PrefaceGeometry and quantity play animportant role in selecting a suitableshaping method for ceramic com-ponents (Fig. 1). Extrusion and injec-tion molding are manufacturingtechnologies of high productivityand a high degree of automationalso for the upstream and down-stream process steps. At the sametime, these near net shape methodscan be used to realize very complexgeometries, e.g. such as thin wallthicknesses and smallest holes. Sum-marized as “Plastic and thermoplas-tic shaping methods“1) extrusionand injection molding combinemany general questions: from theselection of suitable binder systemsfor a homogeneous plasticizationand the adjustment of defined rheo-logical properties through the mod-eling and simulation of shapingprocesses up to the characterizationby non-destructive testing methods.In both technologies high deform-ation degrees are used in order tomold the ceramic bodies in cavitieswith complex geometry so that anear net shape production with highprecision becomes possible also forvery filigree structures. In ceramicinjection molding the component’scontour is completely formed by thetool cavity; shaping takes place cy-clically in the closed tool. In com-parison, extrusion is a continuousprocess through open cavities,where the die geometry forms thecross section of the shaped compon-ent (Fig. 2). The binder concept isdifferent: For the injection moldingprocess thermoplastic binders areused to plasticize the ceramic pow-ders. These binders allow one toshape the component at tempera-tures above their melting point, and

also guarantee a reliable ejection atlow temperatures. In the case ofextrusion, the clay-typical moldablebehavior at temperatures near roomtemperature is adjusted by usingwater- soluble binders on the basis ofcellulose in combination with lubri-cants. When extruding thermoplas-tic masses the shaping process issupported by cooling the extrudateafter it has left the die. Before remov-ing the organic binders the contentof which is lower than in ceramicinjection molding an additional dry-ing step is necessary. Binder removalis identical in both methods.Injection molding and extrusion pro-vide good opportunities for thedevelopment of new as well as thefurther development of existingproducts as well as their improve-ment as they allow for a significantincrease of the level of integration(e.g. the miniaturization of injection-molded components or by reducingwall thicknesses and channel diam-eters of extruded honeycombs).

cfi/Ber. DKG 87 (2010) No. 4 E 17

Many technological solutions suc-cessfully realized in practice, thus,prove the high potential of plasticand thermoplastic shaping meth-ods. At the example of two currentdevelopments the interaction of spe-cific requirements, material concept,

Process Engineering

Product and Process OrientedShaping Techniques forAdvanced Ceramics at theExample of Ceramic InjectionMolding and Extrusion

Fig. 1Selection of shapingmethod in depen-dence of geometryand quantity

Fig. 2 Schematic of the process steps in ceramic injection molding and extrusion1) Topic and introductory lecture of theDKG autumn symposium 2009/Erlangen

Reinhard LenkFraunhofer IKTSDresden/DEReinhard.Lenk@ikts.fraunhofer.de

complexity of geometry

qua

ntiti

y

cold isostaticpressing slip casting

injectionmolding

extrusionuniaxial drypressing

hot molding

pow-der mil-ing

was developed and adapted for usein diesel particle filters in terms ofsize, distribution and volume of itspores. The raw materials are com-paratively inexpensive and can behandled at lower temperatures aswell (approx. 400 K lower than thestate of the art). They have a topposition among the ceramic filtermaterials regarding separation effi-ciency (99,5 %), pressure drop andthermomechanical stability.By a new filter segment design withasymmetric trapezium geometry it ispossible to flexibly produce thegreat variety of filter geometries andsizes. At the same time, the costlyhard machining step with diamondcutters can be avoided which usual-ly results in approximately 20 percent of material loss. Thus, material

and energy resources can be careful-ly used. The channels in the seg-ments are three-cornered (Fig. 3),not square, providing a larger filtersurface. This means that, fittedbehind the engine, it takes longer forsooty particles to accumulate in theindividual channels and to reach thestage where they must be burnt off.The regeneration cycle, thus, can beprolonged and fuel can be saved.Due to this design the filter elementis also more resistant againstmechanical stress and so morerobust.Following the product concept withthe asymmetric segment design, itwas then necessary to overcome various technological challenges. Sothe geometrical and position toler-ances required for the canning of thefilter elements, which are usuallyguaranteed by the machining step,already have to be realized in theceramic shaping process. For this aspecifically developed bonding tech-nology is used which can be adjust-ed to all geometries. The pluggingprocess (more than one hundredcells per segment in a few seconds)also represents a particular chal-lenge. The diesel particle filter (Fig. 4) hasbeen produced in the new produc-tion facilities of CleanDieselCeramicsGmbH in Großröhrsdorf near Dres-den since 2008. In 2009, the con-cept was awarded with the Josephvon Fraunhofer prize.

Inmold Labeling of Metal-CeramicComposites3)

The development of new materialapplications are mainly motivated byan improvement of performance aswell as a reduction of costs, weightand space. By combining differentmaterial properties the functionaldensity may be increased. The com-bination of powder injection mold-ing and green tape technologyoffers interesting possibilities fordesigning multi-component parts.In inmold labeling the main chal-lenges are the compatibility of theused materials and the adjustmentof the shrinkage properties duringthe debinding and sintering process.It is one main advantage of thismethod that the manufacturing ofcomponents with thin functionallayers is significantly simplified, andthus, it can be more reliably trans-ferred into mass production as theactual injection molding process

E 18 cfi/Ber. DKG 87 (2010) No. 4

product design as well as manufac-turing technology is shown.

Highly Efficient CeramicDiesel Particle Filter of CleanDieselCeramicsGmbH2)

Whereas diesel particle filters for carscan be produced in high quantitiesand are standardized the filters fornon-road applications are character-ized by an extremely high degree ofdiversification in terms of batch sizeand geometry. On top of it, the fil-ters have to meet even higherrequirements with regard to rugged-ness, longevity and efficiency. There-fore, a new filter material of liquidsintered silicon carbide (LPS-SiC)

Process Engineering

Fig. 3 leftSchematic of filtratonprocess with three-cornered, recipro-cally closed channels Fig. 4 rightDiesel particule filter (CleanDiesel-Ceramics GmbH)with a segmentationof asymmetric com-ponents

Fig. 5 Schematic processof injected greentapes made ofpowder materials

E 20 cfi/Ber. DKG 87 (2010) No. 4

Process Engineering

remains reduced to one component.The composite is realized by insert-ing prefabricated green tapes madeof a powder material into the cavity,which are then injected with a feed-stock made of another material (Fig. 5). Ceramic or metal green tapes can beproduced in different layer thick-nesses and stamped by suitableposttreatment processes, i.e.microstructuring, screen printing,lamination and punching. In theinjection process the inserted thin-

walled tapes may also take on thecomplex contour given by the cav-ities. At the same time, extremelythin functional layers made of metalor ceramic materials can be realizedas there are no restrictions by limitedflow paths as compared to conven-tional two-component injectionmolding. In order to compensatestresses caused by different thermalexpansion it is also possible to designthe green tapes as laminar structurewith a continuous transition of thematerial composition. Such anexample is shown in Fig. 6. Thepunched green tape made of pow-der steel was inserted into the toolcavities by means of an automatedhandling system, and then injectedwith a zirconia feedstock and sin-tered as composite.

ProspectsFirst of all ceramic shaping methodsmust guarantee that the propertiesexpected from the material are reli-ably transferred to the componentand may be well reproduced. As the

price is important for the success ofa product in the end, the ceramicshaping method must additionallyallow for an efficient production ofthe component in the requiredgeometry and quantity. However, asnecessary as these both require-ments are – in order to develop newceramic applications they often can-not compete with other materialsolutions. The important it is to con-sider the technical possibilitiesalready in the product developmentprocess and to utilize all degrees offreedom given by the specific pro-duction processes. Then, ceramicshaping can be much more than ameans to an end: an important driver and a solid basis for ceramicinnovations in new attractive appli-cations. The realization of new ma-terial concepts using innovative plas-tic and thermoplastic shaping meth-ods can make an important contri-bution to this process. For this pur-pose, joint efforts of material devel-opment, manufacturing technologyand system application are neces-sary.

Fig. 6Prototype, project“GreenTaPIM”3)

(left after defor-ming, right sinte-red part)

2) A joint development of Fraunhofer IKTS and CleanDieselCeramics GmbH, financed with funds of the European Regional Deve-lopment Fund (ERDF) during the period 2000–2006 and the Free State of Saxony. The project partner, funding organization andproject management are gratefully acknowledged.3) Funded by the Federal Ministry of Economics and Technology (BMWi) within theframework of the InnoNet program (16IN0319).The project partners, funding organization and project management are gratefully acknowledged.