Topic: Spot weld classification standard

[RickP330]

Hi guys,
I have hit a dead end on this one.  I am working with the 1967 Weld/sealant manual.  It is calling out Class 1,2 and 3 spot welds.  Class 3 seem to be the most common and structural style welds (Frame rails, torque boxes, rocker panels etc).  Class 1 and 2 seem to be on door skins and hood skins. 

I want to duplicate factory style "structural" Class 3 spot welds.  A typical destructive test is a peel test and a measurement of the weld nugget diameter.  However, I can find no reference to the weld classifications anywhere.  I did find later model specifications, but clearly things have changed, and they classify Class 1 spot welds as structural now.

Does anyone have a reference to the spot weld classifications in '67 that might hint at the peel test weld nugget diameters?

Optionally I am trying to get my hands on some old spot welds to destructively test and measure - but I am hoping to do both.

Much Thanks
Rick

[CharlesTurner]

I'm no expert in this space, but would think that instead of hunting down manufacturer Class designations for spot welds that there should be specifications for spot welding based on the thickness and metal type being welded.


This looks like a decent reference, I'm sure there are many more, maybe library books too.  Ford may have published documentation on this too, like the sheet metal stamping one.


https://www.pwrwp.co.uk/spot-welding-technical/




Sections like frame rails, while thicker, would also be galvanized, so possibly a minor factor when determining current/cycle time.

[RickP330]

Thanks Charles,
Someone from another forum helped me out.  He found the attached document - while dated 2002 it seems reasonable to use it as a guide here.  Apparently the Class 1,2 &3 spot weld refer to the "finish" not the strength of the weld.  Class 1 and 2 are used near body panels where cosmetics are of concern.  There is a table for weld nugget diameter and that seems to agree with some industry standards I found so I think I am okay.  Thank you.
Rick

[CharlesTurner]

Nice!

[jwc66k]

Keep in mind that assembly line spot welds were done by a rather large "pincer" type device that was calibrated.
Jim

[RickP330]

Hi Jim,
Honestly I am concerned about that.  Besides factory welding units were probably much higher current than I have available at home.  I have gotten good welding results with the following welder though.  I'm pretty confident it will work well.
RP

[RickP330]

I made multiple weld coupons.  I am settling on a general weld for now I consider acceptable.  16 ga sheet metal using an all copper weld through primer.  It fits class 3 weld finish and has a minimum of .23" weld nugget.  According to the specifications it needs to be larger than .17".
RP

[J_Speegle]

Part of the challenge I've witnessed through the years is that some of the spot weld areas are just not accessable with the car assembled so those corners, pockets or covered areas are very difficult or impossible to replicate.

Do have a number of Ford Factory welding manuals showing a ton of details about the systems, tools, how to maintain and all that I need to find time to look through to see if it references any of the details you have asked about