ADCATS Conference — 14 15 June 2001 Brigham Young

ADCATS Conference - 14/15 June 2001 Brigham Young University - Provo UT Method & Tools for Geometric Variation Management Benoît Marguet E. A. D. S Corporate Research Center - France Tel : +33 -1 -46 -97 -33 -46 email : benoit. marguet@eads. net Industrial Background Research Problematic Method Overview Key Characteristics Assembly Sequence Conclusion

Industrial Background (I) Complex Product Extensive manufacturing organisation Structural Assembly High number of parts Various Assembly levels } Car Assembly Line Importance of Assembly Cost Aircraft manufacturing cost : Assembly 45% Conversion Material 30% 25% Aircraft Assembly Line Need to manage product’s assemblability

Industrial Background (II) Development cycle of aircraft sections Manufacturing Airbus Design Section architecture Assembly principles Design Airbus or Suppliers Integration Definition Drawings Tooling Design Definition Tooling Definition Manufacturing Aircraft assembly System tests Section assembly System installations Assembly of workpackages Manufacturing of piece parts Manufacturing of assembly toolings Need to manage product’s assemblability as soon as possible during the development cycle

Problematic How to improve product’s assemblability ? • By reducing assembly failures How to reduce assembly failures ? • Parts reduction • Geometric variation management Where to manage product variations ? How to control effect of variations on functional requirements? Sub-section assembly operation Geometric Variation Management Method (GEOVAR)

Method Overview GEOVAR : From product’s Key Characteristics to part’s specifications j 7 Design Principle j 1 j 2 j 3 j 5 j 8 j 4 j 6 Key Characteristics Product Structure Manufacturing Capabilities Part Specifications Assembly Sequence

Product Key Characteristics (I) Concepts • Functional requirements & related geometrical characteristics are too numerous on complex product in order to manage all of them. • Need to focus attention of designers & manufacturers on what is really important for the product. KC Definition “Product Key Characteristics are the geometrical features of component or sub-component whose variation has the greatest influence on the product function”. Identification Process Functional Requirement Identification (1) Geometrical Requirement Identification (2) Product Key Characteristics Identification (3)

Product Key Characteristics (II) Functional Requirement Identification • Inputs : Preliminary Design, Product Structure • Outputs : Technical Requirements, Product Constraints • Tools : FAST Diagram, MIMIO 1

Product Key Characteristics (III) Geometrical Requirements Identification • Inputs : Technical Requirements, Product Constraints • Outputs : Geometrical Requirements (nominal value and tolerance level) • Tools : QFD Matrix Correlation Matrix HOW Objective engineering specification Seat Rail Alignment WHAT Subjective customer preferences Relation Matrix How Much Tolerance Specification QFD Matrix 2 Geometrical Requirements

Product Key Characteristics (IV) Key Characteristics Identification • Inputs : Geometrical Requirements, Assembly Process • Outputs : Hierarchical requirement level, PKCs • Tools : Risk Analysis PKC 3

Product Key Characteristics (V) Benefits of exercise • Defines what is, and is not, important for the variation management. • Targets areas/features that need to be measured and monitored (through SPC). • Helps designers to distribute tolerances & select appropriate datums. Also • Clarifies of Design intent. • Promotes Concurrent Engineering. • Truly links Design, performance, manufacturing.

Assembly Sequence (I) Problematic • Various assembly sequences are available for a single product. • All assembly sequence will have a different quality cost for the product. Question What assembly sequence will minimize impact of part’s variation on PKCs ? Assembly Sequence #1 Assembly Sequence #2

Assembly Sequence (II) Concepts • Assembly Sequence analysis focus on PKCs (for variation impact). • Impact of part variation on PKCs depends on assembly sequence choice. • Selection of assembly sequence is made very early in the design cycle. Goal To analyze as soon as possible during the design cycle, all admissible assembly sequences in order to select the optimal one. Analysis Process Mate & Contact Identification (1) Propagation Chain Identification (2) Worst Case & Statistical Tolerance Analysis (3)

Assembly Sequence (III) Mate & Contact Identification (I) Definition (D. E Whitney) • A mate is an assembly link that establishes constraints and dimensional relationships between part. • A contact is an assembly link that supports and fastens the part once it is located. Property Mate and Contact are related to the assembly sequence. Geometrical variations flow from part to part through mates only. M Benefice • Easy to represent on a graph • Tool for variation propagation analysis. 1 M Mate C C Contact Stringer Cleat M C C C M Cleat M M Pannel M

Assembly Sequence (IV) Mate & Contact Identification (II) Tools : Assembly Oriented Graph. AOG is a directed acyclic graphical representation of an assembly given a picture of the location dependencies of parts and surfaces. Each node represents assembly surface. Oriented arcs represent mates between two assembly surfaces. The arrow points on the positioned component. Oriented dotted arcs represent contacts between two assembly surfaces and dotted line represents geometrical conditions Upper Shell Right Upper Shell Left Assembly Sequence #1 Mate Assembly surfaces Upper Floor Lower Floor Contact Door Tool 1 KC Lower Shell PKC

Assembly Sequence (V) Propagation Chain Identification • Inputs : Assembly Oriented Graph, Key Characteristics • Outputs : Qualitative Assembly Sequence Analysis • Tools : Propagation Chain Definition • A propagation chain is defined by all the mates necessary in order to perform a Product Key Characteristics. Property PKCs quality will be related to the length of the Upper Shell Right Upper Shell Left propagation chain. Upper Floor Lower Shell Lower Floor Door 2 Propagation Chain Tool

Assembly Sequence (VI) Tolerance Analysis • Inputs : Manufacturing Capabilities, Assembly Process, Geometric Characteristics, PKCs. • Outputs : Quantitative Assembly Sequence Analysis. • Tools – Available commercial software (Valisys, Ce. Tol, 3 DCS). – In house development (Ana. Tole). 3

Assembly Sequence (VI) Ana. Tole Software • In house development based on TTRS, Variation Model (EADS C. C. R) and Open Cascade (EADS Matra. Datavision). • Benefits : – Easy to use without a deep knowledge of CAD system. – Very close to manufacturing and Design process. – Over-Constraint Detection and Analysis. – Statistical & Worst Case Tolerance Analysis. – Useable as soon as possible in the design cycle (wireframe geometry only).

Method Summary 2 To translate the functional requirements into geometrical requirement Are all geometrical conditions fulfill ? To improve Manufacturing capabilities To change design principle 6 To analyse the assembly sequence 3 To identify the product’s Key Characteristics 4 To select an admissible assembly sequence 5 To select the Mate / Contact assembly links Yes No Is it possible to choose another assembly sequence ? Yes No Assembly sequence validated + tolerance specification Yes Is it possible to improve the manufacturing capabilities No To choose another assembly sequence 1 To identify the major functional requirements

Conclusion & Future prospect Need to manage tolerance from the functional requirement to ISO specification based on : • Product Key Characteristics • Assembly processes • Manufacturing Capabilities Definition & Deployment of a Variation Management Method • Useful for complex product like aircraft. • Used as soon as possible during the design process. • Allowing to select the optimal assembly sequence. On going Works • Take into account flexible parts in the method • Automatic assembly sequence planning & analysis. • Wide deployment of the method.