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Individual processes offer individual solutions

Focus

Injection Moulding of Lightweight Parts

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*Particle-foam Composite Injection Moulding®

At a glance

Huge potential: production-ready processes and additional equipment are combined with a high level of consulting expertise from

ARBURG to provide ever new solutions for the injection moulding of lightweight components.

Cost savings, increased efficiency, con-servation of resources and lower CO2

emissions: As a “problem-solver”, lightweight construction is a key topic for the future, not only in the automotive industry, but also in are-as as diverse as the logistics, medical and packaging sectors and building technology. The objective is to reduce part weights or replace metals. Inno-vative injection moulding processes are required for this purpose. In order to find the most efficient solution, ARBURG has built up a network of partners, institutes and universities that can be called upon as needed. When it comes to the development of parts, what counts above all is the opti-mal coordination of processes, materials and part design. Functional integration and multi-material design ensure sus-tainable and cost-effective production.

Lightweight construction: A new approach to design and development.

Choice of processes Part design

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ProFoamMuCell® Fibre direct

compoundingFluid injection technology

Thermoplastic composites

PCIM®*

Material selection Functional integration

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Knowing the potential and processesThe potential of lightweight construction has not yet been fully exploited. The optimi-sation of part design and the production process or the combination of different ­processes­and­materials­enable­significant­cost savings to be achieved during manu-facturing and in the daily use of lightweight components. Other advantages include the replacement of conventional materials and efficient­high-volume­production.­Whether­foam­injection­moulding,­integrated­fibre­reinforcement or in combination with other materials such as thermoplastic composites and particle foams: ARBURG is intimately aware of the savings potential and limita-tions of all the processes because ARBURG is a partner in various networks that focus on the optimisation and combination of processes and materials and therefore offers not only the technology, but also compre-hensive application technology consulting.

Designing process-specific technologyUniversal ALLROUNDER injection moulding technology can be adapted to the various lightweight construction processes using the appropriate additional equipment. In-house developments have been produced through intensive cooperation with partners who­have­the­necessary­specific­technical­expertise. The frequently complex produc-tion sequences are managed with up-stream/downstream processing steps, preci-sion injection moulding and detailed quality monitoring via the high-performance SELOGICA­control­system.­When­imple-menting turnkey systems, ARBURG, as a primary contractor, cooperates with leading manufacturers to bring together functions and solutions that are as individual as ­possible­-­after­all­application-specific­ requirements call for precise answers.

Comprehensive consulting and testingAll customers can rely on the same level of comprehensive know-how – from assistance with part design and the choice of material, mould­and­machine­configuration­to­ production optimisation. The ARBURG Customer Center at our headquarters in Lossburg has several ALLROUNDERs that are­already­configured­for­the­respective­lightweight construction processes. This means that detailed trials and tests can­be­carried­out­to­find­the­best­solution.­ARBURG specialists ensure a smooth testing process and detailed documentation. The sales and technical organisations are located in close proximity to the Customer Center, helping to keep the communication chan-nels­short.­When­it­comes­to­problem­solv-ing, the full range of ARBURG expertise is available quickly and directly: it simply couldn’t be better!

Example - laptop cover: modern ALLROUNDER injection moulding technology, together with well-founded expertise,

is opening up new application areas for lightweight plastics in multi-material designs.

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MuCell® screw: reliable homogenisation of

blowing agent and plastic.

Lightweight construction for weight reduction The MuCell® process produces microcellular structures­that­enable­efficient­weight­re-duction. For this purpose, a gaseous blow-ing agent is brought to a supercritical state (SCF). In this state, the blowing agent can be dosed precisely and mixed homogene-ously with the plastic to form a single-phase solution. The blowing agent reduces the vis-cosity. After injection, the expanding blow-

ing agent in the mould assumes the func-tion of providing holding pressure. This re-sults in a component with microcellular foam structures in the core and a compact outer layer. Perfectly coordinated machine technology is key in order to fully exploit the positive properties of foaming. Thanks to its close cooperation with Trexel Inc., ARBURG is in a position to offer extensive process expertise and comprehensive appli-cation technology consulting.

Lightweight construction parts are of interest to many industries. In ther-moplastic foam injection moulding, the plastic granulate is enriched with blowing agent. During the plasticising process, the blowing agent is dissolved in the melt and only emerges again in the form of micro-cellular “bubbles” when the pressure is reduced during injection. Our close cooperation with technology partners Trexel Inc. (Wilm-ington, USA) enables our customers to enjoy all the benefits of the innovative MuCell® process. This not only enables significant savings to be achieved, for example in terms of material use, but also higher component quality, for example through a reduction in distortion and sink marks. Thanks to the physical properties of the blow-ing agent, it us often also possible to reduce the cycle time, thus ensuring cost-effective production.

Thermoplastic foam injection moulding: MuCell® process

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MuCell® – implemented by ARBURGFoaming with blowing agents in the super-critical physical state places extremely high technical demands on the machines. Hydraulic and hybrid ALLROUNDERs are ideal for this purpose because they can be individually tailored to the relevant produc-tion requirements. Thanks to the intuitive SELOGICA control system, all process- related parameters of the injection mould-ing machine and the SCF dosing system are precisely controllable.

Integration of the MuCell® process:• Varan interface to the SCF dosing system

for real-time data transfer• Precise process control: SCF dosing

system integrated in the SELOGICA control system with dedicated symbols

• SELOGICA stores the MuCell® process parameters in data set

• Easy cleaning of the injector in set-up mode via injection moulding machine

MuCell® package

Working in close cooperation with its partner Trexel Inc., ARBURG offers customised turnkey production sys-tems. These systems include the following basic equipment:

• hydraulic or hybrid ALLROUNDER S/H machines

• Injection unit with extended MuCell® cylinder module, including injector, rupture disc and pressure sensor

• MuCell® plasticising screw with special mixing zone and a second non-return valve

• Pneumatic needle shut-off nozzle • Adapted nozzle guard• Varian interface and software• MuCell® SCF dosing system

(Trexel T series)• Functional testing at ARBURG• Requirements:• Position-regulated screw• Pressure accumulator

(recommended from injection unit 800 upwards)

process

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Joint research and further development of the ProFoam process conducted by the IKV and ARBURG make it easier and more efficient to exploit the advan-tages of thermoplastic foam injection moulding. A gaseous blowing agent (N2 or CO2) is applied to the plastic granulate in a granulate lock upstream of the injection unit. In addition to the usual advantages associated with phys-ical foaming, such as weight reduction, possible cycle time reduction and less distortion, the method offers greater flexibility through use of a standard plasticizing screw. As a result, the plas-tic is processed gently, which is particu-larly advantageous for shear-sensitive or fibre-reinforced materials. Further-more, the ProFoam cylinder module can also be used for compact injection moulding.

Foaming­glass-fibre­reinforced­plastics:­

with ProFoam, without additional shearing.

Simple foaming processProFoam can be used to produce extremely fine­cell­structures­in­the­part,­efficiently­re-ducing the amount of material used. The re-quired­gas-filled­plastic­compound­is­produ-ced on conventional injection moulding ma-chines with little additional technical equip-ment.The granulate feed hopper is replaced by a patented granulate lock for the conti-nuous feed of material and gaseous blowing agent, while the plasticising unit is equipped

Thermoplastic foam injection moulding: ProFoam process

with a needle type shut-off nozzleand addi-tionally sealed. This produces a constant blowing agent atmosphere in the granulate feed. During plasticising, the gaseous blow-ing agent diffuses into the melt and forms a homogeneous solution in the space at the front of the screw. During injection, the blowing agent separates from the melt in the form of microcellular bubbles, causing the foam structure to be formed.

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Foaming offers numerous advantagesIn­addition­to­simple­and­efficient­foaming­technology, the ProFoam process provides further interesting properties:• Flexible use: the prepared ALLROUNDERs

can be used for conventional compact injection moulding without limitations

• Simple process control: it is only necessary to take one additional setting parameter for blowing agent pressure into account

Thermoplastic foam injection moulding: ProFoam process Basic ProFoam

Basic equipment for use of the ProFoam technology:• Sealed cylinder module• Standard three-zone plasticising screw

in the material-conveying zone• Hydraulic needle shut-off nozzle

Requirements:• Position regulated screw (standard on hybrid

ALLROUNDERs)• Pressure accumulator (recommended from

injection unit 800 upwards)

• Standard three-zone plasticizing screw: no additional shearing of fibre-reinforced plastics

• Single-phase solution between the plastic and blowing agent: homogeneous foam structure

• ARBURG offers comprehensive applications engineering consulting

• An interdisciplinary team develops individual solutions

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Carbon or glass fibres are used to improve the mechanical properties of components. This effect depends on the length of the fibres introduced into the plastic melt. In order to achieve this cost-effectively in the injection moulding process, ARBURG has devel-oped fibre direct compounding (FDC) in cooperation with the German Plas-tics Centre (SKZ). This method enables the proportion of longer fibres in the component to be increased, making it easier to substitute other materials and to generate new material combinations more effectively. In the FDC process, inexpensive initial materials are used, enabling cost-effective mass production to be achieved at reduced unit costs.

FDC­unit:­cutting­and­inline­feed­of­fibres­into­the­

liquid melt.

High-strength lightweight constructionIn­the­FDC­process,­fibres­are­fed­directly­into the liquid melt. This achieves greater part resilience and reduced wall thicknesses. The FDC process offers new opportunities and­interesting­advantages­over­long­fibre­granulates:• Targeted influencing and optimisation of

mechanical component properties• Detailed process settings, for e.g. fibre

length and fibre proportion, are possible

Fibre Direct Compounding (FDC)

• Longer, individually cut fibres can be fed in• Reduced destruction of fibres

during melt preparation• Compounding with PP, PA, PET,

PC/ABS (more materials available on request)

• Reduced material costs – by up to 45 percent

• Individual material combination

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Integrated fibre reinforcementThe objective during development of the FDC­process­was­integrated­fibre­reinforce-ment at lower unit costs. A servo-electric FDC­unit­cuts­continuous­fibre­strands­into­5.6-33.6 mm lengths and adds them di-rectly to the liquid melt. A two-stage screw is­used­to­homogenise­the­fibres­and­plastic­melt in a special cylinder module for a homogeneous phase.

FDC features

• Turnkey production cell with hydraulic ALLROUNDER S

• FDC cylinder module with adapted geometry

• FDC unit with cutting tool and servo-electric side feeder

• Roving station• Functional testing at ARBURG

The FDC process is fully integrated in the SELOGICA control system and dedicated symbols enable the process to be pro-grammed­easily­and­flexibly.­In­addition,­ the SELOGICA control system uses the sig-nals of the FDC unit to monitor quality. The FDC cylinder module features a plasti-cising screw with adapted geometry. An additional thermoplastic cylinder module allows the ALLROUNDERs to be used for conventional injection moulding.

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Overmoulding thermoplastic composites

Step 1: A robot picks up the thermoplastic com-

posite sheets and pre-heats these in the gripper.

Step 2: IR heaters bring the thermoplastic

composite sheets to forming temperature.

The combination of injection moulding and thermoforming of thermoplastic composites can significantly improve the mechanical properties of compo-nents. Local reinforcement by means of ribs or functional elements such as mountings produces highly resilient, installation-ready products. This makes it possible to replace conventional ma-terials such as metals in many cases. The hybrid lightweight construction with multi-material design offers enor-mous potential for the future. At the same time, the modular ALLROUNDER technology enables fully automated and therefore cost-effective production of such high-quality components.

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Step 3: An optical test system checks whether the thermoplastic composite sheet has reached the forming temperature.

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Step 4: The robot inserts the thermoplastic

composite sheets into the injection mould.

Lightweight construction with multi-material design The substitution of materials in lightweight construction­brings­particular­benefits­when­reinforced plastics are used. Thermoplastic composites are combined with conventional thermoplastic materials, resulting in the mu-tual enhancement of their mechanical prop-erties.­The­continuous­fibres­(glass,­carbon­or aramide) are combined with various matrix materials - this increases mechanical strength, enabling metal materials to be substituted. Parts made from thermoplastic composites generally weigh between 30 and 50 percent less than those made from metal of the same thickness and with similar mechanical properties.

Important: fully automated processThe overmoulding of thermoplastic com-posites involves the manufacture of com-posite­fibre­lightweight­parts­suitable­for­batch production in a fully-automated injec-tion moulding machine. Injection moulding turns thermoplastic composite sections into ready-to-install, high-strength structural components. This process is ideal for high-volume applications, as the cycle times that can be achieved are the same as during injection moulding. A further advantage is that it can be combined with other processes, such as the FDC process. This gives rise to a wide range of options, for example in the areas of part design and function integration.

Cost-effective turnkey solutionAs a general contractor of turnkey systems, ARBURG offers comprehensive expertise in the­processing­of­common­fibre-matrix­semi-finished­products­such­as­UD­tapes,­pre-pregs and thermoplastic composite sheets. Services range from the integration of composite processing or inline quality control­in­the­production­line­to­the­defini-tion of interfaces or coordination and moni-toring of the entire process from acquisition to commissioning. This continues seamlessly in the range of services provided. Here again, ARBURG acts as central point of contact for customers, reliably taking care of everything.

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Step 5: Thermoplastic composite sheets are

formed in the mould and overmoulded.

Step 6: A robot removes the ready-to-install

structural parts.

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Further lightweight construction processes

Compact production cell: six-axis robotic system links foaming system and ALLROUNDER.

The combination of different materials offers new possibilities both in part design and production. As a project partner, ARBURG builds complete pro-duction systems and will support you from the outset with well-founded know-how and cross-functional project teams. Should, for example, particle foam composite injection moulding® be used to exploit the benefits of the unique composite material? Or can fluid injection technology be used to signifi-cantly reduce component weight with-out sacrificing on quality? Innovative processes and close cooperation with our project partners enable us to pur-sue many new and unusual approaches to lightweight construction.

Positive bond: ideal for high loads.

Particle-foam Composite Injection Moulding® The PCIM process was developed in strate-gic partnership between Krallmann, RUCH NOVAPLAST and ARBURG. As the plastic is injected into the mould, the surface of the particle foam part, consisting of expanded polypropylene (EPP) or polystyrene (EPS), is melted­in­a­defined­way:­a­strong,­perma-nent, positive bond is created between the two components. The composite parts are produced in a single step. This means inte-grated functionality without downstream assembly. The ideal conditions for cost-ef-fective high-volume production at reduced unit costs.

The multi-material design involving particle foam and thermoplastic eliminates the weak-nesses of both materials and unites their advantages for lightweight parts such as:• Sturdy lightweight

cladding panels• Energy-absorbent handles with

an attractive tactile surface • Thermally insulating covers with

integrated attachment functions• Noise-reducing, easy-to-assemble

housing• Insulating products with enhanced

rigidity

Particle-foamed part Plastic part

+ Low volumetric weight+ High force absorption+ High thermal insulation

- Relatively high volumetric weight- Low force absorption- Low thermal insulation

- Limited surface- Limited attachment options

+ Functional surfaces+­Wide­range­of­attachment­options

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Precise and space-saving: horizontal removal of a FIT component from the mould with a

compact MULTILIFT H.

Particle foams have a density of between 20 and 60 grams per litre. The foamed moulded parts produced on special foaming systems are accordingly lightweight. To en-sure that these can be safely placed inside the mould and then overmoulded without deformation or damage, special expertise and special technology is required:• A specially coordinated mix of materials

and an appropriate programme for the combination of both materials

• Precise particle-foam inserts with high-contour accuracy

• Near-contour, segmented mould temperature control

• Specially designed sprue system• Reliable handling and precise

positioning of foamed inserts by means of a robotic system

• Precisely regulated, multi-stage injection process

• SELOGICA control system integrates entire peripherals for individual process control

Fluid injection technologyThis technology is available in different vari-ants and is thus individually adaptable to the requirements at hand. Targeted hollow spaces can be produced in the part during the injection moulding process through the introduction­of­gas­(GIT)­or­water­(WIT)­into­the­cavities.­The­relevant­fluid­is­introduced­into the mould via the injection nozzle or by means of injectors. This makes components light as well as mechanically resilient. The SELOGICA control system enables switching from material injection to gas or water injection as a function of time, stroke or pressure.

Fluid­injection­can­achieve­significant­mate-rial savings. The smaller wall thicknesses also result in shorter cooling times and therefore shorter cycle times. To enable the­use­of­fluid­injection­technology,­ALLROUNDER injection moulding machines are equipped with a special interface and a core­pull.­Working­in­close­cooperation­with­various­equipment­manufacturers­for­fluid­injection technology, ARBURG can offer a comprehensive overall package.

Lightweight and absorbent: particle foam cell

structures feature many interesting properties.

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Application examples

Lightweight parts are rapidly gaining significance in many areas of industrial production. Owing to their many excel-lent characteristics such as reduced weight and shorter cycle times, new solutions and product ideas frequently arise with regard to lightweight parts. ARBURG always keeps a close eye on efficient production with low unit costs. ARBURG’s system technology offers you the best basis here, with cost-effective, customised technolo-gy and well-founded expertise. Our experts devise customised concepts and specialise in finding the most efficient production solution.

1 Lightweight construction with

fluid injectionIncreasing­efficiency­while­reducing­weight­and­costs­-­fluid­injection­technology­makes­it particularly easy to produce more light-weight components without compromising on quality. Fluid injection technology shows its strengths based on the example of a refrigerator door handle, which is manufac-tured on a hybrid ALLROUNDER. Carbon dioxide (CO2) is introduced to the liquid melt in the mould cavity. This not only re-duces weight, but also the cooling time by up to 50 percent. At the same time, the ex-posed part features a high-quality surface without sink marks.

2 Foamed, high-gloss part

Dynamic mould temperature control can be used to produce a high-gloss surface. The component, a glove compartment cover, has been consistently designed for foaming. Physical foaming reduces the wall thickness from 2.5 millimetres to 1.8 millimetres. The cover weighs 200 grams, around 30 percent less than a comparable compact part. The prerequisite here is precise process control. This is ensured through the complete inte-gration of the physical foaming process in the SELOGICA control system and intuitive setting of the process parameters.

A coordinated process: the use of CO2­in­the­fluid­injection­technology­leads­to­efficient­part­cooling­

and­thus­to­a­significant­cycle-time­reduction.

High-quality: foamed parts with Class A surface

achieved through dynamic mould temperature control.

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3 Fibre-reinforced housing

Reduction of manufacturing costs and weight­–­through­innovative­fibre­direct­compounding (FDC). An ALLROUNDER fea-turing a FDC unit is used to manufacture ca-ble drive housings for power windows in car doors made of PP with 30 percent long glass fibres.­In­addition­to­an­adapted­cylinder,­this­comprises a special screw and a lateral feeder with integrated cutting device. Long glass­fibres­with­a­length­of­11.2­millimetres­are fed via this unit. Expensive pre-com-pounded granulate mixtures can therefore be dispensed with. The cable drive housings are up to 30 percent lighter than comparable PBT housings - at reduced cycle times.

4 Carbon-fibre part

Stringent demands on material and design call for unique production solutions. A verti-cal ALLROUNDER with rotary table is used to produce laptop covers made of thermo-plastic composite (CF / PC) and PC. The semi-finished­carbon-fibre­product­is­heated­to 250°C directly in the mould, formed and overmoulded. This eliminates the need to heat the thermoplastic composite externally prior to insertion into the mould. This not only reduces the cycle time, but also ena-bles production of high-quality surfaces with­extremely­fine­textures.­The­moulded­parts do not require any pre- or post-pro-cessing, meaning that all the handling tasks can be performed by a single six-axis robot.

5 Standardised fastening elements

The unique combination of particulate foams (EPP) and thermoplastic (PP) materials offers new and unusual ways of designing sealing systems for cables and sensors or for heating and ventilation equipment, as well as easy-to-install insulation panels. Stand-ardised fastening elements of the K-Fix se-ries from the Krallmann Group are inte-grated into foamed housings or panels of the NOVAFeed&Fix series from Ruch No-vaplast, for example. In the fully automated system, a multi-axis robot links the PCIM® foaming system and the ALLROUNDER. Integration of the peripherals in the SELOGICA control system enables individual process control.

Perfected: the ARBURG Customer Center in

Lossburg is available for development work.

Functional: delicate injection moulded structures

combined­with­glass­fibre-reinforced­material.

Flexible: fully automated production of components

made from particle foam and thermoplastics.

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© 2018 ARBURG GmbH + Co KGThe brochure is protected by copyright. Any utilisation, which is not expressly permitted under copyright legislation, requires the previous approval of ARBURG.

All data and technical information have been compiled with great care. However we accept no responsibility for correctness. Individual illustrations and information may deviate from the actual delivery condition of the machine. The relevant valid operating instructions are applicable for the installation and operation of the machine.

ARBURG GmbH + Co KG

Arthur-Hehl-Strasse · 72290 Lossburg · Tel.: +49 7446 33-0 · www.arburg.com · contact@arburg.com

With locations in Europe: Germany, Belgium, Denmark, France, United Kingdom, Italy, Netherlands, Austria, Poland, Switzerland, Slovakia, Spain, Czech Republic, Turkey,

Hungary | Asia: People’s Republic of China, Indonesia, Malaysia, Singapore, Taiwan, Thailand, United Arab Emirates | America: Brazil, Mexico, USA

For more information, please go to www.arburg.com.

ARBURG GmbH + Co KG

DIN EN ISO 9001 + 14001­+­50001­certified 6812

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