Bad welds

[Welderpaul]

Once a month we get a wagon full of broken bits from a civil engineering company for repair.

The photo shows a lighting assembly from a dozer. We get loads of these - they are a mass production part which they have had problems with.

A shining example of a weld with no penetration. Weld looks fine on the surface, but breaks clean off the plates. I knocked the rest of the weld off with a chisel. These have been known to fall off the machine just with the vibrations of the engine running

 

[Robotstar5]

Obviously the manufacturers have no form of inspection! we have to test and record regular samples of our welds for the automotive industry.

 

[Ian D]

That is bad.

 

[PTvor]

It takes a natural talent or some application to make a weld that bad.

I imagine these parts are run off somewhere where they are paid a halfpenny a pop and the percentage that fall apart when chucked into the outbin is calculated by the folks who weld them, if anyone checks.

What's the cosmetic appearance of the new parts like?

 

[Mikey D]

Name and shame then paul what make dozer are theses off ??

 

[knoba]

Will you re-do the job according to the original welding procedure, or choose a different process / side to weld the joint?

Of course, you know you're going to have to show us some pic'ies of the finished piece....

 

[Welderpaul]

Not sure - They are fitted to a few, plus they use them on some of the big dumpers - different manufacturers must buy from the same place. It wouldnt be the first time they have sent us 20+T of machine, rather than just unbolt a simple part that they could have sent in someones car.

The original is only welded on the inside of the joint. I clean everything up, prep the plate slightly on the face that bolts to the machine (as this weld will need to be ground flush), Weld it both sides and clean up. Its nothing critical, so just needs migging back together - but properly this time.

 

[knoba]

It's sad to think that the original, experienced production welder, may well believe that their welding skills are excellent, since; it's probably not the sort of part to be weld-tested. They may not know, care, or even find out that they're a... L.O.P-pot

The other thing that strikes me, is all the same; effort, prep & costs go into making a bad weld, as they do a good one.

It's almost inconceivable to think that what looks like a good weld, from a high energy power source, can in fact, not penetrate the parent metal at all...

Illustrating quite clearly, that the appearance of a weld, is just that: skin-deep.

 

[Hitch]

Bad design too imho. Something like that, i tend to cut the plate 10mm or so bigger than the outside of the channel, weld in and out.

 

[snowcat]

cost is a typical factor on many of these parts, although country of origin has a lot to do with work standard...

US production based plant is often badly mfr and especially welded, much is to do with the skill set and TBH old production techniques, factory's and a unionised way of working Case is one example I can think of that prides itself on cold lapped joints..... although at least they still produce stuff......

I do spend a fair bit of time re making stuff that should have been made correctly the first time around..

 

[brightspark]

on a good note if they were done properly u would be out of a job just the same as me the amount of callouts i get through botched workmanship from so called tradesmen is unreal

 

[Welderpaul]

Bad design too imho. Something like that, i tend to cut the plate 10mm or so bigger than the outside of the channel, weld in and out.

Thats how i would do it, usually 10-15mm all round. There is room where they bolt on to the machines to do that too. I guess they don't want the extra expenditure/time.

I'd rather we didnt get this work tbh. 9 times out of 10 its caked in rubbish and been bashed around long after the part originally started to fail. If they brought it in early on, it would be an easy repair. They never want to pay to repair it properly which is the most frustrating - we end up welding cracks/torn plate rather than cutting out and repairing properly. Bodging bodges.

 

[GeorgiePorgie]

tradesmen

I keep hearing this word....whats a Tradesman?

In my day it was Mastercraftsman ie those who put care and effort into their work,sadly this all went pear shape after Maggie was let loose on Industry.

 

[keith19]

"It's almost inconceivable to think that what looks like a good weld, from a high energy power source, can in fact, not penetrate the parent metal at all..."

I've seen this 'surface welding' happen before, and it can usually only be done on a good-quality machine, with plenty of adjustments, not on a hobby machine. It happens intentionally where there is piece-working and there is little or no inspection. I even told a story about it last Xmas, which was true of course, not a 12th Night's tale: http://www.mig-welding.co.uk/forum/showthread.php?t=23302

So far as I can remember, when the lads tried to set the machine to make the same sort of welds as Howard - Whoops...Charlie - the wire feed was quite fast, the amps only adequate to melt the wire, and the voltage set low to give a few microns of penetration. The welds sat on top and looked pretty, even glistened, but they could be knocked off with a blunt chisel...

 

[KennyC]

What do you make of this weld? It's a frame from a k5/6 GSXR 1000. Loads of these snapped and they had to recall every bike to add a brace to the frame.

 

[Drains]

Thats how i would do it, usually 10-15mm all round. There is room where they bolt on to the machines to do that too. I guess they don't want the extra expenditure/time.

But for more efficient production work the plate should be cut small, leaving a prep gap that the weld can fill. Takes more skill from the welder to shoot the weld into the gap without leaving wee wire stickouts. Or, lets face it, just to set the machine up right in the first place... the slackers.

 

[knoba]

KennyC
What do you make of this weld?

Pretty shocking, really! ...considering the application. Is that porosity along the top root-line or tear-out?

It's been stated that welding is a metal casting process, but I'd not imagined that a similar metal could be used to make the casting mould...

As an aside... can anyone come up with a positive application for this "poor welding / incremental casting" method?

 

[PTvor]

As an aside... can anyone come up with a positive application for this "poor welding / incremental casting" method?

Why would you need a weld which looks sound but will break with good kick?

Possibly a trap door into something.

I can think of several other applications, none exactly positive and all amounting to building a bear trap.

 

[philpullan]

What do you make of this weld? It's a frame from a k5/6 GSXR 1000. Loads of these snapped and they had to recall every bike to add a brace to the frame.

i have one of those hope the brace stops that happening

 

[knoba]

PTvor
Why would you need a weld which looks sound but will break with good kick?

...because the weld (molten metal) is only being used to mirror another surface. Look at the pictures posted above. Where the welds have come away, they have left a fairly decent impression of the surface they were supposed to fuse to.

Let me re-phrase: If one could lay a cold weld (a surface casting), on top of a similar metal (a solid mould), and the two came away easy enough, then one could (for argument sake), make a reverse moulding of the original casting.

Maybe custom lettering stamps & brands could easily be made by using this reverse weld-casting method.

It's "only" an entirely new idea (well, to me anyway).

...just thought it was worth exploring applications for it.