Best Practices for Welding Contact Tips & Nozzles

A lot of time and mon­ey will be spent on con­tact tips and noz­zles so it is impor­tant to look at how to bring the most val­ue to this process. This arti­cle will help to bring a deep­er knowl­edge on weld­ing con­tact tips and nozzles. 

Con­tact Tips 

Con­tact tips are respon­si­ble for guid­ing the wire and trans­fer­ring the cur­rent from the con­duc­tur tube (aka swan­neck) through the filler wire and to the work­piece. They are in charge of the cur­rent trans­fer and wire targeting. 

Under­stand­ing how to keep your con­tact tip per­form­ing at its best is crit­i­cal for your weld­ing appli­ca­tion needs. 

The mate­r­i­al cho­sen for the con­tact tip is impor­tant because a torch con­sum­able is the last line of con­duc­tiv­i­ty in the weld­ing cir­cuit between the part. This means choos­ing the right mate­r­i­al for your pro­duc­tion line needs will pro­vide a high­er qual­i­ty weld product.

The pop­u­lar mate­ri­als to choose from are cop­per, beryl­li­um, cop­per zir­co­ni­um, sil­ver plat­ed, and heavy-duty silver. 

Beryl­li­um cop­per: ben­e­fi­cial char­ac­ter­is­tics includ­ing dura­bil­i­ty, but it is con­sid­ered to be tox­ic as a con­sum­able to pro­duce so engi­neers shy away from using it.

Cop­per: great con­duc­tiv­i­ty, but lacks hard­ness, bet­ter arc char­ac­ter­is­tics lead­ing to bet­ter weld qual­i­ty and less touch-ups or rework. How­ev­er, you will change a pure cop­per tip far more fre­quent­ly than cop­per zir­co­ni­um. Increased down­time and less through­put on the weld­ing cell. 

Cop­per Zir­co­ni­um: greater hard­ness but less conductive. 

Sil­ver-plat­ed con­tact tips: Uses a micron sil­ver plat­ing as it is very hard and con­duc­tive. This can increase the con­tact life 9 times com­pared to a stan­dard cop­per tip. It has a low­er spat­ter adhe­sion and a smoother bore as a result of the drilling process, cre­at­ing a bet­ter heat and cur­rent transference. 

BINZEL’s con­tact tips have the fol­low­ing as a point of reference:

Pic­ture Cred­it: The Defin­i­tive Guide to Robot­ic Weld­ing Torch­es by Abi­cor Binzel

Decid­ing Between Drawn vs. Drilled Con­tact Tips

Drawn: is a com­mon process for cre­at­ing con­tact tips; there is more vari­a­tion and less tol­er­ance con­trol. Cop­per is drawn and extrud­ed from a long cop­per bar and then cooled into the con­tact tip. This is less expen­sive because the drilling step is removed from the pro­duc­tion process. 

Drilled: The bore is indexed, drilled, and machined from a sol­id shape which gives the orfice greater integri­ty. Extrud­ed con­tact tips don’t last as long as drilled tips. 

Dif­fer­ences between Drawn and Drilled:

The integri­ty and repeata­bil­i­ty of the con­tact tip size is the true dif­fer­ence between drawn and drilled con­tact tips. 

For instance, a 0.045’ con­tact tip made from a drawn process is more prone to errors in both bore size and fin­ish. The wire, which always has a cast on it, is only hit­ting the high points of the tip fin­ish so it’s typ­i­cal­ly going to wear on one side. 

Also, the drawn process is not as reli­ably repeat­able or pre­cise as the drilled process. Mar­gins of error exist in the tip bore as an .045” con­tact tip bore may be as large as .049” or as small as .042”.

This incon­sis­ten­cy can lead to low qual­i­ty arc starts, rework, and decreased through­put. It can also lead to wire flip where the wire wan­ders out­side the weld joint entire­ly caus­ing scrap in the part because of incon­sis­tent tolerances.

Noz­zles

One of the most com­mon issues with noz­zles is the spat­ter buildup. A poor noz­zle will incur great amounts of spat­ter build-up in a short amount of time. See below.

Pic­ture Cred­it: The Defin­i­tive Guide to Robot­ic Weld­ing Torch­es by Abi­cor Binzel

Mate­r­i­al selec­tion is also imper­a­tive when choos­ing the cor­rect noz­zles; the more the mate­r­i­al resists heat, the less spat­ter builds up in side the noz­zle. See below. 

Pic­ture Cred­it: The Defin­i­tive Guide to Robot­ic Weld­ing Torch­es by Abi­cor Binzel

For instance, pure cop­per or brass based mate­r­i­al with the weld­ing noz­zle with not last as long as a hard­er plat­ed noz­zle mate­r­i­al like a nick­el or chrome plat­ed noz­zle because of their spat­ter and heat resis­tant prop­er­ties (com­pare first pic­ture of a brass noz­zle above to the sec­ond picture). 

Typ­i­cal­ly, you will find a hard­er con­duc­tive mate­r­i­al that pro­tects against spat­ter and suf­fers less scal­ing such as nick­el. This will offer less ream cycles and ulti­mate­ly greater productivity. 

Slip-On Ver­sus Thread­ed Nozzles

There are two kinds of noz­zles: slip-on and thread­ed. The cost ben­e­fit analy­sis typ­i­cal­ly comes to down­time as it costs mon­ey, sac­ri­fices through­put, and keeps the robot from achiev­ing Return on Invest­ment (ROI).

Slip-on: slip-on noz­zles are believed to be eas­i­er to get on and off how­ev­er they may loosen over time and cause poros­i­ty in the weld. They are also not effec­tive for torch reaming. 

Thread­ed: The risk is min­i­mized to nonex­is­tent. There is a fine thread option and a coarse thread option. Both styles offer more advan­tages to slip-on noz­zles because they are less like­ly to fail. 

Fine thread­ed noz­zles are more dif­fi­cult to install and remove (bind­ing) while also hav­ing have a more dif­fi­cult time deal­ing with debris and spatter. 

Coarse thread­ed noz­zles don’t’ have much impact from spat­ter and debris.

Con­tact Robots​.com Today!

In sum­ma­ry, it is impor­tant to under­stand the fol­low­ing: are you using drawn or drilled con­tact tips? What is the hard­ness and con­duc­tiv­i­ty lev­els for con­tact tips? What is the tip mate­r­i­al and how often chang­ing con­tact tips? noz­zle mate­r­i­al? Are the noz­zles thread­ed or slip-on? How often are the noz­zles need­ing to be changed and what is the cost?

For more infor­ma­tion on weld­ing tips or noz­zles, con­tact Robots​.com experts online or at 877−762−6881.

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