# Cold metal transfer

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Not to be confused with [Cold welding](/source/Cold_welding).

**Cold metal transfer** (**CMT**) is a [welding](/source/Welding) method that is usually performed by a [welding robot.](/source/Robot_welding) The CMT machine detects a short circuit which sends a signal that retracts the welding filler material, giving the [weld](/source/Welding_joint) time to cool before each drop is placed. This leaves a smooth weld that is stronger than that of a hotter weld. This works well on thin metal that is prone to warping and the weld burning through the material. This type of welding is more efficient than other [GMAW](/source/Gas_metal_arc_welding) methods when the metal is thinner than 10mm, anything thicker and the expense begins to overcome traditional welding.[1] [Welding wire](/source/MIG_wire) is fed through the system that is controlled by a computer, the computer adjusts things such as wire feed, welding speed, and [amps](/source/Ampere) going through the wire. This allows precise welding of materials like [steel](/source/Steel) and [aluminum](/source/Aluminium), with very little [slag](/source/Slag_(welding)) and spatter, resulting in a cleaner finish weld.[2]

## Definition

CMT is a subset of [gas metal arc welding](/source/Gas_metal_arc_welding). It works by reducing the weld current and retracting the weld wire when detecting a short circuit, resulting in a drop-by-drop deposit of weld material.[3][4][5][6] Developed for thin materials, CMT requires strict control of weld parameters.[7]

## History

CMT was originally intended for joining [sheet metal](/source/Sheet_metal) in the [automotive industry](/source/Automotive_industry), but has expanded to thicker materials.[3]

## Application

Cold metal transfer is used to [weld](/source/Welding) different types of metal with various thicknesses. This low voltage, low heat welding works well on thin sheet metal. It is also being used for thicker material where the [integrity](/source/Integrity) of the weld is important. When metal is overheated it affects its [structural properties](/source/Structure); CMT welding keeps the heat to a minimum, resulting in little change to the structure of the metal, and a stronger weld.[2] Thin metal has a greater possibility of distorting when heated. During traditional [GMAW welding](/source/GMAW), [heat sinks](/source/Heat_sink) or other heat protection had to be used to prevent the warping of the metal. Heat protection is not needed during the CMT process. CMT has a wide variety of applications in various industries such as [small engine](/source/Small_engine), [automotive](/source/Automotive_industry), and [marine](/source/Marine_industry).[8]

## Specifications

Applications Energy Travel speed Gas Sheet metal Pipeline 0.47 to 0.75 kJ/mm 350 – 406 mm/min Argon/CO2 [3]

## References

1. Imoudu, Nelson Edoh (June 2017). [*The Characteristic of Cold Metal Transfer (CMT) and its application For Cladding*](https://munin.uit.no/bitstream/handle/10037/12968/thesis.pdf?sequence=2&isAllowed=y) (Master's). [University of Tromsø](/source/University_of_Troms%C3%B8) – The Arctic University of Norway.

1. Selvi, S.; Vishvaksenan, A.; Rajasekar, E. (2018). "Cold metal transfer (CMT) technology - An overview". *Defence Technology*. **14**: 28–44. [doi:10.1016/j.dt.2017.08.002](https://doi.org/10.1016/j.dt.2017.08.002)

1. Fokens, Ryan (22 April 2009). ["Cold Metal Transfer - CMT - A Revolution in Mechanized Root Pass Pipeline Welding"](https://www.pipeline-conference.com/abstracts/cold-metal-transfer-cmt-revolution-mechanized-root-pass-pipeline-welding). *Pipeline Technology Conference 2009*. Retrieved 7 March 2017.

1. Pickin, C. G. & Young, K. (2006). ["Evaluation of cold metal transfer (CMT) process for welding aluminium alloy"](http://wrap.warwick.ac.uk/32487/). *Science and Technology of Welding and Joining*. **11** (5): 583–585. [doi:10.1179/174329306X120886](https://doi.org/10.1179/174329306X120886). [S2CID 137026372](https://api.semanticscholar.org/CorpusID:137026372)

1. ["CMT: Cold Metal Transfer"](https://web.archive.org/web/20170713081704/http://www.axson.se/pdf/fro_bro_CMT_eng.pdf). Fronius. Archived from [the original](http://www.axson.se/pdf/fro_bro_CMT_eng.pdf) on 2017-07-13. Retrieved 2017-03-15.

1. Pickin, C. G.; Williams, S. W.; Lunt, M. (2011). ["Characterisation of the cold metal transfer (CMT) process and its application for low dilution cladding"](https://dspace.lib.cranfield.ac.uk/bitstream/1826/7013/1/Characterisation_of_the_cold_metal_transfer-2011.pdf). *Journal of Materials Processing Technology*. **211** (3): 496–502.

1. Talalaeva, Robert; Veinthala, Renno; Laansooa, Andres; Sarkans, Martinš (2012). ["Cold metal transfer (CMT) welding of thin sheet metal products"](https://www.kirj.ee/public/Engineering/2012/issue_3/Eng-2012-3-243-250.pdf). *Estonian Journal of Engineering*. **18** (3): 243–250. [doi:10.3176/eng.2012.3.09](https://doi.org/10.3176/eng.2012.3.09)

1. Eder, Thomas (2010-09-28). ["The CMT Process - News and Its Advantages in Industry"](https://www.sae.org/publications/technical-papers/content/2010-32-0071/). *SAE Technical Paper Series*. Vol. 1. [doi:10.4271/2010-32-0071](https://doi.org/10.4271/2010-32-0071)

## External links

- [Cold metal transfer](https://www.fronius.com/en/welding-technology/our-expertise/welding-processes/cmt) [Archived](https://web.archive.org/web/20180114070306/http://www.fronius.com/en/welding-technology/our-expertise/welding-processes/cmt) 2018-01-14 at the Wayback Machine, [Fronius](/source/Fronius_International_GmbH) welding processes

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Adapted from the Wikipedia article [Cold metal transfer](https://en.wikipedia.org/wiki/Cold_metal_transfer) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Cold_metal_transfer?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.