ME September 2015

aerospace metrology

dimensioned to provide a precise fi t for the fastener. The holes may be countersunk fl ush or un-countersunk. Flush countersunk holes are made to insert a fl ush-type fastener. Most fasteners are countersunk. The countersunk holes are predominantly on the exposed surface of the airframe, wing, and control surfaces and used for fasteners to attach skins to the substructure of the air vehicle. Depending on the size and complexity of the air vehicle, the airframe can contain as many as seven million holes for fasteners. The introduction of compos- ite materials onto air vehicles has complicated the traditional hole/ countersink assessment criteria due its fi nished-part thickness variability; softer and dissimilar properties than the metallic substructure where it is mounted and attached; and the increased attention to other accep- tance criteria such as fi ber tear, fi ber pull, and moisture propagation in the hole that degrades fastener capabili- ty. The addition of composite materi- als further complicates the assembly process by adding a boundary layer of liquid shim or sealant between the composite piece (usually a skin) and the substructure. Current hole inspection systems are absent the ability to assess the interior condi- tion of the composite hole such as fi ber tear, damage to the liquid shim, and debris or burrs between the multiple stacks of dissimilar material. Today more than ever, air vehicle manufacturers recog- nize that the collage of global supply chain manufacturing processes and gages needs a common unifying medium to insure best-fi t at fi nal assembly. The largest component and cost for manufacturing fi t-up at assembly are the holes that bind and hold the airframe together. Mitigating variability and cost from a myriad of inspection instruments used for hole/ countersink assessment and diagnostics would unify the global supply base.

Figure 1: Delamination point cloud resulting from a noncontact laser scan.

across the airframe assembly landscape, automated fasten- ing has been limited due to the inability of current inspection gages and processes to provide the needed diagnostics to “approve” a hole for automated fastener installation. Figure 1 shows a delamination point cloud resulting from a noncontact laser scan. The delamination went undetected by currently used conventional gages. Further complicating the application of automated fastening to composite-incorporat- ed assemblies is the requirement for its 100% hole-counter- sink inspection. Figure 2 shows a hole delamination undetected by conventional gages but revealed by a noncontact ring laser derived point cloud. Specifi ed hole/countersink conformance is generally a com- bination of position and D4&P— evaluation of Dimension, Depth, Damage, Debris, and Perpen- dicularity. In aerospace vernacular perpendicularity is referred to as “normality” or “normal to surface.” The defi nition of the breadth and depth of hole/countersink assess- ment instruments is complicated by specifi c instruments used to evaluate each element of the hole. A countersink depth and angle conformance evaluation may use one instrument and a dimensional hole evaluation another instru- ment, while yet another instrument

A single noncontact gage applied across the global sup- ply chain would also address the increasingly recognized challenges of drilling/countersinking composites by providing fi delity and capabilities not present in current gages. While automated drilling and countersinking continue to spread

is used to evaluate the overall depth of the hole (grip length). The air vehicle manufacturing base and the fi nished air vehicle MRO industry are awash in the variety and complexity of the hole/countersink instruments used today. In addition, current devices have limited or no ability to collect data to populate a knowledge base for analytical assessment and evaluation to improve fi t-up at assembly. A device that can satisfy the full range of D4&P criteria and provide a full evaluation of the composite material and liquid shim condition simultaneously—while also collecting data to populate a knowledge base to facilitate analytics—provides a new disruptive technology to air vehicle makers.

Laser Bond-Line Inspection The inhibitor to a bonded structure airplane sans fasten- ers is the absence of technologies to evaluate the bond-line

140 — Aerospace & Defense Manufacturing 2015

Image courtesy United Sciences.

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