world of innovation

FLUID-ASSISTEDINJECTIONMOLDING For "thick" parts with an attractive surface

Fluid-assisted injectionmolding isa process in whichagas(usually nitrogen)ora liquid isinjected intoa mold cavitypartlyorcompletelyfilled withmelt.Thepressurizedgasformsabubbleatthecenterofthe melt,whichcounteractsshrinkageandthusremovessinkmarks.Byreducingthequantityofplasticmate rialandenlargingthecavity,targetedproductionoflight-weightpartswithexcellentsurfacequalitycan beachievedwithshortcycletimes.Duetoitshighheat conductivity and highdegreeof incompressbility, waterisusedprimarilyasaflexiblepistontoproducecomplexhollowstructures,suchasthree-dimensional mediaductsystems.Bothprocesses openupextensive scopeforpartsdesignerstorealize complexmolded componentsinonepiece and withsmoothsurfaces.Forthesakeof completenessitshouldbementioned thatinbothprocesses mostofthe"fluids"canberestored tothe environmentafterthe partshavebeen formed.

The advantages

_{\mathfrak{D}} Quality improvement
_{rm{\scriptsize3}} Elimination of sink marks
\gg Elimination of warpage due to shrinkage
(3) Reduction of the required clamping force
_{rm{\scriptsize3}} Reduction of cycle time
_{\mathfrak{D}} Weight reduction
》Additional scope for design

AIRMOULD Internal gas pressure process

Internalgaspressuretechnologyisusedinseveraldifferent processvariants,depending onthe parts geometry,the plasticmaterial used and the specific requirements forthe product.Basically, a distinction ismade between the"partial flling process",the"spill-over cavity proces"and the "shrinkage compensation process".The three processes differfrom each otherbytheirspecificmold technologies andthe equipment andcontrolsystemvariantsof theinjectionmolding machine.All three process variants can be realized with the modular Airmould gas supply systems.

AIRMOULD The process variants in detail

》Partial filling process

Partial filling is the standard process. The cavity is partially flled with melt [1]. Next,gas is injected.It forms a gasbubbleinside the hotter core area with lower viscosity and displaces this part of the melt until the cavity is completely flled [2]. The gas pressure is maintained as holding pressureforshrinkage compensation [3] and finally removed prior to mold opening [4]. Gas injection through the Airmould nozzle of themachine serves to seal the sprue.

》Spill-over cavity process

As process step No. 1, the cavity is completelyflled withmelt [1].f necessary. holding pressure is applied to the melt. Then the spill-over cavity (overflow) is opened and nitrogen injected [2].The gas displacesmeltfrom the core area of the plastic material into the overflow.Subsequently, the gas pressure is maintained as holding pressure throughout the entire cooling period [3] and thus counteracts shrinkage.The gas pressure is removed prior to opening the mold [4].

》Shrinkage compensation process First,the cavity is completely filled with melt [1]. Then nitrogen is injected [2] and supplies the holding pressure to counteract shrinkage [3]. The gas forms channels inside themolded part,in which gas pressureis maintained throughout the cooling period and thus counteracts shrinkage.Depending on the molded part,the gas is injected either through aggregates inside themold orthe Airmould nozzle of the machine.The gas pressure is removed prior to mold opening [4].

Differentmoldedpartsmachinesizesandfelsfapplicatinrequirdifferentintagasressureequipm. ForoptimaladjustmenttoalltypesofrequirementsandconditionsWITTMANNBATTENFELDhasdevelopedthe Airmould module system.

Airmould internalgaspressuretechnologyisindependentofmachinemodelsandcanalsobeusedonmachinesof otherbrands.

y Pressure generator

Nitrogen is used as pressure medium,since it does notform any chemical bond with the plastic material.In the pressure generator,the nitrogen is compressed to an appropriate pressurelevel.For low gas consumption,the use of nitrogen bottles orgas cylindermanifolds isrecommended.For equipment with a high nitrogen consumption, the pressure generator can be combined with a nitrogen generatorfrom the Airmould module system and extractthenitrogenfrom the ambient air directlynext to the machine.

》Process control

The Airmould process canbe monitored and controlled via themachine's control system,or alternativelyviathetouchscreenofaseparate controlcabinetoramanualcontrolunit.

》Gas pressure control

To control the gas pressure, individual pressure control modules areusedwhichcanbemounted close to the mold to ensure an optimal, costefficient process bykeeping the gas pipes asshort as possible.

》Gas injection

The gas is injected either through the Airmould machine nozzle orvia gasvalves located directly inside the mold.

GASSUPPLYUNITS Powerful, for one or several machines

Pressure and nitrogen generators

The nitrogen and pressure generation equipment developed and manufactured by WITTMANN BATTENFELD is available in differentsizes and withvarying capacities,eitherto supply individual machines oras central systems to supply several machines.

Control system

The control system of thepressure generatorsisself-explanatory.All important informationfrom the pressure generators and,as anoption,from the nitrogen generators are displayed clearly and in a simple way. The equipment's control systemcan beintegrated into the corporate network.In this way,allparametersettings and signals of the equipment can be transmitted to any network-compatible PC.

Advantages

》 Self-explanatory,clearandsimple
》5.7" color TFT display with touch screen
(3) Network-compatible
(x) Protection bypassword against unauthorized operation

PRESSUREANDGASGENERATION With two output levels

DE pressure generator

Thepressure generators compress the nitrogento asufficient pressure for allAirmould applications.Depending onits capacity,one unit can supply either one orseveral machines.Withthe help of a modern control system,thepressure generatorscanbe operated by remotecontrol via thecorporatenetwork.Withits modular design,everypressure generator canberetrofitted witha nitrogen generatorat anytime.

Advantages

\gg Retrofitwithanitrogengeneratorpossible atanytime y Moderncontrolsystemwithremotecontrolfunction \gg Small footprint
(3) Compact, sound-insulated unit

SE Nitrogen generator

With the nitrogen generator extension modules of the SEseries, everypressuregeneratorcanbeconvertedinto aself-sufficient appliance.Special flter membranes are used to extract the nitrogen from the ambient air.The extension modules are adapted tofit the matching pressure generators of the DE series and caneasilybe retrofitted at any time.

Advantages

_{\Rightarrow} Independent operation, no logistic expense to replace nitrogen bottles
_{\gg} Nitrogenpurity of at least 98%
y One control system forthe entire equipment
》 Compact, sound-insulated unit

The compactsystemforall injectionmoldingmachineswitha EUROMAP62interface

ThankstothemodulardesignfAimould4.0allcomponentscaneeasilyintgratedintoallmachinesandwithout takingupmuchpaceeitherThesystemconsistsofthreecomponents:themanuloperatingterminalforsimplegraph callysupportedprocesscontrolthecentralproessingunittcoordinatellomonentswitheachotherandthepressur control module, to be mounted close to the consumer to minimize gas consumption.

_{\Rightarrow} Extendable to up to 8 modules at any time \gg Space-saving and easy to integrate in all machines (3) Easy data interchangevia USB (3) Access control via user group administration y Pressure monitoring program to detect leakages on the molded part y Impulse programs for automatic purging of the injection components

Manual operatingterminal

The small, compactmanualoperating terminal canbeeasilyattachedtoallmachinesbymeansofawallbracket.

》 Small control unit,measuring no more than 200x165~mm easy to integrate in all m y 5.7" touch screen
y 8 pressure and time profile points are available foreach pressure control module. _{\Rightarrow} Impulseprogramforpurging of gasinjectors atregularintervals
(3) Pressure profile monitoring fora safe process
(3) Graphically supported data input and process control
(3) USB connectionforeasy data transfer
(3) Easy controlling of 1 to 8 modules
y Supports Wittmann 4.0

Central processing unit

The central processing unit can be mounted freely anywhere on the machine.The unit is available intwo different versions:one withits own 24V power connectionto operateup to 8 modules,the other a small version without power plug to operate up to 2 modules

y Modestspace requirements of no morethan 330x300x330mm \gg Easy connection of all components

Control modules

Regulation ofthe gas pressureis carried outvia atleast onepressurecontrolmodule.Thegas present inside the pipe between the gas injection point and the pressure control module islost in every cycle.Shortconnectiondistances aredesirabletominimize thislossof gas.The compact design of thegas pressure controlmodulesenablestheirpositioningclosetothegasinjectionpointeither onthe machine oronthe mold.This ensures accurate pressureregulation and minimizes nitrogen consumptionaswellTheconnectionismadewithshort,smallvolume,high-pressurehoses.hegas pressureisregulatedviahigh-precisionvalves.Thevalves areelectricallyactuateddirectlywithout requiring anyadditionalcompressed airorhydraulics.Thankstothespecialstructureof the control modulepreciseregulationand monitoringofthegaspressureisensuredforbothsmallandlargevolumes ofgas.Thepressure controlmodules areequippedwithinlet andoutlet flters.Foreasypower connection,several modules canbe integrated into in a serial circuit.

PROCESS CONTROL Integrated in the machine's control system

The Unilog B8machine control system is theWITTMANN BATTENFELD solution to simplify the operation of complexprocesses.For this purpose,theintegrated industrial PC hasbeen fitted with an enlarged intuitive touch screen operating panel.The visualization is the interfaceto the newWindows10 loT operating system,which offers extensive process control capacities.In additionto the swivel-mounted display screen unit,the machine's central consoleisequipped with anintegrated manual operation panel/terminal.

Advantages

》The selectedpressure profiles are shown as curves.
》The actual value pressure curves forall pressure control modules canbe displayed simultaneously.
_{\mathfrak{D}} Simultaneous display of gas pressure curves and machine-relevantprocesscurvesin one chart
x The data are saved together with themachine data.
x DataoutputiseffectedviaaUSBflashdrive.

GASINJECTION Nozzles and injection elements

》Nozzles

SpecialAirmouldnozzleshavebeendesignedtoinjectthe nitrogen through the nozzle of the machine.The Airmould nozzles preventthe nitrogenfromentering thebarrelduringgas injection.Thenozzle's connectiondimensionisidenticalwith that of astandard nozzle,so thatitcaneasilyberetrofitted to any machine.

》Injection elements

Via aninjection element,the nitrogenisinjected into the mold.The elements are availablein different lengthsand diameters,so thatasuitable element can be chosen for every application.

Advantages

y Theinjection element is inserted and sealed from the rear of the mold.
\gg Easy cleaning:where necessary,cleaning can be effected within avery short time byunscrewing the element head from the open mold.
(3) Small apertures in the mold:the aperture in the mold correspondstothediameterof theinjection element.

》Projectile injection process

With this fluid injection technology,a displacement body (projectile) isdriven under gaspressurethroughthe previouslyinjected melt.The projectile displaces plastic melt and thus forms a cavity with a uniform diameter.This processis particularly recommended for pipes and media conduits. Handles and other parts withsizeablehollowspaces of uniform diametercanalsobe produced with projectile injection technology.

AIRMOULD Application examples

Automotive

Excellent moldings are achieved with internal gas pressure technology in the production of premium-class door handles,operating levers and handholdsforvehicles and the automotivesector,which also meet theindustry's requirements for high-quality surfaces.In addition to weight reduction,high productivity is achieved with internalgaspressuretechnologythroughshort cycletimesusing the "partial filling process"or the"spill-over cavity process".

Exteriordoorhandle-WITTEAutomotive

Packaging

The carrying comfort of beverage crates isimproved by a targeted wall thickness increase inthe gripping areas.Sink marks in these areas are prevented by the"shrinkage compensation process"using internal gas pressure technology.

Beercrate-OberlandMV

Pipes and media supply lines

Forpipes andmedia supply lines,cavitiescanbe createdatpre defined points by combining the projectile injection process withthe "spill-over cavity process".

Building construction

In additionto reductions in part weights and cycle times resulting from the"partial filling process",theinternalgas pressure process Creates added advantages in using the products.The lighter weight ensures easier handling forproducts used inbuilding construction, such as rubbing boards.

Rubbing board -Plastika Orth& Wachter

Products for daily use

With the help of internal gaspressure technology,the scopefor add ed criteria canbe extended in designingparts likethe coat-hanger shown in thepicture.The design can berealized withinternal gas pressure technology.In additionto reducingboth the part weight and the cycle time, warpage is also minimized by using the"partial flling process".

Design-coat hangers

Sports and leisure products

Thishockey stick,manufactured with internal gas pressure technology in the"partial filling process"provides sportsmen with a lightweight piece of equipment adapted to their require ments.

Hockey sticks

WITTMANN BATTENFELD GmbH
WienerNeustadterStrasse81
2542 Kottingbrunn|Austria
Tel.: +432252404.0\mid Fax: +43 2252 404-1062
info@wittmann-group.com
www.wittmann-group.com