Forum

Composite Technology

Supply chain for the manufacture of fibre-reinforced products

VDMA

Forum Composite Technology

Lyoner Straße 18

60528 Frankfurt am Main

Germany

Phone +49 69 6603-1932

Fax +49 69 6603-2932

E-Mail walter.begemann@vdma.org

Internet http://composites.vdma.org

Processing of thermosetting semi-finished products

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http://composites.vdma.orgwww.composite-arena.com

VDMA Forum Composite Technology

The Forum Composite Technology is made up of nine VDMA

associations bringing together machinery manufacturers’

skills in the conversion of fibre composites. As central contact

point for the industry, the forum is the interface to all firms,

associations and institutes involved in the manufacturing or

conversion process and the application of composites, offering

all partners a platform for cross-technology exchanges.

The Forum is chiefly concerned with

• Markets and customers: cooperation and exchange bet-

ween associations, clusters and other customer industry

organisations

• Exhibitions policy: as sponsor of the COMPOSITES

EUROPE trade fair, the Forum is establishing an important

trade fair hub in Germany

• Understanding the process: fostering innovative ability

based on a common understanding of the process along

the entire supply chain

• Research: networking of research and industry to pro-

mote pre-competitive research

• Public relations: joint articulation of interests and concer-

ted public relations activities

• Sourcing service: the Forum’s member companies present

their range of products and the services they offer in the

Composite Arena

Further flyer available on these topics:

• Resin transfer moulding (RTM)

• Thermoplastics compression moulding

Contact

Dr. Walter Begemann

VDMA Forum Composite Technology

Phone +49 69 6603-1932

E-Mail walter.begemann@vdma.org

Unlike thermoplastics, thermosetting fibre composites have a

chemically cross-linked molecular structure. These links mean

that thermosettings cannot be melted again, but they normally

have a higher mechanical strength and their breaking behaviour

is more brittle.

Typical applications include components for the electrical

industry, sanitation, rail and utility vehicles and increasingly

for aircraft and automotive industry. The thermoset matrix

makes these components suitable for both higher and lower

temperatures, unlike thermoplastics.

The basic principle of thermosettings manufacture is the sepa-

ration of the impregnation process in the making of composite

materials from the moulding process in the press or autoclave.

More recent developments seek to bring the two stages together

in order to reduce cycle time.

Combining thermosettings with carbon fibres offers better me-

chanical properties than using glass fibres, but is also markedly

more expensive.

Process characteristics:

• Complex three-dimensional components possible

• Limited storage time for semi-finished products at room

temperature

• Short cycle times

• Low shrinkage during manufacture

• Geometry limited by flowability of the semi-finished product

• Finishing (cutting, edge processing) required, but some may

be integrated into the press

• Sophisticated plant technology (moulding press, autoclave)

• Manufacturing may be automated

• High temperature stability

• Low elongation at rupture

• Good surface quality on both sides (depending on tool)

Classification of thermosetting semi-finished product processing

Reinforcement fibreThermosetCompositeAlternative processes for composite manufacture

1: Fibre manufacture2: Textile manufacture3: Manufacture of semi-

finished products4: Moulding5: Autoclave6: Finishing7: Testing, joining,

surface treatment8: Recycling

Raw material

Component

Final product

Raw component

Organic sheet

2

4

5

6

7

8

8

3

31

Placed material

Textilestructure

Cut Preform

Resin

SMC/BMC

FibrePrepreg

Fibre and textile manufacture Manufacture of semi-finished products Moulding Machine tools / precision tools Robotics, automation / mearsurement and testing

Alternatively, woven, non-crimp, warp-knitted, braided or knitted

fabrics are made for use in the resin matrix.

Relevant machine groupsMachines for the production and treatment of fibrg

• Machines for the production of carbon fibres

• Machines for the production of glass fibres

• Machines for the production of aramid fibres

• Drafting systems for filaments and tapes

• Cutting converters, stretch-breaking machines

• Preparatory machines for natural fibres

• Accessories

Machines for the production of textile structures

• Machines for the production of yarn

• Machines for the production of nonwovens

• Filament winding machines

• Braiding machines

• Fibre placement lines

• Flat knitting machines

• Warp knitting machines

• Multiaxial warp knitting machines

• Weaving machines

• Accessories

Relevant machine groupsMachines for the manufacture of composites

• Autoclaves

• Coating machines

• Extrusion lines / Extruder

• Laminating

• Peripherals

Relevant machine groupsMachines for composites processing/machining

• Tape laying machines

• Forming machines: High pressure presses for SMC/BMC

Precision tools for composites

• Dies and molds

Relevant machine groupsMachines for composites processing/machining

• Heating and cooling technology

• Forming machines

• Cutting and splitting machines

• Machines for surface treatment

• Drilling and milling machines

Precision tools for composites

• Cutting tools

• Clamping tools

Joining technology for composites

Relevant machine groupsHandling technology

• Robots

• Other handling equipment

• Equipment for linking and transport

Measurement and test systems

• Test systems for fibres, yarns, fabrics, on-line

• Test devices for fibres and filaments, off-line

• Test devices for staple fibre and filament yarns, off-line

• Test devices for composites and fabrics, off-line

• Gages and precision measuring equipment

• Measuring machines

• Machine vision and optical sensors

• Test devices for contaminant

The process chain for the manufacture of fibre-reinforced

thermosettings begins with the production of precursor

fibres from polyacrylonitrile (PAN). They are carbonised

as filament bundles (rovings) and directly cut for further

processing or else impregnated with the resin as endless

fibres in unidirectional, biaxial and multiaxial structures.

The next stage is to process the textile re-

inforcement structures into semi-finished

products. Fillers and dyestuffs are added to

the resin to obtain particular properties.

Sourcing service: www.composite-arena.com

Thermosetting semi-finished products are processed by hot press

moulding or else under pressure at high temperature in an autoclave.

The high temperatures create an irreversible cross-linking of the

material, which cannot be melted again.

The good flow behaviour of semi-finished products made from cut

fibres also means that highly complex geometries can be achieved.

Prepregs on the other hand allow significantly higher fibre contents.

For finishing with high-precision machine tools, a distinction is

made between the introduction of functional geometries and

fine surface finishing. For functional geometries, methods such as

drilling, milling or laser beam and water jet cutting are used, while

fine surface finishing is normally done by grinding and polishing.

The machining of fibre composites presents engi-

neers with completely new challenges for tool de-

velopment, since the familiar laws of metallurgy

cannot simply be transferred.

Unlike metallic materials, the properties of com-

posites are determined chiefly by the direction of

the fibres in the component. This means that fibre

composite materials cannot be machined equally

well in all directions.

If the composite consists of layers with the fibres

in different directions or composite layers are

combined with layers of metal, the machining

process is even more complex.

Robotics + automation covers the three

fields of robotics, integrated assembly

solutions (for assembly and handling) and

industrial image processing. These tech-

nologies are important building blocks

for the economic series manufacture of

filament-reinforced products. The positioning and alignment of

non-crimp fabrics, the handling of semi-finished products and the

robotised finishing of components are examples of how they can

be applied. Image processing provides reliable monitoring to ensure

that all important manufacturing parameters are maintained and

that quality is reproducible and assured.

Quality assurance is an essential aspect

of measurement and testing technology.

Quality assurance systems in the produc-

tion process have many advantages for

the user, such as lower production costs

resulting from the better utilisation of re-

sources. A high level of process reliability

means less waste and hence ultimately lower costs arising from

guarantee commitments and more satisfied end users.

Raw component

SMC (Sheet Moulding Compound) is made by impregnating cut fibres

with resin. This produces a sheet type semi-finished product.

In the case of BMC (Bulk Moulding Compound), cut fibres are added to

the resin to create an amorphous doughy mass which is further worked

by press moulding.

Prepregs are made from pre-impregnated endless fibres (unidirectional

fibres, non-crimp or woven fabrics, etc.) and are cured at high tem-

peratures and under pressure in an autoclave or by hot press moulding.

Large moulded parts (e.g. for aircraft manufacture) are processed in the

autoclave under vacuum since for them press moulding is uneconomic.

Resin

Textilestructure

Prepreg

Two part tool

Semi finished product

Negative form

Vacuum

Prepreg

Absorbent non-wovenVacuumfoil

Autoclave process

Moulding process

Raw marerial

Fibre

SMC/BMC

Placed material

Finalproduct

Component