Arc Welding 101

What is arc welding?

Arc weld­ing fus­es parts per­ma­nent­ly togeth­er by using a pow­er sup­ply to gen­er­ate an elec­tric arc between an elec­trode mount­ed in a torch and a met­al. This arc is an elec­tric cur­rent flow­ing between two elec­trodes through an ion­ized col­umn of gas is able to pro­duce a heat intense enough to melt the metal. 

The heat is pro­duced through a neg­a­tive­ly charged cath­ode and a pos­i­tive­ly charged anode. The neg­a­tive and pos­i­tive ions are bounced off of each oth­er in the plas­ma col­umn at an accel­er­at­ed rate. The elec­trode is typ­i­cal­ly a spe­cial­ly pre­pared rod or wire that not only con­ducts the cur­rent but also melts and sup­plies filler met­al to the joint.

The arc is formed between the actu­al work and an elec­trode (stick or wire) that is guid­ed along the joint. It pro­vides the heat need­ed to melt the elec­trode and the base met­al, and some­times also sup­plies the means to trans­port the molten met­al from the tip of the elec­trode to the work. 

This intense heat (around 6500ºF at the tip) applied at the joint between two parts is melt­ed and caused to inter­mix with an inter­me­di­ate molten filler met­al. This heat melts both the base met­al and the elec­trode, cre­at­ing molten droplets that are detached and trans­port­ed to the work through the arc col­umn when the elec­trode is consumable. 

In car­bon or TIG weld­ing there are no molten droplets to be forced across the gap and onto the work so filler met­al is melt­ed into the join from a sep­a­rate rod or wire.

Regard­less, this pool of molten met­al is some­times called a ​“crater.” The crater solid­i­fies behind the elec­trode (see ​“slag” below) as it is moved along the joint. The result is a met­al­lur­gi­cal fusion bond that pro­duces a weld­ment that has a sim­i­lar strength to the met­al of the parts. This is dif­fer­ent than non-fusion process­es of join­ing where the mechan­i­cal and phys­i­cal prop­er­ties of the base mate­ri­als can­not be dupli­cat­ed at the joint.

This met­al trans­fer can occur one of two ways: Sur­face Ten­sion Trans­fer where a drop of molten met­al touch­es the molten met­al pool and is drawn into it by sur­face ten­sion or Spray Arc where the drop is eject­ed from the molten met­al at the elec­trode tip by an elec­tric pinch pro­pelling it to the molten pool (great for over­head welding).

Pow­er­ing Arc Welding:

Below is a dia­gram of the basic arc-weld­ing cir­cuit that includes a pow­er source. There must be an ion­ized path to con­duct elec­tric­i­ty across a gap and then some sort of igni­tion in order to start the arc. This is usu­al­ly caused by sup­ply­ing an ini­tial volt­age high enough to cause a dis­charge or by touch­ing the elec­trode to the work and then with­draw­ing it as the con­tact area becomes heated.

When weld­ing, one can use a direct cur­rent (DC) with the elec­trode either pos­i­tive or neg­a­tive or alter­nat­ing cur­rent (AC). The choice of cur­rent and polar­i­ty depends on the process, the type of elec­trode, the arc atmos­phere, and the met­al being weld­ed. What­ev­er pow­er source is nec­es­sary is fit­ted with nec­es­sary con­trols that are con­nect­ed by a work cable to the work piece. 

Arc Shield­ing

Arc shield­ing is a nec­es­sary process in arc weld­ing as any met­al at high tem­per­a­tures has a high­er reac­tiv­i­ty to chem­i­cal ele­ments in the air. So, the process has a means of cov­er­ing the arc and molten pool with a pro­tec­tive shield of gas. Shield­ing gas is used while the torch is join­ing parts togeth­er in order to pre­vent con­t­a­m­i­na­tion. This also con­firms the strength of welds and min­i­mizes post weld cleanup of a part.

Robot­ic Arc Welding: 

Since the 1980s, weld­ing automa­tion has become a much more robust and mature process. It has advanced quick­ly and has become extreme­ly effec­tive at meet­ing tedious pro­duc­tion demands at fast rates, while also being eco­nom­i­cal, effi­cient, depend­able, and enabling fur­ther pro­tec­tion of work­ers from dan­ger­ous tasks. 

6‑axis robot sys­tems are able to more than mim­ic a human arm’s move­ment with­in a cell and allow the torch to be placed exact­ly where nec­es­sary in order to work in the most effi­cient, repeat­able position. 

In just about every indus­try, big or lit­tle, weld­ing is used as a prin­ci­pal means of the fab­ri­ca­tion and repair process­es for prac­ti­cal­ly any appli­ca­tion. Robot­ic weld­ing includes process­es like arc weld­ing, MIG weld­ing, TIG weld­ing, laser weld­ing and spot weld­ing.

These ben­e­fits are caus­ing the weld­ing robot mar­ket to yield growth rates faster than any oth­er indus­tri­al robot. This is evi­dent in the esti­mate that the auto­mat­ed weld­ing and acces­sories divi­sion alone will be worth $1.9 bil­lion in 2017.

Ben­e­fits of Robot­ic Weld­ing:

• Speed: Robot­ic weld­ing sys­tems are mas­ters at get­ting the job done quick­ly. Robots don’t have any required lunch breaks nor need­ed vaca­tion times; they will work con­tin­u­ous­ly with­out inter­rup­tion, ²⁴⁄₇. There is less han­dling com­pared to a man­u­al weld cycle so the robot achieves much high­er lev­els of arc-on time and typ­i­cal­ly will increase out­put by a fac­tor of two to four. Sub­se­quent­ly you will see a dra­mat­ic increase in your through­put and pro­duc­tiv­i­ty that increas­es your company’s over­all efficiency.
• Accu­ra­cy: Robot­ic sys­tems have reg­u­la­tions that enable them to make few­er errors than a man­u­al weld­ing sys­tem which helps to decrease wast­ed mate­r­i­al and time. There are also designs to help reach dif­fi­cult or slim places, such as a slen­der robot­ic arm.
• Con­sis­ten­cy: The reg­u­la­tions and result­ing accu­ra­cy pro­duce weld­ments that are extreme­ly con­sis­tent. This increas­es the con­fi­dence in the prod­uct qual­i­ty, every sin­gle time.
• Safe­ty: Weld­ing can be a very dan­ger­ous appli­ca­tion as it deals with flash, fumes, sparks and heat. When you auto­mate, you are able to pro­tect work­ers as the robots can endure these haz­ards. Employ­ees claim­ing com­pen­sa­tion if they are put in harm’s way can also be reduced. Com­pa­nies can reduce the risk of their employ­ees claim­ing com­pen­sa­tion if they are affect­ed by the haz­ardous work­ing environment.
• Cost Reduc­tion: The cost of man­u­al weld­ing can be steep as it requires time, skill, and con­cen­tra­tion. Robot­ic weld­ing takes less time and allows you to cut costs of direct labor, con­serve ener­gy (few­er start-ups), and con­serv­ing mate­ri­als. Insur­ance and acci­dent relat­ed costs are also reduced. The cost sav­ings that robot weld­ing brings can help com­pa­nies to be more com­pet­i­tive with low cost man­u­fac­tur­ing coun­tries in East­ern Europe or China. 
• Qual­i­ty: A robot has an excel­lent path fol­low­ing accu­ra­cy and can present a weld­ing gun at the cor­rect weld­ing angle, speed, and dis­tance at a very high repeat­able accu­ra­cy (± 0.04 mm). This presents the abil­i­ty for opti­mum weld­ing con­di­tions to be used for each and every joint which results in con­sis­tent high qual­i­ty out­put, ²⁴⁄₇, with reduced costs for rework, scrap, wire con­sump­tion, or removal of weld splatter.
• Labor: Man­u­al weld­ing will always be required to some degree, but it brings its own sets of chal­lenges… train­ing, recruit­ment, and deal­ing with a high turnover rate all can come at high costs. Robot­ic automa­tion brings much more sta­bil­i­ty and depend­abil­i­ty for your company’s weld­ing job.
• Flex­i­bil­i­ty: The robot can be used to weld many dif­fer­ent prod­ucts such as MIG, TIG, SMAW, FCAW, SAW, and PAW. This also allows com­pa­nies to pro­duce a vari­ety of prod­ucts with a very quick turnaround. 
• Floor space: Com­pared to the same out­put from man­u­al weld­ing bays the robot requires less floor space.

Get Start­ed with Robot­ic Arc Weld­ing Today: 

The demand for arc weld­ing automa­tion sys­tems today is increas­ing­ly ris­ing as com­pa­nies are aware of the low avail­abil­i­ty in qual­i­fied welders par­al­leled by the increase in com­pe­ti­tion demands seen in the glob­al mar­ket. After view­ing all of the ben­e­fits and look­ing at your pro­ject­ed ROI, you should­n’t need any more convincing. 

Don’t waste any more time, Robots​.com is ready to find you the per­fect arc weld­ing automa­tion sys­tem. We have over 35 years of expe­ri­ence, espe­cial­ly with arc weld­ing automa­tion. We have many dif­fer­ent new and used arc weld­ing robots and work­cells in stock ready for integration. 

Con­tact Robots​.com today online or call us at 877−762−6881.