Machining Tolerance Standards and General Notes 5

[sponcyv]

Hello,

I am a structural engineer, but am working to develop plans for a mechanism in order to make a prototype. I am searching for tolerance guidelines and general drawing requirements. I'm also looking for example drawings that show general notes that I will need to provide on my drawings.

The material that I'm working with is 50 ksi steel. The components will include a semi-spherical ball with a drilled hole through the center and a square plate with a concave spherical section removed. I am working in SI units.

Any help is appreciated.

Thanks

 

[KENAT]

Drawing standards, see faq1103-1039, ASME Y14.5M-1994 is arguably the most significant individual standard.

A resource like Machineries hand book has some tolerance information, and there are a few threads on here and in other areas with links to useful websites etc.

However, most of these are more like rules of thumb, best to talk to the actual machine shop to get some idea of their capabilities.

A good search of this site, especially this forum, forum404 & forum281 should turn up some useful stuff.

thread404-278305 & thread1103-212100 for instance.

Here's the list of notes from our drawing template they are meant to get edited as required. I haven't added all the colored text.

NOTES: UNLESS OTHERWISE SPECIFIED

1. DIMENSIONS AND TOLERANCES ARE IN ACCORDANCE WITH ASME Y14.5M-1994.
2. INTERPRET DRAWING IN ACCORDANCE WITH ASME Y14.100.
3. SCREW THREADS SHALL BE IN ACCORDANCE WITH ASME B1.1.
4. DIMENSIONS ARE IN INCHES.
5. MATERIAL: (INSERT MATERIAL OR DELETE IF USING TITLE BLOCK).
6. SURFACE ROUGHNESS SHALL BE ____ Ra PER ASME B46.1.
7. REMOVE ALL BURRS AND SHARP EDGES ____ MAX RADIUS OR CHAMFER.
8. INTERNAL CORNERS ____ MAX RADIUS.
9. BRIGHT ELECTROLESS NICKEL PLATE, .0003-.0005 THICK IN ACCORDANCE WITH SPEC MIL-C-26074 OR EQUIVALENT. DIMENSIONS APPLY AFTER PLATING.
10. DULL ELECTROLESS NICKEL PLATE, .0003-.0005 THICK IN ACCORDANCE WITH SPEC MIL-C-26074 OR EQUIVALENT. DIMENSIONS APPLY AFTER PLATING.
11. ANODIZE PART PER MIL-A-8625 TYPE IA (CHROMIC ACID METHOD) CLASS 1, COLOR: GRAY. DIMENSIONS APPLY AFTER ANODIZE.
12. ANODIZE PART PER MIL-A 8625 TYPE II, (SULFURIC ACID METHOD) CLASS 2, COLOR: (SPECIFY COLOR). DIMENSIONS APPLY AFTER ANODIZE.
13. ANODIZE PART PER MIL-A-8625 TYPE II, CLASS 2, COLOR: FLAT BLACK. DIMENSIONS APPLY AFTER ANODIZE.
14. HARD ANODIZE PART PER MIL-A 8625 TYPE III, .0020 ± .0005 IN. COLOR: BLACK. DIMENSIONS APPLY AFTER ANODIZE.
15. FINISH: CHEMICAL CONVERSION COATING PER MIL-DTL-5541F TYPE II CLASS 3 (CLEAR).
16. FINISH: BEAD BLAST WITH THE FOLLOWING PARAMETERS:
NOZZLE PRESSURE: 40-60PSI
BEAD SIZE: POTTERS DESIGNATION AE OR #10
US SIEVE: 100/170
THREADED HOLES SHALL NOT BE BEAD BLASTED.
17. FINISH: CLEAN & PASSIVATE TO ASTM-967.
18. INSTALL PRESS FIT STANDOFFS, STUDS, AND NUTS IN ACCORDANCE WITH THE MANUFACTURER’S SPECIFICATIONS.
19. IDENTIFY PART WITH PART NUMBER BY BAGGING AND TAGGING.
20. FINISHED ARTICLE SHALL BE FREE OF OILS, LUBRICANTS AND OTHER CONTAMINANTS PRIOR TO BEING PLACED IN SEALED BAG.


[RED]DRAFTING NOTE: Notes are meant to be added to or deleted, as needed for the individual part or assembly drawing. Textual changes are not to be made, other than where indicated in sky blue. Text colored red or sky blue to be replaced/deleted/verified prior to release, retained text to be made black.

Note 13 is recommended for non-reflective, light sensitive areas in lieu of Note 14, (hard anodize).

If metric threads and/or dimensions are used:
Modify Note 3 to read: 3. METRIC SCREW THREADS TO BE IN ACCORDANCE WITH ASME B1.13M. METRIC THREAD CALLOUTS WITHOUT A PITCH SPECIFIED ARE COARSE PITCH.
Modify Note 4 to read: 4. DIMENSIONS ARE IN MILLIMETERS.

SPECIALIZED DRAWING NOTES[/RED]

TO BE ADDED TO DRAWING NOTES AS NEEDED, INSERTED IN ORDER THEY WILL BE NEEDED WHEN USING THE DRAWING:

21. DIGITAL PRODUCT DEFINITION PREPARED IN ACCORDANCE WITH ASME Y 14.41-2003.
22. THIS DRAWING SHALL BE USED WITH MODEL (INSERT PART NUMBER) (REVISION PER THIS DRAWING) FOR COMPLETE PRODUCT DEFINITION. MODEL GEOMETRY IS BASIC.
23. SYMBOL ¨ DENOTES CRITICAL DIMENSION / FEATURE IN ACCORDANCE WITH 1QA73002.
24. INSTALL HELICAL COIL INSERTS IN ACCORDANCE WITH THE MANUFACTURER’S SPECIFICATIONS.
25. WELD SYMBOLS IN ACCORDANCE WITH AWS A2.4-98.
26. WELD PROCESS GTAW/GMAW IN ACCORDANCE WITH INDUSTRY BEST PRACTICES.
27. CAUTION - ESD SENSITIVE: ELECTROSTATIC DISCHARGE PREVENTION PRACTICES SHALL BE FOLLOWED DURING ASSEMBLY & HANDLING IN ACCORDANCE WITH ANSI/ESD S20.20, OR EQUIVALENT.
28. FINISHED ARTICLE SHALL COMPLY WITH ROHS & WEEE REGULATIONS.
29. STRIP CABLE JACKET _____ FROM END.
30. STRIP INDIVIDUAL CONDUCTORS _____ FROM END AND TIN.
31. ITEM (INSERT ITEM NO.), CRIMP TERMINALS, SHALL BE INSTALLED IN ACCORDANCE WITH MANUFACTURERS INSTRUCTIONS USING TOOL (INSERT CRIMP TERMINAL MANUFACTURERS TOOL PART NUMBER) OR EQUIVALENT
32. HI-POT AND GROUND CONTINUITY TEST REQUIRED. TEST IN ACCORDANCE WITH PROCEDURE 2QZ73001 OR EQUIVALENT. APPLY LABEL “HIGH POT TESTED OK” AFTER SUCCESSFUL TESTING.
33. TEST FOR CORRECT PINOUT, INTERMITTENCE AND SHORTS TO ADJACENT LINES. ADD TESTED LABEL WITH DATE AND INITIALS OF TESTER AFTER SUCCESSFUL TESTING.
34. PAINT: (INSERT PAINT SYSTEM DESIGNATION), COLOR (INSERT COLOR) TO (INSERT COLOR SYSTEM & ID e.g. “PANTONE 427”) IN ACCORDANCE WITH MANUFACTURERS INSTRUCTIONS. AVAILABLE FROM (INSERT MANUFACTURER DETAILS). THREADED HOLES AND INDICATED AREAS TO BE FREE OF PAINT.
35. SILKSCREEN TEXT (INSERT COLOR), (INSERT FONT) FONT, (INSERT SIZE) HIGH, APPROXIMATELY WHERE SHOWN.
36. ‘COMPANY’ LOGO: SILKSCREEN ACCORDING TO ARTWORK FILE 191-015-400.AI. SIZE AND LOCATION INDICATED. COMPANY NAME TEXT COLOR (INSERT COLOR, E.G. ‘BLACK’), ORBIT SYMBOL COLOR (INSERT COLOR, E.G. ‘BLUE TO RAL 260 40 45’).
37. IDENTIFY PART WITH PART NUMBER, REV LETTER AND SERIAL NUMBER BY ELECTRO-CHEM ETCH, METAL STAMPING, ENGRAVING OR LASER ENGRAVING (CHOOSE METHOD) WITH _____ IN. HIGH CHARACTERS WHERE SHOWN.
38. FINISHED ARTICLE SHALL MEET CLEANLINESS REQUIREMENTS OF IEST-STD-CC1246D LEVEL 100 (VERIFY CORRECT LEVEL). IF NOT TO BE USED IMMEDIATELY THEN TO BE ENCLOSED IN PACKAGING TO IEST-STD-CC1246D LEVEL 100 (VERIFY CORRECT LEVEL) LABELED: “CLEANED, DO NOT OPEN OUTSIDE OF CLEAN ROOM”. COMPLIANCE WITH THIS REQUIREMENT BASED ON USE OF A QUALIFIED MANUFACTURING PROCESS IS ACCEPTABLE.
39. ITEM SHALL BE ASSEMBLED IN A CLASS 6 (VERIFY CORRECT CLASS) CLEAN AREA MAINTAINED AS PER ISO 14644-1. (CLEAN AREA TO FED-STD-209, CLASS 1,000 (VERIFY CORRECT CLASS) IS ACCEPTABLE ALTERNATIVE.)

[RED]SOURCE CONTROL DRAWINGS, shall contain the following two notes:[/RED]

40. ONLY THE ITEMS DESCRIBED ON THIS DRAWING ARE APPROVED FOR USE IN THE APPLICATIONS SPECIFIED HEREON. A SUBSTITUTE ITEM SHALL NOT BE USED WITHOUT PRIOR APPROVAL BY THE QUALIFYING ACTIVITY.
41. IDENTIFICATION OF THE APPROVED SOURCE(S) OF SUPPLY HEREON IS NOT TO BE CONSTRUED AS A GUARANTEE OF PRESENT OR CONTINUED AVAILABILITY AS A SOURCE OF SUPPLY FOR THE ITEM DESCRIBED ON THE DRAWING.

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[KENAT]

Oops, all the ASME stds assume that's what you're working too. If you aren't in the US or just choose to use ISO then some things are different. If to Iso you could reference iso2768 though I'm hesitant to recommend it to anyone in the US as it doesn't follow common US practice.

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[dgallup]

At least #1, 2, 4, 5, 6 & 7 should be standard areas in the title block.

 

[KENAT]

Should?

I don't believe they are shown in the title block in ASME Y14.1. At least they aren't in my out of date ANSI version.

It just so happens that we do have a small block for material in our title block but it is frequently too small to properly describe some of the more exotic materials, so we have the note to use when required.

How about instead of picking holes in what I posted, you actually try to help the OP?

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[sponcyv]

KENAT,

Thank you very much for this valuable information!

 

[sponcyv]

KENAT,

For surface roughness (Ra), what would you specify for galvanized steel? Is there something typical or does it depend on other factors?

 

[KENAT]

It's driven 1st by function, second by process capability.

The process capability can be assessed to some extent by looking at one of the standard charts in machineries or somewhere like

http://www.engineershandbook.com/Tables/surfaceroughness.htm

http://icrank.com/cgi-bin/pageman/pageout.cgi?path=/data/surface_finish.htm&t=2

Also are you talking about the surface finish of parts bought already galvanized? In that case you'd rely on the spec of the material to cover it. Your drawing spec may only apply to 'cut surfaces' or similar.

The notes above all not fool proof and there are exceptions.

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[sponcyv]

KINET,

The surface roughness and radii tolerances are important because I need to provide uniform contact between concave and convex surfaces. The members will be in static position permanently, so friction is not an issue. I just need to ensure that the sphere can sit in the socket and be rotated in to position and the contact area stays in tact.

All of this is new to me. To specify surface roughness, I need to understand how they will fabricate the items. Do you know how carbon steel spheres are fabricated? I would think that the socket would be formed by milling. The socket is a plate with a spherical shape removed.

The parts will be bought and then fabricated and galvanized after fabrication.

 

[sponcyv]

KENAT,

I am using only the notes that apply. Thanks!

 

[MintJulep]

To specify surface roughness, I need to understand how they will fabricate the items.

No.

You, as the engineer need to determine what surface roughness is necessary for your design to function properly.

The manufacturing engineer or machinist needs to select the manufacturing process with the capability to provide the required finish.

It's helpful for the designer to understand the capabilities of processes to avoid specifying the impossible to achieve, or something that can only be achieved at unacceptable expense, but it's not necessary.

 

[fsincox]

Mint,
Amen, Seems like lots of people do prefer the other way.
Frank

 

[sponcyv]

I'm trying to determine what my surface roughness needs to be based on my function, but I can't find any literature on it.

 

[dgallup]

Kenat - Sorry, I always forget how many people use quaint local standards instead of international ones. (Not saying ISO is better, I just always think in terms of them.)

But I do think having a list of 40+ standard notes is a bit excessive. How do you fit all that verbiage on a small drawing? I suppose it all depends on what industry you are in.

But I still think a good, standard title block SHOULD have the items that are common to every drawing such as units, dimensioning & tolerancing standards, default tolerances, material spec, etc. If you have a complicated spec the title block can just say see note XXX.

 

[fsincox]

Ken,
Nice list,
Guys,
I think Ken is not recommending all notes on all drawings he is just trying to provide a helpful comprehensive summary of notes he has used or seen used.
This is my same problem with the standard, people think: "If it is shown here like this, it has to be done like that", No it does not! It is only really a guide unless specifically stated as such. This is another reason I apreciate the general guidance provided by ISO there is not a lot to over interpret, I know this is not a popular position, here. Our system is too often interpereted to be "tell me exactly how to do it" and "if it is not shown there, it can't be done".
just my opinion,
Frank

 

[KENAT]

dgallup,

"DRAFTING NOTE: Notes are meant to be added to or deleted, as needed for the individual part or assembly drawing..."

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