84a226035

GE Transportation 19.Apr.2010

1.

General Tolerance Specification

Rev. C

SCOPE This specification defines the general tolerances in the Imperial and Metric systems to be used on GE Transportation parts and products. For cast and forged p arts, see the 84A226035AB. Unless otherwise explicitly specified on a drawing for a particular dimension or characteristic, or in the title block of this drawing (only for legacy drawings), these general tolerances shall be applied to all new drawings created after the revision A issue date of this specification. specification. It shall also apply to all drawings that are formally reissued after the revision A issue date of this specification. Where the primary dimensions on the drawing are Imperial, the Imperial tolerances in this document shall apply. Where the primary dimensions on the drawing are Metric, the Metric Metric tolerances in this document shall apply. 1.1. ORDER OF PRECEDENCE The following order of precedence define how tolerances shall be applied: 1.1.1.1. 1.1.1.2. 1.1.1.3.

1.1.1.4. 1.1.1.5.

2.

Explicit Tolerances – Tolerances – any tolerances on the drawing face take precedence over any of document or instruction invoked. Industry Standards – Standards – Items such as sheet shee t metal thickness, which are driven by other industry standards (such as ASME or ASTM) specified on the drawing face. Implicit Tolerances – Tolerances – any characteristics on the drawing face that do not carry explicit tolerances shall derive their their tolerances from this this document. This excludes items such as thickness, thread creation, etc which shall be driven from other specifications (ANSI, ASA, etc) which which regulate these features. GE Standards – Any – Any internal GE standard invoked on the drawing face (such as the 84A208000 Wiring Standard). Under-defined Under-defined - Any characteristics without a tolerance from any of the previous points shall be considered under-defined and GET Engineering consultation shall be sought.

ABBREVIATIONS, DEFINITIONS, and REFERENCES Abbreviations GD&T GET

Geometric Dimensioning and Tolerancing GE Transportation

For additional tolerance and geometric control definitions and standards, please refer to the 84A222563AD, 84A222563AG and 84A222563AP. Drafting Standards per the 84A222563 series of documents, which are based on the ASME Y14.5 – 1994 and ASME Y14.100 – 2004. 3.

CONFIGURATION CONTROL and REVISION HISTORY For changes to this specification or review cycle, please consult the Standard Work Practice labeled as General Tolerance Practices.

Author: Engineering Issued: GET Engineering

Approval: PE Roundtable BUS. AREA: All

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This Drawing is the Property of GENERAL ELECTRIC COMPANY. This drawing is loaned upon the express condition that it shall not be reproduced in any manner, and shall be returned upon demand. It is submitted for evaluation purposes and it, and the information contained therein, shall not be otherwise used nor disclosed to third parties without written permission of General Electric Co.

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Rev. C

The content of this specification shall be formally reviewed within 1 year after the most recent revision. Table 3a – Revision History

4.

Revision 0 A

Release Date 18.Dec.2009 12.Dec.2010

Author FS Bekeny M McCullough

B C

16.Dec.2010 19.Apr.2010

M McCullough

Summary Initial release Document rewritten to conform with ASME Y14.5M 1994 Update Torque Requirements Add mfging best practices, clarify undercuts / burrs

TOLERANCES FOR DIMENSIONAL CHARACTERISTICS Dimensional characteristics are defined to include but not limited to:  External linear dimensions  Internal linear dimensions  Diameters and radii of holes  Radii (internal and external)  Distances  Chamfers Table 4a – Tolerances for Dimensional Characteristics (Units in millimeters) Tolerance class

Designation

Description

f m c vc

fine medium coarse very coarse

0.50 up to 3 0.05 0.10 0.20 -

Tolerances for Nominal Dimension within Listed Range over over over over over over 3 6 30 120 400 1000 up to up to up to up to up to up to 6 30 120 400 1000 2000 0.05 0.10 0.15 0.20 0.30 0.50 0.10 0.20 0.30 0.50 0.80 1.20 0.30 0.50 0.80 1.20 2 3 0.50 1 1.50 2.50 4 6

over 2000 up to 4000 2 4 8

Table 4b – Tolerances for Dimensional Characteristics (Units in inches) Tolerance class Designation

Description

f m c vc

fine medium coarse very coarse

.02 up to .12 .002 .004 .008 -

Tolerances for Nominal Dimension within Listed Range over over over over over over .12 .25 1.0 5.0 15.0 40.0 up to up to up to up to up to up to .25 1.0 5.0 15.0 40.0 80.0 .002 .004 .006 .008 .012 .020 .004 .008 .012 .020 .032 .050 .012 .020 .032 .050 .080 .120 .020 .040 .060 .100 .160 .250

over 80.0 up to 160.0 .080 .160 .320

Note that for values less than 0.50 millimeters or 0.02 inches; explicit tolerances on the drawing face are required.



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Rev. C

While no reference to the document shall be made, the values used in Table 4a align with the ISO 2768-1 (as released in 2009). The values used in Table 4b are the Imperial equivalent to Table 4a. The default for all drawings shall be the Medium designation un less another is desired by Engineering. To invoke another classification, simply change the callout on the drawing from a –m to the desired designation. To restate, if the Default Tolerance on the drawing face reads “84A226035” and does not carry a designation then that shall be considered 84A226035-m. Recommendations:  Fine - No known application at GET to date.  Medium - Machined components.  Coarse - Assemblies of moving parts.  Very Coarse - Sheet metal, pipe, non-critical assemblies. For cast and forged parts, see the 84A226035AB. When a new drawing is created, the following shall be the default tolerance class applied unless otherwise specified by engineering. Defaults by business: Locomotive – vc   Control – vc  Off Highway (OHV) – vc  Energy Storage – vc  Locomotive Engine & Generator Sets – m  Marine Engine – m  Wind – m  Propulsion – c 5.

ANGULAR DIMENSION TOLERANCES All angles shall be +/- 1°.

6.

SURFACE TEXTURE TOLERANCES There are no general tolerances for surface texture. Surface texture tolerances, when required, shall be explicitly documented on the drawing in accordance with the ASME Y14.36 - 1996. Surface textures are typically documented a s follows:

xxx

For Metric xxx is the micrometer measurement. The default maximum finish value is 6.3. For Imperial xxx is the microinch measurement. The default maximum finish value is 250. Author: Engineering Issued: GET Engineering


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As for tolerancing, this finish value shall be considered a maximum value. In that if a finish of 125 micro-inches is specified then the roughest the part may be is 125 microinches but it could be smoother. Where it is desired to strictly limit the range, this shall be explicitly listed on the drawing. The following table provides a correspondence between metric arithmetical mean deviation (Ra), its Imperial equivalent, and the roughness grade number. These are not direct conversions but rather should be used as similar to. 50µm is similar to 2,000 µin which is also similar to N12. Table 6a – Correspondence of Arithmetical Mean Deviation Ra and Roughness Grade Numbers Roughness Values Ra Roughness Grade Numbers micrometers microinches 50 2000 N12 25 1000 N11 12.5 500 N10 6.3 250 N9 3.2 125 N8 1.6 63 N7 0.8 32 N6 0.4 16 N5 0.2 8 N4 0.1 4 N3 0.05 2 N2 0.025 1 N1



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Rev. C

CORNERS, BURRS, UNDERCUTS

ITEM (A) Chamfer (B) Break Corner

(C) Sharp Corner Radius Corner - (R) or Fillet - (F)

(H) Under-cut (K) Part off Thread Undercut

DRAFTING AND MANUFACTURING PRACTICE Chamfer tolerances should be specified on the drawing face or per 84A226035. Unless otherwise stated on the drawing, break all corners on machined diameters or faces with a chamfer or radius.

Diameter Chamfer Up to 1" 0.005 to 0.02 Over 1" to 2" 0.005 to 0.04 Over 2" 0.005 to 0.06 Must be stated on drawing as "Sharp Corner" and have a maximum radius of 0.005. Specify on drawings only when a chamfer is not acceptable. Unless otherwise specified, radii of corners to be: no radii specified -- See "B" radii - specify on drawing = ± .02 Specified per 84A226035. End projections on part-off cuts must be removed unless otherwise specified. Undercut diameter must be shown when thread is carried up to head undercut.

8. TORQUE Torque tolerance shall be +/- 5% from the nominal value specified on the drawing. Where a torque specification is used, that document shall take precedence over this one and +/- 5% shall only apply where that document does not cover the full engineering definition. Any torqueing requirements not specified on the drawing shall be considered under-defined. 9.

MANUFACTURING BEST PRACTICES 9.1. GENERAL PRACTICES



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All applicable manufacturing best practices shall be used unless prohibitive or otherwise specified on the drawing. Manufacturing best practices can be found in the 84A226035AC. 9.2. WIRING Wiring best practices can be found in the 84A208000. Any drawing detailing wiring design / routing shall follow this document. 10. APPLIED PRACTICES AND STANDING INSTRUCTIONS While these documents shall not be used on the drawing face any longer as default tolerances, they can be used to derive what the tolerance was / should be if the values in this document are not acceptable for a particular feature or part – they are reference only. In that instance, it is recommended to derive what the tolerance would be based on the applied practice and then explicitly define that value on the drawing face. A list of known documents is shown here. Note that the standards listed were the most commonly used; this is not an exhaustive list. Standard Number 41A282000 84A208000 41A213278 41A213279 41A213280 SI-10359 SI-10350 SI-10559 SI-10025 SI-10348 SI-10027 C50E76 C50E82 K4015012 ISO 2768-1-m ISO 2768-2-K ISO 4287 ISO 4288 ISO 13715 ISO 286-1 ISO 286-2 499A981AA 84A216320 84A216320AB B30E501 B30E5 B50E147A B50E147 84D740043AC K5903487 84A224379 M9946126 41C633023 84A225834-mK 84D740043 84D740043AB SI-10013 SI-10017 SI-10011 SI-10008 C50E90 C50E73

Locomotive x x

Engine

Control

Business Propulsion Wind

OHV

x x x x

M&S x x x x

x x x

x x x x x x x

x x x x x x x x x

x x x x x x x x x

x x x x x x x x x x

x x x x x

x x

x x x x x x

x x


Description

Genset

x x

General Assembly Wiring General Assembly Casting Tolerances Machining Tolerances Standard that covers all manufacturing Bus Bar Insulation List of processes for Finishes and Coatings Standard that covers all manufacturing Wiring & assemblies Bolt Torque Material Testing Material Testing Knurling General Machining Tolerances General Machining Tolerances Theoretical Surface Texture Definitions Theoretical Surface Texture Definitions Edges of Undefined Shape Interpreting Dimensions Interpreting Dimensions Pipe Bending Design Guidelines Bldg 10 Light Fabircation Guidelines Heavy fabrication Guidelines Mat'l Comp, Dimensions & Tolerances Tubing Tubing Dimensions & Tolerances Various Torques (GEVO) Tap Depth Critical Fasteners Tap Drill Sizes Counterbore and Spotfacing ISO 2768-mK Various Torques (Generic) Various Torques (????) Gear Casing Painting Machined Assemblies Mounting Pinions Motor Frame Parts Crankshaft Specification Steel Castings


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