Cannon solutions for mass production of composite parts

FEATURE

Reinforced Plastics �Volume 60, Number 5 � September/October 2016 www.reinforcedplastics.com

Cannon solutions for mass productionof composite parts

Max Taverna

Cannon Communication, Italy

A growing environmental problem – created by the effect of human activities on the quality of our

atmosphere – and the increasing scarcity of non-renewable resources are heavily modifying our habits.

‘‘Energy efficiency’’ and ‘‘reduction of carbon emissions’’ have become mantras for any type of human

activity. Weight reduction, smart design of parts, use of renewable resources and more economic

production methods have been perceived as the easiest approach to the solution of this widespread

problem.

Characterized by light weight, good mechanical performances,

relatively low level of energy required for their process,

CFRP (Carbon Fiber Reinforced Plastics) are progressively repla-

cing conventional materials – such as stamped metals or

conventional reinforced plastics – for the manufacture of thou-

sands of ‘‘things’’ that can replace heavier components which

contribute to consume energy or natural resources during their

lifetime. Stimulated by the increasing competitiveness of

these modern composites numerous producers have since many

years oriented their manufacturing strategy toward CFRP tech-

nologies.

Composite production: a multi-step processOne major bottleneck in the manufacture of CFRP parts is still

represented by the high number of operations required to produce

a single piece in composite materials. After nearly a century of

industrial manufacture of injection-molded pieces, where with a

single operation a finished part is extracted from a mold, it is quite

hard to return to a semi-manual method of assembly, at least for

the largest parts. But, by definition, a piece of composite is made

with a reinforcing support impregnated with a polymeric resin.

Superior performances, in terms of cycle time and resin distribu-

tion, are obtained using fluid liquid formulations reacting in the

mold throughout a textile-like support, rather than injecting in it a

plasticized polymer. This ‘‘delicate marriage’’ requires a sequence

of operations that generates rather long cycle times and a costly

manpower.

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To optimize this complex production sequence, a number of

technological improvements had to be developed and industrially

implemented. End users, suppliers of equipment and of chemical

formulations worked hard for several years to analyze the pro-

blems of the process and find the most convenient alternatives.

The longest and more complex operation is usually the deposi-

tion of reinforcement in the mold: this can be the origin of

numerous esthetic defects in the finished parts if creases and

wrinkles are generated during the draping of the reinforcing fiber

and the subsequent mold-closing phase (Fig. 1).

Another key problem is represented by the impregnation meth-

od used to transfer the reactive chemicals in the fiber reinforce-

ment. Since the polymerization phase of the resin depends on the

chemical formulation, a variety of molding solutions were devel-

oped in the past two-three decades. Each of them features different

clamping pressures, different mold temperatures, and different

demolding times.

After demolding a part, a number of finishing steps are required,

more or less complex and costly in terms of labor and scrap

generation. Depending on the molding technology utilized, these

post-processing operations can represent another serious obstacle

to the search of an industrially acceptable cycle time.

More than twenty years of experience in the manufacture of

CFRP composites have oriented the industry toward a restricted

number of processing technologies. Advantages and disadvantages

of each system have driven the investors toward the best combi-

nation of chemicals and molding methods, depending on the

0034-3617/� 2016 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.repl.2016.06.007

http://dx.doi.org/10.1016/j.repl.2016.06.007

FIGURE 1

CFRP part.

FIGURE 2

Characterized by an Automatic Unrolling System and a patented Intelligent

Gripping System the Cannon Carbon Fiber preformers have been used for

many years by BMW, Lamborghini (Audi Group) and major Tier Onesuppliers.

Reinforced Plastics �Volume 60, Number 5 � September/October 2016 FEATURE

FEATURE

technical specifications of the part to be produced. The use of

vacuum-assisted molding and of autoclave curing has been widely

accepted for the production of large, complex parts made in small

and medium series.

A commonly accepted conclusion is that to extend the use of

composites to automotive industry or to other mass products, such

as appliance or sport articles, their cycle times and the cost impact

deriving from labor must be dramatically reduced.

Cannon, dedicated solutions for compositesCannon have, in their 50 years of history, developed a number of

processing solutions that contributed to the reduction of the

environmental impact of human activities, providing technolo-

gies for a more efficient thermal insulation of buildings, for the

replacement of Ozone-depleting foam’s blowing agents, for the

manufacture of energy-efficient vehicle components. In more

recent years a whole set of technologies and equipment – all

industrially capable solutions – has been developed by Cannon

that is able today to deliver dedicated turnkey solutions for the

automated mass production of composites.

Utilizing both Polyurethane and Epoxy formulations, by

leveraging on consolidated and industrially proven technologies

Cannon is able today to propose turn-key packages for different

molding methods:

1. Use of reactive formulations, that are blended in the mold with

a reinforcement� HP-RTM (High Pressure RTM): a resin matrix is mixed and

injected in a preformed fibrous layer,� InterWet: a PUR blend is efficiently mixed with a stream of

chopped glass fiber and open-mold applied,� Spray Impregnation: a PUR blend is sprayed in open mold

over a layer of ready fibrous reinforcement.

2. Use of compression molding, forming reinforcements pre-

impregnated with:� A Thermosetting matrix

� PCM: Prepreg compression molding,

� CF-SMC: Compression molding SMC and Carbon

reinforcement.

� A Thermoplastic matrix

� LWRT (Light Weight Reinforced Thermoplastic), pre-

heated,

� GMT (Glass Mat Thermoplastic), pre-heated.

These available solutions provide viable methods for compo-

sites mass production, addressing several problems:� A reduced cycle time,� The quality of the molded part,� The economy of the whole process,� A clean working environment,� The industrial recovery of an expensive raw material, carbon

fiber.

The available integrated Cannon solutions for the production of

composites can be summarized in eight groups of products.

Smart preformersThe manufacture of complex, three-dimensional composite parts

requires that the reinforcing material – usually composed by one or

more layers of glass- or carbon-fibers – is preformed precisely.

Dedicated machines for glass- or carbon-fibers have been manu-

factured by Cannon in the past 20 years for the major OEMs and

Tier One producers of composites. Characterized by an Automatic

Unrolling System and a patented Intelligent Gripping System

these preformers have been used for many years by BMW, Lam-

borghini (Audi Group) and major Tier One suppliers to the leading

car makers. Initially used for the preliminary development of

composites parts, these machines are now industrially producing

the largest serial-made CFRP parts (Fig. 2).

The Automatic Unrolling System is able to hold several different

rolls of reinforcement fibers, to comply with the most stringent

demand of strength required by the components of the automo-

bile’s structure. It is also possible to integrate in it a bi-dimensional

cutting system for the preparation of irregular shapes of drapes.

Acting like a giant iron to the fibers, an energy-efficient heating

station brings the reinforcement’s temperature up to 200–2208C in

less than a minute, optimizing cycle time. Two sets of intelligent

grippers pick up the hot sandwich and transfer it to the forming

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station where an in-mold, integrated hold-slip frame ensures

optimum draping control of the carbon fiber layers when pressed

in the forming mold.

The patented Intelligent Gripping System that makes possible the

correct draping of the reinforcement in the mold uses a high

number of ‘‘draping grippers’’ or ‘‘hands’’ positioned on two sides

of the sandwich of fibers. Individually calibrated according to its

position over the mold, each gripper holds with a controlled

pressure its part of drape, releasing it under the action of the male

plug in a way that avoids creases.

The Cannon preformer, contrary to other competing models,

carries the sandwich in the forming station by holding it with a

‘‘front-to-back’’ configuration, using a more compact footprint

than the preformers that hold them on the sides of the sandwich,

forcing the design of a larger press (because part of the width

between the clamp’s columns is occupied by the two sets of

opposite grippers) (Fig. 3).

Typically a complex preform is made in 60–80 s, and then it is

extracted by a robot while the next hot sandwich comes in from

the heating station. A Cannon preformer features, as of today, a

clamping area of up to 3 by 3 m that can handle preforms up to

2.5 by 2.5 m, with a clamping force of 3000 kN, but a bespoke

engineering philosophy allows for wider platens and different

clamping forces.

FIGURE 3

A Cannon preformer features a clamping area of up to 3 by 3 m that canhandle preforms up to 2.5 by 2.5 m, with a clamping force of 3000 kN, for a

part-to-part cycle time of 60–80 s.

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A special version of Preformer is now available for the Prepreg

technology. The thick fiber sheets utilized in this process, which

come already impregnated with chemicals, must be softened,

heating them at 808C through a bank of infra-red lamps, and duly

shaped to size in a dedicated preformer press. A bespoke solution

allows for an efficient draping of the Prepreg sheet in the various

sections of the mold cavity, avoiding the formation of wrinkles

during the clamping phase.

Heating by IR, vacuum forming and light compression molding

complete the necessary steps to obtain suitable Prepreg preform.

When the preforming has taken place, the part can be extracted

and trimmed to final size, using either a punching press or a

robotized contour cutter. This step is necessary to obtain a finished

part in the following step. Both trimming solutions are available

from Cannon.

Dedicated pressesAfter preforming, the molding process continues in the polymeri-

zation press. The Cannon equipment designed for this technology

is a short-stroke clamp with active control of parallelism, designed to

work with HP-RTM, Gap Injection and CF SMC. This offers excellent

production flexibility and return on the investment (Fig. 4).

Designed and built upon customer’ specifications, these presses

must provide a number of sometimes conflicting performances

such as, for instance, fast closing operation and precise control of

the parallelism.

Their platen size can be up to 4.5 by 4 m and more than one

large part can fit on it with two molds mounted side by side. With a

typical clamping force of 36,000 kN, this press combines very fast

opening and closing phases, executed at speeds up to 400 mm/s,

with a very accurate final clamping phase, which can be set from 1

to 20 mm/s.

A special Gap Injection design allows for a semi-closed mold

when resin is injected, easing the distribution of the liquid

FIGURE 4

The Cannon short-stroke press with active control of parallelism, designed

to work with HP-RTM, Gap Injection and CF SMC, features platen size up to

4.5 by 4 m and more than one large part can fit on it with two moldsmounted side by side.

FIGURE 6

The Cannon press for the compression molding process of Prepreg withActive Control of parallelism is designed to perform a 3 min part-to-part

cycle, including the service time on the shuttled lower mold half.


FEATURE

throughout the whole surface of the mold, and then shut it

completely to squeeze out all the air trapped in the bulky fibrous

preform. This design makes it possible to have vacuum in the mold

even when the press is not completely shut offering the benefits of

vacuum molding and those of squeeze molding.

A special feature available on all Cannon presses, designed to

reduce the cycle time and ease the manual or automatic service

tasks, is the possibility to apply one or two lower platens shuttling on

the sides of the press. The two-shuttle press design allows for a

substantially higher efficiency, since the press is busy – i.e. it is

closed and working – for most of the time, while one or two

operators attend the service functions (part demolding, visual

inspection of mold and cleaning, positioning of Carbon fiber

layers) in the same time requested by the ‘‘press closing – resin

injection – curing’’ sequence of operations (Fig. 5).

Cure time for conventional HP-RTM parts can vary, increasing

the mold temperatures, from 180 to 90 s, while injections are

typically performed in less than 30 s, with a trend to reduce both

values to increase productivity: the latest chemical solutions allow

for injection times up to 15–20 s followed by a curing time as short

as 30 s (Fig. 6).

For the compression molding process of Prepreg Cannon designed a

special solution that allows achieving the high-productivity per-

formances promised by the manufacturers of today’s innovative

Prepregs, using the right process and the right equipment. The

preformed Prepreg must positioned in the mold cavity – that is

kept at temperatures of 140–1608C or 190–2008C, according to the

different chemistry used – and immediately pressed. The current

demolding times for a typical part vary from 15 to 5 min, depend-

ing on the formulation. The Cannon press is already designed to

perform a 3 minutes part-to-part cycle, including the service time on

the shuttled lower mold half. This press for Prepreg composites

typically features a clamping force of 25,000 to 36,000 kN, with

platens of 4 by 2.4 m and 2.8 m daylight, with two lower platens

shuttling on the sides. Also this press features a very precise Active

Control of parallelism, able to adjust the pushing action of every

hydraulic cylinder during the final phase of closing, in order to

FIGURE 5

A special feature available on all Cannon presses is the possibility to apply

one or two lower platens shuttling on the sides of the press this designallows for a substantially higher efficiency, since the press is busy – i.e. it is

closed and working – for most of the time.

guarantee perfect parallelism of the two mold halves at the end of

the stroke even in presence of very bulky preformed Prepregs with

irregular thickness.

When the mold opens, the extracted part is ready for use. Its

surface has acquired high gloss and the carbon reinforcement is

visible through a perfectly transparent layer of migrated resin. The

only way to get an esthetically perfect part is to respect the

combination between mold temperature, clamping pressure and

curing time. Each type of commercial Prepreg provides a nice

result only if all parameters are kept under the strictest control!

For all composites applications (thermosets and thermoplastics

in a wide variety of technologies) more than 500 Cannon presses

have been put in operation, worldwide, with platens dimensions

of up to 4 by 4.5 m, with up to 3 m vertical draw and up to

36,000 kN of clamping force, with possible extension of these

sizes according to specific needs.

Numerous advantages characterize the Cannon presses versus

the conventional presses for composites:� Customers are happy to find that the Cannon units are 30% less

tall, which helps streamline the layout of their factories, and

provide for a 20% reduction in energy consumption.� Faster cycle time is also to be mentioned. The design of these

presses is such that it can work on a limited amount of hydraulic

oil, leading to shorter pressure build-up time.� Customers also appreciate the dimensional consistency between

the parts, which is hardly negligible when dealing with bulky,

irregular preforms that can interfere with the closing of the press.

Active control of parallelism is of great help.

MoldsA mold designed for composites includes today an impressive

number of parts and functions that must be strictly monitored

and interfaced with the remaining equipment. A dedicated Cannon

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FIGURE 7

A Cannon Company designs and manufactures steel molds specificallydesigned for the preforming and for the molding processes, featuring

sophisticated solutions for the precise control of the parameters of these

very different clamping operations.

FIGURE 8

Innovative dosing units for HP-RTM are available from Cannon for bothPolyurethane and Epoxy resins their output range covers the most typical

demand of this technology, between 20 and 250 g/s with the possibility of

reaching lower or higher limits in case of specific needs.


FEATURE

Company designs and manufactures steel molds specifically

designed for the preforming and for the molding processes, featur-

ing sophisticated solutions for the precise control of the parameters

of these very different clamping operations. Pressure, vacuum and

temperature sensors, limit switches, moving inserts, all must be

controlled and integrated in the production sequence, with contin-

uous dialog with metering unit and mixing head.

All data collected from the two mold halves is conveyed to the

central process controller, that performs the required modifica-

tions of parameters should one of them go out of set during the

process. Mastering in-house the design and manufacture of molds,

as Cannon do, guarantees smooth set-up of the molding process

and constancy of results (Fig. 7).

Dosing unitsInnovative dosing units for HP-RTM are available from Cannon,

featuring innovative characteristics and practical advantages.

Available for both Polyurethane and Epoxy resins, their output

range covers the most typical demand of this technology, between

20 and 250 g/s with the possibility of reaching lower or higher

limits in case of specific needs.

Designed for two components, the new E-System Enhanced high-

pressure machine for Epoxy formulations precisely measures the

hardener by means of a plunger piston controlled hydraulically in

closed loop. The use of stainless steel on the whole circuit of this

corrosive chemical provides long lasting performance, with a

precision degree around �1% on the resin/hardener ratio. An

innovative degassing system on the resin circuit provides an air

extraction capability up to 10 mbar in a very short time, to reduce

the set-up downtimes when loading this component from a drum.

The control of chemical’s temperatures, very important for this

process, is performed by a powerful heating unit able to heat the

resin up to 908C, maintaining the fluid at this temperature up to

the mixing head with a constant recirculation. A third component

– the release agent – can be added to the resin’ stream through a

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static mixer built into the mixing head. The release agent’s dosing

unit, engineered for a direct integration with the main metering

machine with a Plug&Play configuration, works at a very low

output (few grams per minute) by a separate new plunger-piston

high-pressure dosing unit (Fig. 8).

Mixing headsCannon have developed, patented and sold numerous types of

heads suitable for HP-RTM and Spray impregnation processes.

Designed specifically for Epoxy or for Polyurethane chemicals,

these heads feature a very compact footprint and can be mounted

on thin molds, used to produce very small carbon fiber reinforced

composite components.

The suggested head for the HP-RTM process is the Cannon LN6.

Designed specifically for Epoxy chemicals, it keeps all its compo-

nents in a circular section of 120 mm diameter, injectors included.

This very compact footprint and its 15 mm nose allow it to be

mounted on thin molds, widely used by the automotive parts

manufacturers to produce very small CFRP composite compo-

nents. In order to enhance its mount ability on molds character-

ized by a complex three-dimensional design, with an impervious

FIGURE 10

In addition to the fast injection technology for HP-RTM in closed molds,

Cannon have developed the LLD (Liquid Lay Down) system here the Epoxy

formulation is laid over the carbon mat in ‘‘liquid ribbons’’ of varying width,typically from 40 to 120 mm, perfectly impregnating the reinforcement.


FEATURE

access to the injection hole, the LN6 head has been conceived with

all fittings and controls mounted on the rear side, opposite to the

nose (Fig. 9).

This configuration leaves a very sleek design on the sides so to

reduce its impact on the mold even further. Mounting the pressure

injectors parallel to the cleaning rod required a special solution for

their regulation.

This problem was solved by designing the injector’s casing

exploiting the length of the head’s body, rather than its width.

Holding a pending patent, this new Cannon mixing device allows

for both a manual and an automated regulation of the injectors,

obtaining a perfect control of pressures through a micrometric

adjustment.

The small size of the moldings, often required by car and leisure

parts manufacturers, requires the use of low-output dosing

machines and mixing heads: a total output going from 4 to

100 g/s is very common in these applications, allowing the manu-

facture of one cured part every 2–3 min, obtained by injecting the

resin blend at a low output. This way, avoiding a too violent flow of

liquid, the reinforcement positioned in the mold undergoes no

stress.

As said before, the third component, the release agent, is dosed

with extreme precision into the resin stream through a static mixer

FIGURE 9

The suggested mixing head for the HP-RTM process is the Cannon LN6.

Designed specifically for Epoxy chemicals, it keeps all its components in acircular section of 120 mm diameter, injectors included. This very compact

footprint and its 15 mm nose allows it to be mounted on thin molds,

widely used by the automotive parts manufacturers to produce very small

CFRP composite components.

housed right in the mixing head. This integrated solution contrib-

utes to the compactness and the usability of the head. The built-in

hydraulic valve controlling the third component ensures the

synchronization of this stream into the resin, minimizing the

contamination of that material returning to the storage tank, prior

and after the injection. A new LN10 model, designed for output up

to 400 g/s, was released during 2014.

In addition to the fast injection technology for HP-RTM in

closed molds, Cannon have developed the LLD (Liquid Lay Down)

system: here the Epoxy formulation is laid over the carbon mat in

‘‘liquid ribbons’’ of varying width, typically from 40 to 120 mm,

perfectly impregnating the reinforcement and limiting the possi-

bility of air inclusions in the molded part. This technique, wetting

uniformly the almost flat preforms used for huge parts such as

roofs, engine hoods, fenders and doors, is suggested for very large

parts. The optimization of this process not only keeps low part-to-

part cycle time, but also requires lower compression force, and

thus reduced capital investments which in the end leads to lower

part cost (Fig. 10).

For the Gap-injection method – that works by injecting the

formulation while leaving the mold partially open during

the injection still guaranteeing with a special sealing system

the tightness of the mold cavity and applying the final compres-

sion stroke at the end of it – the selected mixing head is a special

version of the FPL 14.

It’s machining tolerances and inner parts are designed to with-

stand the high temperatures and some tough pressure conditions,

typical for the formulation used, when the counter-pressure builds

up in the mold during the injection.

ControlsThe most difficult component of a complex molding island for

composites is the electronic control: each piece of equipment must

work in total coordination with the rest of plant. Purchasing

machinery from various vendors and letting them communicate

properly is the nightmare of every production manager.

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FIGURE 12

The CRESIM pilot plant, available in Cannon R&D Laboratory in Italy, canhandle three different technologies (Liquid Lay Down, HP-RTM, Gap

Injection) for the impregnation of rCF using Epoxy, Vinyl Ester or

Polyurethane.


FEATURE

Cannon develop in-house their own electronic controls

through a Division specializing in dedicated automation systems.

Working with proprietary as well as commercially available elec-

tronics, the integrated controls are built according to the specifi-

cations pertaining to the individual plant.

An example of this vertical integration comes from the RTM Cell

Manager, a unique interface for all the single units that compose an

HP-RTM molding island. Characterized by a central CPU in charge

of the coordination of functions, plus a number of peripheral CPU

dedicated to each task, the RTM Cell Manager controls the pre-

former, the dosing unit and mixing heads, the polymerization

presses and molds, the handling robots and the ancillary periph-

erals. Its open structure allows for the extension of the control

functions to Production Planning and Statistics, Quality Control

and Process Data Analysis, Piece Traceability and Identification,

Raw Materials Provisioning, connection to other production

phases and to smart devices like tablets and smartphones.

FinishingA molded composite part usually requires some finishing opera-

tions, like trimming its edges or piercing holes on its surface.

Cannon provides the full integration of third parties 5- and 6-axes

milling and contour-cutting equipment and of all relevant han-

dling robots.

RecycleUsing limited energy resources during manufacturing and giving a

second life to products significantly contributes to the environmen-

tal friendliness of composites. Cannon is actively pursuing these two

pathways in the design of their equipment and in the definition of

their processes. The CRESIM (Carbon Fiber Recycling by Special

Impregnation) project, aimed at the development of processing

methods for the manufacture of CFRP parts, uses recycled carbon

fibers to produce molded parts featuring mechanical characteristics

and esthetics similar to those made with virgin fibers.

FIGURE 11

The CRESIM (Carbon Fiber Recycling by Special Impregnation) Cannon

project, aimed at the development of processing methods for themanufacture of CFRP parts, uses recycled carbon fibers to produce molded

parts featuring mechanical characteristics and esthetics similar to those

made with virgin fibers.

322

The CRESIM project has been partially funded by the EU Life+

program. It was finalized to the development and demonstration

of innovative processes for fine-tuning, prototyping and launch-

ing on the market of composite parts with high mechanical and

esthetical characteristics obtained with recycled carbon fiber (rCF)

derived by very expensive scraps. These are a classified waste,

whose current disposal method – landfilling – would otherwise

have a high negative impact on the environment (Fig. 11).

The CRESIM pilot plant, available in Cannon R&D Laboratory in

Italy, can handle three different technologies (Liquid Lay Down,

HP-RTM, Gap Injection) for the impregnation of rCF using Epoxy,

Vinyl Ester or Polyurethane. More than ten different parts have

FIGURE 13

Cannon have developed a core competence in the manufacture ofcomposite parts that covers the whole set of required processes and

technologies, with a 3608 approach.


FEATURE

been developed in the 42-months duration of the project, includ-

ing hundreds of test samples for the characterization of the for-

mulations and of different types of rCF, improved satellite dishes

for defense communications, a skate board for sport and leisure

applications, automotive parts for German and Italian vehicles or

Japanese bikes and an innovative hollow part for the arm of a

packaging robot working at very high speed (Figs 12 and 13).

. . . plus the know-how!Cannon have developed a core competence in the manufacture of

composite parts that covers the whole set of required processes and

technologies, with a 3608 approach. A unique portfolio of dedicat-

ed, industrially tried-and-tested solutions is available for compos-

ite mass production, with equipment tailored to the customer

requirements. A staff of competent specialists provides, in a mod-

ern application development laboratory equipped with industrial

press and multiple dosing units, all the needed support to optimize

the production process. A prototyping service is available, for the

preliminary set-up and the production of large pre-series of com-

posite parts, allowing for the industrial evaluation of the molded

component.

Cannon, being able to supply all the required technologies and

equipment with a ‘‘single responsibility’’ contract, provides a One-

Stop-Shop approach to the companies that decide to invest in

complete manufacturing solutions for composites. This is a unique

offer, in a competitive field populated by producers of single pieces

of equipment unable to guarantee the final result when a complex

plant has to be put together.

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Cannon solutions for mass production of composite parts