Computer MCEN 1025
Popular in Course
Popular in Mechanical Engineering
This 9 page Class Notes was uploaded by Deron Schmitt on Thursday October 29, 2015. The Class Notes belongs to MCEN 1025 at University of Colorado at Boulder taught by Staff in Fall. Since its upload, it has received 15 views. For similar materials see /class/232017/mcen-1025-university-of-colorado-at-boulder in Mechanical Engineering at University of Colorado at Boulder.
Reviews for Computer
Report this Material
What is Karma?
Karma is the currency of StudySoup.
Date Created: 10/29/15
g s Q i A Why Is Dimensioning amp Tolerancing Important Dimensioning makes design intent unambiguous Variation is always present in manufacturing processes Tolerancing specifies how much variation is acceptable ie controls variation DampT enables massproduclion If parts are manufactured according to the specifications on the drawing they Will fit together and function as intended ADF527 Dime75 inning amp 7g lensicing 2 1999 0 One team at LockheedMa in in CO sent key information in English units to the Jet Propulsion Lab JPL in CA 0 JPL assumed they were SI units 0 The spacecraft entered the Martian atmosphere at an altitude of 57 km vs 1 0150 ADF527 km Elements of Dimensioning Diameter RRin we so 0 032 Bilateral or mooio tolerance l 25m Basic dimension 2wo Theoreticalty exact Limits of size No tolerances applied Used w GDampT feature control frame Reference 203 Mr M dimension 200 i l See Chapter 17 in Engineering Graphics ADFab Dimei5 inning a in lensicing 4 1092008 Good Dimensioning Practice Avoid crossing dimension lines Do not overdimension Show overall dimensions of object 7 Use reference dimensions ifnecessary x XX07 xxxRef Tg ilv 39v Consider how you would measure the part to confirm dimensions ADF527 ainnns inning amp 7n inranning 5 Place dimensions on most descriptive View Preferred Avoid ll Tl uses hi 3clic39kquot ld m ov39efdim eri39sidns belwee ews n dWorks39drawing ADF527 ainnns inning amp 7n inranning 5 Dimensions should be located outside the boundaries of the object CADFab ainnns inning ca in Manning 7 Stagger Dimensions for Clarity 25 312 j I SEE 7 75mg 5cm u2 62 1 74D 1 A zl a 2 6D r Dimension concentric circles in longitudinal r 32 62 2 4113mm 2 6D 7 75D 1 45 l mu e er CADFab Dime75 inning ca in Manning 3 How Will the Part be Made Total length Good for punched slots 5 7 R5 Center distance Easy to m achine Goodfor milled slots eg a slot ADF527 ainnns inning amp 7n Manning 9 Example of Poor Dimensioning 7138 Slots should be dimensioned to S7 39 correspond wi h the size ofthe punch die 7 is we I as Dimensions taken from wrong edge dil cult to verify Tight tolerance on drilled hole would quire unnecessary reaming HT ADF527 ainnns inning ca in Mrsicing Understand How the Part Will Be Made Before Dimensioning It 397 Q 7 i gt 7 7 1Shear at 2 Shear olf 3 Punch slots 4 Drill hole with pattern corners with notch die standard drill Toolaccess 6 Bend second leg 5Bend shorlleg Q39 CADFab ainnns inning ca in Mrsicing 11 Better Yet Punch entire blank in one operation Blanking Die ADFab Dime75 inning ca in Mrsicing 12 1092008 Example of Good Dimensioning Slots dimensioned to correspond with the size of he punch die I 38 2 PL M IQPL 2H 7 l l l 3 l r GR l l L 25 Dimensions 39 3995 l referenced to 7192 155 4 correct edge 250gg More generous hole tolerance 739 can be drilled in one operation or Coordinate Dimensioning aka Datum Dimensioning or SolidWorks gtBaseline Dimensioning X 1320 Origin 00 CADFab 1 Other Coordinate Dimensioning Styles Hole Table Useful if lots of holes clutter drawing Ordinate Dimension CADFab Dimensianing amp Takers75777 15 Symbols for Drilling Operations 0 w CADFab Dime75 7177777 amp THEM75777 15 1092008 D1mens1on1ng 1n SolldWorks SolidWorks will automatically insert the correct value on a dimensioned drawing Insert Model Items 0 How you dimension features in SolidWorks part models defines how the dimensions will appear in the drawing 0 However you still have control over dimension features 7 Placem ent on drawing 7 Dimensional precision 7 Tolerances ADF527 ainnns inning amp 7n Manning 17 Dimensioning in SolidWorks Ifyou add tolerances to sketch dimensions they will automatically appear on drawing Smeagnmz 1 0001002 Skelchin part model Drawing ADF527 ainnns inning amp 7n Manning 13 Variation In a large batch of identically produced parts there is always a statistical distribution of size Capable process Incapable process nur527 ainnns inning ca in hrswing 19 Tight Tolerances Cost Money MANU FACTU R IN G COST 35 Lo o 5 Loose Tight TOLE RAN C E ADFab ainnns inning ca in hrswing 20 1092008 Examples in diameter 1Turned shall 63 2mquot 2Hole ainnns inning ca 79 innanning 1 Turn on lathe 1 Drill 2 Ream 1 Drill ADF527 Tolerance Styles Tolerance total allowable variation Symmetric 140 l 02 Larger limit on top Li Tolerance 004 1 0 Bilateral 190 02gt Tolerance 003 00 Unllateral 190 D3 ADF527 ainnns inning ca 79 innanning 1092008 Tolerance Styles MINMAX 2 I l l I I ltZgtlOOOf1Agtlt lOO2lllll l 1 nuran ainnns inning ca 79 innanning Implied Tolerances 0 50 in is not the same as 5000 in 0 Decimal precision can be effectively used to imply tolerance To be crystal clear specify your implied tolerances on the drawing ADF527 Dime75 inning ca 79 innanning Typical Implied Tolerances Dim ension lm plied Tolerance XX 01 XXX 002 XXXX 0005 Fractional l64 in ADF527 ainens inning amp 7972137757779 25 Specify Implied Tolerances Explicitly in Title Block El uLEwAchs 2m nnz Angles t n han the previous slide ADF527 ainens inning amp Ta Mrswing 25 Avoid Tolerance StackUp Tolerance 002 in 7 7 3 G d dimensmnin A 400 l DI Nnmlnzl Mln Max E I A 358 492 5 a BIS n23 n27 c lpa 161 155 Allowable ange thickness D l 63 l m l 65 E I 25 rm m vanatlon 023 027 In nam39 n25 u35 um Large variation possible ADF527 ai ensv39unv39ng a Tn7eranm ng 27 Tolerances Guarantee Proper Fit lfthese parts are the same size It is very unlikely theywill t together T om in al 7 7 7 7 A l Dim e nsion 39 J Varia ion ADF517 ainen inning amp Tu Manning 23 1092008 Two Important Conditions MMC Maximum Material Condition V A LMC Least Material Condition A VA Shaft Z MJMC V i an i 1 Variation ADF527 ainnns inning amp 7n Manning 29 Standard Fits amp Clearances 0 RC 7 Runningsliding clearance ts 0 LC 7 Location clearance fits 0 LT 7 Locationtransition fits LN 7 Location interference press ts 0 FN 7 Force or shrink fits Tighter ADF527 ainnns inning amp 7n Manning 30 Running Sliding Clearance RC Fits RC 1 Close sliding fits 7 accurate location no play RC 2 Sliding fits 7 accurate location turn easily RC 3 Precision running fits 7 run freely at low speeds RC 4 Close running fits 7 run freely moderate speeds RC 5 RC 6 Medium running fits 7 run freely higher speeds Similar specifications exist for other classes of fit LC LT LN FN nur527 ainnns inning n in Mrswing 1 Running Sliding Clearance RC Fits Basic hole system Limits are in thousandths of an inch FmmANsiBA14967011987 Similar specifications exist for other classes of fit LC LT LN FN ADFab Dime75 inning n in Mrswing 2 1092008 Example 0 A l shaft is intended to tum freely in the hole using an RC 6 running t Specify the tolerances on the shaft and hole sizes WT ADF527 ainens inning amp 7972731757779 53 1092008 Look up tolerances under RC 6 1102 equotquotquot 1mu I ym gt1 nunnr unis I 9m gt1nnnnr EIqu ADF527 ainens inning amp 7972731757779 54