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Production Engineering

, Volume 13, Issue 1, pp 89–97 | Cite as

Reusable unit process life cycle inventory for manufacturing: gas metal arc welding

  • Hao Zhang
  • Fu ZhaoEmail author
Production Process
  • 22 Downloads

Abstract

The paper develops a unit process life cycle inventory (UPLCI) for gas metal arc welding (GMAW) process. UPLCI is a modeling approach that allows users to estimate the energy and materials flow of a unit process. A UPLCI model can be reused in different manufacturing settings where a wide range of machines and materials are used. GMAW is in the joining category of the taxonomy of manufacturing processes, and this work is part of the effort to build UPLCI models for all common manufacturing processes. Following UPLCI approach, the energy consumption is not limited to the energy needed to initiate and maintain the arc (i.e. active energy). Energy spent during idle and standby are also accounted. An example calculation is provided to demonstrate how the GMAW model can be used. It should be noted that the GMAW model can be linked to UPLCI models of other unit processes. This makes it possible to estimate the materials loss and energy use (thus environmental impacts) of a product made by a sequence of manufacturing processes.

Keywords

Gas metal arc welding Process energy Unit process Unit process life cycle inventory UPLCI 

Abbreviations

LCI

Life cycle inventory

UPLCI

Unit process life cycle inventory

GMAW

Gas metal arc welding

CO2

Carbon dioxide

Ar

Argon

List of symbols

A

Weld cross sectional area

a

Leg length of weld cross section

cp,electrode

Specific heat of electrode

cp,sub

Specific heat of melted substrate

d

Gap width of square-groove butt weld

delectrode

Diameter of electrode

E

Electricity consumption by arc

Ea

Actual electricity consumption

Ebasic

Basic energy

Eidle

Idle energy

Etip

Tip energy

Etotal

Total energy

F

Wire feed speed

f1

Arc efficiency

f2

Melting efficiency

f3

Fraction of total heat in the super-heated molten drop of electrode material out of total energy supplied to the welding pool

∆Hf,electrode

Latent heat of fusion for electrode

∆Hf,sub

Latent heat of fusion for melted substrate

I

Arc current

L

Length of weld

melectrode

Mass of electrode consumption

melectrode loss

Mass of electrode loss

mfume

Mass of fume

mgas,i

Mass of shield gas i

msub

Melted substrate

mweld

Mass of weld

Pidle

Idle power

Pbasic

Basic power

Ptip

Tip power

Qbm

Heat generated is lost to the surrounding base metal due to conduction

Qenv

Heat generated is lost to the environment due to convection and radiation

Qg

Flow rate

Qheat loss

Heat loss

Qpool

Heat needed to create the welding pool

T

Thickness of the metal

tidle

Idle time

tbasic

Basic time

ttip

Tip time

U

Arc voltage

Vtravel

Travel speed

Vi

Volume of shield gas i

V

Total volume of shield gas

ρelectrode

Electrode density

ρAr

Argon density

\({\rho _{{\text{C}}{{\text{O}}_2}}}\)

CO2 density

ρi

Density of shield gas i

\({{{\eta}} _{{\text{electrode}}}}\)

Electrode efficiency

\({\eta _{{\text{inverter}}}}\)

Convert electricity consumed by arc to actual energy from power grid

θi

Composition of shield gas

Notes

Acknowledgements

The authors would like to acknowledge Michael Overcash, Janet Twomey, and Jackie Isaacs for their work on developing the unit process life cycle inventory methodology. We also acknowledge Vance Murray for his contribution to data collection. Thanks also go to John W. Sutherland and Michael Overcash for their feedbacks.

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Copyright information

© German Academic Society for Production Engineering (WGP) 2018

Authors and Affiliations

  1. 1.Department of Aerospace and Mechanical EngineeringUniversity of OklahomaNormanUSA
  2. 2.School of Mechanical EngineeringPurdue UniversityWest LafayetteUSA
  3. 3.Environmental and Ecological EngineeringPurdue UniversityWest LafayetteUSA

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