1、 National Aeronautics and Space Administration John C. Stennis Space Center Stennis Space Center, MS 39529-6000 SSTD-8070-0098-SHOP Rev. Basic February 2012 COMPLIANCE IS MANDATORY John C. Stennis Space Center MACHINE SHOP TOLERANCES Original signed by Richard Harris_ 02/23/12 NASA SSC Center Operat
2、ions Directorate Date Operations and Maintenance Division Issued by Issued CEF_ 02/24/12 Central Engineering Files Date RELEASED - Printed documents may be obsolete; validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis Stan
3、dard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 2 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances Document History Log Change/ Revision Change Date Originator/ Phone Description Basic 0
4、2.24.2012 B. Farner/2967 Initial release, supersedes SSC 66-505. RELEASED - Printed documents may be obsolete; validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Da
5、te: February 24, 2012 Review Date: February 24, 2017 Page 3 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances Table of Contents 1.0 PURPOSE 5 2.0 APPLICIBILITY 5 3.0 REFERENCES 5 4.0 RESPONSIBILITIES . 5 5.0 GENERAL . 6 5.1 Dimensioning and Tolerance .
6、 6 5.2 Dimensions 6 5.3 Tolerances, Material 7 5.4 Countersinks and Counterbores . 7 5.5 Threads . 7 5.6 Surface Roughness . 7 5.7 Spot Face . 7 5.8 Welding . 8 5.9 Notes 8 6.0 MEASUREMENTS 8 6.1 Linear Dimensions . 8 6.2 Relation Of Linear Tolerance And Angularity Tolerance . 9 7.0 BORED HOLES, ALI
7、NGMENT AND SQUARENESS . 10 7.1 Tolerances . 10 7.2 Total Indicator Run-out (TIR) . 10 7.3 Out Of Roundness 10 7.4 Alignment 10 8.0 BURRS AND SHARP EDGES 11 8.1 Burrs 11 8.2 Sharp Edges 11 9.0 CORNERS, INTERNAL AND EXTERNAL . 12 9.1 Internal Corners. 12 9.2 Notches And Cutouts . 13 10.0 DOWLING 13 10
8、.1 Matched Parts 13 10.2 Redoweling 14 11.0 DRILLED HOLES 14 11.1 Bolt Circle Hole Spacing . 14 11.2 Hole Alignment. 15 11.3 Squareness Of Hole Centerline . 16 11.4 Round Holes, General 17 11.5 Round Holes, Tolerances . 18 12.0 FINISHES 18 13.0 FORMED PARTS . 19 13.1 Angularity Of Frames 19 13.2 Ali
9、gnment Of Holes And Slots 19 RELEASED - Printed documents may be obsolete; validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: F
10、ebruary 24, 2017 Page 4 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances 13.3 Bending And Forming . 20 13.4 Cut Surfaces . 22 13.5 Irregularities Of Cut-Offs . 22 13.6 Surface Flatness Of Formed Parts . 23 13.7 Twist On Formed Parts . 24 13.8 Welded A
11、luminum Corners 24 14.0 KEYWAYS 25 14.1 Radial Position Of Keyways 25 14.2 Alignment Of Keyways 26 15.0 PUNCHED HOLES 27 15.1 Concentricity of Washer Type Punchings . 27 15.2 Alignment of Holes, Slots, Etc. 27 16.0 SURFACES . 28 16.1 Formed Parts Surfaces 28 16.2 Machined Parts 28 17.0 TAPPED HOLES
12、30 17.1 Countersink For Tapped Holes and Tap Depths 30 17.2 Countersink For Tapped Holes 30 17.3 Angularity of Drilled and Tapped Holes . 31 18.0 THREADS . 32 18.1 Chamfer on Threaded Ends (Except Rolled Threads) . 32 18.2 Thread Length 32 18.3 Thread to a Shoulder . 33 18.4 Squareness and Concentri
13、city of Threads . 33 19.0 TOOL RELIEF . 34 19.1 Tool Relief for Grinding 34 19.2 Tool Relief in Holes 35 20.0 TURNED PARTS 35 20.1 Centers for Machining . 35 20.2 Squareness of Ends, Faces And Shoulders 36 20.3 Lateral Run-out 37 20.4 Internal Corners. 37 20.5 Concentricity and Roundness of Cylindri
14、cal Surfaces . 37 20.6 Straightness of Cylindrical Parts 38 21.0 RECORDS AND FORMS 40 22.0 ACRONYMS AND ABBREVIATIONS . 40 RELEASED - Printed documents may be obsolete; validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis S
15、tandard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 5 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances 1.0 PURPOSE This John C. Stennis Space Center (SSC) standard (SSTD) specifies the sh
16、op tolerances for the use of the designer or for shop use when no tolerances are specified on a drawing. 2.0 APPLICIBILITY a. Tolerances specified on a drawing shall have precedence over tolerances in this SSTD. b. For unspecified tolerances, the shop supervisor shall be responsible for using tolera
17、nces in compliance with this SSTD. 3.0 REFERENCES All references are assumed to be the latest version unless otherwise indicated. ANSI B46.1, Surface Texture, Surface Roughness, Waviness and Lay ANSI Y14.5, Dimensions and Tolerancing FED-STD-H-28/2, Screw-Thread Standards for Federal Services Sectio
18、n 2 Unified Inch Screw-Thread-UN and UNR Thread Forms SPR 1440.1, SSC Records Management Program Requirements SSTD-8070-0005-CONFIG, SSC Preparation, Review, Approval, and Release of SSC Standards 4.0 RESPONSIBILITIES a. Users of this SSTD shall comply with its requirements, ensure use of the correc
19、t version of this Standard and the documents it references, and inform the appropriate organization of needed changes in accordance with SSC Standard SSTD-8070-0005-CONFIG. b. Responsibilities for the use and control of this SSTD and for the review and approval of revisions or cancellation of this S
20、tandard shall be as specified in SSTD-8070-0005-CONFIG and the applicable documents referenced therein. RELEASED - Printed documents may be obsolete; validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0
21、098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 6 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances 5.0 GENERAL 5.1 Dimensioning and Tolerance a. Interpretation of dimensions and tolerances shall be in a
22、ccordance with ANSI Y14.5 and as supplemented herein. b. Parts exceeding tolerance limits to any degree, regardless of magnitude, shall not be considered as meeting drawing requirements. c. When linear tolerances are not given, the following shall apply: DIMENSION ALLOWABLE TOLERANCE No fractional o
23、r decimal 1/8” Fractional 1/16” One decimal place .030” Two decimal places .020” Three decimal places .010” 5.2 Dimensions 5.2.1 Dimensions and Finishes Measurement of dimensions and tolerances include applied metallic finishes such as electroplate, immersion plate, etc. and also include inorganic f
24、inishes such as anodic treatment, metal coloring, localizing and chromate treatment. Measurements do not include applied organic finishes such as paints, varnishes, enamels, phosphates, etc. 5.2.2 Dimensions Reference Dimensions marked “Reference” are not to be used for inspection purposes. 5.2.3 Di
25、mension Reference Temperature All dimensions are expressed in inches at the international standard reference temperature of 20C (68F). The manufacturer is responsible for making the necessary conversion for temperature variation. RELEASED - Printed documents may be obsolete; validate prior to use. P
26、rovided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 7 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: M
27、achine Shop Tolerances 5.2.4 Machine Setting Dimensions Four or five place decimal dimensions without tolerance are used as machine setting dimensions for precise machining such as jig bore work, gear cutting, and for data dimensions such as gear Ditch center lines, screw Ditch diameters, and simila
28、r applications. Such dimensions are not for inspection purposes. 5.3 Tolerances, Material When standard raw material cross-sections are specified without tolerances on the drawing, the tolerances referenced in the material specification shall apply. 5.4 Countersinks and Counterbores Countersink or c
29、ounterbore diameter shall be concentric within .005 inch to the hole diameter. 5.5 Threads Screw thread form shall meet the requirement of FED-STD H-28/2. All threads are right hand unless otherwise specified. 5.6 Surface Roughness a. Interpretation of finish symbols such as 16/ and 63/ shall be in
30、accordance with ANSI B46.1. The finish symbol indicates that material must be allowed for machining to the specified roughness. b. When a surface is produced by other methods such as casting, forging, and broaching, the finish is indicated with added notes such as follows: 500 as cast 250 as forged
31、5.7 Spot Face A spot face is a round flat surface (usually around a clearance hole) machined on a finished or unfinished surface in a plane perpendicular to the axis of a hold through the “spot”. The “spot” can be an accurate or an approximate diameter as specified. RELEASED - Printed documents may
32、be obsolete; validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 8 of 40 Responsible Office: CO Operation
33、s and Maintenance Division SUBJECT: Machine Shop Tolerances 5.8 Welding a. All weld splatter shall be removed. b. High spots and irregularities shall be within the finish requirements specified for the weld. c. Contrasting surface appearance on the area adjacent to welds shall be acceptable. 5.9 Not
34、es The figures in this document are used for illustration only, and may be over-detailed or incomplete. 6.0 MEASUREMENTS 6.1 Linear Dimensions a. Measurements Linear dimensions locating features from an edge are measured from the extremity of the edge. b. Irregularities Of Cut-offs The cut-off on th
35、e edge of a part shall not vary from the plane shown on the drawing by more than the tolerance “Y”. Tolerance “Y” must not cause overall dimension to exceed its tolerance. RELEASED - Printed documents may be obsolete; validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking
36、 permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 9 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances Thickness of Material Dimension Tol
37、erance “Y” Up to validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 10 of 40 Responsible Office: CO Oper
38、ations and Maintenance Division SUBJECT: Machine Shop Tolerances 7.0 BORED HOLES, ALINGMENT AND SQUARENESS 7.1 Tolerances Table 1 gives the tolerances which apply to alignment, squareness and out-of-round holes having a total diameter tolerance of .002” or less. 7.2 Total Indicator Run-out (TIR) The
39、 total run-out of precision holes delineated in line with other precision holes, and the squareness of these holes in relation to other precision holes or machined surfaces shall be within the values shown in Table 1. (See Figure 2) 7.3 Out Of Roundness The out of roundness of precision holes shall
40、not exceed the tolerance of the hole diameter. (See Figure 2) 7.4 Alignment The alignment of precision holes delineated in line with other precision holes shall be measured in terms of TIR. Figure 2 RELEASED - Printed documents may be obsolete; validate prior to use. Provided by IHS Not for ResaleNo
41、 reproduction or networking permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 11 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances Table 1
42、 Distance A Total Run-out (TIR) between Bores B validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without license from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 12 of
43、 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances b. When sharp corner is specified on the drawing, the radius or chamfer shall not exceed .010 max. c. When not specified 0 the drawing, but delineated sharp, the radius or chamfer shall not exceed .030 ma
44、x. 9.0 CORNERS, INTERNAL AND EXTERNAL 9.1 Internal Corners a. When internal corners are shown on a drawing but no dimension specified (See Figure 4), the part shall be made as shown in Figure 5. Figure 4 Figure 5 b. When sharp corner is specified on the drawing, the radius shall be .010 max., with u
45、ndercut not permitted. c. When sharp corner is shown on the delineation, but not specified, the radius shall be .030 max., with undercut not permitted. RELEASED - Printed documents may be obsolete; validate prior to use. Provided by IHS Not for ResaleNo reproduction or networking permitted without l
46、icense from IHS-,-,-Stennis Standard SSTD-8070-0098-SHOP Basic Number Rev. Effective Date: February 24, 2012 Review Date: February 24, 2017 Page 13 of 40 Responsible Office: CO Operations and Maintenance Division SUBJECT: Machine Shop Tolerances 9.2 Notches And Cutouts a. When a sharp corner is show
47、n but not specified on a drawing, the radius shall be .06 maximum. (See Figure 6) b. When a sharp corner is specified by note or a drawing, the radius shall be .01 maximum. (See Figure 6) Figure 6 10.0 DOWLING 10.1 Matched Parts a. In order to ensure accurate alignment after disassembly and reassembly, matched parts shall have a press-fit on the pin in one member and sha
