From Rapid Prototypingto Rapid ManufacturingA rapid prototyping system as a production site for series parts? This is soon to become everydayreality in the automotive industry. Laser-sintering from EOS is developing into a standardmethod for the series production of plastic parts.

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38 AutoTechnology 2/2002

When Toyota Formula 1 driverMika Salo climbs into the defini-tive 2002 challenger, TF 102,which had it´s race debut on 3rdMarch at the Australian GP inMelbourne, he is accompanied bythe good wishes of John Mitchell.He is the engineer who has beenclosely involved in the develop-ment of the new 10-cylinder rac-ing car over a period of threeyears. John Mitchell is head of thecomposites manufacturing depart-ment of the Formula 1 productionsite of Toyota Motorsport GmbH(TMG) in Cologne. It is under hisleadership that the many individ-ual parts are developed from high-stability carbon fibre and recentlyfrom sintered speciality plastics.

Laser-sintered parts and com-ponents are made in Toyota’smodern model workshop. Thetechnical heart of this workshop isformed by two laser-sintering sys-tems supplied by the Germanmanufacturer EOS. Both systems –

one of which is a latest-genera-tion double-laser version – manu-facture components hour afterhour directly from thermoplasticpowders on the basis of three-dimensional CAD data. These aremodels and variants which aretested in the wind tunnel versionof the racing car and sometimesalso in the actual car itself. Timepressure is enormous and expec-tations are high. "Our laser-sinter-ing systems run 24 hours a day ",explains John Mitchell, pointingout just how important theserapid engineering tools are.

Process and Application

Laser-sintering technology isnow a standard feature in theengineering departments of auto-motive companies all overEurope. As the state of the art isconstantly moved forward, thetechnology is able to conquernew application fields. In theearly 1990s, laser-sintering start-ed as a rapid prototyping solution

for saving time and money inmodel making. Today, the sys-tems are emerging as productionsites for small series, producing atever faster rates with increasingbuild envelopes, and they arehighly automated too, turningout parts with excellent mechan-ical strength, resistance to hightemperature and outstanding sur-face quality. These were also thedecisive reasons for John Mitchellof Toyota Motorsport to invest inlaser sintering. As an aircraftengineer, he already had someexperience of rapid prototypingtechnologies such as 3D printingand stereolithography. However,John Mitchell and his team puttheir trust in laser-sinteringright from the beginning. "Themechanical properties of the partsachieved through the sintering ofthe thermoplastic powder, theuser-friendly handling and pro-ductivity of the machines and theexceptionally large build enve-lope, especially of the new doublelaser system, are indisputable cri-teria which cannot be fulfilled byother rapid technologies."

Plastic laser-sintering is a dryand direct layer-manufacturingprocess. CO2 lasers – controlledby CAD data – are used to buildparts layer by layer, directly frombiocompatible polyamide or poly-styrene (for investment castingpatterns). Depending on the parti-cle size of the powder used, aswell as on the geometry, numberand size of the building parts, thistakes only few hours. After a

by Michael Stöcker

John Mitchell,head of the com-posites manufac-

turing depart-ment of Toyota

Motorsport.

Toyota TF102Formula 1 Race Car.

AutoTechnology 2/2002

short surface finishing, the parts can be used immedi-ately. The particular strength of this method has alwaysbeen in the direct manufacture of parts which offerhigh functionality and close-to-series properties andperformance.

All the information needed to control the laser isgenerated directly from the 3D CAD data of the design.For this purpose, the CAD data are converted into anSLI format (slice layer information) which can be read

by the systems. These SLI data comprise all the geo-metrical data required for the building of the laser-sin-tered part (contours, position, layer thickness). In otherwords, the three-dimensional design data of volumemodels are converted into two-dimensional layer orcontrol data. This is normally done via the STL con-verting step, which can be performed by the export fil-ters of most of the 3D CAD programmes. For the laststep in the chain – i.e. the conversion of STL to SLIdata – EOS offers their own tools or recommends theuse of software products from Materialise or Deskartes.

Prototyping and Production

TMG uses laser sintering for building test componentssuch as hubs, brake parts, shock absorbers and engineparts, as well as components to be used on the windtunnel model. Although only a small amount of theactual race car is produced from laser-sintered materi-al, the wide range of applications means that bothlaser-sintering systems [EOSINT P 360 and EOSINT P700 (double-laser system)] are in constant demand atTMG. Both systems can build several plastic partssimultaneously, and new jobs can be fed into themachine during the building process, thus using thesystem to its full capacity. In the double-laser system,parts up to a size of 700 x 380 x 580 mm can be builtin one piece, or series of up to 1,000 pieces at a time(depending on the geometry).

Independent studies (source: Rapid ManufacturingConsortium under the leadership of Prof. PhilipDickens) prove that the direct laser sintering of plasticparts can be more cost-effective than for exampleinjection moulding up to a series of several tens ofthousands of parts.

A threshold has been crossed. Laser-sintering,which has already become established as an effectivetool for simultaneous engineering, is now a realmethod of rapid manufacturing. Prototyping and pro-duction are now taking place on the same system. EOSproduct manager Volker Junior puts it in a nutshell:"Laser sintering combines the flexibility of rapid tech-

Toyota TF 102:Many parts are

developedhigh-stabilitycarbon fibre.

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nologies with the automation andefficiency of mass production.Mass customization thus becomesaffordable."

At the latest Euromold showin Frankfurt, EOS showed howthey are equipping their systemsfor this new era. A new peripheryfor higher automation andprocess integration includes: anautomatic powder feeding systemdesigned as a closed cycle toaccelerate and simplify the han-dling – and recycling – of thepowder; an integrated break-outstation to quickly remove the part

from the powder; an exchange-able frame system to easily andquickly remove the built part(s)from the process chamber tomake the machine ready for thenext job.

Prior to this "IntegratedProcess Chain Management"solution, there is a new datapreparation software calledEOSPACE. This new product hasbeen developed by Materialiseand is available from EOS. Theautomatic surface-oriented nest-ing software EOSPACE positionsbuilding parts in the build enve-

lope fully automatically, in such away that the volume is fullyexploited without parts touchingor sticking to each other, therebyreducing building height to theminimum necessary for thebiggest part. This saves buildingtime and costs and avoids errors.

ConclusionIn the Formula 1 world, thereare already teams which sendtheir cars into the race withlaser-sintered components. Thisis more than a foretaste of theindustrial mass production ofthe future. Both the propertiesand performance of the parts aswell as the opportunities of themachine technology are suitablefor the cost-effective and fastproduction of plastic parts usedas small series for racing cars orluxury cars. Moreover, this tech-nology simplifies the custom-tailored manufacture of one-offparts and spare parts ondemand. Therefore, the benefitsof the rapid technology of lasersintering apply to all stages ofthe product life cycle – fromdevelopment to series produc-tion and after-sales service. Itoffers its users a means of react-ing to the ever-changingrequirements of the market, fastand flexibly, to an unprecedent-ed extent. (www.eos-gmbh.de)

Laser-sintered parts and components are produced inToyota’s modern model workshop.

Toyota’s modern model workshop.

The technical heart of this workshop is formed by two laser-sintering systems supplied by the German

manufacturer EOS.

New peripheryfor high automa-tion and process

intergration.