L. Gintert – 8/8/02 Other Product Forms Considerations RTM and VARTM RTM and VARTM –Materials (Constituents – resin, fiber, tackifiers, cores, stitches/pins, special forms; also consumable materials) –Processes (Fiber processing, ply cutting, lay-up, preforming, demolding, post-mold operations) Sandwich Sandwich –Materials (Constituents – skin, core, adhesives, core splice; also consumable materials) –Processes (Core processing, special details, inspection)

L. Gintert – 8/8/02 RTM and VARTM Material Considerations Procurement considerations similar to that of the prepreg material producer Procurement considerations similar to that of the prepreg material producer All constituent materials (including fiber sizing, tackifiers, additives, additives, pins, stitching, etc.) need to be controlled via material specs. with out time, packaging, & other critical parameters properly controlled & documented. All constituent materials (including fiber sizing, tackifiers, additives, additives, pins, stitching, etc.) need to be controlled via material specs. with out time, packaging, & other critical parameters properly controlled & documented.

L. Gintert – 8/8/02 RTM and VARTM Material Considerations (cont’d) Cores, fly-away mandrels (density and stability), consumable/wash-out tooling Cores, fly-away mandrels (density and stability), consumable/wash-out tooling Tooling and consumable materials including release agents, cleaning techniques, sealing techniques, bagging materials/bleeders, bagging techniques, and flow media Tooling and consumable materials including release agents, cleaning techniques, sealing techniques, bagging materials/bleeders, bagging techniques, and flow media

L. Gintert – 8/8/02 RTM and VARTM Material Considerations (cont’d) Neat resin controls are numerous and dependant on material forms Neat resin controls are numerous and dependant on material forms –Hot melt, heat-activated ingredients, degassed liquid resin, viscosity, visual/color, cure parameters, other parameters Tackifiers Tackifiers –Liquid/aqueous and powder –Physical parameters (powder size, viscosity), cure parameters, ingredients/chemistry, other –Resin compatibility

L. Gintert – 8/8/02 RTM and VARTM Process Considerations Fiber processing Fiber processing –Braiding, specialty weaving, stitching, pinning, hybrids, special forms (T’s, H’s, etc.), automation, consumables Lay-up and Preforming (MOST CRITICAL!)* Lay-up and Preforming (MOST CRITICAL!)* –Special tooling/fixturing for complex shapes –Special details (braids, cores, T’s, noodles, etc.) –Ply cutting and handling – multi-ply packs/kits –Preform locating techniques (tooling pins, features) –Tackifiers, pins, stitches, etc. –Special tooling/fixtures and processes * If the preform is wrong, STOP!

L. Gintert – 8/8/02 RTM and VARTM Process Considerations (cont’d) Tool Closure, Injection and Cure Tool Closure, Injection and Cure –Gap measurement, vacuum check, bag check –Resin injection/infusion sequence/cycle »Critical heating areas, heat-activated ingredients/cure agents (preform=filter) »Heat-up »Vacuum (hard) »Inject/infuse resin »Bleed technique/sequence, bag check »Ramp-up, back pressure –Plumbing diagram (consumable plumbing, preheater)

L. Gintert – 8/8/02 RTM and VARTM Process Considerations (cont’d) Demolding Demolding –Mandrel extraction - critical sequences –Wash-out mandrels –Tooling holes/fixturing features –Neat resin sample or witness laminate –Tool cleaning and prep Post-molding Operations Post-molding Operations –Typical but usually more complex

L. Gintert – 8/8/02 Sandwich Material Considerations Generally the same as hand lay-up Generally the same as hand lay-up Core control/core storage and preparation Core control/core storage and preparation Core orientation – L & W (&Z) properties Core orientation – L & W (&Z) properties Core corrosion control/treatment Core corrosion control/treatment Core splice and other materials Core splice and other materials Bleeders and other consumables Bleeders and other consumables Resin flow parameters criticality – determines fillet characteristics/strength Resin flow parameters criticality – determines fillet characteristics/strength

L. Gintert – 8/8/02 Sandwich Process Considerations Similar to hand lay-up Similar to hand lay-up Core handling, core cutting Core handling, core cutting Special details/hard points – bond prep and location features Special details/hard points – bond prep and location features Orientation - L, W & Z directions Orientation - L, W & Z directions Core forming & core splice Core forming & core splice Cure parameters Cure parameters Inspection – Coin-tap? Other testing? Inspection – Coin-tap? Other testing?