method to make its acoustic parts.Thesimulation approach, which took twoyears to develop, became available forthe company’s use this summer.It is cur-rently limited to drape and vacuumforming technologies,but Rieter is work-ing to extend it to compression molding.

The ultimate idea is to predict andoptimize heating and cooling times,energy cost, material distribution, and

COMPOSITES

■ Rieter Automotive Systems,a globalproducer of automotive trim compo-nents and a leader in acoustic systems,unveiled several new technologies lastJune at its 17th biennial acoustics con-ference for customers at its headquar-ters in Winterthur, Switzerland. Fore-most among these was novel softwarefor simulating Rieter’s many processand material options for making car-peted acoustic laminates. Other newdevelopments include acoustic lami-nates with full or partial foil heatshields and new technology for usingglass or natural fibers in direct com-pounding and molding of long-fiberthermoplastic (DLFT) composites.

Simulating laminatesRieter, which has U.S. offices near

Detroit, makes acoustic laminates bydrape forming, vacuum forming, andmatched-metal compression molding,among other methods. The companyalso has a wide range of acoustic mate-rials to choose from, such as coconutfiber,cotton shoddy (shredded clothing),and small air-filled pouches of PE filmglued to the underside of parts.With thehelp of the Royal Institute of Technol-ogy in Stockholm,Sweden,Rieter devel-oped simulation software to help choosethe most efficient manufacturing

Close-Up

residual stresses during and after form-ing.The software simulates deformationwith single- or double-sided tooling,either draping with heat and gravity orthermoforming with heat and vacuum.

Rieter’s software combines com-mercial finite-element software mod-ules to model the shear behavior of com-posite textile fabrics (woven,non-woven,and tufted). Rieter also used experi-mental software developed by Dr. J.Bergstrom of Exponent Inc. in Natick,Mass. This models the relative vis-coelastic behavior of mono- and multi-layer polymeric materials, using anapproach originally developed for par-ticle-filled elastomers.

Rieter tested its new program bysimulating relatively simple axialstretching of a multi-layer carpetedmaterial in a “picture-frame” appara-tus.The frame applies shear by pullinga square shape into a rhomboid whilemeasuring the temperature and the

New Technologies for AutomotiveTP Composites & Acoustic Laminates

www.ptonline.com December 2005 37

Novel software allows Rieter to simulate different process options tofind the most efficient way to make carpeted acoustic-shield parts.

Rieterdeformedmulti-layercarpetedsamples in atest frameand foundthey matchedthe simulateddeformations.

December 2005 www.ptonline.com38

COMPOSITES Close-Up

stress applied in a single plane.Rieter tested a floor underlay

panel of nylon-tufted carpet backedwith layers of nonwoven reinforcementfibers, latex adhesive, mixed-feltacoustic substrate,and multi-layer PEfilm.The acoustic substrate was cottonshoddy (40% to 90% cotton) madefrom shredded clothing. Rieter foundgood agreement between the simulated“picture-frame” stretching and actualshear deformation behavior.

Foil heat shieldsRieter’s latest compression mold-

ing innovation,called Al-FA (aluminumfoil application), molds a sandwich ofDLFT composite with one or two skins

of aluminum foil as a heat shield.A pro-totype part with one foil skin is beingroad tested.

Rieter says it is far more difficultto apply a partial heat shield than tocover an entire part surface with foil.Until now, parts with partial foil cover-ings were made in two steps: First thepart was formed, and then foil wasapplied with secondary heating. Rieterhas now developed a one-step methodfor partial heat shields.

Natural-fiber compositeRieter’s most celebrated recent

DLFT achievement is its first natural-fiber part, a spare-wheel pan cover forDaimlerChrysler,which is also the first

natural-fiber exter-nal body part for aproduction car. Ituses abaca fibermade by ManilaCordage in thePhilippines. Abacais a relative of thebanana plant that israised for makingmarine rope andtwine. A compoundof polypropyleneand 30% choppedabaca fiber waspatented by Daim-lerChrysler for auto-

motive molding. The part won the topautomotive prize at the JEC show inParis last spring and the Environ-mental category of the SPE Automo-tive Innovation Awards last month.Part of Rieter’s achievement was mov-ing the part from R&D to production inonly 18 months.

Rieter uses a new servo-controlledprofiling die to control the thickness ofthe extruded molten slab.Such a die isalso used for glass-filled DLFT,but it ismore essential for natural-fiber com-pounds because they are much moreviscous. Without profiling they wouldrequire extremely high tonnage topress into thin-wall parts.

Rieter places different profiles ofmolten abaca/PP slab in specific toollocations to optimize the molding cycle.Multiple profiles overlap, so there isno weld-line problem, Rieter says.

A second new Rieter device makesit possible to feed either glass or nat-ural-fiber rovings without changing theproduction set-up. Also, Rieter devel-oped “two-component” compressionmolding, using materials with higherand lower percentages of long-glassfiber at specific locations in a tool.Thisapproach is being tested for an under-floor part. —JanH.Schut

NEED TO KNOW MORE?

Manila Cordage Co., Manila, Philippines+63 (2) 895-0481 • www.manilacordage.com

Rieter Automotive Systems, Farmington Hills, Mich.(248) 848-0100 • www.rieter.com

Carpet-forming simula-tions allow tool designsto be optimized longbefore metal is cut.

New technol-ogy allowssingle-stepproduction ofparts with par-tial foil heat-shield cover-ings, whichpreviouslyrequired multi-ple steps.

For a link to related articles involving RieterAutomotive, visit www.ptonline.com/articles/200512cu2.html

•Composites: New Rapid Molding Technolo-gies and Unusual Reinforcements at ParisJEC Show, June ’05

•Long-Fiber Thermoplastics Extend TheirReach, April ’03

•Why Long-Glass Molders Are CompoundingIn-Line, April ’02