IE550 - Manufacturing Systems PART DESIGN SPECIFICATION Spring 2011 Dr. R. A. Wysk 3/21/2016 1 IE550 - Manufacturing Systems Agenda • Go over engineering specifications • Functional requirements • Form, fit and function – – – – 3/21/2016 Dimensioning Tolerancing Engineering drawings datum 2 IE550 - Manufacturing Systems Materials • Read Chapter 2 and 3 from Computer Aided manufacturing (3rd Edition) • Overview of engineering design • Mechanical design representations • Engineering drawing • Geometric dimensioning and tolerancing • AMSE Y14.5 3/21/2016 3 IE550 - Manufacturing Systems THE DESIGN PROCESS Product Engineering Design Process Design Process Off-road bicycle that ... How can this be accomplished? 1. Conceptualization 2. Synthesis 3. Analysis 4. Evaluation 5. Representation 1. Clarification of the task 2. Conceptual design 3. Embodiment design 4. Detailed design Functional requirement -> Design 3/21/2016 Steps 1 & 2 Select material and properties, begin geometric modeling (needs creativity, sketch is sufficient) 3 mathematical, engineering analysis 4 simulation, cost, physical model 5 formal drawing or modeling 4 IE550 - Manufacturing Systems DESIGN REPRESENTATION Design Engineering Representation Manufacturing • Verbal • Sketch • Multi-view orthographic drawing (drafting) • CAD drafting • CAD 3D & surface model • Solid model • Feature based design Requirement of the representation method • precisely convey the design concept • easy to use 3/21/2016 5 IE550 - Manufacturing Systems A FREE-HAND SKETCH Orthographic Projection 3/21/2016 6 IE550 - Manufacturing Systems A FORMAL 3-VIEW DRAWING 0.9444" 4 holes 1/4" dia around 2" dia , first hole at 45° 2.000 0.001 A 3/21/2016 7 IE550 - Manufacturing Systems DESIGN DRAFTING Y top Pr o f ile b d c f p lan e e g a H o r iz o n t a l h i side j I I I X I I I Z I V Fr o n t a l p lan e front Drafting in the third angle 3/21/2016 Third angle projection 8 IE550 - Manufacturing Systems INTERPRETING A DRAWING 3/21/2016 9 IE550 - Manufacturing Systems DESIGN DRAFTING A Partial view A 2.0000.001 A-A A Cut off view and auxiliary view Provide more local details 3/21/2016 10 IE550 - Manufacturing Systems DIMENSIONING Requirements 1. Unambiguous Incomplete dimensioning 2. Completeness 3. No redundancy 0.83 ' 0.98 ' 1.22 ' 3.03 ' 1.72 ' Redundant dimensioning 0.86 ' 1.22 ' 0.83 ' 3.03 ' Adequate dimensioning 3/21/2016 11 IE550 - Manufacturing Systems TOLERANCE Dimensional tolerance - conventional Geometric tolerance - modern nominal dimension 1.00 + - 0.05 means a range 0.95 - 1.05 tolerance unilateral bilateral 3/21/2016 0.95 + 0.10 - 0.00 1.05 + 0.00 - 0.10 1.00+ - 0.05 12 IE550 - Manufacturing Systems TOLERANCE STACKING 1. Check that the tolerance & dimension specifications are reasonable - for assembly. 2. Check there is no over or under specification. "TOLERANCE IS ALWAYS ADDITIVE" why? 0.80 ' ±0.01 1.20 ' ±0.01 1.00 ' ±0.01 ? What is the expected dimension and tolerances? d = 0.80 +1.00 + 1.20 = 3.00 t = ± (0.01 + 0.01 + 0.01) = ± 0.03 3/21/2016 13 IE550 - Manufacturing Systems TOLERANCE STACKING (ii) 0.80 ' ±0.01 ? 1.20 ' ±0.01 3.00 ' ±0.01 What is the expected dimension and tolerances? d = 3.00 - 0.80 - 1.20 = 1.00 t = ± (0.01 + 0.01 + 0.01) = ± 0.03 3/21/2016 14 IE550 - Manufacturing Systems TOLERANCE STACKING (iii) x 0.80 ' ±0.01 ? 1.20 ' ±0.01 3.00 ' ±0.01 Maximum x length = 3.01 - 0.79 - 1.19 = 1.03 Minimum x length = 2.99 - 0.81 - 1.21 = 0.97 Therefore x = 1.00 ± 0.03 3/21/2016 15 IE550 - Manufacturing Systems TOLERANCE GRAPH A d,t B d,t d,t C D E d,t G(N,d,t) N: a set of reference lines, sequenced nodes d: a set of dimensions, arcs t: a set of tolerances, arcs d t ij ij : dimension between references i & j : tolerance between references i & j Reference i is in front of reference j in the sequence. 3/21/2016 16 IE550 - Manufacturing Systems EXAMPLE TOLERANCE GRAPH A A d,t B B C d,t D C d,t E D E d,t d DE = d DA + d AE = – d AD + d AE = – (d AB + d BC + d CD) + d AE different properties between d & t t DE = t AB + t BC + tCD + t AE 3/21/2016 17 IE550 - Manufacturing Systems OVER SPECIFICATION If one or more cycles can be detected in the graph, we say that the dimension and tolerance are over specified. A d1,t1 d2,t2 B B d2 C d3 Redundant dimension d3,t3 A d1 C A t1 B t2 C t3 Over constraining tolerance (impossible to satisfy) why? 3/21/2016 18 IE550 - Manufacturing Systems UNDER SPECIFICATION When one or more nodes are disconnected from the graph, the dimension or tolerance is under specified. A d1 B C d2 D E d3 A B C D E C D is disconnected from the rest of the graph. No way to find dBC and dDE 3/21/2016 19 IE550 - Manufacturing Systems PROPERLY TOLERANCED A A d,t B B C d,t D C d,t E D E d,t d DE = d DA + d AE = – d AD + d AE = – (d AB + d BC + d CD) + d AE t DE = t AB + t BC + tCD + t AE 3/21/2016 20 IE550 - Manufacturing Systems TOLERANCE ANALYSIS For two or three dimensional tolerance analysis: i. Only dimensional tolerance Do one dimension at a time. Decompose into X,Y,Z, three one dimensional problems. ii. with geometric tolerance ? Don't have a good solution yet. Use simulation? diamet er & t olerance t rue posit ion 3/21/2016 A circular tolerance zone, the size is influenced by the diameter of the hole. The shape of the hole is also defined by a geometric tolerance. 21 IE550 - Manufacturing Systems 3-D GEOMETRIC TOLERANCE PROBLEMS datum surface datum surface ±t Reference frame perpendicularity 3/21/2016 22 IE550 - Manufacturing Systems TOLERANCE ASSIGNMENT Tolerance is money • Specify as large a tolerance as possible as long as functional and assembly requirements can be satisfied. (ref. Tuguchi, ElSayed, Hsiang, Quality Engineering in Production Systems, McGraw Hill, 1989.) function Qu al it y Co st cost +t -t Tolerance value 3/21/2016 d ( nom inal dim ensio n) Quality cost 23 IE550 - Manufacturing Systems REASON OF HAVING TOLERANCE • No manufacturing process is perfect. • Nominal dimension (the "d" value) can not be achieved exactly. • Without tolerance we lose the control and as a consequence cause functional or assembly failure. 3/21/2016 24 IE550 - Manufacturing Systems EFFECTS OF TOLERANCE (I) 1. Functional constraints e.g. flow rate d±t Diameter of the tube affects the flow. What is the allowed flow rate variation (tolerance)? 3/21/2016 25 IE550 - Manufacturing Systems EFFECTS OF TOLERANCE (II) 2. Assembly constraints e.g. peg-in-a-hole dp dh How to maintain the clearance? Compound fitting The dimension of each segment affects others. 3/21/2016 26 IE550 - Manufacturing Systems RELATION BETWEEN PRODUCT & PROCESS TOLERANCES • A ± 0 .0 1 t olerances Design specifications • • Set up lo cat o r s ± 0 .0 0 5 • ± 0 .0 0 5 ± 0 .0 0 5 Machine uses the locators as the reference. The distances from the machine coordinate system to the locators are known. The machining tolerance is measured from the locators. In order to achieve the 0.01 tolerances, the process tolerance must be 0.005 or better. When multiple setups are used, the setup error need to be taken into consideration. Process tolerance 3/21/2016 27 IE550 - Manufacturing Systems TOLERANCE CHARTING A method to allocate process tolerance and verify that the process sequence and machine selection can satisfy the design tolerance. st ock boundary ± 0 .0 1 ± 0 .0 1 ± 0 .0 1 blue print Dim t ol 1 .0 1 .0 3 .0 0 .0 1 0 .0 1 0 .0 1 Not shown are process tolerance assignment and balance Op code Operation sequence 10 lat he 10 lat he 20 lat he 20 lat he 10 12 process tol of 10 + process tol of 12 20 3/21/2016 produced tolerances: 22 process tol of 20 + process tol 22 process tol of 22 + setup tol 28 IE550 - Manufacturing Systems SURFACE FINISH waviness roughness roughness widt h waviness widt h Usually simplified: roughness height 63 (m inch) waviness height waviness width 0.002 - 2 0.010 0.005 Lay 3/21/2016 63 roughness width cutoff default is 0.03" (ANSI Y14.36-1978) roughness width (inch) 29 IE550 - Manufacturing Systems PROBLEMS WITH DIMENSIONAL TOLERANCE ALONE As designed: 1 .00±0.0 01 6.00±0.001 As manufactured: 1 .0 0 1 Will you accept the part at right? 1 .0 0 1 1 .0 0 1 Problem is the control of straightness. How to eliminate the ambiguity? 3/21/2016 6 .0 0 30 IE550 - Manufacturing Systems GEOMETRIC TOLERANCES ANSI Y14.5M-1977 GD&T (ISO 1101, geometric tolerancing; ISO 5458 positional tolerancing; ISO 5459 datums; and others), ASME Y14.5 - 1994 FORM ORIENTATION straightness perpendicularity Squareness flatness angularity Circularity parallelism roundness cylindricity LOCATION RUNOUT circular runout total runout concentricity true position symmetry PROFILE profile profile of a line 3/21/2016 31 IE550 - Manufacturing Systems DATUM & FEATURE CONTROL FRAME Datum: a reference plane, point, line, axis where usually a plane where you can base your measurement. A Symbol: Even a hole pattern can be used as datum. Feature: specific component portions of a part and may include one or more surfaces such as holes, faces, screw threads, profiles, or slots. Feature Control Frame: // symbol 3/21/2016 datum 0.005 M A modifier tolerance value 32 IE550 - Manufacturing Systems MODIFIERS M Maximum material condition MMC assembly Regardless of feature size RFS (implied unless specified) LMC less frequently used L Least material condition P Projected tolerance zone maintain critical wall thickness or critical location of features. O Diametrical tolerance zone T Tangent plane F Free state MMC, RFS, LMC MMC, RFS RFS 3/21/2016 33 IE550 - Manufacturing Systems SOME TERMS MMC : Maximum Material Condition Smallest hole or largest peg (more material left on the part) LMC : Least Material Condition Largest hole or smallest peg (less material left on the part) Virtual condition: Collective effect of all tolerances specified on a feature. Datum target points: Specify on the drawing exactly where the datum contact points should be located. Three for primary datum, two for secondary datum and one or tertiary datum. 3/21/2016 34 IE550 - Manufacturing Systems DATUM REFERENCE FRAME Pr i m a r y Three perfect planes used to locate the imperfect part. T e rt ia r y a. Three point contact on the primary plane Sec on dar y C b. two point contact on the secondary plane c. one point contact on the tertiary plane primary O 0.001 M A Secondary B C Tertiary B A 3/21/2016 35 IE550 - Manufacturing Systems STRAIGHTNESS Tolerance zone between two straightness lines. 0.0 01 1.000 ' Value must be smaller than the size tolerance. ±0.002 Measured error Š 0 .0 0 1 0.0 01 0.0 01 1.000 ' Design 3/21/2016 ±0.002 Meaning 36 IE550 - Manufacturing Systems 3/21/2016 37 IE550 - Manufacturing Systems FLATNESS Tolerance zone defined by two parallel planes. 0.0 01 1.000 ' ±0.002 p ar al l e l p lanes 0.0 01 3/21/2016 38 IE550 - Manufacturing Systems CIRCULARITY (ROUNDNESS) a. Circle as a result of the intersection by any plane perpendicular to a common axis. b. On a sphere, any plane passes through a common center. Tolerance zone bounded by two concentric circles. 0.01 1.00 ' ±0.05 0 .0 1 Tolerance zone At any section along the cylinder 3/21/2016 39 IE550 - Manufacturing Systems CYLINDRICITY Tolerance zone bounded by two concentric cylinders within which the cylinder must lie. 0.01 1.00 ' ±0.05 Rotate in a V 0.01 Rotate between points 3/21/2016 40 IE550 - Manufacturing Systems PERPENDICULARITY A surface, median plane, or axis at a right angle to the datum plane or axis. A .0 0 2 T .0 0 2 A 1.000 ' 0.500 ' ±0.005 0.0 0 2 t olerance zone perpendicular t o t he dat um plane ±0.005 A 2.000 ' ±0.005 A O 1 .0 0 ± 0 .01 .0 02 3/21/2016 A 0 .0 0 2 diamet er t ol zone is perpendicular t o t he dat um plane 41 IE550 - Manufacturing Systems ANGULARITY A surface or axis at a specified angle (orther than 90°) from a datum plane or axis. Can have more than one datum. 0 .0 0 5 A 1.5 0 0 ± 0 .0 05 40° 3.500 ' 3/21/2016 ±0.005 A 42 IE550 - Manufacturing Systems PARALLELISM The condition of a surface equidistant at all points from a datum plane, or an axis equidistant along its length to a datum axis. .0 0 1 A 1.000 " ±0.005 A 2.000 " 3/21/2016 ±0.005 0.0 01 43 IE550 - Manufacturing Systems PROFILE A uniform boundary along the true profile within whcih the elements of the surface must lie. 0 .0 05 A B B A 3/21/2016 0.0 01 44 IE550 - Manufacturing Systems RUNOUT A composite tolerance used to control the functional relationship of one or more features of a part to a datum axis. Circular runout controls the circular elements of a surface. As the part rotates 360° about the datum axis, the error must be within the tolerance limit. A 1.500 " ±0.005 0 .0 0 5 A 0.361 " ±0.002 Dat um ax is 3/21/2016 Deviat ion on each circular check ring is less t han t he t olerance. 45 IE550 - Manufacturing Systems TOTAL RUNOUT A 1.500 " ±0.005 0 .0 0 5 A 0.361 " ±0.002 Dat um axis 3/21/2016 Deviat ion on t he t ot al swept when t he part is rot at ing is less t han t he t olerance. 46 IE550 - Manufacturing Systems TRUE POSITION Tolerance zone 0.0 2 2 Dimensional tolerance 1 .00 ± 0 .0 1 1.2 0 ± 0 .0 1 O .8 0 ± 0 .02 Hole center tolerance zone O 0 .0 1 M A B True position tolerance Tolerance zone 0 .0 1 dia 1 .0 0 B A 3/21/2016 1.2 0 47 IE550 - Manufacturing Systems HOLE TOLERANCE ZONE Tolerance zone for dimensional toleranced hole is not a circle. This causes some assembly problems. For a hole using true position tolerance the tolerance zone is a circular zone. 3/21/2016 48 IE550 - Manufacturing Systems TOLERANCE VALUE MODIFICATION O 1.0 0 ± 0 .0 2 O 0 .0 1 M A B Produced 1 .00 hole size B 1 .2 0 A The default modifier for true position is MMC. 0.97 MMC LMC 3/21/2016 S out of diametric tolerance 0.98 0.01 0.05 0.01 0.99 0.02 0.04 0.01 1.00 0.03 0.03 0.01 1.01 0.04 0.02 0.01 1.02 0.05 0.01 0.01 1.03 For M True Pos tol M L out of diametric tolerance the allowable tolerance = specified tolerance + (produced hole size - MMC hole size) 49 IE550 - Manufacturing Systems MMC HOLE LMC hole MMC hole hole axis t olerance zone MMC peg will f it in t he hole , axis must be in t he t olerance zone Given the same peg (MMC peg), when the produced hole size is greater than the MMC hole, the hole axis true position tolerance zone can be enlarged by the amount of difference between the produced hole size and the MMC hole size. 3/21/2016 50 IE550 - Manufacturing Systems PROJECTED TOLERANCE ZONE Applied for threaded holes or press fit holes to ensure interchangeability between parts. The height of the projected tolerance zone is the thickness of the mating part. .3 7 5 - 1 6 UNC - 2 B O .0 1 0 M A B C .2 5 0 p 0.01 0.25 Project ed zone t olerance Produced part 3/21/2016 51 IE550 - Manufacturing Systems SOME NUMBERS Krulikowski, A., GD&T Challenges the Fast Draw, MFG ENG, Feb 1994. GD&T drawings are more expansive to make, however, saves revision cost. Drawing revision costs $500 - $2000 on the paper work How much does it cost to “put a part number” onto a part? Estimates range from $1,000 -$10,000. 3/21/2016 52