Download - Internal Envelope Vac Bagging
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Internal Envelope Vac Bagging
Findhan Strain
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Split Tooling• 5083 Aluminium (cost)• CNC’ed• Finished with 800 grit • Not well polished as good
surface finish not essential due to time constraint
• Multiple layers of Frekote 700 NC
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First Layer• Leave material over the edge• Trim with v. sharp blade• May require further trimming after
debulk
• Do not cut tool or release agent
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First Layer• Place first layer in tool• Rough Trim first ply on both
halves
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Debulking• After debulking the initial half layer: 20 mins with perf release film• Further trimming if required along split line – possibly leave all until
after debulk
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Subsequent layers• Layers laminated on half of tool• Prior to closing
• Layers seen here above tool are plies 2, 3 and 4• Place a layer of non-stick material
eg backing film between last inch of each ply (not shown here)
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Subsequent Layers• Instead of this approach, could simply close two halves of mould and
lay one full layer around mould after the first layer• This product required a localised thickness at the centreline so ply overlap
provided this build-up
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Tool closure• Bring two halves together carefully• Overlap both ply no.2s from each
half• Remove backing film between layer
2 and 3• Place and overlap layers 3 from both
halves• Repeat for plies 4
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Tool Closure Detail• Ensure good compaction
between overlapping layers• Place bagging materials on
carefully• Plenty of slits in perforated
film• Ensure film and breather are
well taped down to avoid them slipping off when placing the bag through the middle
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Bag Preparation• Cut a BIG bag• Takes a much bigger
bag than you think!
• Place PS tape at one side
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Bag Preparation• Close bag over on top of tape• On reverse side of bag, place PS tape
on the outside• Inner and outer tapes must connect to
ensure no leaks
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Bagging Preparation• Place bag through the middle of tool
(shown here also going through a cylindrical tool at the same time)
• Place vac ports inside bag
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Bagging Preparation• Pull bag through and
back on itself• Attach bag to
remaining tape, ensuring all tape is once again connected at any intersection• Bag now sealed
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Draw Vacuum• Draw vacuum• Can place arm up the middle if done correctly!
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Finished Part• Tool split with hammer and chisel at
non-machined faces• Part removed with ease due to good
release, easy geometry and split tooling
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Mould Split Line• Can be minimised with pin-point machining• Leave rough cut then hand polish• Final CNC-ing
• Can be degraded by Stanley knife when trimming• Usually hard to completely avoid this
• This ridge is quite small for 3 bar + vac bag!