Clarification on Current and Polarity Abbreviations

[Anban]

Dear Experts
Pls enlighten me if thse abbr. are same and explain the correlation and difference


1 -  DCEP x DC+VE  x DCSP
2 -  DCEN x DC-VE x DCRP

DCEP - Direct Curent Electrode Positive
DCSP - Direct Current Straight Polarity
DCRP - Direct Current Reverse Polarity

Appreciation in advance

[John Henning]

As I understand from welding people even older than I;  in the beginning days of welding, DC welding was performed with direct current power supplies with the electrode being the negative pole.  As welding progressed some, people found that SMAW welding with cellulosic  coverings “ran” better with the electrode positive or “reverse” polarity.  This may be a true story or it may just be propagated mythology.  At any rate -

 

For basic welding you can have an alternating current (AC) power supply or a direct current (DC) power supply.  With DC you have two options:   (1) electrode as the negative pole and the work piece the positive pole or (2) electrode as the positive pole and  the work as the negative pole.

 

DC straight polarity (DCSP) is the same as DC electrode negative (DCEN).  There may also be non-standard designations such as DC-, or DC-VE.

 

DC reverse polarity (DCRP) is the same as DC electrode positive (DCEP).  Or similar to above, non-standard DC+, or DC+VE.

 

Hope this helps.

 

John A. Henning

Welding & Materials

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[jiji lal]

Dear Anban,

 polarity related to the flow direction of current in a welding circuit.

Technically , we assume the current starts flowing from +ve terminal of the power source then  returns through -ve terminal and hence the item(electrode/parent metal) wchich connects in +e terminal can produce more heat(66%) than -ve(33%).

In DCSP Electrode will connect to -ve terminal only ,so in other means we can say  DCSP= DC-VE= .DCEN
In DCRP Electrode will connect to +ve terminal only ,so in other means we can say DCRP= DC+VE= DCEP

Regards

Jijilal K M,

Tecpro Infra projects Ltd.

Kochi. S.India

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[Sinadurai Sripadmanaban]

Please give a list of metals & other items including stainless steel for which +ve to be connected to electrode as well as for which metal -ve to be connected to electrode.

Sinnadurai.S

[John Henning]

The choice of polarity is generally not determined by the base metal but by the process or process parameters.  For SMAW the choice of electrode will often dictate the optimum polarity.  Polarity issues/selection for various processes are discussed in the ASM Handbook, Volume 6, the AWS Welding Handbook, Volume 2, or many basic welding text books.

 

One exception would be materials that develop a very tenacious, fast reforming, refractory oxide layer such as aluminum.  In that case, AC is often preferred for some processes, such as GTAW.  The alternating current helps to break and lift off the oxide layer.

 

John A. Henning

Welding & Materials

 

[kannayeram gnanapandithan]

Current ( electron) flows from Negative to Positive . When Electron hits the +ve, more heat (2/3) is generated in +ve terminal( say holder)

[c sridhar]

 Mr. Sinnadurai,

Apart from knowing about polarity selection like,

DC EN (Electrode Negative) / DC -ve  (electrode Holder connected to Negative side of the pole)  /

DC Straight Polarity (Electrode / Holder connected  Straight  to Negative side of the pole  ---
are all same. Electrode coating / binder used to bond the chemicals makes this choice possible.

All Rutile coated  type & added and with Potassium silicate as a binder works well with DCEN  only ..
example - E6013, E7013 or all electrodes ( EXXX3) ending with numerical no.3  

All Rutile coated - iron powder type & added with Titania  also works well with DC EN. only.
example - E7014, E7024 or all electrodes ( EXXX4) ending with numerical no 4  

------------

DC EP (Electrode Positive) / DC +ve  (electrode Holder connected to Positive side of the pole)  /

DC Reverse Polarity (Electrode / Holder Reversed from Straight  to Positive side of the pole  ---
are all same. Here also electrode coating / binder used to bond the chemicals makes this choice possible.

All Cellulose coated  type & added  with Sodium silicate as a binder works with DCEP  only.
example - E6010, E7010 or all electrodes ( EXXX0) ending with numerical no..0  

All  basic / low hydrogen coated type  & added with Sodium silicate as a binder works with DC EP.
example - E7015, E 9015 or all electrodes ( EXXX5) ending with numerical no.5  

All  basic / low hydrogen coated type  & added with Potassium silicate as a binder works with DC EP.
example - E7016, E 10016 or all electrodes ( EXXX6) ending with numerical no.6  

All basic / low hydrogen coated - iron powder type & added with Potassium  silicate as a binder also works

well with DC EP.     example - E7018, E9018 or all electrodes ( EXXX8) ending with numerical no 8.

In SS electrode category, all types of electrodes including E 308 -17 / E316 -17  or  E308 -16 / 316 -16 (Rutile coated)

works  with DCEP as well as AC also.

All types of SS electrodes including E 308 -15 / E316 -15 ( basic coated) works with DCEP only..

Trust above info. will be  of help to you.

Sridhar.