Victor,
forget the face of the welds for a minute and do two things:
1. Pulse some 100 A DC through the welds and monitor the voltage drop across
the weld. There are graphs telling what the voltage should be vs geometry,
pulse duration and pulse current. Most CD companies have such on the web.
2. Pull off some stripes and measure the force needed to separate the parts.
Same as above, look in the CD web sites.
Here is what you need. I've used these tests myself.
http://batteryuniversity.com/parttwo.htm
In the end, it's these two parameters that decide the weld quality.
Inge
----- Original Message -----
From: <[log in to unmask]>
To: <[log in to unmask]>;
<[log in to unmask]>
Cc: <[log in to unmask]>
Sent: Thursday, August 27, 2009 5:45 PM
Subject: FW: [TN] Spot weld formation photos
Folks,
These are the anomalies that I see on nickel metal strips. I see a
tear/split/voiding/shrinkage one or both side of the metal strip
interfaces. IMHO this is not an acceptable weld spot formation. I
feel that it is a weaken interface. I need supporting data to make
suck a statement.
Victor,
-----Original Message-----
From: Robert Kondner [mailto:[log in to unmask]]
Sent: Thursday, August 27, 2009 10:31 AM
To: Hernandez, Victor G
Subject: RE: [TN] Spot weld photos
Victor,
For sample reference welds I use the production packs that come from
production vendors. On these packs the top side has a impression but no
obvious melt. If I use too much power or my electrode tips are pointed I
get
top side melt and electrode stick. You do not want sharp points on your
electrodes.
Using a welding head would produce a more consistent pressure. I don't
think you can get real good consistent welds using hand pressure.
See www.kondner.com/files/Welds.JPp
for a weld I just did.
The 4 bottom welds were done by a production house. This old cell came
out
of an old power drill battery pack, I use them to play.
The top 4 welds I just did. I ripped the strip off the left side, you
can
see the strip hanging on the side. There is little top side deformation,
I
would say this is a pretty good set of welds.
Pressure, power and probe shape, these are the key items.
Bob Kondner
-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Thursday, August 27, 2009 10:17 AM
To: [log in to unmask]
Subject: RE: [TN] Spot weld photos
Bob,
Can you share any photos of what you feel is an adequate spot weld on
a nickel metal stripe. I am not sure what spot weld process is being
used. I see a lot of variation in spot weld formation and amount of
reflowed material on the pheriphy of the 1.7mm circle depression. Some
even exhibit a well/depression on the thickness of the first layer
metal. I have search for articles on the internet but not sure of what
is acceptable.
Can the signature of the spot weld tell which process is being used?
Vic,
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Wednesday, August 26, 2009 8:22 AM
To: [log in to unmask]
Subject: Re: [TN] Spot weld photos
Hi,
I have a small dual pulse spot welder I use for proto battery backs. I
know from experience that pressure and electrode shape make a big
difference.
In one photo the welds seem rather large, I wonder if the pressure was
being maintained. If you loose pressure magnetic forces will open the
joint
and you get an arc. The arc can make quite a mess as it dumps more
energy at
the locations.
My "Test" is that pulling a nickel strip after welding should result in
the
weld spots being torn out of the strip. IE the weld is stronger than the
material.
Bob Kondner
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of stephengregory5849
Sent: Wednesday, August 26, 2009 9:07 AM
To: [log in to unmask]
Subject: Re: [TN] Spot weld photos
Morning Victor,
Got your pictures. Here they are:
http://stevezeva.homestead.com/files/Batt-1.JPG
http://stevezeva.homestead.com/files/Batt-Orange-1.jpg
While I'm no expert on spot welds, I'm pretty sure you won't see any
sort of
"reflowed" appearance with a spot weld. You'll just see a mark or
indentation of where the electrodes contact the metal. Have these
battery
terminals been falling off the batteries?
Steve
----- Original Message -----
From: "Victor Hernandez" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, August 26, 2009 8:19 AM
Subject: [TN] Spot weld photos
Steve,
Can you please post these photos on your home page. Many thanks,
Vic,
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