Fortron PPS Replaces Steel in DaimlerChrysler Fuel ... - Hi Polymers

Application StoryFortron ® polyphenylene sulfideFortron ® PPS Replaces Steel in DaimlerChrysler Fuel Rail,Cuts Weight 25%, Reduces Cost 30%Switch to PPS Consolidates Seven Parts to One, Simplifies ProductionDaimlerChrysler chose Fortron ® 1140L4 linear polyphenylene sulfide (PPS) when itswitched from steel to plastic fuel rails in its 2.7 liter V-6 engines. Fortron PPS is made byFortron Industries, a joint venture of Kureha Chemical Industries (Japan) and Ticona, thetechnical polymers business of Celanese AG (NYSE: CZ). The new rails weigh 25 percentless and cost 30 percent less than those they replaced. Much of the savings occurred byconsolidating the seven components in the metal rail into a single molded component,which greatly simplified production.For Current U.S. DaimlerChrysler VehiclesThe fuel rail, which began production in the 2001 MY LH series cars (Intrepid andConcorde) and JR series cars (Stratus andSebring), is 10.5 in. long, 0.5 in. in diameterand has 2.5 mm (0.1 in.) walls. Each D-shaped rail feeds fuel to three cylinders.Fortron ® PPS fuel rail forDaimlerChrysler 2.7 liter V-6 enginesin U.S. vehiclesFuel enters the rail from a stainless steel tubeattached to the fuel line. The fuel then movesdown the rail and passes into injector ports.The cylindrical ports project upward 0.75-in.and retain the fuel injector at each cylinder.Two brackets off the body of the rail hold it tothe intake manifold.Manufacturing Efficiencies vs. Previous Fuel RailThe prior steel rail had a tubular body to which three injector ports, two brackets and anend cap were added. Production steps for the body included forming, brazing, flushing andplating, while the brackets and ports were stamped, formed and then welded and brazed tothe body.

2“In contrast to the many processes needed with metal, the PPS rail is just injection moldedand deflashed inside and out with shot blast,” says Mark Cerny, Engineering Supervisor inPremium Vehicle Power Train Adaptation at DaimlerChrysler. “The efficiencies inherentin fabricating the rail in plastic have saved us significant money, time and labor.”Material Selection and Testing“We chose Fortron PPS because of its long track record in auto engine and fuelapplications and because our experience with it showed it had the chemical, thermal andmechanical capabilities we needed,” says Cerny. “We also considered polyphthalamideand nylon, but PPS offered better dimensional stability in this part, which is exceptionallyimportant since the injectors must line up precisely with the engine cylinders. PPS alsohad better permeation resistance and flex fuel compatibility than nylon.”“We also looked at branched PPS and a phenolic thermoset, but did not choose thembecause they tend to be more brittle than linear PPS.”DaimlerChrysler tested the Fortron PPS fuel rail extensively to ensure it would meet thedemands of engine compartment operations. The rail was subjected to a series of pressurecycle tests at fuel pressure levels up to three times normal rail pressure over an extremetemperature range. Other bench tests looked at bending fatigue, vibration, impact strengthand compatibility with a range of common auto fuels and fluids.In field testing, DaimlerChrysler evaluated the Fortron PPS rails in more than 100 vehiclesfor up to 18 months. Normally, field testing in the development phase involves fewer than30 vehicles. The automaker also performed extensive vehicle impact testing.Molding Challenges“The plastic rail poses a range of molding challenges,” says Dan Kreiman, an accountmanager at Dana Corporation, which fabricates the rail under contract to Bosch. Boschadds the injectors and supplies finished rails to DaimlerChrysler.“The main rail body uses a floating core pin since its far end is closed. This presents achallenge because it calls for tightly mating the core pin and the sliding pins that comethrough the injector ports during molding so as to minimize flash. Other moldingchallenges include the undercut for the O-ring in the stuffer pack where the metal tubeenters the rail and ensuring that all areas of the mold fill fully, especially the cornersaround the mounting brackets and the intricate quick-connect area at the open end.”According to Chuck Johnston, operations manager at Multi-Plastics Inc., which hasrecently taken over molding the part from Dana, this application demands a lot from thematerial and requires an exceptionally stable process with tight-fitting tools.

“It requires great attention to detail and good control,” says Johnston. “We carefullymonitor each molding cycle to ensure the injector port pins and the floating core areproperly seated. We also measure the high-wear area around the O-ring undercutregularly to retain tool integrity. And, since the part must be free of flash, we check andclean the tool frequently, especially near the injector ports and on the sealing surfaces ofthe long core.”Cooperative Design and Process DevelopmentTicona worked with Dana from early in the project, performing finite element analyses todefine wall thickness and other factors. To aid tooling design, Ticona provided moldflow analyses and made prototypes in molding trials at its Application DevelopmentCenter in Auburn Hills, Michigan, and helped optimize molding once production began.Fortron PPS for Automotive Fuel ApplicationsFortron PPS has been widely used in automotive fuel applications. A recent 5,000-hourstudy by Ticona of how commonly used fuel system plastics age when exposed to fivedifferent auto fuels at 121°C, a temperature typical of engine compartments, showed thatFortron PPS had the best performance of the plastics tested. Fortron PPS had the leastweight and dimensional change and the highest tensile strength retention. For instance, itwas superior to high-temperature nylon (HTN) in aggressive fuel blends and equal to orbetter than HTN in milder blends.Ticona LLC90 Morris AvenueSummit, NJ 07901-3914Technical Information: 1-800-833-4882Customer Services: 1-800-526-4960www.ticona.comTicona GmbHD-65926 Frankfurt am MainTel: +49(0)69-305-16299Fax: +49(0)180-2021202NOTICE TO USERS: To the best of our knowledge, the information contained in this publication is accurate; however, we do notassume any liability whatsoever for the accuracy and completeness of such information. The information contained in this publication should not beconstrued as a promise or guarantee of specific properties of our products.Any values shown are based on testing of laboratory test specimens and represent data that fall within the standard range of properties for naturalmaterial. These values alone do not represent a sufficient basis for any part design. Colorants or other additives may cause significant variations in datavalues.Properties of molded parts can be influenced by a wide variety of factors including, but not limited to, material selection, additives, part design,processing conditions and environmental exposure. Any determination of the suitability of a particular material and part design for any use contemplatedby the users and the manner of such use is the sole responsibility of the users, who must assure themselves that the material as subsequently processedmeets the needs of their particular product or use.It is the sole responsibility of the users to investigate whether any existing patents are infringed by the use of the materials mentioned in this publication.Please call the numbers listed for additional technical information. Call Customer Services for the appropriate Materials Safety Data Sheets (MSDS)before attempting to process our products.The products mentioned herein are not intended for use in medical or dental implants.