Assembly automation and product design

396 Assembly Automation and Product Design Small Parts for Automatic Handling (Choice of the first digit) Parts can easily be fed (but not necessarily oriented) using conventional hopper feeders (see note 1) Rotational parts (see note 2) Triangular or square prismatic parts (see note 3) Rectangular parts (see note 4) Parts are difficult to feed using conventional hopper feeders (see note 1) L/D < 0.8 Discs (see note 5) 0.8 ≤ L/D ≤ 1.5 (see note 5) 0.8 ≤ L/D ≤ 1.5 (see note 5) L/D > 1.5 (see note 5) L/D > 1.5 (see note 5) L/D < 0.8 (see note 5) Short cylinders Long cylinders Cubic parts Cubic parts Flat parts Flat parts Long parts Long parts A/B ≤ 3, A/C > 4 (see note 6) A/B ≤ 3, A/C ≤ 4 (see note 6) A/B > 3 (see note 6) 0 1 2 3 4 5 6 7 8 9 Appendix D 397 Small Parts for Automatic Handling (Choice of the first digit) 1. A first digit of 0-8 is for parts that can be fed easily (but not necessarily oriented) using conventional vibratory or nonvibratory hopper feeders. Parts having characteristics making them difficult to feed, irrespective of basic shape, are assigned a first digit of 9. Difficult-to-feed parts include those that are flexible, delicate, sticky, light, overlap, large, very small, nest, severly nest, tanlge, severly tangle or are abrasive. 2. A part whose basic shape is a cylinder or regular prism whose cross section is a regular polygon of five or more sides is called a rotational part. 3. A part whose basic shape is a regular prism whose cross section is a regular polygon of three or four sides is called a triangular or square part. 4. A part whose basic shape is a regular prism is called a rectangular part. 5. L is the length and D is the diameter of the smallest cylinder that can completely enclose the part. 6. A is the length of the longest side, C is the length of the shortest side, and B is the length of the intermediate side of the smallest rectangular prism that can completely enclose the part. 398 Assembly Automation and Product Design Rotational Parts (Parts with a first digit of 0, 1, or 2) Centroid SECOND DIGIT Part is not ALPHA symmetric [code the main feature or features, causing ALPHA asymmetry] (see note 3) Principal axis Side view End surface Transverse axis Side surface End view Part is ALPHA symmetric (see note 2) Part can be fed in a slot supported by large end or protruding flange with center of mass below supporting surfaces (see note 4) BETA symmetric steps or chamfers on external surfaces (see note 5) On both side and end surfaces On side surface only On end surfaces only BETA symmetric grooves, holes or recesses (see note 6) BETA symmetric hidden features with no corresponding exposed features (see note 7) BETA asymmetric features or BETA symmetric parts with features other than steps, chamfers or tapers but too small for orientation purposes (see note 9) BETA symmetric step, chamfer or taper too small for orientation purposes Other features, slight asymmetry, features too small or non-geometric features [such as paint, lettering, etc.] (see note 8) Part is BETA symmetric (see note 9) BETA asymmetric projections [can be seen in silhouette] BETA asymmetric grooves, holes, recessess on external surfaces To be fed end-to-end (see note 11) To be fed side-by-side (see note 11) Part is not BETA symmetric [code the main feature or features causing BETA asymmetry] (see note 10) On side surface only On end surfaces only On both side and end surfaces rough grooves can be seen in end view rough grooves cab be seen in a side view On end surfaces On side surface Holes or recesses [cannot be seen in outer shape of silhouette in end views] Other features, slight asymmetry, features too small or, non-geometric features [such as paint, lettering, etc.] 0 0 1 1 2 3 4 5 6 7 8 9 2 3 4 5 6 7 8 9 THIRD DIGIT Appendix D 399 Rotational Parts (Parts with a first digit of 0, 1, or 2) 1. A rotational part is one whose basic shape is a cylinder or regular prism having five or more sides. The part is not difficult to feed. 2. The part does not require orientation end to end. 3. A main feature causing ALPHA asymmetry is one defining the end- to-end orientation of the part. 4. These are parts that will orient themselves with their principal axis vertical when placed in a parallel-sided horizontal slot. 5. A BETA-symmetric step or chamfer is a concentric reduction in diameter. The cross section can be circular or any regular polygon of four or more sides. Discrete projections, recesses or irrelevant features should be ignored in choosing this digit. 6. The reductions and increases in diameter forming the groove must be concentric. The cross sections can be circular or any regular polygon of four or more sides. Discrete projections, recesses or irrelevant features should be ignored in choosing this digit. 7. These parts have an ALPHA-symmetric external shape but their center of mass is not at the geometric center of the part. 8. If exposed features are prominent but the symmetry caused by these features is too small to be employed for orienting purposes, then the symmetry is said to be slight asymmetry. 9. A BETA-symmetric part does not require orientation about its principal axis. 10. A main feature causing BETA asymmetry is one that completely defines the orientation of the part about its principal axis. 11. Some parts can only be fed one way. However, when a choice exists, the technique employed and hence the code can be affected by the delivery orientation. 400 Assembly Automation and Product Design Triangular and Square Parts (Parts with a first digit of 3, 4, or 5) 1. A part whose basic shape is a regular prism whose cross section is an equilateral triangle or square is called a triangular or square part. The part is not difficult to feed. 2. Part does not require orientation about its principal axis. 3. A part has rotational symmetry about a specified axis if the part’s orientation is repeated by rotating it through a certain angle (less than 360 deg) about that axis. 4. When the envelope of a part is a perfect cube, the principal axis should be selected according to the following priorities: a. Any axis about which the part is 90 deg rotationally symmetric. b. An axis about which the part has 180 deg rotational symmetry and clearly not 90 deg rotational symmetry. c. An axis about which the part has 180 deg rotational symmetry and almost 90 deg rotational symmetry. d. When a part has no rotational symmetry and there is more than one main feature, the principal axis should be the axis of symmetry of one of the main features. When utilizing the above rules and multiple choices still exist, then the axis that will provide a code with the smallest third digit should be selected as the principle axis. 5. Part does not require orientation end to end (it has 180 deg rotational symmetry about at least one transverse axis). 6. A main feature causing ALPHA asymmetry defines the end-to-end orientation of the part and distinguishes the end and side surfaces. 7. The various aspects of a part resting on a plane are called natural resting aspects. 8. If exposed features are prominent but the symmetry caused by these features is too small to be employed for orienting purposes, then the asymmetry is said to be slight asymmetry. When the part is 180 rotationally symmetric about a certain axis, slight asymmetry implies that the part is almost 90 deg rotationally symmetric about the same axis. 9. Steps, chamfers or through grooves are features which result in a deviation of the silhouette of the part from the silhouette of its envelope. 10. These are parts that will orient themselves with their principal axis vertical when placed in a parallel-sided horizontal slot. Appendix D 401 Triangular and Square Parts (Parts with a first digit of 3, 4, or 5) Part can be fed in slot and supported by large end or protruding flanges with center of mass below supporting surfaces and the part is not triangular (see note 10) Part cannot be fed in slot and supported by large end or protruding flanges with center of mass below supporting surfaces or part is triangular Centroid Principal axis Side view Side surfaces End view End surfaces Transverse axis Part is ALPHA symmetric (see note 5) Part has 90Њ or 120Њ rotational symmetry about the principal axis (see notes 2, 3 and 4) Part has only one natural resting aspect or end and side surfaces can be readily distinguished by their shapes or dimensions (see note 7) End and side surfaces can be distinguished because of steps, chamfers, holes or recesses End and side surfaces can only be distinguished because of other features, features too small or slight asymmetry (see notes 8 and 12) Steps or chamfers (see note 9) rough grooves (see note 9) Can be seen in end view (see note 11) Can be seen in side view (see note 11) Holes or recesses (cannot be seen in outer shape of silhouette) Other geometric features Slight asymmetry, features too small or non-geometric features [such as paint, lettering, etc.] (see notes 8 and 12) Part is not ALPHA symmetric [code the main feature or features causing ALPHA asymmetry] (s ee note 6) 0 0 1 2 3 4 5 6 7 8 9 THIRD DIGIT 402 Assembly Automation and Product Design Triangular and Square Parts (Parts with a first digit of 3, 4, or 5) (continued) SECOND DIGIT Part has 180Њ rotational symmetry about the principal axis [code the main feature or features causing 180Њ rather than 90Њ rotational symmetry about the principal axis] (see notes 4 and 13) Part does not have 180Њ rotational symmetry about the principal axis [code the main feature or features causing rotational asymmetry] (see notes 4 and 14) Steps or chamfers can be seen in side or end views (see note 9) rough grooves can be seen in side or end views (see note 9) Holes or recesses [cannot be seen in outer shape of silhouette] Other features, features too small or slight asymmetry (see notes 8 and 12) Steps or chamfers can be seen in side or end views (see note 9) External to the envelope Non-external rough grooves can be seen in side or end views (see note 9) Holes or recesses [cannot be seen in outer shape of silhouette] Other features, features too small or slight asymmetry (see notes 8 and 12) Part is ALPHA symmetric (see note 5) Code the same feature or features coded in the second digit Steps, chamfers or grooves can be seen in side view or other features on side surfaces (see note 9) Steps, chamfers or grooves can be seen in end view or other features on end surfaces (see note 9) End and side surfaces can only be distinguished because of features too small or slight asymmetry (see notes 8 and 12) Part is not ALPHA symmetric [code the main feature or features causing ALPHA asymmetry] (see note 6) Steps or chamfers provided by external features (see note 9) Steps or chamfers provided by non-external features (see note 9) Holes or recesses [cannot be seen in outer shape of silhouette] Features on side surfaces (see note 15) Features on side surfaces (see note 15) Features on end surfaces (see note 15) Features on end surfaces (see note 15) On side surfaces (see note 15) On end surfaces (see note 15) Other features, slight asymmetry or features too small (see notes 8 and 12) 0 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 Centroid Principal axis Side view End surface Transverse axis Side surface End view Appendix D 403 Rectangular Parts (Parts with a first digit of 6, 7, or 8) 1. A part whose basic shape is a rectangular prism is called a rectangular part. The part is not difficult to feed. 2. 180 deg rotational symmetry about an axis means that the same orientation of the part will be repeated only once by rotating the part through 180 deg about that axis. 3. Part can be oriented without utilizing features other than the dimensions of the envelope. 4. Steps, chamfers or through grooves are features which result in a deviation of the silhouette of a part from the silhouette of its envelope. 5. If exposed features are prominent but the symmetry caused by these features is too small to be employed for orientation purposes, then the symmetry is said to be slight asymmetry. For a part with 180 deg rotational symmetry about a certain axis, slight asymmetry implies that the part is almost 90 deg rotationally symmetric about the same axis. 6. A feature is too small, if it is too small to be employed for orientation purposes. 7. A part having no rotational symmetry means that the same orientation of the part will not be repeated by rotating the part through any angle less than 360 deg about any one of the three axis X, Y, and Z. The X- axis is parallel to the longest side of the envelope, the Y-axis is parallel to the intermediate side and the Z-axis is parallel to the shortest side. 8. A main feature is a feature that is chosen to define the orientation of the part. All the features that are chosen to completely define the orientation of the part should be necessary and sufficient for the pur- pose. Often, features arise in pairs or groups and the pair or group of features is symmetric about one of the three axis X, Y, and Z. In this case, the pair or group of features should be regarded as one feature. Using this convention, two main features at most are needed to completely define thed orientation of a part. 9. Sometimes, when a part has no rotational symmetry, its orientation can either be defined by one or by two main features. Under these circum- stances the part code is determined by the following in decreasing order of preference: a. Choose one main feature, if it results in a third digit less than 5. b. Choose two main features if they result in a third digit less than 5. c. Choose one main feature, if it results in a third digit greater than 5. d. Choose two main features if they result in a third digit greater than 5. 10. The symmetric plane is the plane that divides the part into halves that are mirror images of each other. 404 Assembly Automation and Product Design Rectangular Parts (Parts with a first digit of 6, 7, or 8) THIRD DIGIT Part has 180Њ rotational symmetry about all three axes (see note 2) ree adjacent surfaces of the envelope have significant differences in dimensions (see note 3) Two or more adjacent surfaces of the envelope have similar dimensions [code the main feature or features which distinguish the adjacent surfaces having similar dimensions] Steps or chamfers (see note 4) rough grooves (see note 4) Parallel to X axis Parallel to Y axis Parallel to Z axis Parallel to Z axis Parallel to X axis Parallel to Y axis Holes or recesses (cannot be seen in outer shape of silhouette) Slight asymmetry or features too small (see notes 5 and 6) Other geometric features or non-geometric features (such as paint, lettering, etc.) 0 0 1 2 3 4 5 6 7 8 9 Rectangular envelope Y axis X axis A Z axis B C Appendix D 405 SECOND DIGIT Part has 180Њ rotational symmetry about one axis only (see note 2) Part has no rotational symmetry [code the main feature or features that can completely define the orientation] (see notes 7 and 8) About X axis About Y axis Steps or chamfers (see note 4) rough grooves (see note 4) About Z axis Part has no slight asymmetry and its orientation can be defined by one main feature only or by two main features at least one of which is a step, chamfer or through groove or group of such features (see note 5) Part’s orientation is defined by one main feature only (see note 90 Part’s orientation is defined by two main features and at least one of them is a step, chamfer or through groove or a group of such features (see note 9) Part has a symmetric plane (see note 10) Part has no symmetric plane (see note 10) One feature is symmetric about X axis and the other one is symmetric about Y axis One feature is symmetric about Y axis and the other one is symmetric about Z axis One feature is symmetric about Z axis and the other one is symmetric about X axis Part has slight asymmetry about at least one of its axes or the orientation of the part can only be defined by two main features neither of which are steps, chamfers or through grooves (see notes 5 and 8) 9 8 7 6 5 4 3 2 1 0 1 2 3 4 5 6 7 8 9 Code the main feature [code the feature that gives largest third digit, if more than one feature is utilized to define the orientation of the part] (see note 8) Parallel to X axis Parallel to Y axis Parallel to X axis Parallel to Y axis Parallel to Z axis Parallel to Z axis Holes or recesses [cannot be seen in outer shape of silhouette] Other geometric features Features too small (see note 6) Non- geometric features [such as paint, lettering, etc.] Rectangular envelope Y axis X axis A Z axis B C [...]... severely tangle or nest Parts are small and non-abrasive SECOND DIGIT 0 Sticky 0 Nonflexible Parts will severely nest but not severely tangle Parts will tangle or nest but not severely Parts will not tangle or nest Parts will severely tangle THIRD DIGIT 9 408 Assembly Automation and Product Design D.2 Feeding and Orienting Techniques Data sheets showing feeding and orienting techniques catalogued under... velocity E = Efficiency where: Feed rate = d Part orientations b d Sloped track and groove* (device code 22) a 0 0.2 0.4 0.6 0.8 1.0 Plan view Side view 0 0.2 D e 0.6 PART CODE L/D 0.4 Wiper blade* (device code 10) b and c reorient to a e VIBRATORY BOWL FEEDER Efficiency, E L 2 0.8 L 0 7 3 420 Assembly Automation and Product Design c v ϫE L a *For devices see section D3 b r Plan view Side view a D 0 0... PART CODE X MAGNETIC DISC HOPPER FEEDER X Magnet diameter ~ D Parts delivered per magnet, Np 412 Assembly Automation and Product Design 0 0.2 0.4 0.6 0.8 1.0 0 L/D Feed rate = Np ϫ n Np = Parts delivered per cycle n = Rotational frequency where: 0.7Di 51D View on arrow X 1.25D D L 0 1 Head of the pin is designed to accept only one part Shroud Pin Orienting track 0.14 D deep Orienting track Feed chute... VIBRATORY BOWL FEEDER Efficiency, E 414 Assembly Automation and Product Design v ϫE D a d *For devices see section D3 b Plan view Side view 0.6 L D L/D 0.7 c, d 0.8 0.35D 0 0 6 Wiper blade* (device code 10) Portion of b 0 0.5 0.2 0.4 0.6 0.8 1.0 Proportion of b reorients to a v = Conveying velocity E = Efficiency where: Feed rate = c Part orientations b Sloped track and rail* (device code 24) a Efficiency,... rate = a 0 0.2 0.4 0.6 0.8 1.0 Wall projection and narrowed track* (device code 11) a Plan view Side view c, d D D1 0 2 D1/D 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.6 0.8 0.2 0.4 L/D = H/L = 0.9 See second sheet for other H/L values b PART CODE H Wiper blade* (device code 10) VIBRATORY BOWL FEEDER Efficiency, E L 1 416 Assembly Automation and Product Design Efficiency, E Efficiency, E c d L/D 0.4 0.6 0.8... and ledge* (device code 25) VIBRATORY BOWL FEEDER L 5 d v ϫE L a *For devices see section D3 v = Conveying velocity E = Efficiency where: c e Part orientations b Wall projection and narrowed track* (device code 11) Feed rate = a b 0 0.2 0.2 0.4 0.6 0.8 1.0 f VIBRATORY BOWL FEEDER Efficiency, E a D 0.3 0.4 0.5 0.6 0.7 0.8 L/D c, d, e, f Plan view Side view PART 0 3 CODE L 1 418 Assembly Automation and Product. ..406 Assembly Automation and Product Design Difficult-to-Feed Parts (parts with a first digit of 9) Flexible A part is considered flexible if the part cannot maintain its shape under the action of automatic feeding so that orienting devices cannot function satisfactorily Delicate A part is considered delicate if damage may occur during handling, either due to breakage caused... Side view a D PART CODE L/D L 1 4 1 0 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 0.2 0.4 0.6 0.8 1.0 f VIBRATORY BOWL FEEDER Efficiency, E 422 Assembly Automation and Product Design b *For devices see section D3 v = Conveying velocity E = Efficiency v Feed rate = ϫ E L where: a Grooved track and hood* (device code 12) Part orientations a c Efficiency, E 0 1.5 0.2 0.4 0.6 0.8 1.0 b, c 2.0 b a D 2.5 3.0 L/D r Plan view Side... CODE D Level of parts d ~ 20; I = 3.5 D D Orientation problems X Stationary hopper ROTARY DISC HOPPER FEEDER Stationary plate Ns slots Parts delivered per slot, Np Hopper Efficiency, E 410 Assembly Automation and Product Design r 1 0.30 3 5 7 Nb blades Parts delivered per blade, Np X 0.35 0.45 L/D 0.40 Delivery chute X 0.50 I 1.5D 1.1D 45Њ Blade D 0.55 Parts delivered per blade Nb = Number of blades n =... jam Delivery chute 1.1D 1.1D Hopper I D PART CODE Level of parts Hopper I = 20 r = D D Rotational frequency, n BLADED WHEEL HOPPER FEEDER Nb blades r Parts delivered per blade, Np 424 Assembly Automation and Product Design Parts cannot be oriented 7 6 5 4 3 2 1 0 1 2 L/D Reciprocating tube Stationary hopper (truncated cone) 3 Reciprocation frequency, n Parts delivered per cycle, Np 4 45Њ L 0 0 n = . choice exists, the technique employed and hence the code can be affected by the delivery orientation. 400 Assembly Automation and Product Design Triangular and Square Parts (Parts with a first digit. tend to overlap during feeding SECOND DIGIT 408 Assembly Automation and Product Design D.2 Feeding and Orienting Techniques Data sheets showing feeding and orienting techniques catalogued under part codes. REVOLVING. (see notes 8 and 12) Part is not ALPHA symmetric [code the main feature or features causing ALPHA asymmetry] (s ee note 6) 0 0 1 2 3 4 5 6 7 8 9 THIRD DIGIT 402 Assembly Automation and Product Design Triangular

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