PDD Quality Assurance Requirements
Goleta California
1.0
INTRODUCTION
A Partially Defined Drawing (PDD) is a drawing that has been simplified in that it does not
contain a complete set of dimensions. For complete product definition the dimensional
information is queried from the model geometry contained in the CAD digital data file.
2.0
APPLICABLE DOCUMENTS
ASME Y14.5-2009
ASME Y14.41-2003
Dimensioning and Tolerancing
Digital Product Definition Data Practices
3.0
DEFINITIONS
3.1
DEFINITION OF A DESIGN MODEL
As defined by ASME Y14.41 the Design Model is the CAD digital data file which contains the
3D model geometry. The standard file format for the Design Model is a STEP file (.stp file
extension). Other formats including the Pro/Engineer file format can be provided upon
request. Nonstandard format requirements for the Design Model shall be specified in the
purchase order.
3.2
DEFINITION OF AN ATK PARTIALLY DEFINED DRAWING
A PDD is a drawing in which basic dimensions aren't shown and are to be queried from the
Design Model (CAD digital file).
All other dimensions, tolerances, notes, etc… are shown as on a fully defined drawing. See
section 6.1 for reference information regarding this definition.
3.3
PERTINENT REQUIREMENTS FROM THE ASME STANDARDS
ASME Y14.5-2009 Dimensioning and Tolerancing
1.4 (b) Dimensioning and tolerancing shall be complete so there is full understanding of
the characteristics of each feature. Values may be expressed in an engineering drawing or
in a CAD product definition data set. See ASME Y14.41.
ASME Y14.41-2003 Digital Product Definition Data Practices
7.2.1 Basic Dimensions. Queried model values shall be interpreted as basic dimensions
unless superseded by a toleranced dimension or defined as a reference dimension.
7.3 Drawing Requirements
Basic dimensions not displayed on a drawing shall be obtained by querying of the model.
ATK-FORM-293
Functional Manager:
S. Quinn
Date:
01-11-10
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PDD Quality Assurance Requirements
Goleta California
3.4
DEFAULT PROFILE TOLERANCE
A key element of a PDD is the "Default Profile" – a relatively loose, unless-otherwisespecified, GD&T profile tolerance that applies to all features that do not have their tolerance
explicitly defined. The Default Profile appears on the face of the drawing in one of the drawing
views and is designated by use of the annotation "ALL OVER UNLESS OTHERWISE
SPECIFIED" as shown:
.030 A B C
ALL OVER UNLESS
OTHERWISE SPECIFIED
3.5
PDD DRAWING NOTE
The following note is placed on all PDD drawings. It specifies the data file name and that the
geometry represents the nominal size (perfect form).
3. DESIGN MODEL IS REPRESENTED IN CAD DIGITAL
DATA FILE XXXXXX.STP. DESIGN MODEL
REPRESENTS PART AT NOMINAL SIZE BEFORE FINISH.
DESIGN MODEL AVAILABLE IN OTHER 2D AND 3D
DIGITAL DATA FORMATS ON REQUEST. INTERPRET
PER ASME Y14.41-2003.
3a. PARTIALLY DEFINED DRAWING. THIS DRAWING
SHALL BE USED WITH THE DESIGN MODEL FOR
COMPLETE PRODUCT DEFINITION. QUERY OF
THE MODEL IS REQUIRED FOR UNDIMENSIONED
FEATURES.
3b. VALUES QUERIED FROM THE MODEL ARE BASIC
UNLESS OTHERWISE SPECIFIED.
4.0
INSPECTION REQUIREMENTS
4.1
PDD PRODUCT ASSURANCE REQUIREMENTS
ATK requires suppliers to have:
1. Digital inspection software (e.g. PC-DMIS).
2. Inspection hardware (e.g. CMM) that is controlled by the digital inspection software.
3. Software and hardware configured to utilize the Design Model in generating numerically
controlled inspection routines.
4. Standardized inspection report formats that can graphically present inspection data of all
part features.
5. Standardized procedures that define and control the above processes. This shall include
configuration control of all electronic files and a process to validate that machined parts
meet the PDD.
ATK-FORM-293
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PDD Quality Assurance Requirements
Goleta California
Requirements are based on the ATK PDD and its associated Design Model (CAD digital file).
As defined in section 3.2 a Partially Defined Drawing or PDD per ASME Y14.41-2003 is a
drawing in which basic dimensions are not shown and must be queried from the Design
Model. All other dimensions, tolerances, notes, etc… are shown as on a fully defined drawing.
The PDD and its associated Design Model are provided to the seller for use in planning and
programming digitally controlled machining and inspection equipment and seller is responsible
for meeting all requirements specified therein. ATK will provide the Design Model with a file
name structure that will include part number and revision as a minimum (for example:
3039K4802-1_D_3D.STP); The ATK PDD revision and Design Model revision are always the
same. All changes conveyed to the seller will be via an ECO that describes “Was” and “Is”
conditions along with the revised drawing and its associated Design Model.
Configuration – Seller shall have a documented control system to assure that both the ATK
Design Model/PDD and seller derived files are placed under seller configuration control; seller
derived files shall be validated by the seller's internal quality procedures prior to use, and
maintained in a manner that prevents misuse or alteration of the file. All revisions shall be
controlled. Seller requests for changes to the Design Model/PDD shall be documented and
submitted through the ATK Buyer.
Inspection Report – Seller is required to provide an Inspection Report for each production lot
that documents compliance to each of the requirements of the ATK PDD and associated
Design Model. Note that although the PDD drawing is partially defined (missing basic
dimensions) the presence of the Design Model as the source of the basic dimensions fully
defines the part and therefore all features must be inspected whether dimensioned or not.
4.2
INSPECTION OF DEFAULT PROFILE
PDD's contain a Default Profile GD&T callout as defined in section 3.4 that specifies the
tolerance requirement for all features whose tolerance is not defined by some other tolerance
callout. The Default Profile is designated by use of the annotation: "ALL OVER UNLESS
OTHERWISE SPECIFIED".
Features on PDD's whose profiles are covered by the Default Profile shall have their
inspection data recorded in the inspection report as follows:
The report shall provide the value of the maximum variation from perfect form from among all
the features covered by the Default Profile callout. Actual measured variations from perfect
form for every feature covered by the Default Profile callout shall be retained under seller
configuration control per PO requirements and be available upon buyer request as needed
after delivery.
4.2.1
Enhanced PDD Report Option: If required by the PO all features covered by the Default
Profile callout shall be identified by ID codes that are automatically generated by the
inspection software. The ID codes shall be displayed on a graphical representation (picture) of
the Design Model such that it is clear which feature is associated with each ID code.
ATK-FORM-293
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PDD Quality Assurance Requirements
Goleta California
These ID codes shall link features displayed in the graphical representation to actual
measured inspection data. The inspection software shall also generate a section of the report
in tabular format that includes the tolerance requirements, the actual measured deviations,
and the out of tolerance data for each of the features as identified by the ID codes. See
section 6.2 for an example of a graphical representation with ID codes generated by PC-DMIS
inspection software.
The capabilities of PC-DMIS are representative of the capabilities required of inspection
software that is compliant with these inspection requirements.
4.3
MANUAL INSPECTION OF DEFAULT PROFILE
Sellers who do not have the computer controlled inspection equipment and software that
enables them to meet the requirements of this section in an automated manner may propose
a manual method and submit it to the buyer for approval. Sellers in this category shall be
subject to a site visit prior to seller approval for ATK Goleta PDD products.
4.4
INSPECTION REPORT REQUIREMENTS
The inspection results from the Default Profile report defined in section 4.2 shall be
incorporated into the Inspection report required in AEC-FORM-003 Supplier Quality
Assurance Requirements.
5.0
ACRONYMS
CAD
CMM
GD&T
Computer Aided Design
Coordinate Measurement Machine
Geometric Dimension and Tolerancing
6.0
REFERENCE INFORMATION
6.1
RATIONALE FOR DEFINITION OF A PDD
A piece part defined by a PDD must have a defined, unambiguous tolerance for every single
feature or surface on the part just as a part with a fully dimensioned drawing does – This is a
fundamental requirement of ASME Y14.5 Dimensioning and Tolerancing. A PDD must fully
comply with the requirements of ASME Y14.5-2009 and ASME Y14.41-2003.
Traditional or X-Y type dimensions cannot be left off a drawing because there are multitudes
of ways in which a given feature can be defined by an X-Y dimension. For example; features
can be dimensioned either from one end of the part or the other; successive features can be
dimensioned either as coordinate dimensions or serially from one to the next; etc… A PDD
with X-Y dimensions left off therefore fails the requirement that every feature have a single
unambiguous tolerance.
Basic dimensions on the other hand do not define tolerances. Basic dimensions by definition
describe the theoretically exact size, profile, orientation, or location of a feature whose
tolerance is defined by GD&T feature control frames.
ATK-FORM-293
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PDD Quality Assurance Requirements
Goleta California
As such, a basic dimension can be queried from a Design Model (CAD digital file) which is a
theoretically exact geometric representation of a part.
A PDD piece part's tolerances, by design, are predominantly defined by GD&T. This enables
the majority of its dimensions, were they present, to be basic.
6.2
GRAPHICAL INSPECTION REPORT EXAMPLE
ATK-FORM-293
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