Andrew,
EMD used all types of welding including MIG welding, but for heavy
operations, at the time, it was not considered satisfactory and, as I
noted in an earlier post, it was a very difficult area to weld.
Setting up a MIG welder would have been a real problem.
MIG welding has a tendency to produce a beautiful looking weld that,
in fact, has not penetrated both pieces of steel adequately. EMD had
exactly that problem on a large group of GP38 and GP40 locomotives
built from 1965 to about 1968 or 1969. The truck bolster was designed
in such a way that the weld between the base of the bolster and the
bottom plate inside the frame was not very accessible. MIG welding
was used and they were good looking welds to the naked eye. However,
after several years of service, almost all failed. The bolster was
still attached to the "T" beam sidesills, so it was held in place.
Inspection of the failed welds showed good penetration on one piece
of the structure, but not on the other.
To repair the locomotives, and there were hundreds of them, EMD
established a warranty repair program at several locations off the
RRs' property. A few repairs were made on customer property, but most
didn't want non RR welders doing the work. Some units were repaired
at La Grange in the wreck bay at the north end of the plant. EMD
contracted with a couple of third party companies to do some of the
repairs under EMD supervision. One of these was Pittsburgh - Des
Moines Steel which had two facilities. In order to provide
replacement power while the customer's locomotives were under repair,
EMD built a fleet of about 20 GP40s and leased other units. After the
program, the GP40s were sold off.
To make the repairs, the locomotive had to be untrucked. Holes were
cut into the bottom plate at strategic locations to inspect and, if
possible, make repairs at both ends of the unit. If the structure
could be salvaged, the failed weld had to be air arced out and then
rewelded using stick welding. All welds were ultasonically checked.
It was a long, hot, laborious task.
Each unit took a week or more to repair. On many units, the damage
was so bad that the entire bolster assembly had to be replaced. EMD
had designed a new bolster for the replacement and for new
production. This allowed for much better and easier welding.
Fortunately, the SD models had a different bolster design and were
not affected by this problem.
EMD could have used MIG welders to weld the crankcase "A" frames, but
the results might have been the same. The design change solved the
problem reliably and effectively.
Bill Barber
Gravois Mills, MO
On Aug 20, 2009, at 7:43 AM, CBQ@yahoogroups.com wrote:
> +Re: SD 45
> Posted by: "ANDREW KOETZ" andrewkoetz@gmail.com andrewkoetz
> Wed Aug 19, 2009 7:56 pm (PDT)
>
>
>
>
> Then why didn't EMD then use wirefeed welding / mig? This process
> does not produce the "slag" that "stick welding" does. Although the
> weld penetration would be about 1/2 to what stick welding would be.
>
> If it was only one welder that welded improperly, and it certainly
> could have been, I am surprised that Engineering and Service didn't
> figure that out more quickly. There was a great amount of
> investigative work done once the first several failures occurred
> about 1968 and the design was changed in the very early '70s. In
> general, the welders that were assigned to critical crankcase welding
> were the more senior and skilled. As an interesting sidelight, in
> that period, EMD was the largest user of welding rod in the entire
> state of Illinois!
[Non-text portions of this message have been removed]
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