Welding Basics

0:00hey this Professor Lewis we're going to

0:02talk about welding Basics here in just a

0:04short lecture just to kind of understand

0:06what welding is how do we call it out

0:08how we inspect it and where we expect it

0:09to break as well as some of the

0:11processes if you were really interested

0:13in welding where could we go learn

0:16further education on this if you're

0:17wanting to get an actual degree in

0:19welding engineering uh Ohio State lerno

0:23down in Texas they'll have good programs

0:25in that as well as Master programs I've

0:27seen some students go to graduate school

0:29at Ohio

0:31another good source of information would

0:33be to study up with link and electric

0:35they have a really good school where

0:37they focus on blet weldment design very

0:40good classes to go to um very very um

0:44indepth and very useful um let's get

0:47into this uh we're just going to hit

0:49some high points I'm going to be

0:50leveraging some slides possibly I use

0:51from other courses I'm not going to

0:52spend a lot of time because this is

0:54short but there's key things that I want

0:55you to pick up and in the process of

0:57welding the key thing is it's Fusion we

1:00would like to see some molten weld

1:02material being typically added and we

1:04would like to see a really good Fusion

1:06taking on with the base material in the

1:09pieces that we're welding together now

1:11when we do that we're going to have what

1:12we call a ha Zone a heat affected zone

1:16right here and the further we get away

1:18from the weld the temperature goes down

1:21and we're not going to change any of the

1:22original micr structure in the base

1:25Metals so we can get hot enough that we

1:27can actually change the structures near

1:30the weld that may weaken That Base

1:32material we could have some mixing of

1:35the base material with the weld

1:36materials and later on you guys are

1:38going to have a course in machine

1:39elements machine design and you'll have

1:41uh shigley's book does a great job of

1:43talking about how to calculate the

1:45strength of the weld assuming mixture

1:47effects on base material goes into a lot

1:49of depth there really good design and a

1:52lot of his stuff keys off of to the uh

1:54blet methods if you read his references

1:57in his books he's coming up with the

1:59stuff from from what Lincoln teaches

2:01very good good content so we're going to

2:04have things happening due to heat in

2:06this

2:07weld when we call a weld out on a print

2:10uh this is just a quick reference

2:12drawing of a typical weld call out we're

2:15going to have an arrow pointing to the

2:16pieces that we want to weld together

2:19we're going to have a section called the

2:20reference line and then a tail typically

2:22in the tail sections where we're going

2:24to designate the process what are we

2:26going to weld this with is it stick

2:29welding or MIG welding that's the slang

2:30term we can't put those on a print we

2:32have to use the American Welding Society

2:35term so we'll be talking about some of

2:36that as well as some of the reference

2:38symbols here and how to apply them

2:41probably the reference M um uh symbol

2:44that we're going to use in this class

2:45and that I really care for you to know

2:47about is the fillet symbol right here

2:49there's a lot of other symbols that we

2:51can put on that reference line as well

2:54as some modifiers or supplementary type

2:56symbols if we're going to weld all the

2:57way around something we' put a circle

2:59around that symbol right here but we're

3:03just going to do a typical fail welds

3:05and this is a a picture of a call out

3:07for a part where we're pointing here and

3:10it just

3:10demonstrates the sides that we're going

3:13to weld on so here's the arrow here's my

3:15reference line if I put the symbol on

3:18the bottom side of the reference then

3:19that means the side that I'm looking at

3:21if I put that symbol up here on the top

3:24it would be the other side this quarter

3:27inch is going to re reference in terms

3:28of the leg the size of the

3:31weld now this is a neat little slide I

3:34put in here because we can have

3:36different size or legs of welds on

3:39different sides for example and so here

3:41we could call them out again these call

3:43outs typically if they're going to be

3:45the same on the whole weldman we might

3:46put it in the notes that all welds are

3:48going to be quarter inch unless

3:49otherwise specified and that saves you

3:52from have to type it in there time and

3:53time

3:55again now let's look at some terms we've

3:58got the leg of the weld that's the

4:00distance from here to this far point

4:02which is the toe that's going to be our

4:04leg of the weld it's typically where we

4:05measure the welds so quarter inch half

4:08inch 3/16 things like that we're going

4:10to draw a line from Toe to Toe from

4:13right here to here and then a line right

4:16here that comes at 45 degre is going to

4:18be our theoretical throat the effective

4:22um section of that Weld and so what

4:24we're saying is basically that if we're

4:27going to break this weld this is where

4:29it's probably going to breakout is

4:30across that theoretical throat and so

4:32we're really interested in that throat

4:34size and and inspecting that we're also

4:36interested in the depth of diffusion on

4:38this so again we're going to be looking

4:40at maybe how the material the heat from

4:42the the fusion the weld ties into these

4:44and that we don't have any uh cracks or

4:46overlapping of the materials as

4:49well now I'm going to go ahead and skip

4:51this little slide down here and get to

4:53this slide we're going to use a filet

4:54gauge and hopefully it'll go slower here

4:56for us a filet gauge is a series of

4:58gauges that we can measure me the convex

5:00and concave features of a weld here

5:02we're going to come in here and check

5:04this and we're going to see that the

5:05filet weld measures 38 here okay and

5:09that's looking really really good we're

5:11going to come in here and check the

5:13other leg as well so that was leg one

5:16and so now we want to check leg two with

5:18that

5:21gauge so we're going to come down and

5:23make sure it fits good on the metal in

5:25the metal and we're going to check and

5:27draw a line and looks like our legs are

5:28good here

5:30the next thing we're going to do is come

5:31in and check our throat of this Weld and

5:34so the other side of the gauge it has 38

5:36has this raised portion we should be

5:38able to come in here with it lined up

5:40here and make it contact and it should

5:42touch the Weld and we know we have a

5:44good weld there okay that our throat is

5:46a 38

5:49weld inspecting the welds we want to do

5:52a quick visual for that paracity in the

5:54weld we want to think did we have

5:55shielding gas here's a nice weld here's

5:58a weld without shielding gas gas and

6:00these little proes that get in the weld

6:02are going to cause defects and make the

6:04weld break now this is a multi-pass weld

6:07and we had issues with gassing at each

6:09pass

6:11here now let's talk about the two

6:13processes that I expect you to know for

6:15this course the first one is going to

6:17be esol

6:20shielded metal arc welding okay s Ma and

6:25so the acronym that's where we would put

6:28it on the tell is s small and that now a

6:31lot of you guys are going to call this

6:33stick welding okay that's the slang term

6:35stick welding we're using a rod and a

6:38lot of times we can change the wire

6:39diameters or the Coatings that go on the

6:42here we have a celios fiber and we want

6:43to keep those fairly dry and they may

6:46put additives in there different metal

6:48additives to make them stronger or

6:50weaker so here's a 7018 here's a 6011

6:536010 and we can put different additives

6:55in these um cellulos fibers in and coat

7:00that rod and that will burn off making a

7:03very robust protective atmosphere around

7:05the weld so this process is really good

7:07for outdoors um this is our uh Stinger

7:10that we're going to put a rod in and

7:12then come in here and this consumable

7:13this electrode is going to disappear as

7:16we

7:17weld so shielded metal arc welding as

7:23small now real quick I just threw this

7:25up here they're going to talk about the

7:27rods um in terms of identification

7:30systems on on a SM small rod they're

7:32going to have a e maybe two digits right

7:34here these are the most important for us

7:35that's the tensil strength 60 KSI so if

7:39we had a 7018 Rod the 70 would indicate

7:4270 KSI now these others go into welding

7:45position currents and other things that

7:46we would do if we were in a heavy

7:48welding course we'd expect you to know

7:49all the combinations of those as well

7:51but right now just the 60 and the 70s

7:54are going to be of importance the

7:56strength now if we change from a leading

8:01to a trailing type angle as we move

8:04across a weld we can be pushing there's

8:06going to be Force going on here we might

8:08get a thinner penetration weld so if

8:10we're welding with thinner materials

8:12stuff like that we can actually change

8:14How Deep The penetration that we're

8:16going to get on this versus our our lead

8:18angle likewise the trailing angle we can

8:21really get some more depth on the the

8:24angle on here and again the weld's going

8:25to push up and stack up a little bit

8:27more so welder is going to know how to

8:29do those kind of things and be trained

8:30in it another thing they're going to do

8:32is learn how to do different kinds of

8:33patterns and I just put a simple weave

8:35pattern on here where sometimes I just

8:37do an elliptical type shape and maybe

8:39it's a little tight and a little bit

8:40looser and that's going to change the

8:42depth of the penetration how the welds

8:44tie in and all that and they're going to

8:45be watching those welds seeing what

8:48happens let's get into our second

8:50welding process now this is G gas

8:54metallic arc welding a lot of you guys

8:57are going to reference this as Mig Mig

8:59is the slang shop term world use of it

9:03and it's acceptable to say that in

9:04companies but when I put it on a print

9:06or I'm doing specifications I need to

9:08use the American Welding Society

9:11designation this is where we have a wire

9:13that's going to come through your leads

9:16and it's going to have a contact tip

9:18where we can transfer the electricity to

9:20the wire and we're going to come in here

9:23and melt that there's different transfer

9:25rates and stuff methods that we can go

9:27in there really neat stuff you're going

9:29to have gas shielding gas that's going

9:30to come through here and be released

9:32around this nozzle tip to provide a

9:34protective atmosphere again we don't

9:36want oxygen interfering with the the

9:38melting metal puddle that we have going

9:40on this is not as robust to do outside

9:43this is more of an indoor type process

9:45it's going to be a lot prettier looking

9:47weld okay and there's a lot of

9:49disadvantages and advantages to each

9:51process again we don't have time to go

9:53through all that cuz there's a lot there

9:55on the table we're going to have the

9:57electrode carrying our current coming

9:58through here

10:00now this is a picture of a an example of

10:03a machine where we'd have the wire

10:04coming off here decoiling with a feed

10:06mechanism we would have a bottle back

10:08here with a regulator the electricity is

10:10being transferred through these leads

10:12everything is going to go to the leads

10:13going down to the Weld and again you're

10:15going to be able to change all your

10:16parameters with the machine in terms of

10:20what volts and amps and wire feed you

10:22want to have running do you want it

10:24positive negative there's a lot of neat

10:26stuff there as well let's see here

10:29um the filler rods on this they're going

10:32to have a ER so electrode rod and the 70

10:35representing the again minimum tensil

10:38strength of that weld filler Rod that we

10:41would have on

10:42there and that's gas metallic arc

10:44welding G here's our feed mechanism

10:48where we can come in here and lock these

10:49feed mechanisms and push that wire

10:51through there just kind of gives you a

10:52closeup of that mechanism let's talk a

10:55little bit about shielded gas now if

10:57you're going to be welding in a weld

10:58shop you're probably going to have to do

11:00a fullon um high pressure bottle

11:02training before you ever weld because

11:04these things are up to 3 and 4,000 PSI

11:07and if you knock this head off this

11:09bottle or you open this valve stem and

11:11you're standing in the wrong place these

11:13Regulators these can have tendency to

11:15break over time with the impact of that

11:18pressure hitting or if somebody hit it

11:19or something for example dropped it when

11:21they were changing bottles and didn't

11:23realize they put a small crack in it and

11:25then when it hits at high pressure these

11:27things can pop off and do ser energy or

11:30injury to you um they've even had

11:31bottles get knocked over and go through

11:33solid concrete walls so this you would

11:35really need to talk about how you deal

11:36with uh bottle safety looking at the

11:39gauge here this is going to be our

11:40pressure gauge this is going to be our

11:42flow rate gauge they're going to know

11:43how much gas and they measure that in

11:45cubic feet per hour now they're going to

11:48have all different gases that they're

11:49going to put out there and the bottles

11:51will be properly labeled looking at the

11:53gases we might and I just wanted to

11:55throw something out there A lot of times

11:57we use argon that's going to have a

11:59narrow type but fairly good penetration

12:02the best gas I like for penetration deep

12:04penetration is going to be the CO2 it's

12:06going to have really deep robust

12:08penetration it's going to have splatter

12:10though but you're saying why are you

12:13putting oxygen in there when we're

12:14trying to protect it from oxygen this is

12:17this amount of oxygen in the CO2 is just

12:19enough to help promote Arc growth and

12:21make a hotter weld there's a lot to the

12:23stuff uh argon mix may be really good

12:27for better penetration and look a lot

12:30lot better and not require a lot of

12:32clean up from the

12:34splatter now before we weld a piece of

12:36material let's talk about our base

12:38materials typically we get steel that's

12:40hot rolled steel it's going to be

12:42probably at A36 for a lot of the Steels

12:44and especially what we're doing here in

12:45lab and it's going to have a mill scale

12:48on this sample if I look at this right

12:50here I could see Mill scale on this

12:52sample right here and that can flake off

12:55and that's an oxide that is an insulator

12:58we don't want toy and and weld across

13:00that and get that broken up into the

13:02weld or anything of that nature we want

13:04to come in and maybe grind with a flap

13:06grinder or Belt Disc if we're going to

13:08weld on this surface get rid of that

13:10meal scale here's a part that didn't

13:13have the mill scale removed and when

13:15they welded it it actually looked like a

13:16nice weld but look at it we loaded it

13:19just very lightly and it just broke off

13:21because it couldn't get Fusion in that

13:23side of the weld again kind of a crack

13:26showing here still no real depth of

13:28Fusion on there might look like a nice

13:30weld but we need to load it and see

13:32what's happening here's what we want we

13:34want some fusion some depth of fusion in

13:37this t- weld here now you're saying this

13:40looks kind of like a crazy weld I threw

13:41this up here because if we're looking at

13:43it I can see that here um we're welding

13:47along and then it kind of changes here

13:49because look at the width of the puddle

13:50here the welder that did this started

13:53going wider here was narrower here and

13:56it did break across the throat here's

13:57where they stopped and when we stopped

13:59there could be a crater and that could

14:01become an issue with maybe potential

14:03breakage so we may want to look at the

14:05broken part and see where did we think

14:06it cracked and broke and started from

14:09but we want a nice consistent weld this

14:11is not consistent all the way across but

14:13it did break and we did get good Fusion

14:15where this one would not okay it would

14:18never break the weld across that

14:20theoretical throat here we have um if

14:22you're going to go to a company let's

14:24say you hire a welder and they came from

14:25Tulsa welding school great school

14:27nothing against them it's just if if

14:29you're at ditchwitch or caterpillar or

14:31some other company maoy and you're going

14:32to hire them to do welding for you you

14:34have to test them in your process at

14:36your facility to certify them and so

14:39this is a typical test that they'll do

14:40they'll have it written up and

14:41everything in in long form the welder

14:43will have to set up the machine they'll

14:45have to conduct a series of welds like

14:47this and then load it in a machine where

14:49we just come in there and press it and

14:50they can use a standard shot press for

14:52this and see where the Weld braks and

14:53how much load it held for example and

14:56here we had a nice weld brake across the

14:58throat here so this would be a good Weld

15:01and you can see the weld looks really

15:02nice

15:04there let's talk about a term um fixture

15:08and jig what's the difference between

15:10fixture and jig fixture locates the

15:13parts and that's it a jig will locate

15:17the parts and guide the tool so when

15:20we're going to do a weldment we make

15:21weld fixtures not weld Jigs and a weld

15:25fixture like this is going to locate the

15:26parts and this one is a tack up fixture

15:29where we can come in here and Tack these

15:30parts up and hold them in place and then

15:32weld them now I didn't weld this part I

15:34just put it in the templin grips here to

15:36show you how we can test this where we

15:38can pull that top and bottom and pull

15:40that weld in sheer so again in this

15:43course we're going to talk a little bit

15:44about three different testing methods

15:46we're going to look at Shear bending and

15:49torsion those are three simple equations

15:51we've learned in

15:52strengths and dealt with force over area

15:55MC over I TC over J you guys know those

15:58equ and it's not that hard to apply to

16:00weld design so we're going to see some

16:02of that now then here's a

16:06bending fixture where we can come in

16:09here and Tack this up and then maybe

16:10we're going to slide that sample in here

16:12where we could now come in here and push

16:14on the end and maybe we want to look at

16:16is it better to weld on the top and the

16:18bottom or is it better to weld on the

16:20two sides now somebody's going to say

16:21we'll just weld all the way around the

16:23problem with that is

16:25deposition time to take manufacture that

16:29part if just two welds would hold that

16:30part that's all we want to do we don't

16:32want to weld all around unless it's just

16:33cosmetic and customer is going to pay

16:35for that so we're going to be able to

16:37design this and see what's the correct

16:40placement and size of the welds there

16:43torsion this is a torsion fixture we're

16:45going to locate our parts come in here

16:47and Tack it up and then weld it and

16:48again do we want to weld on the sides or

16:51on this end and the other side

16:53underneath and again we're going to put

16:55it in a fixture and testing fixture and

16:57come in here and load that part and

17:00hopefully break it and see what

17:02happens now then I've mentioned a little

17:04bit about the Heat and the welder can

17:07see something this is where we've

17:09captured some video for you and

17:11leveraging some other people's stuff

17:12here um where we can come in and talk

17:15about the welds and the quality of this

17:18and so what we're going to do is come in

17:19here and watch this weld as we go across

17:21here you can see it's kind of irregular

17:22and a lot of splatter and it was just

17:24all over the place and that's the part

17:26that we got that's not a very pretty

17:29that's not going to test good okay now

17:31the next one we're going to watch and

17:33that's just that same one there I

17:34probably need to hit um there we go let

17:38me get back to the beginning here of

17:40this one let's watch this weld this is

17:43going to be more a consistent and better

17:45weld going across here and see how the

17:47heat is tying in to the tops and bottoms

17:49and you can see it cooling off the slag

17:51off here and this is going to make a not

17:53nicer weld here on this

17:55part and so we would go in there and

17:58then test that weld so the welder is

18:00going to be trained and it takes a lot

18:01of experience to do that stuff it's

18:03something we can't just take you guys

18:04out and do this we do have a welding

18:06certification program that you guys can

18:08go out there and get weld certified and

18:11you're going to spend lots of hours out

18:12there more than what we have time for

18:13this course and this course is not so

18:15much welding more of testing of

18:18weldments and a little bit of the

18:20calculations that go into that so uh for

18:24this one lab so weld defects man things

18:27like over did the weld overlap and not

18:30fuse in here did we undercut is that

18:32going to be a source of it to break did

18:33we get improper Fusion the travel rates

18:36all these kind of things there's a lot

18:38to weld inspection you may have to have

18:41x-ray ultrasonic equipment things like

18:43that so you would really want to study

18:45up on the weld quality so hopefully this

18:47covers uh the basic weld portions I

18:49think the next video we're going to have

18:51is a little bit about the equations and

18:52the analytical some basics of those

18:55three designs that we talked about sheer

18:57bending and

19:00portion