Ch' 6 Feature in manufacturing 6'2'3 6'4

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Ch. 6 Feature in manufacturing6.2.3 6.4
MAE548 Feature based modeling

• Soonhung Han
• shhan_at_kaist.ac.kr
• http//me.kaist.ac.kr/newcourse

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6. Feature in Manufacturing

• 6.1 Manufacturing feature
• 6.2 Issue and Alternative Approach
• 6.3 Generation of Manufacturing Features
• 6.4 Group Technology Coding
• 6.5 Feature-Based Process Planning
• 6.6 Feature-Based Assembly Planning

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6.2 Issue and Alternative Approach

• Level of Abstraction
• Level of Specialization
• Dimensionality
• Completeness of Feature Model
• Feature Relationships
• Temporal Ordering
• Product Family

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6.2.3 Dimensionality6.2.4 Completeness of
Feature Model

• The dimensionality of manufacturing features is
  also related to the relationship between features
  and process models
• Whether all the geometry of a part belongs to a
  feature? completeness of feature model

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6.2.5 Feature Relationships

• To perform geometric reasoning ? information on
  the geometric relationship of the feature
  dimensioning, tolerancing relationship
• Planar, Coplanar, Offset, Parallel, Orthogonal,
  Collinear, Angular

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6.2.6 Temporal Ordering

• Temporal ordering of features unique in
  manufacturing
• Precedence relation
• End-start relation
• Start-start relation

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6.2.7 Product Family
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6.3 Generation of Manufacturing Features

• 6.3.1 Interactive Feature Identification
• 6.3.2 Design by Manufacturing Features
• 6.3.3 Design to Manufacturing Feature Mapping
• 6.3.4 Manufacturing Feature Recognition

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6.3.1 Interactive Feature Identification

• Manufacturing features are identified
  interactively by picking geometric elements of a
  geometric model displayed on computer screen.

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6.3.2 Design by Manufacturing Features

• First-Cut System (Cutkosky 1990)
• By assuming that the designer creates the part
  model directly in terms of its manufacturing
  features ? no conversion or extraction of
  manufacturing features
• HutCAPP System (Mäntylä et al. 1989)
• Chapter 11
• Only negative features are available ?
  destructive solid geometry

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6.3.3 Design to Manufacturing Feature Mapping

• Ideally designer should be given the freedom to
  design in terms of features most convenient for
  design.
• Chapter 7

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6.3.4 Manufacturing Feature Recognition

• Complete separation of concern between design and
  manufacturing
• The recognizer can create several alternative
  models of the part. ? give the planner freedom
  of choosing the best plan

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6.4 Group Technology Coding

• Group technology(GT) exploits similarities among
  parts to classify parts into part families.
• Hyde 1981
• GT can effect considerable cost saving by
• eliminating design and process plan duplication
• automating part data retrieval
• reducing the number of changeovers in tooling and
  fixturing by scheduling similar parts together

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• GT schemes are developed for specific
  applications.
• GT coding is basically a case analysis of
  possible part shapes.

Sample part for GT coding 11106
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• GT schemes are usually partly or fully
  hierarchical ? decision tree
• DCLASS (Allen 1979)
• Parts can be classified differently by different
  people because of the way a person responds to a
  question.
• The process is not automated.
• ? Application of feature for GT coding