Single Step Forming and Moulding of Prepreg Composites for use in Automotive Applications Rachel Weare¹, Fred Walker², Kate Carter², Ken Kendall¹ ¹ WMG, The University of Warwick, UK ² Aston Martin Lagonda Ltd, UK SCOPE WMG and the Automotive Composites Research Centre The InterCOMP Project Blank Development Kit Splits Conclusions WARWICK MANUFACTURING GROUP Academic department within the science faculty of the University of Warwick Established in 1980 to facilitate technology transfer and knowledge creation for industry Over 800 people in 7 buildings Training over 2,500 individuals in the UK and abroad Co-located with Tata Steel, JLR, Tata Motors European Technical Centre & the APC AUTOMOTIVE COMPOSITES RESEARCH CENTRE Opened 2015 20 staff Development of CFRP manufacturing technologies for high volume automotive applications State-of the art, industrial scale composite processing equipment Equipment development to enhance the ACRC capabilities, particularly automation Industrial partners include Ford, JLR, AML, Gestamp, GKN, Expert T&A SCOPE WMG and the Automotive Composites Research Centre The InterCOMP Project Blank Development Kit Splits Conclusions INTERCOMP Integrated COmpression Moulding Process 24 month research project co-funded by Innovate UK Single stage double diaphragm stamp forming process Existing equipment developed to integrate Double dome process steps geometry Generic part for characterising formability Structural components for process development and demonstration INTEGRATED COMPRESSION MOULDING PROCESS Ply assembly Pressing and joining station Blank transfer CNC ply Heating cutting station Ply loading Ply pick robot Ply storage Ply unloading Shuttle Blank loading direction of station travel DOUBLE DIAPHRAGM STAMP FORMING Forming IR Pre-heating Material Loading Curing SCOPE WMG and the Automotive Composites Research Centre The InterCOMP Project Blank Development Kit Splits Conclusions BLANK DEVELOPMENT Max. Length Max Width Area BLANK Blank Image BLANK 2 (mm) (mm) (m²) (oversize) BLANK 1 730 430 0.31 BLANK 4 BLANK 1 (near net-shape) BLANK 2 770 490 0.32 (oversize) BLANK 3 0/90º 660 385 0.22 (net-shape from simulation) ±45º 620 390 0.22 BLANK 4 707 400 0.26 (near net-shape) BLANK 3 BLANK 3 ±45º 0/90º (net-shape) (net-shape) QI layup, 4 plies 2x2TW carbon-epoxy prepreg [0/90º, ±45º]s PREDICTING THE NET-SHAPE BLANK 2. Double dome component 1. Oversized blank periphery projected used to simulate onto formed plies double dome forming behaviour 3. Simulation reversed and plies 0/90º undraped to provide ±45º 4. Edges smoothed to a flattened profile give a uniform blank profile avoiding fibre discontinuities ±45º NET-SHAPE BLANK Only one iteration was required for the double dome geometry Geometries with more complex peripheries require many iterations BLANK 2 BLANK 3 (oversize) (net-shape from simulation) PLY NESTING Software unsuitable for batched runs ~10% decrease in efficiency when batching runs compared to “best-nest” Efficiency levels off at 10 parts BLANK 3 (net-shape) uses least material overall BLANK 3 BATCHED BLANK 3 BEST NEST ROLL WIDTH Material efficiency increased by 5% for 1.25m roll Using BLANK 2 as opposed to BLANK 3 increases material usage by 47% for both roll widths Material Area per part (m²) Roll Width Blank 1 Part 10 Parts 20 Parts (m) BLANK 2 1.79 1.69 1.69 1.00 BLANK 3 1.34 1.15 1.15 BLANK 4 1.51 1.32 1.31 BLANK 2 1.72 1.61 1.60 1.25 BLANK 3 1.27 1.09 1.09 BLANK 4 1.37 1.26 1.26 MOULDING BLANKS 1 & 2 BLANK 2 BLANK 1 (oversize) MOULDING BLANKS 3 & 4 BLANK 3 BLANK 4 (net-shape) (near net-shape) CORRELATION BLANK 2 Focused correlation on blank 2 moulding to simulation Portable CMM with a laser line probe attachment Periphery of the top ply was raised to make it visible on the scan Scanned part Simulation prediction CORRELATION BLANK 3 Ply slippage gives early indication for friction correlation Simulation predicts approximately 2mm slippage between plies compared to 15mm on part 2 mm 15 mm SCOPE WMG and the Automotive Composites Research Centre The InterCOMP Project Blank Development Kit Splits Conclusions KIT SPLITS 3 kit-split designs Improve nesting efficiency Investigate forming behaviour Correlate CAE models KIT SPLIT DESIGN 1 Dome 1 0° 385mm -45° 45° Ply 1 and 4 split across part PLY 1 2 3 4 centre-line (orange) 90° Tracer fibre placed 5mm 0/90 0/90 Dome 2 either side of split (green) ±45 ±45 Illustration on formed 490mm geometry KIT SPLIT DESIGN 2 PLY 1 2 3 4 Ply 1 split across dome 1 Dome 1 (orange) 0° 385mm -45° 45° 0/90 0/90 90° Ply 4 split across dome 2 ±45 ±45 (orange) PLY 1 2 3 4 Dome 2 Tracer fibre placed 5mm either side of split (green) 0/90 0/90 ±45 ±45 Illustration on formed 490mm geometry KIT SPLIT DESIGN 3 PLY 1 2 3 4 Ply 3 split across dome 1 Dome 1 (orange) 0° 385mm -45° 45° 0/90 0/90 90° Ply 2 split across dome 2 ±45 ±45 (orange) PLY 1 2 3 4 Dome 2 Tracer fibre placed 5mm either side of split (green) 0/90 0/90 ±45 ±45 Illustration on formed 490mm geometry KIT SPLIT NESTING x 10 BLANK 2 – 16.91m efficiency: 77% BLANK 2 KIT SPLIT 1 – 15.75m efficiency: 83% BLANK 2 KIT SPLIT 2 – 15.43m efficiency: 84% BLANK 2 KIT SPLIT 3 – 15.39m efficiency: 84% KIT SPLIT NESTING Kit split 3 most material efficient; reduction of 10% Kit splits improve material efficiency, BUT at what penalty? Length per part (m) Blank 1 Part 10 Parts 20 Parts BLANK 2 1.79 1.69 1.69 BLANK 2 KIT SPLIT 1 1.64 1.58 1.58 BLANK 2 KIT SPLIT 2 1.57 1.54 1.54 BLANK 2 KIT SPLIT 3 1.58 1.54 1.54 KIT-SPLIT MOVEMENT Where plies separate, resin flows to fill the void and washes fibres Constant thickness – varying fibre volume content Internal split areas are easily identified by resin richness on part surface KIT SPLIT 1 KIT SPLIT 2 KIT SPLIT 3 Centre (outer) Centre (underside) Dome 1 (outer) Dome 2 (outer) Dome 1 (outer) Dome 2 (outer) PREDICTING KIT SPLIT MOVEMENT Kit split behaviour predicted through CAE forming analyses Simulations predicted ply separation at the butt joint Analysis important for FEA correlation Ply slippage data used to correct model friction KIT SPLIT 1 KIT SPLIT 2 KIT SPLIT 3 (ply 1 shown) (ply 1 shown) (ply 2 shown) CORRELATION 1 2 3 Dome 1 4 5 6 Centre 7 8 9 Dome 2 Separation Distance Separation Distance (mm) Illustration on formed geometry SCOPE WMG and the Automotive Composites Research Centre The InterCOMP Project Blank Development Kit Splits Conclusions CONCLUSIONS Excess material can exacerbate wrinkling Blank optimisation increases material efficiency The simulated net-shape blank does not produce a true net-shape part and using a net-shape part will not increase material efficiency if the entire part is to be scrapped! Simulation models needs improving to account for ply interactions (friction and interface) Blank positioning must be improved to mould net-shape components Kit splits most material efficient but are unpredictable Geometry specific Any Questions? Thank you for listening Rachel Weare [email protected].