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Up Topic Welding Industry / General Welding Discussion / E7018 electrode
- - By waqasmalik (**) Date 05-11-2016 11:21
Hi all, i went to purchase a stick welding plant in the local market. Amperage requirement was 300 amps. I took welder along with me and we started searching the welding plants. We saw two plants, both having same amperage range, one being costly than the other. Welder said this cheaper one wont run E7018, it will easily run E6013. He demonstrated me there. Arc was unstable on E7018. My question is why it is difficult to run E7018 electrodes? Whats diffrent about them?
Thank you in advance
Parent - By Northweldor (***) Date 05-11-2016 11:41
Were the machines the same in all specifications? What make and model?
Parent - - By TimGary (****) Date 05-11-2016 12:19
Perhaps it was an AC only machine?
Parent - - By waqasmalik (**) Date 05-11-2016 12:48 Edited 05-11-2016 12:52
It was local made, it did not have the polarity change option.
I guess timgary is right. Its working on AC. It wont have rectifier. But then why it runs good on 6013 and unstable on 7018.
BTW 7018 can work on AC too per AWS 5.1
Parent - - By waqasmalik (**) Date 05-11-2016 12:49 Edited 05-11-2016 13:01
Machine costs 300 us dollars and is china made. While other having same amperage was 700 us dollars made by Lyon company UK. It run both 6013 and 7018.
Parent - By TimGary (****) Date 05-11-2016 13:30
You're right of course, 6013 and 7018 will both run on AC current.
Most SMAW electrodes however work better with DC.
The ingredients in the flux, which may vary from various manufacturers, and the storage method of the electrodes will also affect the way they burn.
Perhaps part of the machine problem you noticed may be summed up in 5 letters - CHINA....
I've attached some helpful info.

Tim
Attachment: SMAWElectrodes.pdf (124k)
Parent - By Northweldor (***) Date 05-11-2016 13:26
The rod he was using may not have been the 7018 specially designed for AC use.
Parent - - By jwright650 (*****) Date 05-11-2016 14:14
Check the open circuit voltage, 7018 needs more voltage to fire off and run.
Parent - - By waqasmalik (**) Date 05-11-2016 15:52
I shall go tomorrow and read its manual. I shall upload tomorrow
Parent - - By jwright650 (*****) Date 05-11-2016 17:19
You probably need 60 OCV  or more to run the E7018 without sputtering. Some of the smaller A/C E7018's will run with about 40 or more volts and are made to run on the smaller machines.
Parent - - By waqasmalik (**) Date 05-12-2016 12:04
I checked the manual today, ocv is 70v and machine model is BX-315 china made. I think there are two reasons that it did not run 7018 properly.
1) china made
2) The electrode 7018 could not have been designed for use specifically on AC.
3) Inherent Arc stability problems associated with AC
Parent - - By 803056 (*****) Date 05-13-2016 17:21
The arc stabilizer for AC is potassium, while sodium is used as the arc stabilizer for DC. Not all electrodes are created equal, not all electrodes can be used with both AC and DC. Most E7018 electrodes are intended to be used with DC, however, some E7018 electrodes are formulated to run with either AC or DC. The container often indicates whether the electrode can be used with DC only or AC and DC.

Inexpensive "buzz boxes" are typically fine for welding with AC and low open circuit voltage. DC electrodes usually require higher open circuit voltage to provide easy arc initiation because of the higher ionization voltage required by sodium.

The voltage under load, i.e., while welding, is a function of the rated amperage of the welding machine. The formula is V = 20 + 0.04X Amperage. This is the case if they meet the requirements of the NEMA. If they don't comply with the NEMA, all bets are off.

A 200 amp machine will only provide 28 volts while welding. A 300 amp machine will provide 32 volts. One must consider both the amperage required to weld with a rod of a certain diameter and the arc voltage while welding. In addition, the length of the welding leads, oxidized connections, etc. add to the voltage needed to provide the proper conditions to weld successfully.

Interestingly, I find the E6010 usually runs with a higher arc voltage than an E7018 of the same diameter because most E7018 is intended to run with a short arc length.

Good luck - Al
Parent - By Northweldor (***) Date 05-13-2016 19:13
Thanks for the explanation! (I always wondered why 6010 did not run well on certain DC machines).
Parent - By kcd616 (***) Date 05-20-2016 03:56
Al,
this is hard core electrical stuff
voltage drop and amps
you even made me think:eek::red::surprised:
btw I have NEMA 2014 code book along with Industrial and Commercial books
being a general contractor cost $$$$$$ for books:sad:
sincerely,
Kent
Parent - - By 357max (***) Date 05-13-2016 19:36
Does the machine have overlapping amperage ranges? In other words, a finite/limited wattage machine. Volts high amps low or versa vice Volts low amps high. If so, the highest OCV will be found by setting the machine at the lowest overlapping amperage range with the required welding amperage adjusted towards the higher end of the fine current adjustment. This can be checked with a handheld voltmeter and ammeter.
Parent - - By waqasmalik (**) Date 05-17-2016 16:22
Sir, are you talking about low power factor? When there is a phase shift, current is zero and voltage is maximum? often used for improvig arc stability with AC.

P= V*I*Cos phi
phi is a phase angle, max value is when it is zero.
Parent - By 357max (***) Date 05-20-2016 02:45
No, limited wattage machines that have overlapping amperage/current ranges have two or more ranges of amperage/current. The set amperage range will cause or reflect an increase or decrease in the voltage. With an increase in amperage/current output the open circuit voltage will be lower to provide the wattage. A decrease in amperage/current range will provide a higher voltage. A higher voltage will stabilize the 7018 arc at a set amperage. This voltage may be measured with the machine turned on with no welding arc. Try measuring the voltage at various amperage ranges. This is if the machine has overlapping amperage range control.
Up Topic Welding Industry / General Welding Discussion / E7018 electrode

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