Sear
Magnetic pulse
welding
Magnetic pulse welding (MPW) is a solid st at e welding process t hat uses magnet ic forces t o
weld t wo workpieces t oget her. The welding mechanism is most similar t o t hat of explosion
welding.[1] Magnet ic pulse welding st art ed in t he early 1970s, when t he aut omot ive indust ry
began t o use solid st at e welding. The biggest advant age using magnet ic pulse welding is t hat
t he format ion of brit t le int ermet allic phases is avoided. Therefore, dissimilar met als can be
welded, which cannot be effect ively joined by fusion welding. Wit h magnet ic pulse welding high
qualit y welds in similar and dissimilar met als can be made in microseconds wit hout t he need for
shielding gases or welding consumables.
Magnetic pulse welded space frame
Process
Magnetic pulse welded HVAC pressure vessel
Magnet ic pulse welding is based on a very short elect romagnet ic pulse (<100 µs), which is
obt ained by a fast discharge of capacit ors t hrough low induct ance swit ches int o a coil. The
pulsed current wit h a very high amplit ude and frequency (500 kA and 15 kHz) produces a highdensit y magnet ic field, which creat es an eddy current in one of t he work pieces. Repulsive
Lorent z forces are creat ed and a high magnet ic pressure well beyond t he mat erial yield st rengt h
causing accelerat ion and one of t he work pieces impact s ont o t he ot her part wit h a collision
velocit y up t o 500 m/s (1,100 mph).[2]
During magnet ic pulse welding a high plast ic deformat ion is developed along wit h high shear
st rain and oxide disrupt ion t hanks t o t he jet and high t emperat ures near t he collision zone. This
leads t o solid st at e weld due t o t he microst ruct ure refinement , dislocat ion cells, slip bends,
micro t wins and local recryst allizat ion.[3]
Principles
In order t o get a st rong weld, several condit ions have t o be reached:[4]
Jetting condition: t he collision has t o be subsonic compared t o t he local mat erial's speed of
sound t o generat e a jet .
High pressure regime: t he impact velocit y has t o be sufficient t o obt ain a hydrodynamic
regime, ot herwise t he part s will only be crimped or formed.
No fusion during the collision: If t he pressure is t oo high, t he mat erials can locally melt and resolidify. This can cause a weak weld.
The main difference bet ween magnet ic pulse welding and explosive welding is t hat t he collision
angle and t he velocit y are almost const ant during t he explosive welding process, while in
magnet ic pulse welding t hey cont inuously vary.
Advantages of MPW
Allows welding of designs which wit h ot her processes are challenging or not possible.
High-speed pulse last s from 10 t o 100 µs, t he only t ime limit at ion is loading and unloading and
capacit or charge t ime.
Lower down-t ime due t o lack of consumable part s (e.g. elect rodes) and no need for cleaning.
Suit ed t o mass-product ion: t ypically 1-5 million welds per year.
Dissimilar met als welding is possible.
Weld wit h no heat -affect ed zone.
No need for filler mat erials.
Green process: no smoke, no radiat ion and no ext ract ion equipment required.
Bulk and surface purit y is preserved.
Can produce welds wit h no shielding gas, can be used t o seal part s under vacuum.
Mechanical st rengt h of t he joint is st ronger t han t hat of t he parent mat erial.
High precision obt ainable by adjust ment of magnet ic field, weld paramet ers can be changed
elect ronically.
Zero dist ort ion can be achieved depending on part mat erials & geomet ry.
Almost zero residual st resses.
No corrosion development in t he welding area.
Disadvantages
Challenging t o apply t o welds t hat are not roughly circular.
Geomet ry of part s may have t o be changed t o allow t he magnet ic pulse process.
If t he part s cannot be slid int o and out of t he pulse coil a more complex mult i-part coil must
be designed.
Pulse coil may have t o be re-designed if mat erials or dimensions are changed.
Brit t le component s can be fract ured by t he shock (does not exclude t he use of mat erials like
glass, but must be considered).
May produce an EMP effect on any elect ronics present inside or near t he part .
Init ial invest ment cost may out weigh t he lower price-per-weld for low volume part s.
Numerical simulations of MPW
Various numerical invest igat ions were carried out t o predict t he int erface behavior of t he MPW
and t he in-flight behavior of t he flyer t o det ermine t he collision condit ions. Generally, t he flyer
velocit y prior t o t he impact governs t he int erfacial phenomena. This is t he charact erist ic
paramet er t hat should be known based on t he process and adjust able process paramet ers.
Alt hough, Experiment al measurement s using laser velocimet ry met hods provide an accurat e
assessment of t he flyer velocit y, (one example of such measurement is Phot on Doppler
velocimet ry (PDV)), numerical comput at ion offers a bet t er descript ion of t he flyer velocit y in
t erms of spat ial and t emporal dist ribut ion. Moreover, a mult i-physics comput at ion of t he MPW
process t ake int o account of t he elect rical current t hrough t he coil and comput e t he physical
behavior for an elect romagnet ic-mechanical coupled problem. Somet ime, t hese simulat ions also
allow t o include t he t hermal effect during t he process.[5][6] A 3D example model used for LSDYNA simulat ion is also described in, and it also provides some det ails of t he physical
int eract ions of t he process, t he governing equat ions, t he resolut ion procedure, and bot h
boundary and init ial condit ions. The model is used t o show t he capabilit y of 3D comput at ion t o
predict t he process behavior and part icularly, t he flyer kinemat ics and macroscopic
deformat ion.[7][8]
References
1. Weman, Klas (2003), Welding processes handbook (https://books.google.com/books?id=yIJm5uL9_sAC
&pg=PA91) , CRC Press, pp. 91–92, ISBN 978-0-8493-1773-6.
2. Magnetic Pulse Welding Illustration (http://www.bmax.com/technology/magnetic-pulse-welding/)
3. A. Stern, V. Shribman, A. Ben-Artzy, and M. Aizenshtein, Interface Phenomena and Bonding Mechanism
in Magnetic Pulse Welding, Journal of Materials Engineering and Performance, 2014.
4. Magnetic Pulse Welding: J.P. Cuq-Lelandais, S. Ferreira, G. Avrillaud, G. Mazars, B. Rauffet: Welding
windows and high velocity impact simulations.
5. Sapanathan, T.; Raoelison, R.N.; Buiron, N.; Rachik, M. (2016). "Magnetic Pulse Welding: An Innovative
Joining Technology for Similar and Dissimilar Metal Pairs". Joining Technologies. doi:10.5772/63525 (ht
tps://doi.org/10.5772%2F63525) . ISBN 978-953-51-2596-9.
. Raoelison, R.N.; Sapanathan, T.; Padayodi, E.; Buiron, N.; Rachik, M. (2016). "Interfacial kinematics and
governing mechanisms under the influence of high strain rate impact conditions: Numerical
computations of experimental observations". Journal of the Mechanics and Physics of Solids. 96: 147.
Bibcode:2016JMPSo..96..147R (https://ui.adsabs.harvard.edu/abs/2016JMPSo..96..147R) .
doi:10.1016/j.jmps.2016.07.014 (https://doi.org/10.1016%2Fj.jmps.2016.07.014) .
7. L'Eplattenier, Pierre; Cook, Grant; Ashcraft, Cleve; Burger, Mike; Imbert, Jose; Worswick, Michael (May
2009). "Introduction of an Electromagnetism Module in LS-DYNA for Coupled Mechanical-ThermalElectromagnetic Simulations". Steel Research International. 80 (5): 351–8.
. I. Çaldichoury and P. L’Eplattenier, EM Theory Manual, Livermore Software Technology Corporation,
California, USA, 2012.
External links
The Electromagnetic Pulse Technology (EMPT): Forming, Welding, Crimping and Cutting (ht t p
s://web.archive.org/web/20140414134031/ht t p://www.pst product s.com/empt %20forming%2
0welding%20crimping%20and%20cut t ing.pdf)
by R. Schäfer, P. A. Pasquale and S. W. Kallee
3D Impacts Modeling of the Magnetic Pulse Welding Process and Comparison to Experimental
Data (ht t ps://www.researchgat e.net /publicat ion/302889281_ 3D_ Impact s_ Modeling_ of_ t he_
Magnet ic_ Pulse_ Welding_ Process_ and_ Comparison_ t o_ Experiment al_ Dat a)
by J.-P. Cuq-
Lelandais*, G. Avrillaud, S. Ferreira, G. Mazars, A. Not t ebaert , G. Teilla, V. Shribman
Automotive Applications of Electromagnetic Pulse Technology (EMPT) (ht t ps://web.archive.or
g/web/20181123191946/ht t p://www.english.pst product s.com/Aut omot ive%20Applicat ions%
20of%20EMPT.pdf)
by S. W. Kallee, R. Schäfer and P. A. Pasquale.
Special Issue "Impulse-Based Manufacturing Technologies" (ht t ps://www.mdpi.com/journal/jm
mp/special_ issues/impulse_ based_ manufact uring)
Process. 2021, 5(3), 96, ISSN 2504-4494.
by Verena Psyk et al, J. Manuf. Mat er.
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