb panels

Very capable, light-weight stiffening and vibration dumping element for metal

doors and roofs

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Honeycomb sandwich panel for heavy duty applications

Honeycomb with 0/90° UD Glass

fiber / PP composite skins

Honeycomb with woven glass fiber /

PP composite skins

Honeycomb with woven carbon fiber /

epoxy composite skins

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Honeycomb organosandwich – mechanical performance

Weight reduction

(=cost reduction)

Rigidity increase

(at minimal weight/cost gain)

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Ultra-light honeycomb sandwich parts

• Massive weight reduction through replacement of plywood and conventional sandwich panels

• Mostly applicable for dry freight constructions but do offer enhanced thermal insulation

• Applications include: roofs, walls, floors, doors, inner structures, aerodynamic elements

• Increased rigidity / weight reduction through replacement of conventional sandwich panels

• Short cycle thermo-formability into complex parts, acoustic absorption benefits

• Applications include automotive interior parts and small cargo van’s inner cladding

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ThermHex organosandwich – thermoforming/overmolding

Process

Preheating

(e.g. with IR)

Transfer of the Organo-

sandwich into the mould

Forming while

closing the mouldFunctionalisation/

overmoulding

Demoulding of the part

Pick up of the

Organo-sandwich

1-step

Process integration – the key to executer the cost saving potential of a sandwich material

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Organosandwich – mechanical performance

Load (80mm diameter)

995 mm

420 mm

Customized Trunk Floor load test

All sandwich panels with a thickness of ca. 20mm

UNDER DEVELOPMENT:Trunk Compartment -

thermoplastic alternative to the

conventional, “dirty”

paper honeycomb – PU – glass fiber

sandwich panel

0

20

40

60

80

100

120

0 5 10 15 20 25 30 35

Ce

nte

red

we

igh

t (Ø

80

mm

are

a)

in k

g

Flexural deflection in mm

Load - Deflection curve

ThermHex honeycomb sandwich

with woven GF/PP skins

ThermHex honeycomb sandwich

with 0/90° GF/PP skins

Glass fiber-PU - paper honeycomb

sandwich panel

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Organosandwich – integration

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Ultra-Light Honeycomb sandwich parts

Replacement of 1500-2000 gsm monolithic NF/PP composites and injection molded PP and ABS parts

Honeycomb panel with natural fiber / PP skins = ca. 800gsm

over 50% weight savings!

Summary on Continuous Honeycomb Sandwich Part Production

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MINIMAL WEIGHT MINIMAL COST

MINIMAL ENVIRONMENTAL IMPACT

Thermoplastic honeycomb technology

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Let´s build the future of honeycomb sandwich materials together!

Thank You !