SPE ACCE 2016 September 7-9 2016, Novi Mi, USA 2-COMPONENT AIR GUIDE PANEL MANUFACTURED BY CO- MOLDING AND FOAMING USING CORE-BACK TECHNOLOGY A. Roch, A. Menrath Fraunhofer ICT (Pfinztal, Germany) B. Schmid BBP Kunststoffwerk Marbach Baier GmbH (Marbach, Germany)
Content Foam Injection Molding (FIM) Lightweight Potential of Core-Back Technology Air-Guide Panel Summary & Conclusion Slide 2
Foam Injection Molding (FIM) A bionic lightweighting technology 1 cm 1 mm Cross section of a human humerus [www.britannica.com] Cross section of a integral foam component (PP-LGF30) Slide 3
Foam Injection Molding (FIM) Functional principle: physical aspects Blowing Agent single-phase gaspolymer mixture Polymer gas sorption and diffusion mixing / solving nucleation cell growing and stabilization injection unit mold cavity Shut-off nozzle screw position / back pressure control Slide 4
Foam Injection Molding (FIM) Functional principle: integral foam structure foamed core solid skin Slide 5
position in cross-section Foam Injection Molding (FIM) Functional principle: integral foam structure I-beam Sandwich local density Slide 6
Foam Injection Molding (FIM) Mold technologies low-pressure vs. high-pressure process Low-pressure Partial filling of the cavity low cavity pressure by partial filling heterogeneous foam structure low density reduction bad surface quality High-pressure (core-back technology) Complete filling of the cavity high cavity pressure through complete filling packing pressure / compression stroke avoids cell creation and improves surface delay time determines skin thickness opening stroke determines density reduction and initiate cell creation homogeneous foam structure independent from flow path high density reduction Slide 7
Foam Injection Molding (FIM) High pressure process (core-back technology) Source: Engel Austria GmbH Slide 8
Foam Injection Molding (FIM) High pressure process (core-back technology) Tool concepts Equal initial wall thickness Different final wall thickness increasing overall thickness increasing local areas where high flexural stiffness is needed different density reductions Slide 9
Content Foam Injection Molding (FIM) Lightweight Potential of Core-Back Technology Air-Guide Panel Summary & Conclusion Slide 10
Lightweight Potential of Core-Back Technology Advantage for applications exposed to bending loads M B = E B I y with 2 nd moment of inertia I y = b h3 12 Bending stiffness integral foam z F F F h F M B M B 0 compact z C C C h C M B M B 0 Slide 11
relative bending modulus [ ] Lightweight Potential of Core-Back Technology Substitution of a compact component 1,1 determination of index n 1,0 0,9 0,8 0,7 n=0,3 n=0,8 delay time increasing wall thickness decreasing density 0,6 0,5 n=1,2 PP-LGF30 CBA PP-LGF30 MuCell PP-LGF30 LFT-D 0,4 0,6 0,7 0,8 0,9 1,0 relative density [ ] X S : property foam X K : property compact Slide 12
Lightweight Potential of Core-Back Technology Substitution of a compact component Design according to equal bending stiffness S B equal max. bending moment M B,max compact h C injection gap h 0 h F necessary wall thickness of integral foam to obtain equal bending stiffness / equal max. bending moment taken n = 0,8 as an example Slide 13
relative bending stiffness [] Lightweight Potential of Core-Back Technology Substitution of a compact component greater opening stroke thicker skin m smaller gap n=0,8 n=0,3 n=0 integral foam compact 1 1 relative weight per unit area [] Slide 14
Content Foam Injection Molding (FIM) Lightweight Potential of Core-Back Technology Air-Guide Panel Summary & Conclusion Slide 15
Air-Guide Panel Development part of BMW 7er Two-component injection molding Hard component: non-reinforced Polypropylene (black + yellow + green) Soft component: TPE (blue) Phyisical blowing agent (nitrogen, N 2 ) Pressure drop realized by local core-back expansion (yellow areas) 20 % weight / material reduction over compact version Project partner: BBP Kunststoffwerk, BMW, Fraunhofer ICT, Lyondell Basell Slide 16
Air-Guide Panel Development part of BMW 7er TPE Foamed PP TPE is co-molded on the face of the hard component Foamed PP (no-core back) needed to ensure defined boundary surface Reduced wall thickness PP Core-back expanded PP provides flexural rigidity through high 2 nd moment of inertia Core-back expanded PP Slide 17
Content Foam Injection Molding (FIM) Lightweight Potential of Core-Back Technology Air-Guide Panel Summary & Conclusion Slide 18
Summary & Conclusion For the foamed Air-Guide Panel a 20 % weight / material reduction could be achieved over the unfoamed version injection into a small mold gap and core-back expansion to a higher wall thickness led to less material consumption through strongly rising 2 nd moment of inertia the same or even a better bending stiffness can be achieved structural-lightweight effect for parts exposed to bending or torsion Slide 19
SPE ACCE 2016 September 7-9 2016, Novi Mi, USA Thank you for your kind attention!