µm. Another is that length-to-diameter ratio is too small. Tey also found they need 10–30% carbon fill, which is expensive. Teir future work is to move the research to the next level by creating a system that works with continuous nanofibers, of about 100–200 nm in diameter. “Tis will eliminate some of the clogging problems, and we found we can use much less carbon fill and get the same mechanical properties,”
Metals Expand Their Palette: Multimetals Another distinct advantage of some additive manufactur-
ing techniques featuring metal is the ability to “mix-and- match” materials at the point of deposition, expanding the palette by creating multimaterial parts and objects. “Multi- material manufacturing has been one of the key attributes to direct metal deposition from the beginning,” explained Bhaskar Dutta, chief operating officer of DM3D (Auburn Hills, MI). Unlike conventional plating or coating, DMD is capable of processing medium to large size parts with multiple materials, according to the company. It uses various metallic powders that are fused with a high-power laser. Te result- ing layer can be from micrometers to millimeters thick. “It’s a user-defined alloy layer with a metallurgical bond to steel or other metallic substrates,” explained Dutta. “It creates near net shape and controls heat input, which reduces post processing of the product.” Varieties of materials are available including tool steels,
stellites, nickel-based superalloys, titanium alloys, and cer- mets. “Te question is, how do we put them together for a particular part,” he said. Te starting point for that discussion is from the needs of the engineering designer, what combi- nation of properties, such as yield strength and elongation is needed. Teir machines have four hoppers for different powders, which can be mixed simultaneously or as individual layers or points of metal from a single hopper. An interesting twist on this is parts made of layers of
materials with quite different properties. Dutta presented an example of a powder compaction tool with fatigue cracks in corners, replaced with a multi-material solution. Tey used hard and soſt metals alternately layered, with the hard metals providing strength and stiffness and the soſt metal layers ar- resting fatigue cracks as they formed. Another important consideration for using multiple mate-
rials is when engineers are considering using additive manu- facturing for part consolidation. “Tat is a great application for additive manufacturing, to reduce part count by produc- ing an end item that replaces many component pieces with one. Our special application is when the components you are trying to consolidate are made of different materials, that is where directed energy technologies like ours are quite unique compared to powder bed technologies,” he said. Fabrisonic (Columbus, OH), a spin-off from the Edison Welding Institute, is marketing machines that use ultrasonic
The Fabrisonic technique solid-state additive manufacturing process for metals uses sound waves to merge layers of metal foil.
solid-state bonding to combine thin sheets or foil of metal. “Te advantage is we are not melting and resolidifying. If you melt the layers and resolidify them, you change the proper- ties dramatically—if you do solid-state bonding, you get the same material properties as the metal you are building with,” he said. It works with a variety of metals such as aluminum, copper, stainless steel, and titanium Tey combine a wide variety of materials in 1" (25.4-
mm) thick strips, creating materials with custom mechanical properties. “We create materials with custom CTE or with a specific modulus of elasticity,” he said. Tis is useful in appli- cations from electronics to tooling to custom defensive armor. Using the Fabrisonic technology to create metal matrix
composites in particular is interesting to aerospace. “We are taking aluminum and inside of it we are printing continu- ous, ceramic fibers that have 10 times the yield strength of the aluminum matrix,” said Norfolk. “We combine them in off-setting weaves to create a material with performance and weldability of a metal, with a lighter weight, higher strength material because of the ceramic fibers.” He also noted that while this can be done with casting, the advantage of a 3D printer is practically any shape desired can be created without the investment required in tooling for casting. Another unique feature of the Fabrisonic technology is
size. Te ultrasonic solid-state bonding technology is embed- ded in three-axis CNC machines, so that any cutting, drilling, routing, and surface finish required is done in one setup. Te largest machine is the SonicLayer 7200, with a 72 × 72 × 36" (1.8 × 1.8 × 0.9 m) print volume. By combining additive with CNC processing, SonicLayer machines can create deep slots, hollow, latticed, or honeycombed internal structures, and other complex geometries. ✈
Aerospace & Defense Manufacturing 2014 149
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132 |
Page 133 |
Page 134 |
Page 135 |
Page 136 |
Page 137 |
Page 138 |
Page 139 |
Page 140 |
Page 141 |
Page 142 |
Page 143 |
Page 144 |
Page 145 |
Page 146 |
Page 147 |
Page 148 |
Page 149 |
Page 150 |
Page 151 |
Page 152 |
Page 153 |
Page 154 |
Page 155 |
Page 156 |
Page 157 |
Page 158 |
Page 159 |
Page 160 |
Page 161 |
Page 162 |
Page 163 |
Page 164 |
Page 165 |
Page 166 |
Page 167 |
Page 168 |
Page 169 |
Page 170 |
Page 171 |
Page 172 |
Page 173 |
Page 174 |
Page 175 |
Page 176 |
Page 177 |
Page 178 |
Page 179 |
Page 180 |
Page 181 |
Page 182 |
Page 183 |
Page 184 |
Page 185 |
Page 186 |
Page 187 |
Page 188 |
Page 189 |
Page 190 |
Page 191 |
Page 192 |
Page 193 |
Page 194 |
Page 195 |
Page 196 |
Page 197 |
Page 198 |
Page 199 |
Page 200 |
Page 201 |
Page 202 |
Page 203 |
Page 204 |
Page 205 |
Page 206 |
Page 207 |
Page 208 |
Page 209 |
Page 210 |
Page 211 |
Page 212 |
Page 213 |
Page 214 |
Page 215 |
Page 216 |
Page 217 |
Page 218 |
Page 219 |
Page 220 |
Page 221 |
Page 222 |
Page 223 |
Page 224 |
Page 225 |
Page 226 |
Page 227 |
Page 228 |
Page 229 |
Page 230 |
Page 231 |
Page 232 |
Page 233 |
Page 234 |
Page 235 |
Page 236 |
Page 237 |
Page 238 |
Page 239 |
Page 240 |
Page 241 |
Page 242 |
Page 243 |
Page 244 |
Page 245 |
Page 246 |
Page 247 |
Page 248 |
Page 249 |
Page 250 |
Page 251 |
Page 252 |
Page 253 |
Page 254 |
Page 255 |
Page 256 |
Page 257 |
Page 258 |
Page 259 |
Page 260 |
Page 261 |
Page 262 |
Page 263 |
Page 264 |
Page 265 |
Page 266 |
Page 267 |
Page 268 |
Page 269 |
Page 270 |
Page 271 |
Page 272 |
Page 273 |
Page 274 |
Page 275 |
Page 276 |
Page 277 |
Page 278 |
Page 279 |
Page 280 |
Page 281 |
Page 282 |
Page 283 |
Page 284 |
Page 285 |
Page 286 |
Page 287 |
Page 288 |
Page 289 |
Page 290 |
Page 291 |
Page 292 |
Page 293 |
Page 294 |
Page 295 |
Page 296 |
Page 297 |
Page 298 |
Page 299 |
Page 300 |
Page 301 |
Page 302 |
Page 303 |
Page 304 |
Page 305 |
Page 306 |
Page 307 |
Page 308 |
Page 309 |
Page 310 |
Page 311 |
Page 312