FAA/NASA Workshop on Key Characteristic's for Composite Material Control Chicago, IL Cytec Engineered Materials August 6th 2002
Agenda Goal of Prepreg Material Specification Sources of Variation Material Consistency and Reliability End-User Material Specification Industry Material Specification Changes to Qualified Materials Future Needs
Prepreg Material Specification Primary Objective: Consistent and reliable prepreg materials with time stable processing and properties. Secondary Objective: Procurement of prepreg materials manufactured with systems that imposes controls and requirements on the key physical,chemical, mechanical properties of prepreg material.
Sources of Variation Raw Material Components Product Scale-Up Process Baseline Cure Process Test Methods and Analysis Historical Data Bases
Sources of Variation Product ScaleUp: Manufacturing Process The prepreg manufacturing process must be developed and controlled though production trials on production equipment not laboratory scale equipment. This requires the raw materials, resin formulation, resin mix process, resin filming process and impregnation process be defined and controlled prior to qualification activities.
Sources of Variation Baseline Cure Process Failure to define the baseline process and determine the impact of critical process cure variables on material properties: Time Temperature Heating Rate Pressure Oven/Autoclave Thermal Variation
Material Consistency and Reliability Function of the following inputs: Raw Material Components Manufacturing Equipment-mixing and impregnation People-knowledge level and training Quality System-well defined and controlled manufacturing procedures Management Passion for product quality Six Sigma-reducing product variation
End-User Material Specification Current Practice Partnership between material supplier and end user is formed. MOU and LTA basis of the relationship. Supplier and end user develop baseline cure process used in the material specification prior to qualification. End user and supplier jointly develop qualification database based upon resources and knowledge levels. PCD used to define and control manufacturing process.
End User Specification:Military Programs Material Property Data Bases are developed under many military programs: F-18, B-2,F-22, V-22 and JSF. F-22 and V-22 Programs are shared databases. Defense to Commercialization Process Supported The data bases are eventually used for commercial applications over material lifetime. Impact of industry material specification process
Industry Material Specifications Criteria needed for determination of the qualification test plan Lack of specific market or application focus Differentiation process of material specifications and slash sheets. Batch definition issue is key for fibers,resin,and prepregs. Batch definition may be application specific.
Industry Material Specifications Definition of a change may be application specific Issue of changes to materials-regulatory Process Audit of material supplier process outlined in PCD 3rd Party Accreditation
Changes to Qualified Materials
Changes to Qualified Materials Definition of material equivalency and engineering judgement Impact of different alpha values for material equivalency and batch acceptance limits Proposed requirements in Section 8.0 are more restrictive than current MIL-HDBK-17F, Volume I, Section 2.3.4.2. requirements.
Changes to Qualified Materials F-22 Program can be used as a model for evaluation and change criteria of qualified materials Changes addressed with no impact PAN Fiber Lines Fiber Mfg. Process Raw Material Components Resin Mixing and Fabric Weaving Equipment Facility Qualification Prepreg Mfg. Process Changes
Future Needs Development of advanced prepreg chemical/physical characterization techniques and analysis methods for detecting significant changes in prepreg materials. Current practices of destructive testing and focus on structural mechanical property test programs provides low sensitivity and detection level. New change procedures for changes to qualified materials-system approach.