1 00:00:21,370 --> 00:00:18,550 okay we'll take a look at this furnace 2 00:00:24,670 --> 00:00:21,380 for checking the carbon content and you 3 00:00:28,300 --> 00:00:24,680 see this is just an ordinary induction 4 00:00:31,750 --> 00:00:28,310 coil put the stuff in there heat it up 5 00:00:35,880 --> 00:00:31,760 to about 2600 degrees with oxygen and it 6 00:00:38,619 --> 00:00:35,890 will burn and then you can proceed now 7 00:00:40,270 --> 00:00:38,629 on the resistance high temperature 8 00:00:44,560 --> 00:00:40,280 furnace which is another one that's used 9 00:00:50,800 --> 00:00:44,570 you have carbide or moly die silicide 10 00:00:52,930 --> 00:00:50,810 elements then the accelerators use you 11 00:00:56,830 --> 00:00:52,940 have a catalysts in it and then you can 12 00:00:58,990 --> 00:00:56,840 detect the separated gases by one of the 13 00:01:00,880 --> 00:00:59,000 two detection systems that we had 14 00:01:04,229 --> 00:01:00,890 previously mentioned that provide a 15 00:01:07,060 --> 00:01:04,239 specific and consistent signal and 16 00:01:09,609 --> 00:01:07,070 process it electronically it's a lot of 17 00:01:13,240 --> 00:01:09,619 a lot of electronic stuff but you can 18 00:01:18,730 --> 00:01:13,250 come up with an answer on the infrared 19 00:01:21,120 --> 00:01:18,740 detection you can apply it on the basis 20 00:01:23,740 --> 00:01:21,130 that various gases can absorb energy 21 00:01:26,850 --> 00:01:23,750 within a specific wavelength of the 22 00:01:31,649 --> 00:01:26,860 infrared spectrum now this is similar to 23 00:01:34,060 --> 00:01:31,659 a scanning electron microscope analysis 24 00:01:35,830 --> 00:01:34,070 when you analyze something and you 25 00:01:38,620 --> 00:01:35,840 actually have a wavelength for a given 26 00:01:42,399 --> 00:01:38,630 element so that you can determine how 27 00:01:45,070 --> 00:01:42,409 much of each one you have in it there on 28 00:01:47,230 --> 00:01:45,080 the thermal conductive detection system 29 00:01:49,810 --> 00:01:47,240 it's based on the principle that each 30 00:01:52,780 --> 00:01:49,820 gas has a distinct capability of 31 00:01:56,499 --> 00:01:52,790 carrying heat from the body so you can 32 00:01:58,899 --> 00:01:56,509 take the carbon dioxide and determine 33 00:02:02,050 --> 00:01:58,909 the thermal conductive chains generated 34 00:02:05,609 --> 00:02:02,060 by it and come up with the amount of 35 00:02:09,550 --> 00:02:05,619 carbon that was expected and in any 36 00:02:11,350 --> 00:02:09,560 sense you can determine then the total 37 00:02:14,970 --> 00:02:11,360 amount of carbon that was in the sample 38 00:02:17,920 --> 00:02:14,980 and get it a an accurate reading on it 39 00:02:21,940 --> 00:02:17,930 now let's go to thread inspection and 40 00:02:25,780 --> 00:02:21,950 this one is something that people talk 41 00:02:27,340 --> 00:02:25,790 about a lot but kind of like politics 42 00:02:30,790 --> 00:02:27,350 they talk about it a lot but 43 00:02:34,330 --> 00:02:30,800 but it's not a lot done so I found out 44 00:02:38,050 --> 00:02:34,340 when I went to checking into it the 45 00:02:39,880 --> 00:02:38,060 common methods of inspection that are 46 00:02:44,530 --> 00:02:39,890 given once again in this Mel handbook 47 00:02:48,990 --> 00:02:44,540 age 28 and are the system's 21 22 and 23 48 00:02:52,480 --> 00:02:49,000 they're also covered in antsy B 1.3 em 49 00:02:56,350 --> 00:02:52,490 now in general the system 21 requires 50 00:02:58,480 --> 00:02:56,360 the least amount of inspection system 22 51 00:03:04,450 --> 00:02:58,490 is an intermediate amount and 23 is the 52 00:03:06,220 --> 00:03:04,460 most stringent and so our each one of 53 00:03:08,110 --> 00:03:06,230 these is practically a separate document 54 00:03:10,330 --> 00:03:08,120 so I'll just try to summarize them a 55 00:03:15,030 --> 00:03:10,340 little bit but one of the things we 56 00:03:20,260 --> 00:03:15,040 found out is that most people just use 57 00:03:25,200 --> 00:03:20,270 system 21 and on system 21 all you're 58 00:03:29,980 --> 00:03:25,210 doing is checking the OD your ID and 59 00:03:32,380 --> 00:03:29,990 using a go/no-go gage anyway some of the 60 00:03:34,570 --> 00:03:32,390 things that you are looking for on 61 00:03:36,460 --> 00:03:34,580 threads now this was up earlier in the 62 00:03:37,630 --> 00:03:36,470 course but nevertheless just to go 63 00:03:41,320 --> 00:03:37,640 through it again to familiarize 64 00:03:42,730 --> 00:03:41,330 ourselves with it here is the the pitch 65 00:03:44,710 --> 00:03:42,740 of the threads the distance between 66 00:03:47,680 --> 00:03:44,720 threads here is that angle which is 67 00:03:50,110 --> 00:03:47,690 usually this alpha 1 alpha 2 the sum of 68 00:03:53,650 --> 00:03:50,120 those normally is 60 degrees on threads 69 00:03:59,500 --> 00:03:53,660 here is your banish cone where you run 70 00:04:02,440 --> 00:03:59,510 out your threads and here is the major 71 00:04:05,470 --> 00:04:02,450 diameter which is the outside rest of 72 00:04:08,620 --> 00:04:05,480 the threads the minor diameter which is 73 00:04:10,630 --> 00:04:08,630 from the diameter at the root and then 74 00:04:12,010 --> 00:04:10,640 the pitch diameter which is a very 75 00:04:14,410 --> 00:04:12,020 important thing and that's of course 76 00:04:17,220 --> 00:04:14,420 where if you mated the threads up 77 00:04:19,960 --> 00:04:17,230 perfectly you would have the same 78 00:04:23,620 --> 00:04:19,970 thickness through the cross-section of 79 00:04:29,140 --> 00:04:23,630 the thread as you do in here as you do 80 00:04:31,420 --> 00:04:29,150 in the mating thread here and here is 81 00:04:36,010 --> 00:04:31,430 here's another one that I wanted to show 82 00:04:37,690 --> 00:04:36,020 you for this reason this is kind of a 83 00:04:40,920 --> 00:04:37,700 close-up that shows the difference 84 00:04:44,640 --> 00:04:40,930 between having an unrated through 85 00:04:48,540 --> 00:04:44,650 and having a radius thread the other 86 00:04:52,620 --> 00:04:48,550 thing is this circle here represents the 87 00:04:55,290 --> 00:04:52,630 pins that are used for measuring the 88 00:04:57,780 --> 00:04:55,300 pitch diameter there's a method to call 89 00:05:00,210 --> 00:04:57,790 the three pin method that they can put 90 00:05:02,129 --> 00:05:00,220 the pins a two on one side one on the 91 00:05:04,350 --> 00:05:02,139 other side but flat plates across 92 00:05:07,469 --> 00:05:04,360 measure it then you go to a table and 93 00:05:09,659 --> 00:05:07,479 you can find out from this table based 94 00:05:11,760 --> 00:05:09,669 on the size thread you're using the 95 00:05:15,240 --> 00:05:11,770 diameter of these pins you can come up 96 00:05:21,629 --> 00:05:15,250 with an accurate reading of the pitch 97 00:05:27,800 --> 00:05:21,639 diameter of the thread now for external 98 00:05:31,140 --> 00:05:27,810 threads system 21 just includes go/no-go 99 00:05:34,409 --> 00:05:31,150 diameter and the major diameter that's 100 00:05:37,080 --> 00:05:34,419 all that they do and you can either 101 00:05:39,420 --> 00:05:37,090 measure this you usually measure it with 102 00:05:43,379 --> 00:05:39,430 what the color ring gauge which is 103 00:05:46,710 --> 00:05:43,389 nothing more than a calibrated thread in 104 00:05:48,690 --> 00:05:46,720 a ring that to replace replace what you 105 00:05:51,240 --> 00:05:48,700 would normally use as a nut and you try 106 00:05:55,710 --> 00:05:51,250 to thread the fastener into it if it 107 00:05:57,870 --> 00:05:55,720 goes it's fine you turn the the use the 108 00:05:59,670 --> 00:05:57,880 other one the no go and if it doesn't go 109 00:06:02,760 --> 00:05:59,680 in that one that means you are within 110 00:06:06,150 --> 00:06:02,770 the acceptable limits it doesn't tell 111 00:06:07,650 --> 00:06:06,160 you exactly what your dimensions are but 112 00:06:10,560 --> 00:06:07,660 it just tells you that the thing will 113 00:06:15,480 --> 00:06:10,570 work so that's called the the functional 114 00:06:17,820 --> 00:06:15,490 diameter if you will system 22 includes 115 00:06:20,250 --> 00:06:17,830 the system 21 measurements plus pitch 116 00:06:27,629 --> 00:06:20,260 diameter you can either measure it with 117 00:06:33,600 --> 00:06:27,639 a pitch micrometer which is a micrometer 118 00:06:36,360 --> 00:06:33,610 that has a grooved head on one end of it 119 00:06:39,390 --> 00:06:36,370 that fits over a thread then you have a 120 00:06:44,270 --> 00:06:39,400 pin type on the other one that fits in a 121 00:06:49,589 --> 00:06:44,280 thread and you can span this across the 122 00:06:54,529 --> 00:06:49,599 OD of the threaded area and get a 123 00:06:57,269 --> 00:06:54,539 reading which will give you the actual 124 00:06:59,399 --> 00:06:57,279 diameter pitch diameter that you want 125 00:07:00,989 --> 00:06:59,409 and you can look on the table in and see 126 00:07:04,679 --> 00:07:00,999 whether it's within the tolerances that 127 00:07:08,699 --> 00:07:04,689 you want the thread groove diameter 128 00:07:11,819 --> 00:07:08,709 which is the measurement between threads 129 00:07:14,069 --> 00:07:11,829 at the pitch diameter point the 130 00:07:17,699 --> 00:07:14,079 functional diameter which you get from 131 00:07:20,719 --> 00:07:17,709 up here with a go/no-go gauge leading 132 00:07:23,669 --> 00:07:20,729 flank angles and that's just go no go 133 00:07:27,659 --> 00:07:23,679 minor diameter and then you can measure 134 00:07:30,329 --> 00:07:27,669 the route profile but I found that that 135 00:07:34,699 --> 00:07:30,339 is not done that much unless somebody 136 00:07:37,589 --> 00:07:34,709 insists that it's done system 23 137 00:07:39,629 --> 00:07:37,599 includes all the others plus now you get 138 00:07:43,739 --> 00:07:39,639 into the roundness of the pitch cylinder 139 00:07:46,129 --> 00:07:43,749 itself the taper of it in other words if 140 00:07:50,189 --> 00:07:46,139 you take the whole thing as a cylinder 141 00:07:54,119 --> 00:07:50,199 do you have a taper on it is it round or 142 00:07:56,429 --> 00:07:54,129 is it lopsided the cumulative thread 143 00:07:58,949 --> 00:07:56,439 form variation going through the thing 144 00:08:01,559 --> 00:07:58,959 and checking to see whether it varies 145 00:08:03,869 --> 00:08:01,569 any from one end to the other the 146 00:08:07,949 --> 00:08:03,879 leading helix angle variation the flank 147 00:08:11,519 --> 00:08:07,959 angle variation on the threads run out 148 00:08:14,069 --> 00:08:11,529 an even surface texture now surface 149 00:08:17,159 --> 00:08:14,079 texture on the threads usually is not a 150 00:08:19,279 --> 00:08:17,169 problem but you could measure can see it 151 00:08:21,839 --> 00:08:19,289 would only be if the thing had been 152 00:08:25,739 --> 00:08:21,849 coated with some sort of a coating that 153 00:08:28,199 --> 00:08:25,749 was not electronically directly 154 00:08:30,239 --> 00:08:28,209 deposited in other words if you had 155 00:08:33,980 --> 00:08:30,249 galvanized threads then you could have 156 00:08:36,629 --> 00:08:33,990 have a problem because you'd have extra 157 00:08:38,670 --> 00:08:36,639 plating material in the threads and 158 00:08:44,179 --> 00:08:38,680 after you've gone through all of these 159 00:08:46,470 --> 00:08:44,189 things this is just four threads 160 00:08:48,720 --> 00:08:46,480 nothing's been done on on the rest of 161 00:08:50,249 --> 00:08:48,730 the fastener so you could have a huge 162 00:08:52,259 --> 00:08:50,259 crack in and it wouldn't make any 163 00:08:53,790 --> 00:08:52,269 difference because if you passed 164 00:08:55,759 --> 00:08:53,800 everything else the guys say well I 165 00:08:58,170 --> 00:08:55,769 inspected the threads and they're good 166 00:09:02,470 --> 00:08:58,180 so you still have to look to see if 167 00:09:08,890 --> 00:09:05,500 now for internal threads you have the go 168 00:09:11,830 --> 00:09:08,900 no-go and the minor diameter and that's 169 00:09:15,700 --> 00:09:11,840 about all it's usually check the the go 170 00:09:17,890 --> 00:09:15,710 no-go gauge one end fits the other one 171 00:09:20,590 --> 00:09:17,900 doesn't and then with the minor diameter 172 00:09:22,420 --> 00:09:20,600 you use a regular plug to slip in to 173 00:09:26,920 --> 00:09:22,430 check to see if it is okay 174 00:09:29,320 --> 00:09:26,930 then you move to the system 22 it 175 00:09:31,540 --> 00:09:29,330 includes the 21 and then you go for 176 00:09:34,060 --> 00:09:31,550 minimum material pitch diameter a thread 177 00:09:36,610 --> 00:09:34,070 groove diameter and the angles on the 178 00:09:39,610 --> 00:09:36,620 threads but since this is internal 179 00:09:43,320 --> 00:09:39,620 thread this is hard to do so usually 180 00:09:47,560 --> 00:09:43,330 people don't do it now here's a go/no-go 181 00:09:49,900 --> 00:09:47,570 gauge one side will thread in if it's in 182 00:09:53,950 --> 00:09:49,910 normal tolerance the other side won't 183 00:09:57,580 --> 00:09:53,960 and this is used to check internal 184 00:09:59,440 --> 00:09:57,590 threaded or tapped holes and that's the 185 00:10:02,950 --> 00:09:59,450 only usually that's about the only 186 00:10:06,870 --> 00:10:02,960 acceptance that people use I found here 187 00:10:10,150 --> 00:10:06,880 is the go no-go pen for just checking 188 00:10:15,270 --> 00:10:10,160 the minimum diameter in a threaded hole 189 00:10:18,550 --> 00:10:15,280 to see if it is within tolerances and so 190 00:10:22,950 --> 00:10:18,560 this one is fine if it and this one's 191 00:10:25,480 --> 00:10:22,960 not supposed to go it is bigger than the 192 00:10:32,310 --> 00:10:25,490 tolerance bandwidth will a lot would 193 00:10:35,620 --> 00:10:32,320 allow it the hole to be then for the 194 00:10:37,630 --> 00:10:35,630 system 23 it includes the the others 195 00:10:42,270 --> 00:10:37,640 plus the roundness of the pitch cylinder 196 00:10:46,900 --> 00:10:42,280 and they taper the pitch cylinder and 197 00:10:49,840 --> 00:10:46,910 but still nothing on the internal thread 198 00:10:52,180 --> 00:10:49,850 radius regardless of what you call out 199 00:10:54,520 --> 00:10:52,190 it's not measured unless you would go in 200 00:10:57,250 --> 00:10:54,530 and tell somebody you have to have it 201 00:11:01,960 --> 00:10:57,260 and then as as I mentioned earlier using 202 00:11:04,180 --> 00:11:01,970 this dental plaster type stuff you can 203 00:11:06,310 --> 00:11:04,190 you can actually cast it and then take 204 00:11:07,780 --> 00:11:06,320 it put it on an optical comparator to 205 00:11:11,480 --> 00:11:07,790 see whether you have the radius that you 206 00:11:19,220 --> 00:11:15,829 so now we move on and and to the the 207 00:11:21,290 --> 00:11:19,230 cold hard facts of life that even though 208 00:11:23,780 --> 00:11:21,300 you've inspected the heck out of the 209 00:11:25,429 --> 00:11:23,790 threads if with these three systems if 210 00:11:26,540 --> 00:11:25,439 you run it through all of them 211 00:11:29,960 --> 00:11:26,550 you still haven't looked for 212 00:11:36,679 --> 00:11:29,970 manufacturing defects for defects in the 213 00:11:38,929 --> 00:11:36,689 the threads FF s eighty-six federal spec 214 00:11:41,869 --> 00:11:38,939 gives examples of acceptable and 215 00:11:46,759 --> 00:11:41,879 unacceptable defects and we'll look at 216 00:11:48,829 --> 00:11:46,769 those and subsequent figures and you 217 00:11:51,350 --> 00:11:48,839 will note that the acceptance of the 218 00:11:53,540 --> 00:11:51,360 thread defects becomes more critical as 219 00:11:56,299 --> 00:11:53,550 the fastener strength increases and the 220 00:11:59,030 --> 00:11:56,309 ductility decreases so there has to be 221 00:12:03,109 --> 00:11:59,040 some engineering judgment exercised on 222 00:12:05,660 --> 00:12:03,119 it now here's one of the things threads 223 00:12:09,169 --> 00:12:05,670 should have no laps or seams at the root 224 00:12:11,900 --> 00:12:09,179 or the flanks the here's the root here's 225 00:12:14,749 --> 00:12:11,910 the flank of the thread and so in 226 00:12:18,470 --> 00:12:14,759 general what you're saying on this is 227 00:12:21,289 --> 00:12:18,480 any defects below the pitch diameter 228 00:12:23,929 --> 00:12:21,299 because you're loading this part of the 229 00:12:26,809 --> 00:12:23,939 thread a lot more than you are this part 230 00:12:29,869 --> 00:12:26,819 so anything below the pitch diameter in 231 00:12:33,079 --> 00:12:29,879 the way of a defect a noticeable defect 232 00:12:35,869 --> 00:12:33,089 you're not going to accept when you get 233 00:12:39,259 --> 00:12:35,879 things above the pitch diameter or 234 00:12:41,210 --> 00:12:39,269 outboard of it here now you can accept 235 00:12:44,600 --> 00:12:41,220 more defects there because it is more 236 00:12:47,499 --> 00:12:44,610 likely loaded but even so there are 237 00:12:51,049 --> 00:12:47,509 limits on how much you can accept on it 238 00:12:52,369 --> 00:12:51,059 so so it once again you look at it and 239 00:12:55,639 --> 00:12:52,379 if you find too many cracks in a 240 00:12:58,129 --> 00:12:55,649 fastener you really should reject it now 241 00:13:01,069 --> 00:12:58,139 here's something that is a lesser 242 00:13:02,809 --> 00:13:01,079 problem it just looks bad having little 243 00:13:04,489 --> 00:13:02,819 nicks or something like that as long as 244 00:13:07,359 --> 00:13:04,499 it's not a crack that's just a nick from 245 00:13:09,530 --> 00:13:07,369 handling and it doesn't affect the 246 00:13:11,900 --> 00:13:09,540 functioning of the threads you could 247 00:13:15,559 --> 00:13:11,910 probably accept a nick on the outside 248 00:13:18,379 --> 00:13:15,569 surface of the threads now here is 249 00:13:23,650 --> 00:13:18,389 another method of thread inspection a 250 00:13:25,220 --> 00:13:23,660 laser inspection method most 251 00:13:27,950 --> 00:13:25,230 manufacturing facility 252 00:13:33,250 --> 00:13:27,960 would not have this at all because it is 253 00:13:35,830 --> 00:13:33,260 a set up with a full computer printout 254 00:13:39,560 --> 00:13:35,840 availability and I think cost about 255 00:13:43,280 --> 00:13:39,570 $100,000 so you wouldn't find them in 256 00:13:46,450 --> 00:13:43,290 your normal inspection shop but it is a 257 00:13:51,350 --> 00:13:46,460 very accurate method of checking threads 258 00:13:55,430 --> 00:13:51,360 it uses laser triangulation sensors and 259 00:13:58,640 --> 00:13:55,440 a motion sensor to digitize the thread 260 00:14:02,840 --> 00:13:58,650 and form and it's a non-contact method 261 00:14:04,940 --> 00:14:02,850 you're using a laser beam and the the 262 00:14:07,280 --> 00:14:04,950 measurements are made by comparing the 263 00:14:09,650 --> 00:14:07,290 data obtained by laser scanning the 264 00:14:11,840 --> 00:14:09,660 thread to a perfect mating part that has 265 00:14:17,480 --> 00:14:11,850 been mathematically created in software 266 00:14:19,160 --> 00:14:17,490 and the thread axis is the method you 267 00:14:23,500 --> 00:14:19,170 use for spinning it around so you can 268 00:14:29,470 --> 00:14:23,510 check it at different points now these 269 00:14:31,940 --> 00:14:29,480 machines though are used for inspecting 270 00:14:33,650 --> 00:14:31,950 inspection equipment because they're 271 00:14:36,290 --> 00:14:33,660 accurate enough for instance you can use 272 00:14:40,160 --> 00:14:36,300 them to inspect the thread plug gauges 273 00:14:42,980 --> 00:14:40,170 and go/no-go gauges dyes and taps and 274 00:14:45,830 --> 00:14:42,990 they can handle parts up to six inches 275 00:14:48,920 --> 00:14:45,840 in diameter and four to 64 threads per 276 00:14:51,620 --> 00:14:48,930 inch now it's a time consuming thing so 277 00:14:56,600 --> 00:14:51,630 the the places that you would use it as 278 00:14:59,180 --> 00:14:56,610 say you don't have very many bolts 279 00:15:03,020 --> 00:14:59,190 holding an engine on a plane so on a 747 280 00:15:05,240 --> 00:15:03,030 if you wanted to inspect the super high 281 00:15:07,580 --> 00:15:05,250 strength alloy steel bolts that are 282 00:15:09,410 --> 00:15:07,590 holding it on you would run them through 283 00:15:14,060 --> 00:15:09,420 an inspection procedure like this check 284 00:15:18,260 --> 00:15:14,070 every one up because they're your it's a 285 00:15:20,360 --> 00:15:18,270 super critical application on the figure 286 00:15:23,540 --> 00:15:20,370 seventy eight is a picture of this one 287 00:15:26,750 --> 00:15:23,550 you set the fastener down on the the 288 00:15:30,860 --> 00:15:26,760 head you can turn it you scan the thread 289 00:15:38,180 --> 00:15:30,870 in and because this is on a rotary 290 00:15:42,290 --> 00:15:38,190 spindle here and once you you scan it 291 00:15:47,139 --> 00:15:42,300 then the the table will index to another 292 00:15:49,699 --> 00:15:47,149 location then you get a thread profile 293 00:15:54,139 --> 00:15:49,709 that you can compare it to a perfect 294 00:15:56,210 --> 00:15:54,149 thread so if you're really doing 295 00:16:00,230 --> 00:15:56,220 something critical this will work in 296 00:16:03,199 --> 00:16:00,240 fact I believe marshal I think got one 297 00:16:06,679 --> 00:16:03,209 of these machines because they wanted to 298 00:16:11,769 --> 00:16:06,689 use it for checking some of the super 299 00:16:13,670 --> 00:16:11,779 critical flight Hardware for shuttle and 300 00:16:16,610 --> 00:16:13,680 installations that they were putting 301 00:16:18,769 --> 00:16:16,620 together there so I went looked at him 302 00:16:21,650 --> 00:16:18,779 there's a company here in West Lake I 303 00:16:25,610 --> 00:16:21,660 believe handles them and they do work 304 00:16:28,790 --> 00:16:25,620 well except that you would not inspect 305 00:16:30,619 --> 00:16:28,800 something that was just an ordinary 306 00:16:34,819 --> 00:16:30,629 production part because it's too eh too 307 00:16:37,699 --> 00:16:34,829 time-consuming too expensive now there 308 00:16:41,449 --> 00:16:37,709 have been various discussions through 309 00:16:44,889 --> 00:16:41,459 the years on how variation in pitch 310 00:16:49,550 --> 00:16:44,899 diameter on a fastener can do them in 311 00:16:51,800 --> 00:16:49,560 and I guess this arguments been going on 312 00:16:54,050 --> 00:16:51,810 for 30 or 40 years or something like 313 00:16:57,829 --> 00:16:54,060 that so the industrial fasteners 314 00:17:01,189 --> 00:16:57,839 Institute here in Cleveland initiated a 315 00:17:03,829 --> 00:17:01,199 research effort in 1993 to manufacture 316 00:17:06,529 --> 00:17:03,839 measure and test a bunch of fasteners 317 00:17:09,230 --> 00:17:06,539 that were deliberately made out of 318 00:17:12,649 --> 00:17:09,240 tolerance on pitch diameter just to see 319 00:17:14,899 --> 00:17:12,659 how bad it was and they put out an 320 00:17:19,299 --> 00:17:14,909 article on that in mechanical 321 00:17:23,539 --> 00:17:19,309 engineering in the December 1996 edition 322 00:17:26,960 --> 00:17:23,549 and the conclusion was the variations in 323 00:17:28,820 --> 00:17:26,970 pitch diameter don't have a very big 324 00:17:31,279 --> 00:17:28,830 effect on the joint strength fatigue 325 00:17:33,020 --> 00:17:31,289 life and clamping performance in other 326 00:17:37,039 --> 00:17:33,030 words it can be out of Tolerance quite a 327 00:17:39,470 --> 00:17:37,049 bit and still pass the standard tensile 328 00:17:42,860 --> 00:17:39,480 and proof load requirements which kind 329 00:17:44,060 --> 00:17:42,870 of surprised a lot of people I I thought 330 00:17:46,460 --> 00:17:44,070 it would have more effect than that 331 00:17:49,360 --> 00:17:46,470 because varying the pitch diameter of 332 00:17:51,490 --> 00:17:49,370 course you are loading your threads 333 00:17:55,260 --> 00:17:51,500 unevenly 334 00:17:58,150 --> 00:17:55,270 but evidently what happens is that 335 00:18:01,480 --> 00:17:58,160 though you are loading them unevenly 336 00:18:03,760 --> 00:18:01,490 you're spreading the load around of 337 00:18:04,900 --> 00:18:03,770 where you get more yielding and it'll 338 00:18:08,200 --> 00:18:04,910 still carry the load 339 00:18:11,380 --> 00:18:08,210 so they some of the people who did the 340 00:18:15,940 --> 00:18:11,390 testing were surprised if it was that it 341 00:18:17,950 --> 00:18:15,950 was that good now moving to the other 342 00:18:22,990 --> 00:18:17,960 parts of the fastener the head and shank 343 00:18:24,940 --> 00:18:23,000 inspection there's one of the places 344 00:18:27,460 --> 00:18:24,950 where you can really get in front into 345 00:18:31,810 --> 00:18:27,470 trouble with a fastener is having any 346 00:18:33,940 --> 00:18:31,820 kind of a defect in the Phillip radius 347 00:18:37,240 --> 00:18:33,950 under the head because since that is one 348 00:18:40,600 --> 00:18:37,250 of your highest loaded areas any kind of 349 00:18:46,120 --> 00:18:40,610 a crack there usually will propagate to 350 00:18:48,640 --> 00:18:46,130 cause failure so a list of defects and 351 00:18:54,010 --> 00:18:48,650 their definitions are given an ASTM F 352 00:18:59,130 --> 00:18:54,020 788 that is for the fasteners and nut 353 00:19:01,930 --> 00:18:59,140 inspection is covered in ASTM F 812 354 00:19:05,320 --> 00:19:01,940 there are very similar methods of 355 00:19:10,210 --> 00:19:05,330 inspections so I'll cover primarily the 356 00:19:16,260 --> 00:19:10,220 ones here just for fasteners and leave 357 00:19:23,260 --> 00:19:19,350 quench cracks are caused by excessively 358 00:19:29,650 --> 00:19:23,270 high thermal and transformation stresses 359 00:19:32,170 --> 00:19:29,660 during heat treatment and so getting one 360 00:19:35,530 --> 00:19:32,180 of those means that you've got problems 361 00:19:42,760 --> 00:19:35,540 with the material so you could have a 362 00:19:46,930 --> 00:19:42,770 problem with it so in general quench 363 00:19:49,290 --> 00:19:46,940 cracks of any detectable size by visual 364 00:19:52,360 --> 00:19:49,300 inspection make the fastener 365 00:19:57,630 --> 00:19:52,370 unacceptable and here's another one this 366 00:20:01,330 --> 00:19:57,640 is a pet peeve of mine socket head depth 367 00:20:04,030 --> 00:20:01,340 even though if you go to any of the Aunt 368 00:20:07,300 --> 00:20:04,040 suspects and 369 00:20:08,380 --> 00:20:07,310 or mil spects any of these on socket 370 00:20:11,500 --> 00:20:08,390 head fasteners 371 00:20:14,770 --> 00:20:11,510 they give dimensions for the depth of 372 00:20:20,250 --> 00:20:14,780 socket but I have yet to find anybody 373 00:20:25,840 --> 00:20:20,260 that's ever checked one we had a problem 374 00:20:29,410 --> 00:20:25,850 here a couple years ago with some na s 375 00:20:32,310 --> 00:20:29,420 fasteners that the heads popped off of 376 00:20:36,990 --> 00:20:32,320 them in a wind tunnel installation and 377 00:20:42,480 --> 00:20:37,000 when we looked at him the socket depth 378 00:20:45,370 --> 00:20:42,490 was too deep well see in a socket head 379 00:20:48,070 --> 00:20:45,380 if that depth gets too deep you wind up 380 00:20:51,120 --> 00:20:48,080 with a small annulus of area there is 381 00:20:53,650 --> 00:20:51,130 all you have left if you get below the 382 00:20:56,830 --> 00:20:53,660 the bottom of the head with the socket 383 00:21:01,240 --> 00:20:56,840 depth you're in trouble and that's what 384 00:21:06,100 --> 00:21:01,250 was happening and although everybody 385 00:21:13,080 --> 00:21:06,110 talks about him there like UFOs no 386 00:21:22,350 --> 00:21:17,640 here are some examples of the things in 387 00:21:26,310 --> 00:21:22,360 head and shank inspection and cracks in 388 00:21:29,460 --> 00:21:26,320 general these are quenched cracks which 389 00:21:34,830 --> 00:21:29,470 you can see can happen in the heads in 390 00:21:36,210 --> 00:21:34,840 the shank around the top of the head but 391 00:21:38,850 --> 00:21:36,220 here's the one that really gets you if 392 00:21:42,000 --> 00:21:38,860 you have any cracks here in this radius 393 00:21:42,750 --> 00:21:42,010 fill it radius under the head you're in 394 00:21:50,880 --> 00:21:42,760 real trouble 395 00:21:53,640 --> 00:21:50,890 so that is from that FF s 86 or ASTM 788 396 00:21:57,780 --> 00:21:53,650 I don't remember now which forging 397 00:22:01,050 --> 00:21:57,790 cracks now remember I mentioned on 398 00:22:04,830 --> 00:22:01,060 fasteners that the higher strength ones 399 00:22:08,850 --> 00:22:04,840 usually have forged heads because you 400 00:22:11,580 --> 00:22:08,860 don't want to have the discontinuity in 401 00:22:14,940 --> 00:22:11,590 green flow at the particularly tough 402 00:22:17,790 --> 00:22:14,950 illustrate Phillip radius so you can get 403 00:22:19,710 --> 00:22:17,800 forging cracks during the cut off or 404 00:22:21,870 --> 00:22:19,720 forging operation or even cold forging 405 00:22:24,240 --> 00:22:21,880 you can get some on the material if the 406 00:22:26,970 --> 00:22:24,250 material is a little bit too hard when 407 00:22:29,220 --> 00:22:26,980 you're when you're cold forging it and 408 00:22:31,680 --> 00:22:29,230 these are located on the top of the head 409 00:22:36,330 --> 00:22:31,690 or on the raised periphery around the 410 00:22:38,940 --> 00:22:36,340 indented head bolts and screws and you 411 00:22:41,370 --> 00:22:38,950 can you can except some of them if they 412 00:22:43,710 --> 00:22:41,380 are very very slight so that they're 413 00:22:47,790 --> 00:22:43,720 more or less a street grid than a crack 414 00:22:52,890 --> 00:22:47,800 just just a indentation mark as long as 415 00:22:55,080 --> 00:22:52,900 they have a very shallow depth but once 416 00:22:57,510 --> 00:22:55,090 again depends on the criticality of the 417 00:23:03,390 --> 00:22:57,520 installation as to how much you accept 418 00:23:06,440 --> 00:23:03,400 in the cracks here's one that shows a 419 00:23:10,050 --> 00:23:06,450 forging track on the top of the head and 420 00:23:15,180 --> 00:23:10,060 if you look at those a limits on depth 421 00:23:20,430 --> 00:23:15,190 you'll see that if you take 0.04 times 422 00:23:23,460 --> 00:23:20,440 the diameter or something like that for 423 00:23:26,370 --> 00:23:23,470 a bolt that is a 1/4 inch in diameter 424 00:23:26,700 --> 00:23:26,380 that's a pretty shallow crack it's 425 00:23:29,269 --> 00:23:26,710 enough 426 00:23:32,789 --> 00:23:29,279 more than a streak that you can see so 427 00:23:35,220 --> 00:23:32,799 so so that type of crack wouldn't so 428 00:23:41,220 --> 00:23:35,230 called crack would be acceptable now 429 00:23:44,909 --> 00:23:41,230 here is a fear burst and that's an open 430 00:23:51,889 --> 00:23:44,919 break in the in the metal from forming 431 00:23:55,769 --> 00:23:51,899 and you can you can accept these only if 432 00:23:57,720 --> 00:23:55,779 there is it's in the flats and extends 433 00:23:59,279 --> 00:23:57,730 in the crown chamfer circle at the top 434 00:24:03,419 --> 00:23:59,289 of the head or in the under head bearing 435 00:24:05,519 --> 00:24:03,429 circle and none of you located at the 436 00:24:07,769 --> 00:24:05,529 intersection of the wrenching flats that 437 00:24:10,230 --> 00:24:07,779 reduces the width across corners below 438 00:24:15,000 --> 00:24:10,240 its specified minimum in other words you 439 00:24:18,480 --> 00:24:15,010 can you can accept some of these once 440 00:24:21,210 --> 00:24:18,490 again if they are so shallow that they 441 00:24:25,289 --> 00:24:21,220 don't look like a crack itself but just 442 00:24:27,570 --> 00:24:25,299 beware of them because the this is one 443 00:24:29,220 --> 00:24:27,580 here and you see this is really this one 444 00:24:31,950 --> 00:24:29,230 amounts to just a little dent on the 445 00:24:34,049 --> 00:24:31,960 corner of the flat so so that would 446 00:24:36,889 --> 00:24:34,059 probably be acceptable as long as it did 447 00:24:39,720 --> 00:24:36,899 not look like a crack itself 448 00:24:43,019 --> 00:24:39,730 Foles that's the kind of a doubling over 449 00:24:46,049 --> 00:24:43,029 material which occurs during the forging 450 00:24:48,919 --> 00:24:46,059 operation and usually occurs near the 451 00:24:53,570 --> 00:24:48,929 intersection of diameter changes 452 00:24:56,460 --> 00:24:53,580 particularly with non circular heads and 453 00:25:00,419 --> 00:24:56,470 the only problem that you look at with 454 00:25:02,430 --> 00:25:00,429 that is you can allow them in some cases 455 00:25:08,760 --> 00:25:02,440 at the corners but you don't want any 456 00:25:12,510 --> 00:25:08,770 near the Phillip radius of the fastener 457 00:25:15,899 --> 00:25:12,520 in in this area here now here you're 458 00:25:21,990 --> 00:25:15,909 getting it because you're trying to form 459 00:25:23,669 --> 00:25:22,000 a round cross-section in the square so 460 00:25:26,669 --> 00:25:23,679 it's kind of hard to form that without 461 00:25:31,350 --> 00:25:26,679 getting some deformation and burgers 462 00:25:34,110 --> 00:25:31,360 around it so so once again you look to 463 00:25:39,730 --> 00:25:34,120 see where it's at and evaluate it before 464 00:25:48,200 --> 00:25:44,060 now seams are usually in the raw 465 00:25:51,830 --> 00:25:48,210 material before forming and they're 466 00:25:54,380 --> 00:25:51,840 pretty straight and see seams are 467 00:25:58,010 --> 00:25:54,390 acceptable because usually they're 468 00:26:00,590 --> 00:25:58,020 they're not a crack per se and they're 469 00:26:02,930 --> 00:26:00,600 they're shallow and don't have and have 470 00:26:07,550 --> 00:26:02,940 a pretty good radius now see here if you 471 00:26:13,430 --> 00:26:07,560 look at this it's point O three times 472 00:26:15,410 --> 00:26:13,440 the diameter so if you go with a 1/2 473 00:26:16,820 --> 00:26:15,420 inch fastener you see you still have 474 00:26:19,790 --> 00:26:16,830 something there that you would have 475 00:26:26,000 --> 00:26:19,800 trouble even seeing it's so shallow so 476 00:26:28,670 --> 00:26:26,010 so that would be okay surface voids you 477 00:26:33,230 --> 00:26:28,680 can get this in a material due to the 478 00:26:35,870 --> 00:26:33,240 way it's formed but you got to watch if 479 00:26:37,280 --> 00:26:35,880 it's it indicates there's probably 480 00:26:40,010 --> 00:26:37,290 something wrong with the chemistry of 481 00:26:43,550 --> 00:26:40,020 the material if you're getting a lot of 482 00:26:47,840 --> 00:26:43,560 voids in the surface and once again the 483 00:26:50,780 --> 00:26:47,850 void depth look at the amount here that 484 00:26:53,030 --> 00:26:50,790 you're allowed point O two times the 485 00:26:55,780 --> 00:26:53,040 shank diameter that's still or ten 486 00:26:59,600 --> 00:26:55,790 thousandths all right at ten thousandths 487 00:27:04,520 --> 00:26:59,610 void is a pretty shallow one and then 488 00:27:10,370 --> 00:27:04,530 the this one I would look at if you had 489 00:27:13,430 --> 00:27:10,380 void areas that are that high a 490 00:27:15,410 --> 00:27:13,440 percentage of the under head bearing 491 00:27:18,590 --> 00:27:15,420 area I would look at the material to see 492 00:27:20,570 --> 00:27:18,600 whether I had the right material 493 00:27:24,410 --> 00:27:20,580 chemistry or not and whether I'd want to 494 00:27:28,850 --> 00:27:24,420 reject it on that basis now tool marks 495 00:27:31,490 --> 00:27:28,860 Nicks and gouges they're permitted on 496 00:27:34,850 --> 00:27:31,500 the under head surface but you notice 497 00:27:39,940 --> 00:27:34,860 the restriction on that astonish your 498 00:27:44,420 --> 00:27:39,950 micro inch surface roughness does not go 499 00:27:48,620 --> 00:27:44,430 under the 125 well you see a 125 is 500 00:27:52,250 --> 00:27:48,630 really not not too rough it's a rough 501 00:27:54,830 --> 00:27:52,260 machining surface and 502 00:27:56,810 --> 00:27:54,840 so the the other place that you would 503 00:27:59,390 --> 00:27:56,820 look at if the head is banged up a 504 00:28:02,330 --> 00:27:59,400 little bit and it's on the corners out 505 00:28:05,770 --> 00:28:02,340 of the way you could probably accept it 506 00:28:10,310 --> 00:28:05,780 as long as the plating surface is not 507 00:28:11,780 --> 00:28:10,320 gouged now plating inspections this is 508 00:28:15,890 --> 00:28:11,790 another this is another one of those 509 00:28:18,730 --> 00:28:15,900 that we talked about and people don't do 510 00:28:21,440 --> 00:28:18,740 other than look at it same yep that's 511 00:28:24,380 --> 00:28:21,450 that's a gold color so it means it's got 512 00:28:28,220 --> 00:28:24,390 chromate in it and don't see that it's 513 00:28:31,610 --> 00:28:28,230 got up too much so guess it's alright 514 00:28:33,980 --> 00:28:31,620 most of the platings we've discussed 515 00:28:36,230 --> 00:28:33,990 earlier and but we didn't discuss 516 00:28:41,900 --> 00:28:36,240 discuss anything on the inspection of 517 00:28:44,000 --> 00:28:41,910 them so we'll kind of limit our coverage 518 00:28:46,460 --> 00:28:44,010 here to zinc and cadmium platings 519 00:28:51,890 --> 00:28:46,470 except for just visually looking at the 520 00:28:54,680 --> 00:28:51,900 things and the substitution of zinc for 521 00:28:59,270 --> 00:28:54,690 cadmium and using a dye and amassed the 522 00:29:04,549 --> 00:28:59,280 color is a common way to cheat it's done 523 00:29:08,390 --> 00:29:04,559 off a lot and because the the chromate 524 00:29:11,060 --> 00:29:08,400 dye that you use usually you look at it 525 00:29:15,020 --> 00:29:11,070 and the fasteners are gold type color 526 00:29:18,260 --> 00:29:15,030 and it you can't tell by looking at it 527 00:29:22,159 --> 00:29:18,270 whether it's a zinc or cadmium so the 528 00:29:26,870 --> 00:29:22,169 only way to find out is actually to run 529 00:29:31,669 --> 00:29:26,880 a test now you can do two different 530 00:29:33,289 --> 00:29:31,679 things on it you can destroy the plating 531 00:29:35,330 --> 00:29:33,299 on a fastener and take a chunk of the 532 00:29:38,530 --> 00:29:35,340 plating and go put it in a scanning 533 00:29:42,320 --> 00:29:38,540 electron microscope and see whether it's 534 00:29:43,730 --> 00:29:42,330 mostly cadmium are mostly zinc but then 535 00:29:52,690 --> 00:29:43,740 there are other things that you can do 536 00:29:55,010 --> 00:29:52,700 here too then in inspecting now zinc is 537 00:29:58,580 --> 00:29:55,020 usually covered by ASTM 538 00:30:04,789 --> 00:29:58,590 B 633 and cadmium is covered by a 539 00:30:06,080 --> 00:30:04,799 federal spec uqp 416 you can do process 540 00:30:10,130 --> 00:30:06,090 control inspection 541 00:30:12,710 --> 00:30:10,140 and the plating outfits are supposed to 542 00:30:15,560 --> 00:30:12,720 do that and most of them do so that they 543 00:30:17,720 --> 00:30:15,570 control the amount of additives they put 544 00:30:19,760 --> 00:30:17,730 in if their bath gets tired they can add 545 00:30:26,870 --> 00:30:19,770 chemicals to it and so on and take new 546 00:30:29,170 --> 00:30:26,880 readings determine how it is plating and 547 00:30:31,700 --> 00:30:29,180 you can do a lot sampling inspection 548 00:30:36,500 --> 00:30:31,710 visual inspection and plating thickness 549 00:30:38,360 --> 00:30:36,510 tests there is in fact I believe a guy 550 00:30:41,330 --> 00:30:38,370 from here at Lewis just recently 551 00:30:45,230 --> 00:30:41,340 developed a method of inspecting the 552 00:30:47,870 --> 00:30:45,240 thickness of plating Dan Roth works over 553 00:30:49,550 --> 00:30:47,880 in M and s or the what used to be M and 554 00:30:52,310 --> 00:30:49,560 s I believe developed one but there are 555 00:30:54,410 --> 00:30:52,320 methods of looking at and I think 556 00:30:58,820 --> 00:30:54,420 ultrasonically measuring plating 557 00:31:01,190 --> 00:30:58,830 thickness on materials you can do an 558 00:31:03,590 --> 00:31:01,200 adhesion test you can do a corrosion 559 00:31:06,560 --> 00:31:03,600 test and you do hydrogen embrittlement 560 00:31:11,060 --> 00:31:06,570 test although the hydrogen embrittlement 561 00:31:13,280 --> 00:31:11,070 test you can get that with both zinc and 562 00:31:17,270 --> 00:31:13,290 cadmium so that in itself would not be 563 00:31:22,430 --> 00:31:17,280 conclusive the lot sampling technique 564 00:31:25,760 --> 00:31:22,440 you can take a lot of plated fasteners 565 00:31:29,150 --> 00:31:25,770 of the same metal composition and so on 566 00:31:32,300 --> 00:31:29,160 and take a bunch of samples out visually 567 00:31:34,490 --> 00:31:32,310 inspect them look to see if the plating 568 00:31:36,620 --> 00:31:34,500 is smooth and to see whether that here 569 00:31:40,520 --> 00:31:36,630 is properly whether it has blisters in 570 00:31:42,350 --> 00:31:40,530 it fits and that sort of thing and then 571 00:31:44,990 --> 00:31:42,360 you could alright you can measure them 572 00:31:47,510 --> 00:31:45,000 non-destructively by these various 573 00:31:50,540 --> 00:31:47,520 testers an electronic test eddy current 574 00:31:52,640 --> 00:31:50,550 magnetic beta radiation back scatter and 575 00:31:59,440 --> 00:31:52,650 all these things that's covered in one 576 00:32:05,930 --> 00:31:59,450 of the sections of the mill handbook h28 577 00:32:08,360 --> 00:32:05,940 you can take plated specimens for the 578 00:32:10,490 --> 00:32:08,370 required adhesion corrosion and hydrogen 579 00:32:13,550 --> 00:32:10,500 embrittlement tests from a production 580 00:32:17,899 --> 00:32:13,560 lot at scheduled times you can determine 581 00:32:19,759 --> 00:32:17,909 the adhesion and this is a real 582 00:32:22,969 --> 00:32:19,769 scientific method by scraping the 583 00:32:25,039 --> 00:32:22,979 surface with a knife and then looking at 584 00:32:27,889 --> 00:32:25,049 it to see whether it is adhering 585 00:32:30,049 --> 00:32:27,899 properly with a magnifying glass that's 586 00:32:35,769 --> 00:32:30,059 a method of inspection that you can do 587 00:32:42,190 --> 00:32:38,899 now corrosion resistance is determined 588 00:32:47,840 --> 00:32:42,200 of course by doing your salt spray test 589 00:32:51,139 --> 00:32:47,850 which runs 96 hours and after the 590 00:32:54,619 --> 00:32:51,149 exposure the presence of corrosion 591 00:32:56,299 --> 00:32:54,629 products visible to the unaided eye at 592 00:32:58,549 --> 00:32:56,309 normal reading distance is caused by 593 00:33:03,379 --> 00:32:58,559 rejection because you should not get any 594 00:33:05,810 --> 00:33:03,389 rusting on it or deposition of corrosion 595 00:33:10,279 --> 00:33:05,820 products and for the 96 hours now 596 00:33:13,099 --> 00:33:10,289 hydrogen embrittlement testing this one 597 00:33:15,440 --> 00:33:13,109 is there are different schools of 598 00:33:17,690 --> 00:33:15,450 thought on where you should start on the 599 00:33:19,969 --> 00:33:17,700 hydrogen embrittlement testing some of 600 00:33:22,849 --> 00:33:19,979 the faster manufacturers of the lower 601 00:33:24,799 --> 00:33:22,859 strength fasteners say gee you don't 602 00:33:26,359 --> 00:33:24,809 have to do it on lower strength 603 00:33:30,009 --> 00:33:26,369 fasteners because you can't get hydrogen 604 00:33:33,349 --> 00:33:30,019 embrittlement well a guy by the name of 605 00:33:37,519 --> 00:33:33,359 Lou Raymond who is kind of the Guru in 606 00:33:40,219 --> 00:33:37,529 the US on hydrogen embrittlement ran 607 00:33:42,200 --> 00:33:40,229 some tests and decided that you get 608 00:33:44,869 --> 00:33:42,210 hydrogen embrittlement all the way down 609 00:33:47,080 --> 00:33:44,879 to about a great 5 fastener the only 610 00:33:54,669 --> 00:33:47,090 thing is it takes it longer to show up 611 00:33:57,080 --> 00:33:54,679 so in this ASTM spec it only they go 612 00:33:58,879 --> 00:33:57,090 anything above a hundred and forty four 613 00:34:01,930 --> 00:33:58,889 which means your grade eight would be 614 00:34:07,849 --> 00:34:01,940 the first one that you would test and 615 00:34:10,099 --> 00:34:07,859 put it at crank it up to 85% of tensile 616 00:34:11,750 --> 00:34:10,109 element for a minimum of a 70 to 72 617 00:34:14,000 --> 00:34:11,760 hours and you shouldn't have heads 618 00:34:18,609 --> 00:34:14,010 popping off if you have heads popping 619 00:34:23,629 --> 00:34:21,500 now the sample size and rejection 620 00:34:25,490 --> 00:34:23,639 criteria 621 00:34:31,640 --> 00:34:25,500 normally you pick a bunch of random 622 00:34:39,500 --> 00:34:36,110 the ASTM f 788 has a table which will 623 00:34:41,360 --> 00:34:39,510 show later that gives you the number of 624 00:34:45,710 --> 00:34:41,370 samples that you should take for a given 625 00:34:49,250 --> 00:34:45,720 production lot another one is given in 626 00:34:52,370 --> 00:34:49,260 this aunt cas qcz 1.4 627 00:34:55,700 --> 00:34:52,380 which superseded mil standard one 105 628 00:35:00,670 --> 00:34:55,710 and then we have aunt suspect be 629 00:35:04,370 --> 00:35:00,680 eighteen eighteen point one that gives 630 00:35:08,180 --> 00:35:04,380 some sampling techniques the basis of 631 00:35:11,470 --> 00:35:08,190 all of these is to randomly pick a small 632 00:35:17,750 --> 00:35:11,480 sample and any failure of the samples 633 00:35:21,890 --> 00:35:17,760 rejects the whole life here is one from 634 00:35:24,110 --> 00:35:21,900 ASTM f 788 which shows you the sample 635 00:35:30,440 --> 00:35:24,120 size that you should take for a given 636 00:35:32,900 --> 00:35:30,450 lot size and you check it for all of 637 00:35:35,990 --> 00:35:32,910 these different tests that you want to 638 00:35:37,910 --> 00:35:36,000 run and once again the amount of testing 639 00:35:43,700 --> 00:35:37,920 that you do depends on the criticality 640 00:35:46,850 --> 00:35:43,710 of the design so if you find that there 641 00:35:49,550 --> 00:35:46,860 okay you can proceed and accept the 642 00:35:51,770 --> 00:35:49,560 quantity of fasteners that you have if 643 00:35:54,460 --> 00:35:51,780 you find problems and you could go ahead 644 00:35:57,380 --> 00:35:54,470 and insist on more testing to verify 645 00:36:01,510 --> 00:35:57,390 that it's not as serious as it appears 646 00:36:03,650 --> 00:36:01,520 on the surface now for macroscopic 647 00:36:07,780 --> 00:36:03,660 examination of predix with seam 648 00:36:13,760 --> 00:36:07,790 indications here is a sample table from 649 00:36:15,770 --> 00:36:13,770 ASTM f 788 and you can take them a look 650 00:36:19,880 --> 00:36:15,780 at them according to this sampling 651 00:36:24,410 --> 00:36:19,890 technique and if they are not judged 652 00:36:31,240 --> 00:36:24,420 acceptable then you can either conduct 653 00:36:37,329 --> 00:36:34,609 there's been a lot of talk on the lot 654 00:36:40,099 --> 00:36:37,339 traceability and commingling and 655 00:36:42,440 --> 00:36:40,109 certifications and so on 656 00:36:45,309 --> 00:36:42,450 concerning the fastener quality act 657 00:36:51,589 --> 00:36:45,319 which is also known as public law 101 658 00:36:54,559 --> 00:36:51,599 amended its 101 592 as amended by 104 - 659 00:36:56,660 --> 00:36:54,569 113 and of course one of the things that 660 00:37:00,410 --> 00:36:56,670 is covered in that law is lot 661 00:37:02,569 --> 00:37:00,420 traceability of fasteners the customer 662 00:37:05,540 --> 00:37:02,579 can ask for the steel manufacturers name 663 00:37:07,400 --> 00:37:05,550 the lot number chemical analysis of the 664 00:37:10,520 --> 00:37:07,410 wire from the which the fasteners were 665 00:37:13,099 --> 00:37:10,530 made and of course from domestic 666 00:37:16,010 --> 00:37:13,109 suppliers this information is readily 667 00:37:18,920 --> 00:37:16,020 available because most companies when 668 00:37:21,890 --> 00:37:18,930 they make fasteners they get a bill of 669 00:37:24,770 --> 00:37:21,900 lading with the coil material that gives 670 00:37:27,380 --> 00:37:24,780 all this information on it and but on 671 00:37:29,270 --> 00:37:27,390 imported fasteners then it's a bit of a 672 00:37:32,870 --> 00:37:29,280 problem to get it because you have to 673 00:37:36,740 --> 00:37:32,880 get the certification from the person 674 00:37:39,890 --> 00:37:36,750 who made it in the foreign country now 675 00:37:44,420 --> 00:37:39,900 on co-mingling this is something that's 676 00:37:48,970 --> 00:37:44,430 kind of a new word but what it is in the 677 00:37:51,470 --> 00:37:48,980 past the fastener distributors would get 678 00:37:55,370 --> 00:37:51,480 fasteners from all different suppliers 679 00:37:57,109 --> 00:37:55,380 put them together in a barrel and when 680 00:37:59,150 --> 00:37:57,119 someone ordered some they get a bunch 681 00:38:01,280 --> 00:37:59,160 out of the barrel so you it would be 682 00:38:04,520 --> 00:38:01,290 theoretically possible for you to get a 683 00:38:08,420 --> 00:38:04,530 hundred fasteners made by 25 or 30 684 00:38:13,309 --> 00:38:08,430 different manufacturers under this this 685 00:38:15,559 --> 00:38:13,319 part of the law the commingling would be 686 00:38:18,559 --> 00:38:15,569 cut way down to where you can only have 687 00:38:20,809 --> 00:38:18,569 the fasteners from two different 688 00:38:23,359 --> 00:38:20,819 manufacturers in the same lot because 689 00:38:26,390 --> 00:38:23,369 each each manufacturer must register his 690 00:38:28,130 --> 00:38:26,400 trademark with asme then he has a stamp 691 00:38:31,190 --> 00:38:28,140 his trademark on all the fasteners 692 00:38:34,609 --> 00:38:31,200 covered by the law now the the minimum 693 00:38:36,730 --> 00:38:34,619 size is covered are quarter inch in the 694 00:38:40,970 --> 00:38:36,740 inch system and five millimeter 695 00:38:43,609 --> 00:38:40,980 diameters in the metric of course that 696 00:38:44,690 --> 00:38:43,619 is not altogether true - because if the 697 00:38:47,030 --> 00:38:44,700 fastener is three 698 00:38:48,950 --> 00:38:47,040 hardened in other words if it's a 699 00:38:51,440 --> 00:38:48,960 heat-treated fastener then smaller sizes 700 00:38:54,500 --> 00:38:51,450 are covered but nearly all the small 701 00:38:56,300 --> 00:38:54,510 sizes are excluded from the law because 702 00:38:58,760 --> 00:38:56,310 they're not heat treated that much 703 00:39:01,370 --> 00:38:58,770 now if the fasteners haven't been 704 00:39:05,540 --> 00:39:01,380 exempted they're now restricted by this 705 00:39:07,490 --> 00:39:05,550 commingling rule and of course you can't 706 00:39:10,490 --> 00:39:07,500 have more than two locks in the same 707 00:39:13,220 --> 00:39:10,500 container at least this way you have a 708 00:39:15,109 --> 00:39:13,230 better idea of who the manufacturer was 709 00:39:22,400 --> 00:39:15,119 on your lot of fasteners that you're 710 00:39:25,430 --> 00:39:22,410 getting for your usage a customer can 711 00:39:27,650 --> 00:39:25,440 demand certifications such as the 712 00:39:31,000 --> 00:39:27,660 material lot numbers chemical analysis 713 00:39:36,020 --> 00:39:31,010 reports in tensile test data and this 714 00:39:39,079 --> 00:39:36,030 documentation is notarized and legally 715 00:39:41,240 --> 00:39:39,089 binding on the suppliers part now in the 716 00:39:46,339 --> 00:39:41,250 past we could get certifications with 717 00:39:48,130 --> 00:39:46,349 fasteners but they normally were a sheet 718 00:39:51,710 --> 00:39:48,140 that the clerk who filled the order 719 00:39:54,109 --> 00:39:51,720 initialed and said these are certified 720 00:39:58,430 --> 00:39:54,119 to be good and that was it and so nobody 721 00:40:01,490 --> 00:39:58,440 was legally responsible so if it is done 722 00:40:04,370 --> 00:40:01,500 this way with the certification then the 723 00:40:08,780 --> 00:40:04,380 supplier is legally responsible for the 724 00:40:10,700 --> 00:40:08,790 fastener so one of the gimmicks that 725 00:40:13,940 --> 00:40:10,710 some of the distributors distributors 726 00:40:16,160 --> 00:40:13,950 are using is they're saying okay you 727 00:40:17,900 --> 00:40:16,170 want certified fasteners it'll cost you 728 00:40:18,800 --> 00:40:17,910 three times as much for certified 729 00:40:28,640 --> 00:40:18,810 fasteners 730 00:40:32,109 --> 00:40:28,650 that's one of the loopholes if the 731 00:40:34,250 --> 00:40:32,119 distributor is not required to provide 732 00:40:38,240 --> 00:40:34,260 certifications he's not responsible for 733 00:40:42,230 --> 00:40:38,250 fasteners anymore the other thing that 734 00:40:48,410 --> 00:40:42,240 is in that law which is a real big 735 00:40:53,030 --> 00:40:48,420 loophole is agreement between customer 736 00:40:55,069 --> 00:40:53,040 and manufacturer now if the customer is 737 00:40:58,550 --> 00:40:55,079 a clerk who knows nothing about 738 00:41:00,110 --> 00:40:58,560 fasteners they can make all sorts of 739 00:41:03,140 --> 00:41:00,120 agreement with the manufacturer without 740 00:41:07,700 --> 00:41:03,150 even knowing it so that so in other 741 00:41:10,400 --> 00:41:07,710 words it's don't-ask don't-tell type 742 00:41:12,800 --> 00:41:10,410 thing with these fastener certifications 743 00:41:14,780 --> 00:41:12,810 if you don't ask for them and insist 744 00:41:16,880 --> 00:41:14,790 that you get them and pay the surcharge 745 00:41:25,580 --> 00:41:16,890 forgetting them you're not going to get 746 00:41:30,800 --> 00:41:25,590 them so that's where the fastener 747 00:41:33,410 --> 00:41:30,810 quality act stands and I am although a 748 00:41:35,330 --> 00:41:33,420 lot of fastener manufacturers are scared 749 00:41:38,930 --> 00:41:35,340 and a lot of companies are scared on it 750 00:41:40,490 --> 00:41:38,940 I don't honestly think myself that it's 751 00:41:46,970 --> 00:41:40,500 going to amount to that much in the long 752 00:41:50,480 --> 00:41:46,980 run it is being handled by NIST and of 753 00:41:53,360 --> 00:41:50,490 course the the government will enforce 754 00:41:57,530 --> 00:41:53,370 the laws how much they enforce them 755 00:42:00,680 --> 00:41:57,540 nobody knows yet I went to the school 756 00:42:02,360 --> 00:42:00,690 that they taught on how it would be 757 00:42:05,420 --> 00:42:02,370 implemented it's something like a 758 00:42:07,730 --> 00:42:05,430 hundred page document even the lawyers 759 00:42:11,480 --> 00:42:07,740 can't agree on how it should be 760 00:42:16,610 --> 00:42:11,490 interpreted so they'll probably ask for 761 00:42:19,820 --> 00:42:16,620 another delay in 98 now as far as 762 00:42:23,030 --> 00:42:19,830 inspection and test standards there are 763 00:42:25,490 --> 00:42:23,040 all kinds of specifications for testing 764 00:42:30,050 --> 00:42:25,500 inspection methods and what we have done 765 00:42:33,470 --> 00:42:30,060 is listed as many of those as we can in 766 00:42:35,870 --> 00:42:33,480 the appendices we also have general 767 00:42:38,030 --> 00:42:35,880 references in the appendices for where 768 00:42:40,280 --> 00:42:38,040 some of this material came from and 769 00:42:44,000 --> 00:42:40,290 additional references in case you'd want 770 00:42:47,350 --> 00:42:44,010 to check further since so many fastener 771 00:42:50,390 --> 00:42:47,360 tests are done per mil standard 13 12 772 00:42:57,230 --> 00:42:50,400 will give a summary of its contents here 773 00:42:59,600 --> 00:42:57,240 just kind of go over it it establishes 774 00:43:04,100 --> 00:42:59,610 standard methods for testing fasteners 775 00:43:07,450 --> 00:43:04,110 in both the metric and the inch pound 776 00:43:11,660 --> 00:43:07,460 system and the standard test methods 777 00:43:14,539 --> 00:43:11,670 yield data and design allowables 778 00:43:18,859 --> 00:43:14,549 that are safe to use in fact mil 779 00:43:21,559 --> 00:43:18,869 handbook five uses mil standard 1312 for 780 00:43:24,170 --> 00:43:21,569 running their tests on both materials 781 00:43:26,660 --> 00:43:24,180 and fasteners that they publish in the 782 00:43:32,559 --> 00:43:26,670 book and also fastener allowables in the 783 00:43:42,289 --> 00:43:37,280 each test has a standard method spelled 784 00:43:44,870 --> 00:43:42,299 out and each and if their book forms for 785 00:43:48,910 --> 00:43:44,880 each one of them so you have a - - 786 00:43:52,339 --> 00:43:48,920 number for it that gives you a 787 00:43:56,900 --> 00:43:52,349 standalone document if you will so if 788 00:43:59,000 --> 00:43:56,910 you turn over to the next page here are 789 00:44:01,010 --> 00:43:59,010 the different categories the salt spray 790 00:44:04,280 --> 00:44:01,020 test that we've covered the interaction 791 00:44:06,890 --> 00:44:04,290 tests humidity lap shear test stress 792 00:44:10,030 --> 00:44:06,900 durability hardness testing tensile 793 00:44:13,069 --> 00:44:10,040 strength stress corrosion stress rupture 794 00:44:20,539 --> 00:44:13,079 fatigue the thickness of metallic 795 00:44:25,030 --> 00:44:20,549 coatings and doubles your testing and on 796 00:44:28,670 --> 00:44:25,040 the then we go to torque tension 797 00:44:30,349 --> 00:44:28,680 clamping forces for installed or 798 00:44:33,589 --> 00:44:30,359 installation for fasteners stress 799 00:44:37,250 --> 00:44:33,599 relaxation elevated temperature tensile 800 00:44:41,180 --> 00:44:37,260 tests sealing single shear sure joint 801 00:44:44,299 --> 00:44:41,190 fatigue receptacle push out panel 802 00:44:46,490 --> 00:44:44,309 fasteners for electrical tensile 803 00:44:53,750 --> 00:44:46,500 strength - panel fasteners and and 804 00:44:56,930 --> 00:44:53,760 receptacle torque out fasteners then you 805 00:44:59,539 --> 00:44:56,940 have grabbing recessed torque for a 806 00:45:03,829 --> 00:44:59,549 quality conformance test structural 807 00:45:06,589 --> 00:45:03,839 panel lap shear sheet pull up now this 808 00:45:11,930 --> 00:45:06,599 is something that is important and some 809 00:45:14,390 --> 00:45:11,940 of the cherry rivet type manufacturers 810 00:45:19,940 --> 00:45:14,400 the pulls damn tape rivet manufacturers 811 00:45:22,670 --> 00:45:19,950 have had trouble meeting the this sheet 812 00:45:25,570 --> 00:45:22,680 pull up because if you have several 813 00:45:29,690 --> 00:45:25,580 sheets together maybe they're not 814 00:45:32,480 --> 00:45:29,700 exactly flat and you try to pull them up 815 00:45:34,730 --> 00:45:32,490 and clinched the rivet sometimes you 816 00:45:37,700 --> 00:45:34,740 have trouble passing this test with 817 00:45:40,100 --> 00:45:37,710 these pull stem rivets so a lot of the 818 00:45:42,200 --> 00:45:40,110 manufacturers have had to go back and 819 00:45:44,420 --> 00:45:42,210 revise things to get a little more pull 820 00:45:47,630 --> 00:45:44,430 in the system so that they can lock the 821 00:45:53,570 --> 00:45:47,640 rivets so that's what that one is 822 00:45:56,000 --> 00:45:53,580 is used for that one there would be for 823 00:45:59,840 --> 00:45:56,010 the blind fasteners then you have 824 00:46:02,660 --> 00:45:59,850 locking torque tests and this last one 825 00:46:05,240 --> 00:46:02,670 here has been I'm not sure whether the 826 00:46:09,470 --> 00:46:05,250 final copy of that one is even in the 827 00:46:11,120 --> 00:46:09,480 book yet but I don't the last committee 828 00:46:13,070 --> 00:46:11,130 meeting we had it was discussed that 829 00:46:16,160 --> 00:46:13,080 that one was being published barrel nut 830 00:46:24,170 --> 00:46:16,170 tension test which which we didn't have 831 00:46:28,070 --> 00:46:24,180 Dave and we did the CM 1b bans now for 832 00:46:30,050 --> 00:46:28,080 the the metric side you have these that 833 00:46:33,140 --> 00:46:30,060 are covered and they for some reason or 834 00:46:35,870 --> 00:46:33,150 rather they changed it to a DoD standard 835 00:46:39,610 --> 00:46:35,880 thirteen twelve for the metric in order 836 00:46:41,930 --> 00:46:39,620 to differentiate in the mil standard and 837 00:46:47,300 --> 00:46:41,940 these are the ones that they have for 838 00:46:50,300 --> 00:46:47,310 testing of metric fasteners now we go 839 00:46:54,730 --> 00:46:50,310 into the the do's and don'ts of fastener 840 00:46:57,710 --> 00:46:54,740 designs and I I kind of come up with a 841 00:47:00,560 --> 00:46:57,720 set of guidelines you're just common 842 00:47:02,900 --> 00:47:00,570 sense type guidelines that for you to 843 00:47:04,370 --> 00:47:02,910 use and it's not a complete list because 844 00:47:07,850 --> 00:47:04,380 you can always come up with an addition 845 00:47:12,170 --> 00:47:07,860 for a list but these at least could be 846 00:47:15,520 --> 00:47:12,180 used as a designer's checklist and one 847 00:47:18,110 --> 00:47:15,530 of the things that's a pet peeve of mine 848 00:47:21,470 --> 00:47:18,120 is a field that enough information 849 00:47:24,380 --> 00:47:21,480 should be given on a drawing to fully 850 00:47:26,420 --> 00:47:24,390 define the fasteners you want and I know 851 00:47:28,750 --> 00:47:26,430 in the past I've been disappointed in 852 00:47:36,950 --> 00:47:28,760 some of the drawings in which they say 853 00:47:38,990 --> 00:47:36,960 all fasteners to be per ffs 86 or 85 now 854 00:47:42,500 --> 00:47:39,000 if you go look at that spec you can 855 00:47:46,210 --> 00:47:42,510 anything from alloy steel stainless 856 00:47:48,530 --> 00:47:46,220 steel down to even nylon fasteners on it 857 00:47:50,570 --> 00:47:48,540 so you're giving the guy a lot of leeway 858 00:47:53,930 --> 00:47:50,580 if you don't define it any further than 859 00:47:56,540 --> 00:47:53,940 that so this is why that I said fully 860 00:47:58,130 --> 00:47:56,550 defined fasteners you want in other 861 00:48:04,010 --> 00:47:58,140 words when you call them out for a 862 00:48:06,050 --> 00:48:04,020 specification give the paragraph of that 863 00:48:10,340 --> 00:48:06,060 specification that covers the fasteners 864 00:48:12,170 --> 00:48:10,350 that you want to use or if you are not 865 00:48:16,240 --> 00:48:12,180 satisfied with how its defined in the 866 00:48:21,560 --> 00:48:16,250 spec give the strength level required 867 00:48:25,280 --> 00:48:21,570 for example on drawings on materials I 868 00:48:27,860 --> 00:48:25,290 know I have seen on drawings where it is 869 00:48:30,290 --> 00:48:27,870 critical enough that you even specify 870 00:48:33,820 --> 00:48:30,300 the grain direction on the drawing 871 00:48:36,530 --> 00:48:33,830 because you know on materials you have a 872 00:48:41,090 --> 00:48:36,540 longitudinal transverse and short 873 00:48:44,360 --> 00:48:41,100 transverse directions on them the short 874 00:48:47,840 --> 00:48:44,370 transverse is usually the weak one so 875 00:48:50,900 --> 00:48:47,850 you specify on the drawing and the the 876 00:48:54,740 --> 00:48:50,910 area of major stress that you want that 877 00:48:57,640 --> 00:48:54,750 to be the longitudinal direction in 878 00:49:00,680 --> 00:48:57,650 order to get better properties so 879 00:49:04,790 --> 00:49:00,690 specify what you want on the face of the 880 00:49:07,880 --> 00:49:04,800 drawing now here I mentioned earlier in 881 00:49:10,070 --> 00:49:07,890 the course using up it's softer than the 882 00:49:12,170 --> 00:49:10,080 bolt that'll keep you out of trouble and 883 00:49:16,670 --> 00:49:12,180 that distributes the loads on the thread 884 00:49:19,640 --> 00:49:16,680 because usually if you torque a fastener 885 00:49:23,900 --> 00:49:19,650 to failure with a nut it will fail in 886 00:49:26,360 --> 00:49:23,910 the first two threads in the thread 887 00:49:31,760 --> 00:49:26,370 run-out area due to stress concentration 888 00:49:34,400 --> 00:49:31,770 so the nut will not fail usually it's 889 00:49:37,910 --> 00:49:34,410 the the bolt that fails and don't use 890 00:49:41,060 --> 00:49:37,920 feather edges on sheets in a joint match 891 00:49:43,310 --> 00:49:41,070 drill for counter sunk holes use 892 00:49:45,380 --> 00:49:43,320 floating nut plates for critical designs 893 00:49:49,640 --> 00:49:45,390 particularly for counter sunk fasteners 894 00:49:52,580 --> 00:49:49,650 so that the countersink can Center the 895 00:49:52,819 --> 00:49:52,590 fastener and the nut plate will not be 896 00:49:56,930 --> 00:49:52,829 try 897 00:49:59,269 --> 00:49:56,940 bend it determine the environmental 898 00:50:02,359 --> 00:49:59,279 conditions before selecting materials or 899 00:50:04,940 --> 00:50:02,369 coatings for fasteners because you want 900 00:50:08,059 --> 00:50:04,950 to make sure that you're covered with 901 00:50:10,039 --> 00:50:08,069 your temperature range and design sure 902 00:50:13,370 --> 00:50:10,049 fasteners to be critical and varying 903 00:50:16,009 --> 00:50:13,380 that means that the fastener is stronger 904 00:50:18,049 --> 00:50:16,019 in shear than the material so therefore 905 00:50:21,049 --> 00:50:18,059 you can elongate the hole and the 906 00:50:26,599 --> 00:50:21,059 material to allow your fasteners to pick 907 00:50:31,069 --> 00:50:26,609 up the load without failing the fastener 908 00:50:33,289 --> 00:50:31,079 don't use Jam nuts for locking check 909 00:50:36,739 --> 00:50:33,299 alignment of fasteners before final 910 00:50:38,930 --> 00:50:36,749 assembly and of course as a corollary of 911 00:50:41,499 --> 00:50:38,940 that avoid head bending because the 912 00:50:44,539 --> 00:50:41,509 fastener bending I think the SAE 913 00:50:47,329 --> 00:50:44,549 handbook says don't go more than plus or 914 00:50:51,079 --> 00:50:47,339 minus two degrees on misalignment on a 915 00:50:54,709 --> 00:50:51,089 fastener head to avoid trouble with 916 00:50:57,469 --> 00:50:54,719 bending and followed the edge distance 917 00:50:59,569 --> 00:50:57,479 and spacing guidelines on fasteners now 918 00:51:01,489 --> 00:50:59,579 you can temper this but one of the 919 00:51:04,489 --> 00:51:01,499 things that you don't do is put a 920 00:51:06,829 --> 00:51:04,499 fastener so close to the edge that if 921 00:51:09,229 --> 00:51:06,839 the tolerance goes against you when the 922 00:51:11,779 --> 00:51:09,239 hole is drilled you'll have it pushing 923 00:51:15,109 --> 00:51:11,789 out of the hitch and I've seen some that 924 00:51:17,479 --> 00:51:15,119 were almost that bad now don't use 925 00:51:20,390 --> 00:51:17,489 fasteners that look alike but are made 926 00:51:22,939 --> 00:51:20,400 of different materials they'll use 300 927 00:51:26,329 --> 00:51:22,949 stainless and 2a 286 stainless the same 928 00:51:27,349 --> 00:51:26,339 size same head everything that so that 929 00:51:29,989 --> 00:51:27,359 you can't tell the difference between 930 00:51:32,120 --> 00:51:29,999 them and don't use fine and coarse 931 00:51:33,589 --> 00:51:32,130 threads in the same assembly unless 932 00:51:37,670 --> 00:51:33,599 there's a big difference in the fastener 933 00:51:40,219 --> 00:51:37,680 diameter so it's not possible to get 934 00:51:42,680 --> 00:51:40,229 them in the wrong holes and here's 935 00:51:44,599 --> 00:51:42,690 something that you can get in trouble 936 00:51:48,170 --> 00:51:44,609 with although we did it on fittings on 937 00:51:51,380 --> 00:51:48,180 cm-1 don't mix metric and inch fasteners 938 00:51:55,039 --> 00:51:51,390 in a design that that'll get you in real 939 00:51:57,589 --> 00:51:55,049 trouble verify that you have the 940 00:52:00,349 --> 00:51:57,599 fasteners you specified and demand 941 00:52:02,120 --> 00:52:00,359 traceability if it is a critical design 942 00:52:05,209 --> 00:52:02,130 make sure that you get the proper 943 00:52:06,710 --> 00:52:05,219 traceability of the fasteners use 944 00:52:08,660 --> 00:52:06,720 inserts and soften 945 00:52:12,470 --> 00:52:08,670 cereals to avoid fastener pull out if 946 00:52:15,470 --> 00:52:12,480 you can't use through holes if the 947 00:52:17,300 --> 00:52:15,480 dominant fastener load is sheer don't 948 00:52:20,210 --> 00:52:17,310 use a high torque on the fastener 949 00:52:23,450 --> 00:52:20,220 because you have to combine the fastener 950 00:52:25,190 --> 00:52:23,460 and shear loads to the total strength of 951 00:52:28,160 --> 00:52:25,200 the material so you don't want to use up 952 00:52:32,720 --> 00:52:28,170 all of it in tension if your primary 953 00:52:35,380 --> 00:52:32,730 load is shear avoid tap poles as much as 954 00:52:40,730 --> 00:52:35,390 possible because you can't inspect them 955 00:52:44,300 --> 00:52:40,740 you're not sure how good they are so if 956 00:52:46,960 --> 00:52:44,310 you can avoid them don't use them use 957 00:52:50,990 --> 00:52:46,970 harden washers under both the head and 958 00:52:54,080 --> 00:52:51,000 the nut on a bolded installation if 959 00:52:57,190 --> 00:52:54,090 possible don't Terk a fastener above its 960 00:53:01,520 --> 00:52:57,200 yield point stay below the yield point 961 00:53:03,740 --> 00:53:01,530 and don't get close to it unless you run 962 00:53:06,020 --> 00:53:03,750 sufficient tests to determine 963 00:53:09,010 --> 00:53:06,030 pretty much where it is then in a 964 00:53:11,780 --> 00:53:09,020 fatigue joint if you have to go up 965 00:53:13,849 --> 00:53:11,790 because of fatigue then you can go up to 966 00:53:18,020 --> 00:53:13,859 a near yield 967 00:53:19,820 --> 00:53:18,030 thou'rt the use of lubricants lowers the 968 00:53:23,320 --> 00:53:19,830 coefficient of friction so the Clerc 969 00:53:26,210 --> 00:53:23,330 values have to be adjusted accordingly 970 00:53:29,359 --> 00:53:26,220 one of the cases we had at the Cape of 971 00:53:31,400 --> 00:53:29,369 this using silver-plated nuts stainless 972 00:53:33,170 --> 00:53:31,410 steel nuts of course the silver 973 00:53:35,870 --> 00:53:33,180 tarnishes so if you have them in a 974 00:53:39,440 --> 00:53:35,880 barrel for a long time they look bad so 975 00:53:42,740 --> 00:53:39,450 some manufacturer decided he would stop 976 00:53:46,400 --> 00:53:42,750 that so he coated these silver plated 977 00:53:48,170 --> 00:53:46,410 nuts with wax from tarnishing they 978 00:53:50,180 --> 00:53:48,180 didn't tarnish but nobody told the guy 979 00:53:51,650 --> 00:53:50,190 using the torque wrench so they were 980 00:53:53,930 --> 00:53:51,660 yielding these things all over the place 981 00:53:56,240 --> 00:53:53,940 and couldn't figure out why they were 982 00:54:00,230 --> 00:53:56,250 yielding well somebody found out that 983 00:54:01,910 --> 00:54:00,240 because the wax actually reduced the 984 00:54:07,099 --> 00:54:01,920 coefficient of friction to about half of 985 00:54:10,460 --> 00:54:07,109 what it would normally be and Clerc 986 00:54:12,079 --> 00:54:10,470 tables are only guidelines the design 987 00:54:16,190 --> 00:54:12,089 engineer should determine the turqu 988 00:54:19,280 --> 00:54:16,200 values for his design because that's why 989 00:54:21,430 --> 00:54:19,290 you don't blindly use a turk table and 990 00:54:24,350 --> 00:54:21,440 will get you in trouble 991 00:54:25,880 --> 00:54:24,360 fasteners loaded in fatigues should be 992 00:54:31,670 --> 00:54:25,890 trucked the near yield values I 993 00:54:35,800 --> 00:54:31,680 mentioned that earlier and before we go 994 00:54:39,910 --> 00:54:35,810 into the frequently asked questions on 995 00:54:43,070 --> 00:54:39,920 for design we'll take a short break and