Magnesium Welding Automation With Robots

Nov 2, 2017

Industrial robots can handle just about any task you throw at them, including magnesium welding. Magnesium welding is performed for primary manufacturing or repair and helps manufacturers increase their productivity and efficiency. Contact experts today for more information about integrating a magnesium welding robot.

Robotic Welder

Weld­ing mag­ne­sium is per­formed for pri­ma­ry man­u­fac­tur­ing or repair.


Mag­ne­sium alloys with a den­si­ty of about 1.74 g per cubic cen­time­ter (0.063 lb. per cu in.), when in cast form alloyed with Alu­minum, Man­ganese, Rare Earths, Tho­ri­um, Zinc or Zir­co­ni­um, dis­play high strength to weight ratio mak­ing them mate­ri­als of choice when­ev­er weight reduc­tion is impor­tant or when it is imper­a­tive to reduce iner­tial forces (for rapid­ly mov­ing machine parts). Mag­ne­sium is rough­ly 20% the weight of steel and 67% the weight of alu­minum. Mag­ne­sium cast­ings exhib­it remark­able damp­ing capacity.

  • Pure Mag­ne­sium melts at 650 degrees Cel­sius (1202 degrees Fahrenheit).
  • Con­trac­tion from liq­uid to sol­id is 3.9 to 4.2% and from liq­uid at melt­ing tem­per­a­ture to a sol­id at room tem­per­a­ture is 9.7%.
  • Mag­ne­sium is used as an alloy­ing ele­ment in the pro­duc­tion of cer­tain alu­minum alloys.
  • In cast iron foundries pro­duc­ing nodu­lar cast iron, mag­ne­sium is used to make the graphite par­ti­cles nodu­lar. It is also used for cathod­ic pro­tec­tion of oth­er met­als from corrosion.


Safe­ty pre­cau­tions must be under­stood and fol­lowed. Mag­ne­sium oxi­dizes eas­i­ly. If ignit­ed when it is in the form of machined turn­ings or pow­ders, it burns intense­ly. Machin­ing must be per­formed under con­trolled con­di­tions, with extin­guish­ing agents on hand.


  • Cast­ing alloys are cov­ered by Spec­i­fi­ca­tions ASTM B80, B94 and B199.
  • Wrought alloys by ASTM B90, B107 and B217.
  • Filler met­als for Weld­ing mag­ne­sium alloys are spec­i­fied in
  • AWS A5.19 Spec­i­fi­ca­tion for Mag­ne­sium Alloy Weld­ing Elec­trodes and Rods
  • ASTM448 Spec­i­fi­ca­tion for Mag­ne­sium-Alloy Weld­ing Rods and Bare Electrodes
  • SAE AMS 4397 Mag­ne­sium Wire, Welding.


Weld­ing mag­ne­sium alloys require low­er amounts of heat to melt than oth­er mate­ri­als. How­ev­er, they are sus­cep­ti­ble to dis­tor­tion, due to the high ther­mal con­duc­tiv­i­ty and coef­fi­cient of ther­mal expan­sion. Ade­quate pre­cau­tions must be taken.

Alloy­ing Elements

Because mag­ne­sium is too mechan­i­cal­ly weak to be used as is, it must be alloyed with oth­er ele­ments which con­fer improved prop­er­ties. The Mg-Al-Zn group of alloys, con­tains Alu­minum, Man­ganese and Zinc, which are the most com­mon alloy­ing ele­ments for room tem­per­a­ture appli­ca­tions. Alloy­ing ele­ments Tho­ri­um, Ceri­um and Zir­co­ni­um (with­out Alu­minum) are used for ele­vat­ed tem­per­a­ture, form­ing the Mg-Zn-Zr group.

An increase in alloy con­tent depress­es the melt­ing point, enlarges melt­ing range and increas­es weld crack­ing ten­den­cy. High alloy con­tent needs less heat for melt­ing and lim­its grain growth, show­ing high­er weld­ing mag­ne­sium efficiency.

  • Alu­minum is the most effec­tive ingre­di­ent in pro­vid­ing improved results. In per­cent­ages of 2 to 10%, with minor addi­tions of zinc and man­ganese, it increas­es strength and hard­ness, at the expense of less duc­til­i­ty. Mag­ne­sium alloys con­tain­ing more than 1.5% Al are sus­cep­ti­ble to stress cor­ro­sion and must be stress relieved after welding.
  • Zinc com­bined with alu­minum helps to over­come harm­ful cor­ro­sive effects of iron and nick­el impu­ri­ties that may be present in mag­ne­sium alloys. The high­er the Zn con­tent (over 1%) the high­er the hot short­ness, caus­ing weld cracking.
  • Man­ganese improves yield strength (slight­ly) and salt-water resis­tance of mag­ne­sium alloys. High­er melt­ing point requires high­er heat input to melt. Grain growth adja­cent to the weld reduces strength.
  • Tho­ri­um or Ceri­um can be added to improve strength at tem­per­a­tures from 260 to 370 degrees Cel­sius (500 to 700 degrees Fahren­heit). Zir­co­ni­um in small amounts is a grain refin­er that improves weldability.
  • Beryl­li­um is some­times added to reduce the ten­den­cy of mag­ne­sium to burn while melt­ing. No adverse effect on weld­ing has been observed. It may be ben­e­fi­cial, in a braz­ing alloy, in reduc­ing the dan­ger of igni­tion dur­ing braz­ing in furnace.
  • Cal­ci­um is added in small amounts to reduce oxi­da­tion, but it can increase the risk of weld cracking.


Weld­ing mag­ne­sium is gen­er­al­ly per­formed with arc process­es using direct cur­rent with reverse polar­i­ty (elec­trode pos­i­tive). Wrought alloys are usu­al­ly more weld­able than cer­tain cast alloys.

Met­al Trans­fer Modes for Gas Met­al Arc Weld­ing mag­ne­sium (GMAW) or Met­al Inert Gas (MIG)
  • Short cir­cuit mode — filler touch­es the work many times per sec­ond and extin­guish­es the arc, the met­al is sup­plied as a sequence of drops.
  • Pulsed arc mode — a pow­er sup­ply pro­vides a mod­u­lat­ed cur­rent. The arc is unin­ter­rupt­ed and the met­al is trans­ferred intermediately.
  • Spray trans­fer mode — met­al is trans­ferred with a spray of droplets.
  • The most used shield­ing gas is gen­er­al­ly argon while mix­tures with heli­um are acceptable.
Gas Tung­sten Arc for Weld­ing mag­ne­sium (GTAW) also known as Tung­sten Inert Gas (TIG)
  • Alter­nat­ing cur­rent machines or direct cur­rent reverse polar­i­ty (elec­trode pos­i­tive) pow­er sup­plies, with high fre­quen­cy cur­rent super­im­posed are used.
  • For thin sheets both are suit­able, for heav­ier sheets alter­nat­ing cur­rent is pre­ferred as it pro­vides deep­er penetration.
  • Direct cur­rent straight polar­i­ty (elec­trode neg­a­tive) is not pre­ferred because it lacks the cathod­ic clean­ing action.

Elec­tron Beam weld­ing mag­ne­sium has been used for repair­ing expen­sive cast­ing on alloys con­tain­ing less than 1% Zinc. The rel­a­tive weld­abil­i­ty of the dif­fer­ent mag­ne­sium alloys is sim­i­lar to that dis­played for the more com­mon arc processes.

The con­di­tions have to be strict­ly mon­i­tored because of the dan­ger of devel­op­ing voids and poros­i­ty due to the low boil­ing point of Mag­ne­sium and the still low­er one of Zinc. A slight­ly defo­cused beam may help to obtain sound welds.

Laser Beam is a pre­ferred method for weld­ing mag­ne­sium because of its low heat input, ele­vat­ed speed and lim­it­ed defor­ma­tion. How­ev­er this method has a ten­den­cy of devel­op­ing porosity.

Resis­tance weld­ing mag­ne­sium for either spots or seams is per­formed on wrought alloys like sheets and extru­sions, essen­tial­ly with equip­ment and con­di­tions sim­i­lar to those used for aluminum.

Repair­ing Cast­ings: One of the most com­mon Weld­ing mag­ne­sium appli­ca­tions is repair­ing cast­ings either as cast or after ser­vice. Prepa­ra­tion is impor­tant and should exclude con­t­a­m­i­na­tion from extra­ne­ous mate­ri­als. Gen­er­ous bevels should be pre­pared to allow for full penetration.

Pre­heat­ing: The need for pre­heat­ing when weld­ing mag­ne­sium is dic­tat­ed by the degree of joint restraint and by met­al thick­ness: for thick walls and a short weld­ing bead, it may not be required. Pre­heat­ing should be per­formed in a fur­nace with a pro­tec­tive atmos­phere for reduc­ing oxi­da­tion. One of the rec­om­mend­ed pro­ce­dures to min­i­mize weld crack­ing is to weld from the cen­ter towards the sides (one half after the oth­er). Ther­mal shocks should be avoided.

For more infor­ma­tion on mag­ne­sium weld­ing, con­tact Robots​.com experts today online or at 8777626881.

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