Welding 1.5/.7 with 9 cycles @ 8,000 Amps, but trouble with pulse command on the Medar. Got the commands for heat and impulse displaying properly by adding the impulse command before the existing heat command. It now displays IMP, COOL TIME, HEAT TIME, HEAT %
But the pulses are not needed for this weld. So changed it to a single heat command. The force was once measured to be 500 pounds at 50 psi, and it requires a special adaptor to apply the force gauge to this gun. So a setting of 50 psi was set, but the welds were cold, and the controller is maxxed out at 95%, and show CF=10.3kA, so adding cycles and/or lowering force can give more heat. Adding cycles may tend to distort the tube, wheras lowering force may cause expulsion, but see what you can do.
Also make sure the Nominal Line voltage in the set-up section is in the middle, as we discussed it should be about 430 Volts.
Set to 30 Squeeze, 10 cycles at 10kA (Got 9.4kA), force possibly was 450 pounds, as psi=45.
Cascading the welds, guns 1, 7, 2, 8, and they are 20mm on center, but one weld is cold, get indentation, but no weld.
Upper tips contact the tube, lowers are on the sheet metal. They all are on the sheet metal at the same time, which is unfortunate, because the current will divide up among the lower electrodes. This is a built-in shunting problem. The lower tips must be pulled away from the sheet metal to stop the shunting. In some cases, with enough power acceptable welds can be made, but it is a poor design, and will always be troublesome, because you want to weld with one lower tip at a time, not all at once. I see this time and time again, and, to me, it reveals that the machine builder doesn't understand current flow in welders.
A check of the cables was made, most are 138 Micro Ohms, but the questionable gun has a 500 Micro Ohm shunt. That is absolutely bad, they should not vary by 10% in a machine like this. If they age to the point of a 20% increase in resistance, they will fail soon, and should be changed right away. A good PM procedure would catch this long before it becane a problem.
Discussed how there was still no weld, but the tube was indented. Unfortunately, no notes were taken for this discussion.
Discussed a machine that gives edge welds because the gun design doesn't allow proper position of the tips.
JCP put a short "A" nose tip on the upper (called "pointed"???), but the lower has a flat, is this good?
Answer, no, the flat will spread out the current on the bottom, and the hottest spot will be on top, causing intermittent welds, and poor upper tip life. Cannot change the bottom one, but can modify it to have less contact area. JCP will close the gun to see what part of the flat doesn't touch the upper, and remove that copper.
2 mins + 10 mins referencing and posting this.
Medar gives "Current Shunting" fault, must call back I will look it up...
"This fault is generated when the control detected that a shorted SCR condition occurred for more than 3 consecutive cycles, but less than the programmed value, in the SHORTED SCR CYCLE LIMIT set-up parameter."
This means that voltage was seen on the output of the SCR when it shouldn't have been. Some of the things that can cause this are:
Voltage picked up from another nearby welder.
Bad firing board, allowing "leakage" through the firing board.
Noise on the power bus from nearby arc welders.
If this gets worse it will start nuisance tripping of the circuit breaker.
You can try:
Go to the SHORTED SCR CYCLE LIMIT and increase the number of cycles required to be a valid short, but I wouldn't go over 10 cycles.
Changing to another firing board, AND MARKING THE OLD ONE with this fault wording!
Check the load resistor, it may be open, should be between 250-1000 ohms for most controllers.
Check to see that the tap switch is not on zero, which can cause this on some controls
Check the calibration of the current readings, in some cases being WAY off can fool the controller into reading a small leakage and registering it as a much higher current. This depends on the controller design also.
Discussed cascade welder and shunting problems with one or two guns passing current when welding on another gun. Since the normal path for current is only through the tips, and this gun is passing current when the tips are open, then there must be a shunt path. Mos often, this indicated bad isolation between the shank adaptor and the cylinder rod that it is mounted to.
Click here for an illustration in .pdf format
You may have to disconnect all guns then measure them one at a time, to identify the bad ones.
JP asked "How do I change the WCU number so it reads out on the DEP correctly. Right now they all read 00"
A- I hope you mean you are using one DEP on the Medlan network to many Medars, because they all read "00" when you put the DEP on the local port of the Medar SLC-500 card.
You plug a DEP into the local port on the Medar card in the SLC-500
and hit the key "Program Mode"
You will see
hit F5 "*" and you will see
hit F4 "Network Addr" and you will see
Hit F1 "Port", and use the number keys to set the address you want
Then hit Enter
Then F3 for "Download" and you will see "Download complete"
Now you can move the DEP back to the MedLan network and address it with that number.
Discussed the 2.5 foot long guns, are hard to align.
Yes, you loosen the bolts on the "Rear Hairpin Mount" as it is called, then tap it with a hammer, then try to tighten it back down without it moving. Very hard to do. It does help if there are two bolts in the groove in the Hairpin mount, then you can tighten them a little bit back and forth. Still very difficult.
And you asked about replacing the A-nose with domes, and that is always good, the extra copper near the weld zone gives greater strength and greater thermal inertia, both good features.
And also the "no-flat" domes will make a 6mm weld, as they sink in during welding, and spread out the current accordingly. The have a regulating effect, which helps control expulsion also.
You say they help with alignment, I wasn't aware of that, I thought they would be worse, but if that is what you get, great, change to domes, much better all the way around.