Sustainable data
Data representation by standardised
information models
Dr. Norman Swindells, CEng, FIMMM
Ferroday Ltd, Birkenhead, U.K.
© Ferroday Ltd 2007
Digital manufacturing
Material
properties
CAD
Cutting
tools
FEA
Process
planning
© Ferroday Ltd 2007
NCcodes
Sustainable information
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Preservation of usable information (represented by
data) implies communication of information to be
understood by:
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unknown users
unknown processing systems
and at unknown times in the future
Different programs represent the same data in
different ways – everyone makes their own nuts and
bolts – software engineering
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Applying real engineering principles will provide a
specification that will accompany the data to ensure
it can be understood – information engineering
© Ferroday Ltd 2007
Information engineering
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An engineering solution to an IT problem
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The information models are:
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Specifies data representation by using computerprocessable information models and dictionaries
International standards developed by global collaboration
Determined by industrial needs
Independent from any computer system
Computer-understandable within an application domain
Computer processable dictionaries support these
models with specific domain knowledge
© Ferroday Ltd 2007
Information models
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An information model is a formal specification for data with
explicit rules for its interpretation
 A sentence in a natural language is an information model
To communicate information unambiguously we always need:
 the data items that represent the information
 an information model to provide the semantics and syntax
for the data items – data structure
 a dictionary to provide a label for each data item and
provide its meaning
Everyone in a communication process must use the same
information model and the same dictionary
© Ferroday Ltd 2007
Global development project
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Global project with more than 20 nations
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The main global manufacturing sectors
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U.S.A, U.K., Germany, France, Japan, Sweden,
China, S. Korea, Spain, Italy, etc.
In ISO Committee TC184/SC4 since 1984
Auto, aerospace, electrical, oil & gas, process
plant, shipbuilding, defence (NATO, MoD, DoD, US
Navy, UK Navy), etc.
Developed by engineers for engineers
© Ferroday Ltd 2007
ISO Standards for information
engineering
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ISO 10303 Product data representation
and exchange (STEP)
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Technology and resources for building and
using information models
Information models for all aspects of a product or
a process and for all stages of the product lifecycle – written in EXPRESS (ISO 10303-11)
ISO 13584 Parts libraries (PLIB)
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Information model for data dictionaries to define
objects, processes and their properties
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Structure of ISO 10303 (STEP)
State
Part 56
Representation
Part 43
Geometry Topology
Part 42
Product
Part 41
Generic
Resources for any product
Processes
Part 49
Maths
Part 50
Properties
Part 45
Generic information model
Application protocols –
Specialisation of generic resources for an engineering need
Application
software
STEP file
Part 21
Application
software
Data file with
semantics from
application©model
Ferroday Ltd 2007
Application
level model
Software
implementation
EXPRESS (ISO 10303-11)
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Enables objects to be described by data
types
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‘is a ….’ – entity data type (class object)
‘has a…’ – attributes
‘inherits from…’ – subtype
‘is related to….’ peer to peer or parent to
child
‘is constrained by ..’ - rule
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Example of data object
ENTITY product;
id
: identifier;
name
: label;
description
: text;
frame_of_reference : product_context;
UNIQUE
UR1
:
id;
END_ENTITY;
Instance of object in STEP data file:
#26 = PRODUCT (’1234’,’NormAL-4S’,’sheet,2.6mm
thick’,#11)
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STEP and properties
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Properties in ISO 10303
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ISO 10303-45 Materials - Integrated
resource
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Information model to link a property to a
product
ISO 10303-235 Engineering properties
for product design and validation Application protocol
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Information model to link a property of a
product to the measurement process
© Ferroday Ltd 2007
ISO 10303-45 Materials
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Generic resource for all properties of a
product
Relates the value of a property to the
conditions of a measurement method –
data environment.
Includes:
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Properties of products or parts of products
Chemical compositions
Uncertainties of values and data qualifications
© Ferroday Ltd 2007
ISO 10303-45 Edition 2
New version adds:
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representation of property values as
mathematical expressions
uncertainty and reliability of values as
expressions
composition values as mathematical
expressions e.g <, >, a+b<c, etc
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ISO 10303-235 Engineering properties for
product design and validation
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Associates the value of a property to
the measurement process
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Information model describes any property
measured by any process
Uses ISO 13584 data dictionaries for the
terminology of specific property domains
Uses the resources of ISO 10303-45 Ed2 to
describe property values by expressions
© Ferroday Ltd 2007
PLIB Dictionaries
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Classification of objects with properties
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Meaning of a property is constrained to a
class
Objects may be features of other classes
Classes can reference properties from
classes in other dictionaries
Standard dictionaries exist for cutting
tools and threaded items, etc.
© Ferroday Ltd 2007
Standard information models
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Provide specifications for data representation
independent from proprietary software :
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Separation of data representation from data
management environment
Preserve original semantics and structure
Augmentation of incomplete data to same
specification from other sources
Distributed sources of data to same specification
Ensure stability of archives for the long term
© Ferroday Ltd 2007
Conclusions
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STEP and PLIB are based on well-established
principles – of software engineering and information
representation
The standards are developed by very rigorous
procedures
The models have been proven for realistic cases and
are in industrial use
The technology is of general validity and not confined
to engineering applications
Use of specifications will enable a supply chain for
data and could support a market for data exchange
© Ferroday Ltd 2007