Rotational Molding Technology
Rotational Molding Technology
Roy J. Crawford
The Queen’s University of Belfast
Belfast, Northern Ireland
James L. Throne
Sherwood Technologies, Inc.
Hinckley, Ohio
Contents
Preface . v
About the Authors . ix
1. Introduction to Rotational Molding 1
1.0 Introduction . 1
1.1 The Process 2
1.2 The Early Days . 4
1.3 Materials . 6
1.4 Advantages and Disadvantages 9
1.5 General Relationships between Processing Conditions
and Properties 11
References . 14
2. Rotational Molding Polymers . 19
2.0 Introduction . 19
2.1 General Characteristics of Polymers 19
2.2 Polymers as Powders and Liquids . 21
2.3 Polyethylene Types 22
2.3.1 Low-Density Polyethylene . 22
2.3.2 Medium-Density Polyethylene . 23
2.3.3 High-Density Polyethylene 24
2.3.4 Linear Low-Density Polyethylene 25
2.3.5 Ethylene Vinyl Acetate 27xii Contents
2.4 Polypropylene . 28
2.5 PVC – Plastisols, Drysols, and Powdered Flexible
Compounds 30
2.6 Nylons . 31
2.7 Other Polymers . 33
2.7.1 Polycarbonate . 33
2.7.2 Cellulosics . 34
2.7.3 Acrylics . 35
2.7.4 Styrenics . 35
2.8 Liquid Polymers 36
2.8.1 PVC Plastisols 38
2.8.2 Polycaprolactam . 39
2.8.3 Polyurethane . 41
2.8.4 Unsaturated Polyester Resin . 42
2.8.5 Silicones . 43
2.9 In-Coming Material Evaluation . 43
2.9.1 Melt Index and Melt Flow Index . 44
2.9.2 Sieving 46
2.10 Product Testing Protocols and Relationship to Polymer
Characteristics 47
2.10.1 Actual Part Testing – Protocol . 47
2.10.2 Actual Part Testing – Entire Parts . 49
2.10.3 Actual Part Testing – Sections 50
2.10.3.1 Molded Part Density . 51
2.10.3.2 Drop Tests 51
2.10.3.3 ASTM Tests for Mechanical
Properties . 54
2.10.3.4 Color . 55
2.10.3.5 Chemical Tests 56
2.10.3.6 Environmental Stress Crack Test . 57Contents xiii
2.10.3.7 Chemical Crosslinking and the
Refluxing Hexane Test . 58
2.10.3.8 Weathering . 61
2.10.3.9 Odor in Plastics 62
2.10.3.10 Fire Retardancy 62
2.11 Desirable Characteristics of a Rotational Molding
Resin . 64
References . 65
3. Grinding and Coloring 69
3.0 Introduction . 69
3.1 General Issues Relating to Grinding 73
3.2 Particle Size Distribution . 75
3.2.1 Particle Size Analysis 77
3.2.1.1 Dry Sieves 77
3.2.1.2 Elutriation . 78
3.2.1.3 Streaming . 78
3.2.1.4 Sedimentation 78
3.2.1.5 Fluidization . 79
3.2.2 Presentation of PSD Data . 79
3.3 Particle Shape 81
3.4 Dry Flow 83
3.5 Bulk Density 84
3.5.1 Packing of Particles . 85
3.6 Factors Affecting Powder Quality . 88
3.6.1 Gap Size . 89
3.6.2 Number of Mill Teeth . 90
3.6.3 Grinding Temperature . 90
3.7 Grinding Costs 91
3.8 Micropelletizing . 93xiv Contents
3.9 Polyvinyl Chloride . 96
3.10 Coloring of Plastics for Rotational Molding 96
3.10.1 Dry Blending . 97
3.10.2 High Speed Mixing (Turbo Blending) . 99
3.10.3 Compounding 101
3.10.4 Types of Pigments 101
3.10.5 Aesthetics of Rotationally Molded Parts 104
3.10.6 Other Types of Additives . 105
References . 108
4. Rotational Molding Machines 111
4.0 Introduction . 111
4.1 Types of Rotational Molding Machines 112
4.1.1 Rock-and-Roll Machines . 113
4.1.2 Clamshell Machines 115
4.1.3 Vertical Machines 116
4.1.4 Shuttle Machines 116
4.1.5 Fixed-Arm Carousel Machine 117
4.1.6 Independent-Arm Machine 118
4.1.7 Oil Jacketed Machines 119
4.1.8 Electrically Heated Machines 120
4.1.9 Other Types of Machines 121
4.2 Machine Design Considerations 122
4.2.1 Mold Swing . 122
4.2.2 Mold Speed . 125
4.2.3 Speed Ratio 126
4.3 The Oven 127
4.3.1 Oven Design . 129
4.3.2 Heat Transfer in Oven . 131
4.3.3 Oven Air Flow Amplification 135Contents xv
4.4 Cooling 137
4.5 Process Monitors 138
4.5.1 Internal Air Temperature Measurement in
Rotational Molding 140
4.5.2 Infrared Temperature Sensors 144
4.6 Servicing . 144
4.7 Advanced Machine Design . 145
References . 147
5. Mold Design . 149
5.0 Introduction . 149
5.1 Mold Materials 151
5.1.1 Sheet Steel . 151
5.1.2 Aluminum 152
5.1.3 Electroformed Nickel . 154
5.2 Mechanical and Thermal Characteristics of Mold
Materials . 156
5.2.1 Equivalent Mechanical Thickness . 156
5.2.2 Equivalent Static Thermal Thickness 157
5.2.3 Equivalent Transient Thermal Thickness . 159
5.3 Mold Design 160
5.3.1 Parting Line Design . 161
5.3.1.1 Butt or Flat 161
5.3.1.2 Lap Joint . 162
5.3.1.3 Tongue-and-Groove . 162
5.3.1.4 Gaskets 163
5.3.2 Mold Frame . 165
5.3.3 Clamping . 166
5.3.4 Pry Points . 167xvi Contents
5.3.5 Inserts and Other Mechanical Fastening
Methods 168
5.3.5.1 Self-tapping Screws . 168
5.3.5.2 Mechanical Fastening 169
5.3.5.3 Postmolded Insert 169
5.3.5.4 Molded-in Insert . 169
5.3.6 Threads . 171
5.3.7 Cut-out Areas 172
5.3.8 Kiss-offs 172
5.3.9 Molded-in Handles 173
5.3.10 Temporary Inserts . 173
5.4 Calculation of Charge Weight . 174
5.4.1 Methodology . 174
5.4.2 Maximum Part Wall Thickness for a Given
Mold 180
5.5 Venting 183
5.5.1 Simple Estimate for Vent Size . 186
5.5.2 Types of Vent 193
5.5.3 Is a Vent Necessary? 195
5.6 Mold Surface Finish 196
5.7 Mold Releases 196
5.7.1 Spray-on Zinc Stearates . 197
5.7.2 Silicones . 197
5.7.3 Disiloxanes . 197
5.7.4 Fluoropolymers . 197
5.7.5 Mold Surfaces to be Coated 198
5.7.6 Controlled Release 199
5.7.7 Mold Release Cost 199
References . 200Contents xvii
6. Processing . 201
6.0 Introduction to Heating . 201
6.1 General Anatomy of the Rotational Molding Cycle 201
6.2 General Process Description 204
6.3 Powder Behavior 205
6.4 Characteristics of Powder Flow 207
6.5 Rheology of Powder Flow 210
6.6 Heat Transfer Concepts Applied to Rotational Molding . 213
6.7 Heating the Mold . 213
6.8 Heating Powder 215
6.8.1 Transient Heating of an Individual Particle 215
6.8.2 Heating the Powder Bed . 217
6.9 Tack Temperature 219
6.10 Mold Cavity Air Heating Prior to Powder Adhesion to
Mold Surface . 221
6.11 Bed Depletion . 222
6.12 Particle Coalescence 223
6.13 Densification . 234
6.14 Phase Change During Heating 243
6.15 The Role of Pressure and Vacuum 244
6.16 Mathematical Modeling of the Heating Process 245
6.17 Total Oven Cycle Time . 251
6.18 Cooling and the Optimum Time for Removal from
Oven . 259
6.19 Some Comments on Heat Transfer During Cooling 259
6.20 Thermal Profile Inversion 262
6.21 Cooling and Recrystallization 266
6.22 Air Cooling – Heat Removal Rate 274
6.23 Water Cooling – Heat Removal Rate . 275xviii Contents
6.24 Pressurization . 276
6.25 Part Removal 276
6.26 Effect of Wall Thickness on Cooling Cycle Time . 277
6.27 Overview and Summary of Thermal Aspects of the
Rotational Molding Process 278
6.28 Introduction to Liquid Rotational Molding . 278
6.29 Liquid Polymers 278
6.30 Liquid Rotational Molding Process . 279
6.30.1 Liquid Circulating Pool 280
6.30.2 Cascading Flow 281
6.30.3 Rimming Flow . 281
6.30.4 Solid Body Rotation . 281
6.30.5 Hydrocyst Formation . 282
6.30.6 Bubble Entrainment . 284
6.30.7 Localized Pooling 285
6.31 Process Controls for Liquid Rotational Molding . 285
6.32 Foam Processing 287
6.32.1 Chemical Blowing Agent Technology 288
6.32.2 Single Layer vs. Multiple Layer Foam
Structures . 295
6.32.2.1 One-Step Process 295
6.32.2.2 Two-Step Process 296
6.32.2.3 Drop Boxes – Inside or Out? 297
6.32.2.4 Containerizing Inner Layers . 298
References . 299
7. Mechanical Part Design 307
7.0 Introduction . 307
7.1 Design Philosophy 307
7.2 General Design Concepts 310Contents xix
7.3 Mechanical Design . 314
7.3.1 Three-Point Flexural Beam Loading 315
7.3.2 Cantilever Beam Loading 316
7.3.3 Column Bending 317
7.3.4 Plate Edge Loading . 318
7.3.5 Hollow Beam with Kiss-Off Loading 318
7.3.6 Creep 322
7.3.7 Temperature-Dependent Properties 323
7.4 Design Properties of Foams . 324
7.4.1 Uniform Density Foams . 324
7.4.2 Multilayer or Skin-Core Foams 329
7.5 Computer-Aided Engineering in Rotational Molding 330
7.5.1 CAD/CAM in Rotational Molding . 332
7.5.2 Computer-Aided Stress Analysis . 332
7.6 Some General Design Considerations . 335
7.6.1 Uniformity in Wall Thickness . 336
7.6.2 Shrinkage During Cooling . 337
7.6.3 General Shrinkage Guidelines 339
7.6.4 Effect of Pressurization . 340
7.6.5 Draft Angles and Corner Angles 341
7.6.6 Warpage Guidelines 344
7.6.7 Corner Radii – The Michelin Man 345
7.6.7.1 Right-Angled Corners . 345
7.6.7.2 Acute-Angled Corners 346
7.6.8 Parallel Walls 348
7.6.9 Spacing and Bridging 348
7.6.10 Internal Threads, External Threads, Inserts,
and Holes 349
7.7 Process Effects on Porosity, Impact Strength 350
7.8 Trimming . 354xx Contents
7.9 Surface Decoration . 357
7.9.1 Painting . 358
7.9.2 Hot Stamping 358
7.9.3 Adhesives . 358
7.9.4 In-Mold Decoration 359
7.9.5 Postmold Decoration . 359
7.9.6 Internal Chemical Treatment . 359
7.10 Troubleshooting and Quality Assurance 360
7.10.1 Coordinate Measuring Machine . 360
References . 362
Appendices . 367
Appendix A. Troubleshooting Guide for Rotational Molding 367
Appendix B. Conversion Table . 375
Author Index . 379
Index 383379
Straight — Text Citing Italic — Reference
Author Index
A
Andrzejewski, S., 11, 16
Arendt, W.D., 6, 15, 96,
109
Arpaci, V.S., 247, 302
Ashby, M.F., 325, 327,
363
Astarita, T., 210, 211, 300
Astarita, G., 210, 211, 300
Attaran, M.T., 248, 302
B
Balmer, R.T., 279, 282,
304, 305
Bawiskar, S., 138, 147
Beall, G.L., vi, 2, 14, 112,
147, 160, 200, 206,
276, 285, 299, 304,
305, 307, 310, 313,
318, 319, 335, 340,
342, 344, 349, 351,
362, 364
Becker, H., 4, 14
Bellehumeur, C.T., 11, 17,
20, 69, 93, 108, 225,
228, 234, 243, 244,
301, 302, 354, 365
Benning, C.J., 28, 59, 60,
65, 68
Bent, A.A., 210, 299
Berins, M.L., 335, 356,
364, 365
Bisaria, M.K., 6, 11, 15,
17
Boenig, H.V., 42, 66
Boersch, E., 1, 14, 96,
104, 109
Bonis, L.J., 225, 300
Bothun, G., 104, 110
Braeunig, D., 6, 15
Brown, R.L., 205, 211,
212, 299
Bruins, P.F., vi, 4, 14, 40,
66, 112, 147
Brydson, J.A., 20, 65,
211, 300
Bucher, J., 4, 14, 367, 374
Burnett, D.S., 333, 335,
363, 364
Burns, M., 332, 363
C
Calafut, T., 28, 65
Campbell, C.S., 210, 300
Carrino, L., 104, 110
Carter, B., 4, 14, 113, 147
Cellier, G., 236, 237, 242,
301
Cerro, R.L., 279, 281, 304,
305
Chabot, J.F., 4, 14
Chan, L.S., 6, 16, 69, 108
Chen, C.-H., 146, 148,
201, 214, 247, 248,
299
Cheney, G., 11, 16
Chiou, Y.H., 228, 229, 237,
301
Clark, D.T., 360, 365
Collins, E.A., 38, 65
Copeland, S., 6, 15, 64,
68
Covington, H., 335, 364
Cowan, S.C., 210, 299
Cramez, M.C., 12, 17, 18,
99, 109, 268, 303
Crawford, R.J., vi, 1, 2, 6,
11, 12, 14–18, 69,
85, 90, 94, 99, 100,
108, 109, 112, 120,
138, 140, 142, 146,
147, 148, 186, 200,
201, 207, 214, 238,
240, 248, 268, 299,
302, 303, 318, 319,
323, 348, 349, 350,
352, 353, 354, 362,
364, 365
Crouch, J., 146, 148
Cumberland, D., 85, 109380 Rotational Molding Technology
Straight — Text Citing Italic — Reference
D
de Bruin, W., 69, 90, 92,
108
Dieber, J.A., 279, 281,
304, 305
Dodge, P., 11, 16
Domininghaus, H., 20,
65, 338, 339, 364
Dority, S., 101, 109, 110
Dusinberre, G.M., 266,
303
D’Uva, S., 287, 306
E
Eilers, K., 330, 363
Elias, H.-G., 267, 268, 303
Epstein, P.S., 240, 302
Ezrin, M., 56, 67, 307, 362
F
Fahnler, F., 39, 66
Fawcett, J., 332, 363
Fayed, M.E., 219, 300
Feast, W.J., 360, 365
Fenner, R.T., 333, 363
Findley, W.N., 323, 362
Flannery, B.P., 333, 363
Fogler, H.S., 239, 302
Foy, D., 101, 110
Frenkel, Ya.I , 225, 300
Frisch, K.C., 59, 67, 291,
306
G
Gachter, R., 63, 68
Gebhart, B., 333, 363
Gianchandani, J., 6, 16,
279, 282, 283, 304,
305
Gibson, L.J., 325, 327,
363
Goddard, J.D., 239, 302
Gogos, G., 142, 148, 240,
250, 251, 273, 274,
303
Goodman, M.A., 210, 299
Goodman, T.R., 249, 302
Gotoh, K., 81, 108
Graham, B., 6, 15, 58, 64,
68
H
Han, C.D., 239, 302
Hang, C.C., 6, 16, 69, 108
Harkin-Jones, E.M.A., 6,
16, 38, 39, 40, 41,
42, 65, 66, 69, 108,
279, 282, 283, 284,
303, 304, 305
Hartnett, J.P., 250, 261,
303
Hausner, H.H., 225, 300
Hentrich, R., 154, 200
Hickey, H.F., 40, 66
Higashitani, K., 81, 108
Howard, H.R., 11, 16, 101,
109, 110
Huebner, K.H., 333, 363
I
Iwakura, K., 146, 148,
201, 214, 247, 248,
299
J
Joesten, L., 6, 16, 64, 68
Johnson, L., 105, 110
Johnson, R.E., 279, 281,
304, 305
Jolly, R.E., 44, 66
K
Kampf, G., 44, 56, 66
Keurleker, R., 39, 66
Khemani, K.C., 291, 305
Kinghorn, K.B., 6, 15
Klempner, D., 59, 67, 291,
306
Kobayashi, A., 356, 365
Kontopoulou, M., 6, 11,
15, 17, 64, 68, 234,
238, 240, 241, 243,
244, 301, 302, 354,
365
Kreith, F., 205, 215, 216,
299, 300, 335, 364
Kuczynski, G.C., 225, 300
Kumar, S., 328, 363
Kurihara, K., 210, 211,
299
L
Lai, J.S., 323, 362
Landrock, A.H., 291, 306
Lang, J., 6, 15, 96, 109
Lefas, J.A., 287, 306
Levitskiy, S.P., 231, 238,
301, 302
Lin, S.T., 228, 229, 238,
301
Liniger, E.G., 211, 300
Linoya, K., 81, 108
Lipsteuer, S.J., 93, 109,
287, 306
Liu, F., 287, 306
Liu, G., 287, 306
Liu, S.-J., 228, 229, 238,
301
Liu, X., 250, 273, 274, 303
Lontz, J.F., 225, 300
Lowe, J., 6, 15Author Index 381
Straight — Text Citing Italic — Reference
Lui, S.-J., 11, 17
Lun, C.K.K., 210, 299
M
Macauley, N., 270, 303
MacKinnon, C., 191, 200
Maier, C., 28, 65
Malkin, B.A., 279, 280,
305
Malloy, R.A., 315, 322,
323, 345, 346,
362–364
Malwitz, N., 291, 305
Mansure, B., 6, 15
Marchal, J.-M., 287, 306
Marion, R.L., 278, 304
Martin, D., 6, 16, 69, 108
Mazur, S., 225, 226, 227,
228, 232, 233, 301
McCarthy, T.J., 360, 365
McClellan, E., 6, 15
McDaid, J., 69, 70, 71, 73,
76, 86, 89, 90, 91,
94, 108
McDonagh, J.M., 6, 15
Mello, J., 335, 364
Mincey, E., 105, 110
Mish, K.D., 335, 364
Mooney, P.J., 1, 14
Morawetz, H., 22, 30, 65
Moroni, G., 104, 110
Muller, B., 6, 15, 101, 102,
110
Muller, H., 63, 68
Murphy, W.R., 270, 303
Muzzio, F.J., 243, 306
N
Nagy, T., 100, 109
Nakajima, N., 38, 65
Narkis, M., 25, 65, 218,
225, 226, 227, 228,
232, 233, 235, 236,
301, 347, 348, 364
Neuville, B., 225, 300
Newman, S.J., 236, 301
Nickerson, J.A., 2, 14
Nugent, P.J., 11, 12,
16–18, 140, 147,
186, 200, 201, 214,
273, 274, 299, 303,
350, 352, 353, 354,
365
O
Ocone, R., 210, 211, 300
Ogorkiewicz, R.M., 4, 14,
44, 52, 66, 67, 268,
270, 271, 272, 303
Ohta, Y., 146, 148, 201,
214, 247, 248, 299
Okoroafor, M.O., 291,
306
Oliveira, M.J., 12, 17, 18,
99, 109, 268, 303
Olson, L.G., 250, 273, 274,
303
Onaran, K., 323, 362
Onoda, C.Y., 211, 300
Orr, J., 6, 16, 69, 108
Otten, L., 219, 300
P
Paiva, M.C., 12, 18
Park, C.P., 59, 67, 291,
306
Park, C.L., 287, 306
Pasham, V.R., 250, 303
Passman, S.L., 210, 300
Peterson, A.C., 315, 362
Petrucelli, F., 6, 15
Pietsch, W., 81, 109
Plesset, M.S., 240, 302
Polini, W., 104, 110
Pop-Iliev, R., 287, 306
Press, W.H., 333, 363
Progelhof, R.C., 20, 22,
23, 44, 45, 50, 53,
62, 63, 65–68, 217,
229, 230, 231, 236,
237, 242, 267, 279,
300, 301, 303,
304, 315, 323, 328,
330, 362, 363
Q R
Rabinovitz, E., 6, 16
Ramesh, N.S., 291, 305
Rao, M.A., 81, 108, 201,
205, 214, 299
Rauenzahn, R.M., 210,
211, 300
Rauwendaal, C., 207, 299
Rees, R.L., 6, 15, 76, 108
Rhodes, M., 77, 108
Richards, J.C., 205, 211,
212, 299
Rigbi, Z., 6, 16
Rijksman, B., 287, 306
Roark, R.J., 318, 362
Rohsenow, W.H., 250,
261, 303
Rosenzweig, N., 25, 65,
218, 225, 226, 227,
228, 232, 233, 235,
236, 301, 347, 348,
364
Ruetsch, R.R., 217, 300
Rumpf, H., 205, 299382 Rotational Molding Technology
Straight — Text Citing Italic — Reference
S
Saffert, R., 6, 15
Sarvetnick, H.A., 37, 38,
65, 278, 304
Schmitz, W.E., 4, 14
Schneider, K., 39, 66
Schneider, P.J., 249, 250,
261, 303
Scott, J.A., 12, 17, 142,
147, 148
Shah, V., 44, 51, 54, 57, 61,
62, 66–68
Shinbrot, T., 243, 306
Shinohara, K., 219, 300
Shrastri, R.K., 48, 49, 67
Shulman, Z.P., 231, 238,
301, 302
Shutov, F.A., 289, 291,
293, 305, 306
Silva, C., 100, 109
Sin, K.K., 6, 16, 69, 108
Smit, T., 69, 90, 92, 108
Sneller, J., 287, 306
Sohn, M.-S., 83, 109, 205,
211, 299
Sowa, M.W., 6, 16
Spence, A.G., 12, 17, 89,
100, 109, 138, 142,
146, 147, 148, 207,
238, 240, 299, 302
Spyrakos, C.C., 266, 303,
310, 333, 334, 362,
363
Stanhope, B.E., 6, 15, 96,
109
Stoeckhert, K., 154, 200
Strebel, J., 89, 90, 91, 109
Strong, A.B., 6, 15
Stufft, T.J., 89, 90, 91, 109
Susnjara, K., 355, 365
Swain, R., 102, 110
Syler, R., 242, 302
T
Takacs, E., 64, 68, 69, 93,
108, 109, 243, 244,
287, 302, 306, 354,
365
Tanaki, A., 36, 68
Taylor, T.J., 348, 364
Teoh, S.H., 6, 16, 69, 108
Teukolsky, S.A., 333, 363
Throne, J.L., 6, 10, 16, 20,
22, 23, 25, 44, 45,
50, 53, 62, 63,
65–68, 81, 83, 108,
109, 201, 205, 207,
210, 214, 215, 217,
218, 224, 229, 230,
231, 235, 236, 237,
238, 239, 242, 245,
246, 247, 248, 251,
267, 275, 279, 281,
282, 283, 288, 291,
293, 299–305, 308,
315, 323, 327, 328,
323, 330, 331, 340,
341, 347, 348, 356,
362–365
Tordella, J.P., 44, 66
Tredwell, S., 64, 68
Turner, S., 47, 67
Turng, L.-S., 287, 306
U V
Vetterling, W.T., 333, 363
Vincent, P.I., 52, 67
Vlachopoulos, J., 6, 11,
15, 17, 64, 68, 69,
93, 108, 109, 225,
228, 234, 238, 240,
241, 243, 244, 287,
301, 302, 306, 354,
365
Voldner, E., 6, 15
W
Walls, K.O., 12, 18
Wang, H.P., 287, 306
Ward, D.W., 38, 65
Ward, W.J., 360, 365
Weber, G., 4, 14
Werner, A.C., 37, 38, 65
White, J.L., 100, 109, 138,
147, 148, 201, 214,
247, 248, 299
Wisley, B.G., 6, 16
Wright, M.J., 138, 120,
147
Wright, E.J., 248, 302
Wytkin, A., 120, 147
X
Xin, W., 11, 16
Xu, L., 240, 302
Y
Yoo, H.J., 239, 302
Young, W.C., 318, 362
Z
Zhang, D.Z., 210, 211,
300
Zimmerman, A.B., 4, 14Index
Figure entries are suffixed “F” and those with “T” refer to tables.
Index terms Links
A
ABS 9
See also Acrylonitrile-butadiene-styrene
Rotational molding grade, discussed 36
Limitations in rotational molding 36
Acrylic 9
See also PMMA, Polymethyl methacrylate
Acrylonitrile-butadiene-styrene
As thermoplastic 19
Discussed 35
Air temperature, inner cavity, measurement 140
Air solubility in polymer 239
Aluminum casting
See also Mold, aluminum, cast
Procedure 152
Amorphous, defined 20
ARM, see Association of Rotational Molders
Arms
Design weight, described 122
Hollow for inert gas injection 146
Hollow for pressuring molds 146
Offset 122
Straight 122384
Index terms Links
Arms (Continued)
Support of molds 122 122F
Swing diameter
Described 123 123F 124F 125F
Examples of 123
Association of Rotational Molders 12
ASTM D-1238 24
See also Melt index
ASTM D-1693 22
See also ESCR; Environmental stress crack test
ASTM D-348 26 32
See also Heat distortion temperature
ASTM D-2765 27
See also Polyethylene, crosslinked
ASTM D-1238 44
ASTM E-11 46
See also Sieve, screen sizes, discussed
ASTM D-1921 46
See also Sieve technology
ASTM D-1505 51
See also Density gradient column
ASTM D-256 53
See also Impact test, pendulum; Impact test, Charpy;
Impact test, Izod
ASTM D-3029 53
See also Impact test, falling weight
ASTM D-790 54
See also Mechanical test, flexural modulus
ASTM D-638 64
See also Mechanical test, tensile modulus385
Index terms Links
ASTM D-2990 55
See also Mechanical test, creep
ASTM D-671 55
See also Mechanical test, flexural fatigue
ASTM D-1693 58
See also Environmental stress crack test, notched strip
ASTM D-1435 61
See also Weathering, accelerated tests
ASTM D-3801 63
See also Fire retardancy, standard match test
ASTM D-2863 63
See also Fire retardancy, oxygen index
ASTM E-11 75T
See also Sieve
ASTM D-1921 76
See also Particle size distribution
ASTM D-1895 84 84F
See also Powder flow, test method
ATM D-1895 46
See also Sieve technology, bulk density; Sieve
technology, pourability
Attrition 69
See also Pulverization, described
B
Baffles
See also Molds
In mold design 136 136F
Bridging, considerations for 311
Brittle fracture, impact test 51386
Index terms Links
Brittle temperature for several polymers 52
Bubbles 15
Bulk density
Grinding factors affecting 89
Powder
Fluidized 88T
Measurement 84F 88
Poured 88 88T
Tamped 88 88T
Vibrated 88 88T
C
CAB, see Cellulose acetate butyrate
CAP, see Cellulose acetate propionate
Carousel machine
Fixed arm 117 118F
Independent arm 118 119F
Cellulose acetate butyrate, discussed 34
Cellulose acetate propionate, discussed 34
Cellulosic 9 21
Discussed 34
General properties, discussion 35
Centrifugal casting 7 15
Charge weight, calculation of 174
For cylinder 175 175F
For rectangle 176 176F 177F
For various shapes 177 179T
Chemical resistance, post-applied 359387
Index terms Links
Chemical test
Crazing 57
Haze formation 56
Plasticization 56
Solvation 56
Solvent migration 56
Stress-cracking 57
Chocolate 7
Clamshell machine
Discussed 115 115F
Oven design 116
Coalescence 26
As sintering 26
Effect of particle size distribution on 87
Color
CIE standard 56
Compounding 96 101
Dry blending 96
Concentration level effect 99F
High speed mixing 97
Low-intensity 97
Low-intensity, equipment 97
Tumbling 96 97
Turbo-blending 97
Effect of blending technique on dispersion of 100F
Effect of blending technique on mechanical properties 101
Factors that affect 55
Methods of, discussed 96
Rotational molding factors that affect 56
XYZ diagram 56388
Index terms Links
Cooling
Air 137 274
Cycle time for
Discussion 259
Mathematical model 260 262
Wall thickness effect on 277
Discussed 137
Effect on shrinkage/warpage 137
Effect of water quench on 275
Experimental and theoretical comparison of 273 274F
Part release from mold during 203F 204
Pressurized mold 276
Recrystallization during 203F 204
Recrystallization effects during 266
Recrystallization effects during, modeling
Temperature measurements during 202F 203F
Thermal inversion
Described 262
Technical description 262 263F 264F
Distributed parameter model 264
Lumped parameter model 266
Water spray/mist 137
Cooling methods, discussed 137
Cooling rate 16
Coordinate measuring machine, discussion 360
Cracking, localized, impact test 51
Crazing 57
Creep modulus, see Mechanical test, creep modulus;
Mechanical test, creep
Crystallinity, defined 20389
Index terms Links
D
Decoration
Adhesives 358
Hot stamping 358
In-mold 359
Methods of, discussion 357 357T
Painting 358
Post-mold 359
Design
Of molds, see Molds, design of
Of parts, see Parts, design of; Parts design
Part removal 276
Design, mechanical
CAD/CAM in 332
Cantilever beam flexural 316
Column bending 317
Computer-aided stress analysis for 332
Computer-aided stress analysis for; see Finite-element
analysis
Computer aids for, discussed 330 331F
Computer aids in prototyping 332
Greep in 322
Criteria for parts 314
Finite difference analysis for 333
Finite-element analysis for 333
Foams, discussion 324
Skin-core foams
Stiffness of 329
I-beam model for 329 330F
Polynomial beam model, discussed 330 331F390
Index terms Links
Design, mechanical (Continued)
Uniform density foams 324
Stiffness of 325
Modulus for 325
Foaming efficiency of 325 326T
Tensile strength for 327
Impact characteristics of 327 328T
Ductile-brittle characteristics of 327 328F
Hollow beam with kiss-off 318
Long-term loading 314
Moderate-term loading 314
Plate bending, edge-on 317
Ribbed plate 319
Short-term loading 314
Temperature-dependency in 323 324T
Tensile creep in 323 323F
Three-point flexural 315
Demolding, schematic 5 2F
Density gradient column 51
Density, polyethylene property changes with 25T
Differential Scanning Calorimetry 268 270 271F 272F
DIN 6174 56
See also Color, CIE standard
DIN 5033 56
See also Color, XYZ diagram
Distortion 16
Dry blender
Double-cone 97 98F
Double-ribbon 97
Vee mixer 97 98F391
Index terms Links
Dry blending
See also Color
Additives in melt-blending 98
Additives in tumble-blending 97
Additives suitable for 97
Effect on mechanical properties 99
Effect on polymer crystalline nucleation 99
Effect on polymer morphology 99
Henschel-type mixer 99
Rotational molding powders 97
Turbo mixing 99
Drying conditions for polymers 34T
Ductile failure, impact test 51
Ductile yield, impact test 51
Ductile-brittle transition, impact test 52 52F
E
Electroformed nickel
Procedure 155
See also Molds, electroformed nickel
Environmental stress crack resistance, LDPE 50 50F
Environmental stress crack test
Bent strip 57 57F
Constant stress test 58
Defined 57
Notched strip 58
Polyethylene 58
Epoxy 9
As liquid polymer 37
ESCR, see Environmental stress crack test392
Index terms Links
Ethylene vinyl acetate
Chemical structure 27
Density 28
Environmental stress crack resistance 28
Extent of vinyl acetate 28
Foamability 28
Melt temperature range 28
Shore hardness 28
EVA, see Ethylene vinyl acetate
F
FDE, see Finite difference analysis
FEA, see Finite-element analysis
FEP, see Fluoroethylene polymer
Finite difference analysis 333
Finite-element analysis 333
Arithmetic for 334
Formalization of 334T
Limitations of 335
Fire retardancy
Defined 62
Oxygen index 63 63T
Standard match test 63
Flexural modulus, see Mechanical test, flexural modulus
Fluorocarbon 9
Fluoroethylene polymer, as thermoplastic 19
Foam rotational molding
Blowing agent efficiency in 290
Bubble nucleation in 291
Chemical foaming agents for 287 288T 289T393
Index terms Links
Foam rotational molding (Continued)
Endothermic 288
Exothermic 288
Containerized inner layer in 298
Diffusional bubble growth in 291
Discussed 287
Inertial bubble growth in 291
Limitations of 292
One-step process in 295
Oven conditions for 293 293T
Physical foaming agents for 287
Single layer structures in 295
Skin/core structure in 287
Terminal bubble growth in 292
Two-step process in 296
Fracture, brittle, impact test 51
G
Glass transition temperature, defined 20
Grinding 69
See also Pulverization, described
Ball-mill 69
Costs associated with
Discussion 91
Factors 92
Economies of scale 92
Frictional heat 71
Gap size effect on powder quality 89
Hammer-mill 69
Horizontal mill 72 73F394
Index terms Links
Grinding (Continued)
In-house v. outsourcing 91
Mill tooth number effect on powder quality 90
Parallel plate 69
Particle sieving 71
Powder characteristics 73
Particle size distribution 74
Flow 74
Bulk density 74
LLDPE 74
As related to rotational molding parameters 74 75
Particle shape 75
Process control 72
Process equipment 69F 72F
Skill factors involved in 92
Temperature effect on powder quality 90 90F 91F
Vertical mill 70 70F
H
Haze formation 57
HDPE
Crystallinity of 20T
See also Polyethylene, high-density
Heat capacity, of powder 218
Heat transfer
Coefficient of
For air 274
For water 275
Combustion 129 130T
Conduction 213395
Index terms Links
Heat transfer (Continued)
Defined 127
Convection 213
Defined 127
Coefficient 127 127T
Effect of polymer morphology on 243 244F
Modes, defined 127
Radiation 213
Defined 127
Thermal lag in mold 214 222 245
To coalescing powder bed 223
To powder 215
To powder bed 217
To powder particle 215
To mold 213
To mold assembly 139
To mold assembly, measurements of 139 139F
Transient heat conduction in 216F
Transient heat conduction model 247
Types in rotational molding 213
Heating
See also Oven; Heat transfer
Cycle time of 251
Actual 258T
Oven temperature effect on 255T 256 256T 258
Thickness effect on 254 255T 256 256T
Direct-gas impingement 113
Discussion of 201
Effect of pressure on powder behavior during 244
Effect of vacuum on powder behavior during 244396
Index terms Links
Heating (Continued)
Kink temperature during 202 203F 220 253
Mathematical modeling of 245 246F
Mold cavity air temperature during 221
Mold energy uptake to polymer uptake ratio 252
Polymer morphology effect on rate of 223 224F
Temperature measurements during 201 202F 203F
Time to inner cavity temperature, thickness effect on 255
Time to kink temperature, thickness effect on 255
Overall cycle time, thickness effect on 256 257F
Henry’s law 239
And foam rotational molding 293
I
Igepal 22 23 24 27
28 49 58
Impact, process effects on 350 350F 353F 354F
Impact test
Charpy 53
Constant velocity puncture 53
Described 51
Failure type 51
Factors affecting 53
Falling weight 53
Bruceton method 53
ARM standard, see Impact test, falling weight,
Bruceton method
ARM standard, low-temperature, see Impact test, falling
weight, Bruceton method
Probit method 53397
Index terms Links
Impact test (Continued)
Staircase method, see Impact test, falling weight, Bruceton
method
“Up-and-down” method, see Impact test, falling weight,
Bruceton method
Izod 53
Low-temperature, ARM terms 52
Pendulum 53
Test types 53
Tensile 53
L
Latex rubber 7
LDPE
See also Polyethylene, low-density
Crystallinity of 20T
Environmental stress crack resistance, melt index effect 50 50F
Liquid polymers 69
Discussed 36
Liquid rotational molding
Bubble entrainment in 284
Cascading flow in 280F 281 283F 286F
Circulating pool in 280 280F 283F 286F
Discussed 278
Flow behavior in 280 280F 283F 286F
Hydrocyst formation in 282 282F 284F
Ideal fluid for 286
Localized pooling in 285
Polymers used in 278
Process 279398
Index terms Links
Liquid rotational molding (Continued)
Process controls for 285
Rimming flow in 280F 281 283F 286F
Role of reaction in 285
Role of gelation in 285
Solid body rotation in 281 283F 286F
Time-dependent viscosity in 279 279F
LLDPE
See also Polyethylene, linear low-density
Crystallinity of 20T
M
Machines
Basic elements of 112
Clamshell 115 115F
Cooling design in, see Cooling
Compared with competition 111
Electrically-heated molds for 120 120F 121F
Fixed-arm carousel 117 118F
Limiting factors 118
Heat transfer in, see Heat transfer
Home-built 111
Independent-arm carousel 118 119F
Advantages of 118
Infrared heated 121
Make-Vs-buy 111
Oil-jacketed molds for 119
Oven design in, see Oven
Process control of, see Process control
Rock-and-roll 113399
Index terms Links
Machines (Continued)
Shuttle 116 117F
Types of, discussed 112
Vertical 116 116F
MDPE, see Polyethylene, medium-density
Mechanical Properties 16
Mechanical test
Creep, defined 54
Creep modulus 55
Creep rupture 55
Defined 54
Flexural fatigue 55
Flexural modulus 54
Tensile modulus 54
MEKP, see Methyl ethyl ketone peroxide
Melt flow index 28
See also Melt index
Described 44
Melt index 28 45F 64
HDPE 24
LDPE 22
MDPE 23
Polyethylene property changes with 25T
Process effects on 352F
Quality control of 43 44
Described 44
Melt index test conditions
Nonpolyolefins 44 45T
Polyolefins 45T 46T
Melt indexer 44 45F400
Index terms Links
Melt viscosity 15 43
Melt elastic modulus 64
Melting temperature, defined 20
Methyl ethyl ketone peroxide, catalyst for Unsaturated
polyester resin 42
Micropellet 46
See also Polyvinyl chloride
Coloring of 95
Comparison with conventional pellet 94 95T
Discussed 93
Method of production 93
Processing comparison with powder 94 95T
Polyethylene 69
PVC, discussed 96 96T
Reason for use 93
Mold charging, schematic 5 2F
Mold cooling, schematic 5 2F
Mold heating, schematic 5 2F
Mold release 103
Cost of 199
Discussed 196
Disiloxanes 197
Early part release with 199
Fluoropolymers 197
Selection criteria for 198
Silicone 197
Spray-on 197
Surfaces coated by 198401
Index terms Links
Molds
Air flow around deep pockets 136 136F
Air flow using baffles 136 136F
Air flow using venturi 136 137F
Alignment methods for 165 164F
Aluminum 150 150F 150T 152
Cast 150 152 154F
Welded 152
Machined 152 152F
Clamping of 166 166F
Commercial 149
Design of
Discussion 160
For pressurization 276
Parting line 161
Butt or flat 161 161F
Lap joint 162 162F
Tongue-and-groove 162 163F
Gaskets 163 163F
Electroformed nickel 149 150T 154 155F
Frames for 165
Heat transfer to 213
J-clamps for 166 168F
Manual clamps for 166
Materials for
Discussed 149
Properties 150T
Nonmetallic 149
Pressure buildup without venting 183
Pressurization for 340402
Index terms Links
Molds (Continued)
Pressurized 146
Pry points, location for 167 167F
Sheet-metal 149 149F 150T 151
Spiders for 165 165F
Surfaces coated with mold releases 198
Surface finishes for 196
Thermal behavior of
Various types 156 157F 158F 159F
Equivalent mechanical thickness 156 157F
Equivalent static thermal thickness 157 158F
Equivalent transient thermal thickness 159 159F
Toggle clamps for 166 167F
Use of drop-box in 297
Use of drop-box on 296 297F
Venting of, see Venting
Moment of area, second, see Moment of inertia
Moment of inertia, defined 315
Morphology
Changes in PP, due to cooling rate 270T 273 273T
Crystallinity level and 267 267T
Effects of additives on 272 272T
Recrystallization rates and 267 268T 269F 270T
N
Natural gas combustion 129 130T
Nylon 9
As thermoplastic 19
Chemical structure 31
Chemical types 32T403
Index terms Links
Nylon (Continued)
Crystallinity of 20T 32
Fiber-reinforced 9
Melting temperature 32T
Moisture concerns with 310
Rotational molding grades 32 32T
Nylon 6, WLF constants for 324T
Nylon 12, as liquid polymer 40
O
Odor
Defined 62
Test
Olfactory 62
Gas chromatography 62
Oven time 14
Effect on design parameters 351T
Oven temperature 14
Oven
Air flow around molds with deep pockets 136 136F
Air flow in 136
Design of, discussed 127 129
Efficiency of operation of 130
Heat transfer in 131
Heat transfer in
Examples of 133404
Index terms Links
P
PA-6
See also Nylon: Polycaprolactam
As liquid polymer 36
Flexural modulus 32
Heat deflection temperature 32
Melting temperature 32
Part design
Acute-angled corners in 346 347F
Aesthetics 307
Almost kiss-offs in 312
Appearance effect on 308
Application effect on 308
Assembly constraints effect on 309
Bridging criteria for 311
Cavity depth criteria for 312
Competition effect on 309
Computer-aided technique effect on 310
Concerns of warpage in 311
Control of wall thickness in 312
Coordinate measuring machine use in 360
Corner radius guidelines in 345 345T 347F
Cost effect on 309
Criteria 307
Criteria for kiss-off 318
Cycle time effect on 310
Decoration effect on 309
Detents in 312
Dimensional tolerance effect on 31
Draft angles 341 342T405
Index terms Links
Part design (Continued)
Female molds in 312
Polymer-specific 341 342T
Texture 342 342T
Environment effect on 308
External threads in 312 349
Fiber-reinforcement in 312
Flat panels in 311
General guidelines for, discussed 310
General considerations for 335
Gussets in 312
Holes in 349
Improving mechanical strength through 312
Insert 349
Criteria for 312
Stresses around 312
Internal threads in 312 349
Kiss-offs in 312
Limitations of 309
Market considerations 307
Material choice effect on 309
Mechanical
Criteria for 314
Discussion 307 317
Metal molded-in inserts for 313
Minimum wall thickness in 336
Mold cost effect on 309
Molded-in holes in 312
Mold texture transfer to parts in 312
Nominal wall thickness in 336406
Index terms Links
Part design (Continued)
Parallel walls in 311 348
Part function effect on 308
Part wall separation for 348
Philosophy 307
Powder flow effect on 310
Pressurization effects on 340
Process effects on
Discussion 350
Impact 350 350F
Melt index 352F
Radius concerns in 312 313
Right-angled corners in 345
Ribs in 311
Rim stiffening in 312
Shrinkage guidelines in 337
Size effect on 309
Surface decoration; see Decoration
Wall thickness considerations for 311
Wall thickness in 336 337T
Wall thickness limitation effect on 309
Wall thickness range in 337T
Warpage guidelines for 344 344T
Warpage in 311
Undercuts in 311 312
Particle size distribution 75
Data presentation 79 79F 80T 80F
Discussed 74
Dry sieving 77
Elutriation 78407
Index terms Links
Particle size distribution (Continued)
Fluidization 79
Light scattering 78 79
Measurement 77
Sedimentation 78
Streaming 78
Test method 76 78
Factors affecting 78
Test purpose 77
Particle shape
Acicular 81
Discussed 81
Effect on part performance 81
Methods of classification 81
Particle size analyzers 82
Physical methods 82
Shape factor 81 82T
Spherical 81
Squared-egg 81
Terms defined 82T
Particle size analysis 77
Parting line
See also Molds, design of, parting line
Butt or flat 161 161F
Design of 161
Gaskets 163 163F
Lap joint 162 162F
Tongue-and-groove 162 163F
See also Part design408
Index terms Links
Parts
Blowhole problems in 183
Cutout areas in 172
Failure
Discussed 307
Fracture 307
Creep 307
Crazing 307
Stress cracking 307
Fatigue 307
Adhesive failure 308
Warpage 308
Shrinkage 308
Color change 308
Additive migration 308
Cracking element migration 308
Inserts for 168
Kiss-offs for 172 173F
Mechanical fastening of 169
Molded-in handles for 173
Molded-in inserts for 169 170F
Molded-in threads for 171 171F
Post-molded fasteners for 169
Self-tapping screws for 168
Suck-hole problems in 185
Temporary inserts for 173
Warpage with mold release 199
PC, see Polycarbonate
PEEK 9
See also Polyether-ether ketone409
Index terms Links
Phenolic 9
As thermoset 19
Crosslinked, discussion 19
Pigments
Classes of 101
Classification of 104T
Color shift in 103
Discussion of 101
Dry-color blending of 101
Heavy metals, restricted use of 101
Organics 102
Azo-type 102
Polycyclic-type 102
Processing concerns of 102
Fluorescents 103
Plate-out of 103
Special-effect 103
Temperature effect on selection of 101
Pinholes 15
Plaster, molding, properties 154
PMMA, see Polymethyl methacrylate
Poly-a-aminoacid, see Nylon
Polyacetal 9
See also POM, Polyoxymethylene
Polyamide, see Nylon
Polybutylene 9
Polycaprolactam
Chemical structure 39
Defined 32
Fillers for 41410
Index terms Links
Polycaprolactam (Continued)
Gellation rate 40
General production method 40
Time-dependent crystallinity 40F
Time-dependent viscosity during reaction 39F
Polycarbonate 9
As thermoplastic 19
Chemical resistance, discussed 34
Chemical structure 33
Drying for rotational molding, discussed 33 34T
Flexural modulus 33
Heat distortion temperature 33
Impact strength, discussed 33
Moisture concerns with 310
WLF constants for 324T
Polyester
Unsaturated 9
As thermoset 19
Polyether-ether ketone 21
As thermoplastic 19
Polyethylene terephthalate, crystallinity of 20 20T
Polyethylene
As thermoplastic 19
Branched, see Polyethylene, low-density
Chemical structure 22
Crosslinked 9
Advantages 58
Crosslinking agents 27 58 59T
Density 27
Discussion 19 27411
Index terms Links
Polyethylene (Continued)
Environmental stress crack resistance 27
Flexural modulus 27
Gel content 27
Peroxide level 60F
Time dependency 60F
Test 59
Level, procedure 59
Shore hardness 27
Crystallinity of 20T
Early applications 6
High-density
Chain configuration 23F
Crystalline morphology 24
Crystallinity 24
Defined 24
Density 24
Environmental stress crack resistance 24
Flexural modulus 24
Melt index 24
High-pressure, see Polyethylene,low-density
Low-density
Chain configuration 23F
Crystallinity 22
Defined 22
Density 22
Environmental stress crack resistance 22
Flexural modulus 22
Melt index 22
Shore hardness 22412
Index terms Links
Polyethylene (Continued)
Low-pressure, see Polyethylene, high-density
Linear, see Polyethylene, high-density
Linear low-density
Chain configuration 23F
Crystallinity 27
Density 26
Defined 25
Environmental stress crack resistance 27
Flexural modulus 27
Medium-density
Crystallinity 23
Defined 23
Density 23
Environmental stress crack resistance 23
Flexural modulus 23
Melt index 23
Metallocene, discussed 26
Micropellet 69
Odor 15
Powder 69
WLF constants for 324T
Polyimide 21
Polymer morphology, discussed 20
Polymethyl methacrylate, chemical structure 35
Polyolefin 7
Polypropylene 9
As thermoplastic 19
Atactic, defined 28
Chemical structure 28413
Index terms Links
Polypropylene (Continued)
Copolymer
Defined 29
Effect on properties 29 29T
Crystallinity of 20 20T
Fillers in 29
High-temperature stability of 29
Homopolymer, flexural modulus 28
Isotactic, defined 28
Melt flow index 28
Recrystallization of 30
Syndiotactic, defined 28
WLF constants for 324T
Polystyrene 9
See also Styrenics
As thermoplastic 19
Discussed 35
Impact, discussed 35
WLF constants for 324T
Polytetrafluoroethylene, crystallinity of 20
Polyurethane 9
As liquid polymer 37
As thermoset 19
Chemical structure 41
Nature of reaction 42
Time-dependent viscosity during reaction 41
Polyvinyl chloride 21
As thermoplastic 19
Chemical structure 30
Drysol, discussed 30414
Index terms Links
Polyvinyl chloride (Continued)
Drysol hardness 31
Drysol v. micropellet 96 96T
Liquid 6
Micropellet 31
Micropellet characteristics 96 96T
Plastisols, discussed 30
Plastisol hardness 30
Plastisol v. micropellet 96 96T
Role of plasticizers in 30
Types of additives for 30
Porosity, discussed 242
Powder density
Discussed 84
Related to powder flow 85F
Powder
Coalescence 12
Consolidation 14
Densification 12
Fusion 14
Sintering 15
Size 21
Powder particle characterization, quality control 44
Powder flow
Discussed 74 83
Effect of tails on 83
Grinding factors affecting 89
Related to powder density 85F
Test method 84415
Index terms Links
Powder packing 85
See also Powder flow; Particle shape
Bulk density
Fluidized 88T
Measurement 84F 88
Poured 88 88T
Tamped 88 88T
Vibrated 88 88T
Deviation from ideal packing 86
Equal spheres 85 86F 86T
Packing fraction defined 85
Particle size distribution effect 87
Powder quality
See also Grinding
Discussed 88
Grinding factors effecting 89
Powder
Airborne dust generation with 207
Antistatic agents for 105
Avalanche flow of 208 208F 209T 222
Bed behavior during heating 222
Bubble dissolution in coalesced 235F
Bulk density of various 206T
Carbon black in 106
Coalescence 203 235F
Defined 223
Coulomb flowing 207
Temperature effect on 219
Densification in 203 235F
Air absorption 238416
Index terms Links
Powder (Continued)
Rayleigh.s model for 238
Capillary action 236
Defined 236
Network collapse 236 237F 238F
Particle size distribution during coalescence 242
Rate of 242
Three mechanisms for 234
Under vacuum 237
Flow aspects of 206
Fluidizing 207
Mathematical modeling
Bed 248
Static bed 249
Circulating bed 248 250
Moisture concerns with 310
Neck growth
Compared with heating profile 226F
Defined 223
Viscous model 225 225F 227F
Neck growth rate 226 227T
Creep compliance model 232 232F 233F
Hertzian 228
Linear viscoelastic 229F 230 231F
Newtonian 227F 228
Packing aspects of 205
Polyethylene 69
Polymer elasticity effect on coalescence of 234
Rheology of flowing 210
Rotating cylinder flow of 211 212F417
Index terms Links
Powder (Continued)
Sintering of, defined 223
Slip flow of 208 208F 209T 222
Steady-state circulation of 207 208F 209T 222
Stearates for 106
UV additives for 106
Viscous flowing 207
Process control
Discussed 138
Inner cavity air temperature monitoring for 140
Process cycle
Discussion of 201
Steps in 201 204 205T
Processing and properties, general considerations 14
Propane combustion 129 130T
PS, see Polystyrene; Styrenics
PSD 74 77
See also Particle size distribution
Pulverization, described 69
P-V-T curves
HDPE 338F
Polycarbonate 339F
Shrinkage and 337
PVC plastisol 9 21
As liquid polymer 36
Effect of heat on molecular characteristics 37F
Effect of heat on viscosity 38F
Fusion 37F 38
Gellation 37F 38
Method of production 38418
Index terms Links
PVC plastisol (Continued)
Product types 39
Shore hardness 39
PVC, see Polyvinyl chloride
Q
Quality assurance, discussion 360
R
Rayleigh.s equation
Inviscid 238
Newtonian 238
Viscoelastic 239
Recrystallization, part design restrictions for 311
Ribs, design criteria for, discussed 311
Rock-and-roll machine 113 114F 115
Oven design 114F 115
Products made on 113
Rotation
Fixed ratio, discussed 125
Major-to-minor axis ratio 125
Speed of, discussed 125
Speed ratio
Defined 126
Recommended for various geometries 126T
Rotational molding
Advantages 10 12 14
Applications 3T
Basic process 5 10
Cooling 16419
Index terms Links
Rotational molding (Continued)
Competition 4 6 10T
Defined 4
Degradation 15
Design 8 11
Desirable polymer characteristics 64
Disadvantages 10 14
Heating 15
History 6
Internal surface appearance 15
Markets 4 5F
Materials 9 10F
Molder consumption 21T
Nature of polymer in 69
Polymer use 21T
Powder flow 15
Rotational molding process
Limitations 145
Advances in 146
Rotocasting, see Rotational molding
Rotomolding, see Rotational molding
S
SAN, see Styrene-acrylonitrile
Service station, discussed 144
Shrinkage
Discussion 337
Guidelines for 340
Linear 338 340T
Volumetric, discussion 338420
Index terms Links
Shuttle machine 116 117F
Dual carriage 117 117F
Sieve technology
Bulk density 46
Described 46
Dry sieving 46
Pourability 46
ARM recommendation 46
Sieve
See also Powder technology
Grinding 71
Dry, types of 77
Elutriation 78
Screen sizes, discussed 46
Shaker sizes 76F
Sizes of 75T
Sonic sifter 78
Silicone 9
As liquid polymer 37
Chemical structure 43
Method of reaction 43
Sintering 26
See also Coalescence
Slip casting, ceramics 7
Slush molding 278
Society of Plastics Engineers Rotational Molding
Division 12
Spin casting 7
Stress concentration factor 346F
Stress-cracking 57421
Index terms Links
Styrene-acrylonitrile, see Styrenics
Styrenics, chemical structure 35
Surface treatment
Activation methods for 104
Applied graphics as 105 105F
Discussed 104
Plasma 104
T
Tack temperature
Amorphous 219 220T
Crystalline 219 220T
Defined 219
Related to kink temperature 220 253 253T
Temperature measurement
Correlation of
Bubble dissolution time 142 142F
Coalescence time 141
Part release from mold 143
Process step 140 141F
Recrystallization time 143
Infrared method 144
Inner cavity air temperature 140
Interpretation 140 141F
Mold assembly 139
See also Heat transfer
Tensile modulus, see Mechanical test, tensile, modulus
Testing protocol
Actual part 47
Costs 48 49T422
Index terms Links
Testing protocol (Continued)
Defined 47
Full-scale 47
Segment 48
Test acceptability criteria 48
Testing
Environmental stress crack resistance 50 50F
Full-scale 49
Molded density 51
Sections 50
Tg, see Glass transition temperature
Thermal lag 214 222 245
See also Heat transfer, to mold
Mathematical model of 245
Thermal conductivity, of powder 217 218F
Thermal diffusivity 248
Powder 218
Thermoplastics
Defined 19
Discussed 6
Thermosets
See also Thermosetting polymers
Defined 19
Rotational molding advantages 43
Thermosetting polymers, liquids 36
Thermosetting liquids, nature of reaction 36
Thermosetting, discussed 6
Titanium dioxide
As opacifier 107
As UV additive 107423
Index terms Links
Tm, see Melting temperature
Trimming
Cutting characteristics 356T
Various polymers 356
Discussion 354
Multiaxis 354 356T
Troubleshooting
Discussion 360
Guidelines, Appendix A
U
UHMWPE, see Ultrahigh molecular weight, polyethylene
ULE-84 tunnel test 62
See also Fire retardancy
UL 94 63
See also Fire retardancy, standard match test
Ultrahigh molecular weight polyethylene, characteristics 22
Undercuts, design criteria for, discussed 311
Unload/load process station, see Service station
Unsaturated polyester resin
As liquid polymer 37
Chemical structure 42
Fillers for 42
Processing difficulties with 42
Reaction via MEKP 42
UPE, see Unsaturated polyester resin
UV additive
Carbon black as 106
Classification of 106
Hindered amine light stabilizers as 106424
Index terms Links
UV additive (Continued)
Titanium dioxide as 107
V
Venting
Design guidelines for 186 190F 192F
Discussion 183
Disposable 193
Permanent 193 194F
Pressure buildup without 183
Requirements for 195
Types of 193
Selection criteria 193
Vacuum without 185
Venturi
See also Molds
Mold design with 136 137F
Vertical machine, discussed 116 116F
W
Wall thickness
Calculation of 174
Maximum allowable 180 181F
Warpage 16
Weathering
Accelerated tests 61
Acid rain 61
Defined 61
Resistance of polymers 61
Ultraviolet effect 61425
Index terms Links
Williams-Landel-Ferry model 323
Constants for 324T
WLF equation 323 324T
See also Williams-Landel-Ferry model
X
XLPE, see Polyethylene, crosslinked
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