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FAA Specification Meeting

FAA Specification Meeting. Steven Peake FiberCote Industries Waterbury, CT. General Comments. This specification is an excellent framework, but… It tries to achieve quality by inspection We should control the product with SPC, “ISO” and a process control document.

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FAA Specification Meeting

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  1. FAA Specification Meeting Steven Peake FiberCote Industries Waterbury, CT

  2. General Comments • This specification is an excellent framework, but… • It tries to achieve quality by inspection • We should control the product with SPC, “ISO” and a process control document Customer view of FCI contribution FCI View of Contribution Customers Feel the Variance, Not the Mean

  3. General Comments • Some certification tests are redundant and not tied to key attributes • Many changes that require are 3 batch qual are not reasonable and exceed common industry practice • Not every contigency must be in the spec. • Users can add conditions [to a PO]

  4. Specification Purpose • Qualification Material characterization • Allowables • Prepregging processing • Certification  Material consistency • Tests must relate to key attributes in prepreg manufacture and end-use application • Avoid the inspection mentality: • Use certification tests to monitor product consistency

  5. Qualification Testing • Chemical Tests to “fingerprint” resin • IR, HPLC, rheology • Physical tests to define prepreg system • Resin content. FAW, volatile • Mechanical tests to provide allowables data • Processing prepreg and laminates at extremes • Process Control Document for prepreg • Statistical basis for certification tests

  6. Certification Issues • Choose tests that relate to product variability • Choose tests that measure fundamental properties and relate to material key parameters: • Resin composition (HPLC, IR) • Fiber properties (tension) • Flow and gel (Rheology) • Fiber-resin interface (flex) • Service temperature (Tg or elevated temp. compressive) • Need procedures for • retest with assignable cause • Shelf-life recertification • Lot/batch testing based on resin film set or fiber creel set change

  7. Tests to avoid • Repeat testing on the same variable • HPLC, IR & DSC (cure) • Fiber tensile, fabric tensile, laminate tensile • Tests that are dependent on 2 or more process parameters • Flow: resin content, rheology, composition, advancement • Gel: rheology, resin composition, advancement, technique

  8. Certification Tests for Uncured Prepreg Fundamental Prop. Reproducibility Comments Key attribute Fast & easy Good Fair Poor

  9. Certification Tests for Laminates Fundamental Prop. Reproducibility Key parameter Comments Fast & easy Good Fair Poor

  10. Specific Comments • P 10 - What are the criteria for an acceptable PCD? Must insure uniform standards among ACO’s • P11 - How is the composition of the industry committee determined? • P12 - What is the procedure for PCD revision if it not a major change? Will they be audited? • P 18 - Supplier must have raw material specifications for all raw materials. • P19 - Why restrict this spec to epoxy resins and carbon fiber • P20 - Resin properties: • HPLC and IR are redundant tests (for certification). Test on the prepreg, not resin. • Why test moisture diffusion? Moisture absorption OK, but test on laminate. • Microcracking on neat resin? Stress cracking with solvent maybe. • P21 – Spreadability should not be in a spec. It is a supplier issue.

  11. Specific Comments (cont.) • P 21 - Uncured Prepreg properties: • HPLC, IR and DSC are redundant for certification. Use HPLC & don’t run on uncured resin. • Use Fiberite system for tack • What is meant by spool length? Sides of spools? • Roll edge alignment is only critical for ATL • P22 – Procedure needed to re-certify if out of storage life. • P24 Cured laminate properties: • Hot/wet Tg not practical for certification; method dependent test • Uni compression more sensitive than [0,90] to use for certification • What are we learning from RT short beam shear? • P31 – need to define prepreg batch and resin batch • P31 – cure cycles: • not practical to have material with longest shelf life: what if it has a 2 year shelf life? • Need to define slow/fast cure cysle, long/short thermal history. OEM cure cycles are typically much longer than spec. certification cure cycles.

  12. Specific Comments • P34 - Level 2 Changes • What is change in feedstock? Why different than “Alternate vendor for chemically identical raw materials”. • Is T300/Toray to T300 AMOCO a level 1 or 2 and who decides? • Level 2 “Modifications to process equipment… that do not change key characteristics…. If a new pump is added, is that a level 2 change? Suggest equipment for this description be Level 1 and process changes be level 2. • P35 – Level 3 Changes • What test are required beyond certification tests? 3 Batches is onerous for these changes • Changes in tack should not be Level 3 • I doubt that the current industry practice for OEM’s for cure cycle changes is level 3 • P36 – Level 4 Changes • These should not be level 4 FAW, resin viscosity, tow count changes • P 40 – Future needs • Measure only to remove and monitor sources of variability • HPLC and IR can already quantitatively determine resin components • Equipment already exists for in-line FAW and resin content determination

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